JP5151166B2 - Semiconductor light emitting device - Google Patents

Description

  The present invention relates to a semiconductor light emitting device, and more particularly to a semiconductor light emitting device having a light transmitting member on the surface.

  A semiconductor light emitting device usually has a flat semiconductor layer formed thereon, and an electrode layer and an insulating layer formed on the semiconductor layer are also flat. Therefore, part of the light from the light emitting layer is part of the interface between the layers and the device surface. It was totally reflected and could not be taken out. Therefore, conventionally, there has been proposed a light emitting element that changes the angle of light by forming irregularities on the light extraction surface side to reduce total reflection (for example, Patent Documents 1 to 3). An example is shown in FIG. The light-emitting element shown in FIG. 8 has an n-type GaN layer 82, an InGaN light-emitting layer 83, and a p-type GaN layer 84 having a concavo-convex surface in this order on a substrate 81. An n-side electrode 85 is formed, a p-side translucent electrode 88 and a bonding electrode 86 are formed on the p-type GaN layer 84, and a current blocking layer 87 is formed on the p-type GaN layer 84 below the bonding electrode 86. Is formed. The surface of the p-side translucent electrode 88 is similarly uneven since the surface of the underlying p-type GaN layer 84 is uneven. As described above, since the surface of the p-type GaN layer 84 and the p-side translucent electrode 86 provided on the light extraction side is uneven, total reflection on the uneven surface can be reduced, and light is emitted to the outside. The extraction efficiency can be improved.

  Patent Documents 4 and 5 describe providing a gallium oxide film on a semiconductor layer made of a III-V group compound semiconductor.

JP 2000-196152 A JP-A-2005-79266 WO2003 / 066544 JP-A-52-47377 JP-A-55-138286

However, in the above conventional semiconductor light emitting device, the convex portion of the p-side translucent electrode surface is provided on the convex portion of the interface between the p-type GaN layer and the p-side translucent electrode, and the light extraction efficiency is improved. In addition, a material different from the GaN layer such as ITO is used as a p-side translucent electrode on the GaN layer, and there is a problem in that the diffusion to the GaN layer has an effect.
On the other hand, Patent Documents 4 and 5 disclose that a gallium film is oxidized on a III-V group compound semiconductor layer by heating to form a gallium oxide film. However, the heat treatment affects the element. There is a problem of affecting. Further, since the gallium oxide film described in Patent Document 4 is a uniform film and is provided on a flat semiconductor surface, the light extraction efficiency cannot be improved.
Further, in the concavo-convex structure on the surface of the semiconductor layer as shown in Patent Document 1, or the concavo-convex structure on the surface of the translucent electrode or translucent protective film provided on the surface, light scattering, refraction, etc. from the semiconductor layer In the light extraction mechanism to the outside of the element, the other surface facing the uneven structure surface is a flat boundary surface, or the uneven surface where the concave and convex portions coincide with each other, the mechanism does not function sufficiently Was newly found.

  Therefore, the present invention has an object to provide a semiconductor light-emitting device having a light-transmitting member having a group III element and having excellent light-emitting characteristics such as high output or high orientation, or a semiconductor light-emitting device having excellent device reliability. And

Means for Solving the Problems and Effects of the Invention

In order to achieve the above object, a semiconductor light emitting device of the present invention includes a semiconductor layer structure including a light emitting region and having a group III element-containing region on the light extraction side, and a light extraction side of the group III element containing region. A film-shaped light transmitting member having a refractive index lower than that of the group III element-containing region, and the light transmitting member includes a group III element common to the group III element-containing region, and has a convex portion on the light extraction side surface. The group III element-containing region has a concave portion at the interface with the light transmission member, and the convex portion and the concave portion are arranged so as to overlap in the plane of the semiconductor layer structure. As a result, the two opposing surfaces of the light transmitting member are provided with respective convex portions facing each other, while the semiconductor layer (group III element-containing region) is provided with a concave portion facing the convex portion. As a result, the light propagating in the semiconductor layer structure reaches the concave portion protruding in the inner direction of the semiconductor layer structure, and is captured in the relatively wide medium of the convex portion of the light transmitting member, and the convex on the light extraction side surface. It is possible to obtain a high-power semiconductor light-emitting element that is preferably taken out to the outside. In addition, since the light transmitting member has a group III element in common with the group III element-containing region, a good medium boundary between the semiconductor and the light transmitting member in the light propagation can be formed, and a protective film excellent in element operation and durability Can function as.

In the semiconductor light emitting device according to another aspect of the present invention, in combination with the above aspect,
(1) The light transmission member is an insulating film of an oxide of a group III element.
(2) The semiconductor layer structure has a covered region in which the light extraction side surface is coated with a light transmitting member and an electrode forming region in which an electrode is provided.
(3) The concave portion of the semiconductor structure has a shape that is recessed from the surface of the electrode forming region to the light emitting region side.
(4) The semiconductor layer structure has a first conductivity type semiconductor layer between the light emitting region, the covering region, and the electrode forming region, and the film thickness of the first conductivity type semiconductor layer is larger than the covering region.
(5) The semiconductor structure is arranged on the light extraction side, the first conductivity type semiconductor layer on the side of the covering region and the electrode formation region across the light emitting region, the second conductivity type semiconductor layer facing the first conductivity type semiconductor layer, and And an exposed portion of the second conductive type semiconductor layer spaced from the light emitting region in the semiconductor layer structure surface on the light extraction side, and having an electrode provided on each of the first and second conductive type semiconductors. In the part, the electrode forming region of the second conductivity type semiconductor layer, and a covering region covered with the light transmitting member,
(6) The exposed portion is disposed at the outer edge of the light emitting region, and the covered region of the exposed portion is disposed so as to surround the light emitting region.
(7) The light-transmitting member has a film shape and has a concavo-convex structure on the light extraction side surface, and has a plurality of thick film portions of the convex portions and a plurality of thin film portions of the concave portions in the concavo-convex structure adjacent to the thick film portions.
(8) The group III element common to the light transmitting member and the group III element-containing region is selected from the group consisting of gallium, aluminum, or indium.
(9) An insulating protective film having a material different from that of the light transmitting member is provided on the light transmitting member.
(10) The light transmitting member has a concavo-convex structure having a plurality of convex portions on the light extraction side surface, the protective film is disposed opposite to the convex portions and the concave portions of the concavo-convex structure, and is provided on the light extraction side surface. Comprising an uneven surface having
It can be set as each aspect.

  In the above (1), the oxide insulating film can function as a protective film for the light extraction window portion of a suitable element. In the above (2), the electrode portion and the covering portion (window portion) are arranged in the semiconductor structure plane. In the element structure separated in step (3), light propagating in an oblique direction from the light emitting region directly below the electrode to the covering region can be effectively extracted by the window structure. In (3) above, the electrode portion is a non-window portion. However, the concave portion on the surface of the semiconductor layer that protrudes inwardly can effectively capture light propagating in the direction of the electrode, and can have a concave shape that is particularly suitable for the structure. In the medium from the light emitting area to the light extraction side surface, the electrode part realizes suitable current injection and diffusion by the relatively thick first conductivity type layer, and the window covering part becomes a relatively thin film in the light emitting area. It is possible to achieve suitable light extraction close to .

  In the above (5), in the structure in which the electrodes of the first and second conductivity type layers are provided on the same surface side of the light extraction side, the light emitting region is removed, for example, in the exposed portion separated from the region. By adopting a structure including the electrode and the light transmitting member, light propagating in the in-plane direction from the light emitting region can be preferably extracted. In (6), the covered region is defined as the outer edge of the element. The light that reaches the light emitting region can be suitably extracted by providing the light emitting region.

  In (7) above, the uneven structure on the surface of the light-transmitting film is a thick film part and a thin film part, so that light is preferably captured by the thick film part and the semiconductor concave part, and the thin film part is suitably used by the semiconductor convex part. In (8), a light-transmitting film suitable for light emission characteristics and device reliability and an insulating film can be formed. In (9), the convex / concave structure of the light transmitting member is opposed to it. A suitable protective function or a refractive index distribution function to the outside of the element suitable for light extraction can be added without impairing each of the above functions due to the semiconductor recess / concave structure.

<Embodiment 1>
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B are a cross-sectional view and a top view showing a semiconductor light emitting device according to the present embodiment. 1A and 1B, a semiconductor layer structure having an n-type semiconductor layer 6, an active layer as a light-emitting region 7, and a p-type semiconductor layer as a group III element-containing region 8 on a growth substrate 1. 2 is provided, and a p-side ohmic electrode 31 and a p-side pad electrode 32 are provided as p-electrodes on the surface of the group III element-containing region 8, and are exposed from the group III element-containing region 8. An n-electrode 4 is provided on the surface of the layer 6. Further, a light transmitting member 5 having a refractive index lower than that of the group III element-containing region 8 is provided on the surface of the group III element-containing region 8, a convex portion is provided on the surface of the light transmitting member 5, and A recess is provided at the interface between the light transmitting member 5 and the group III element-containing region 8. As shown in FIG. 1A, the convex portion and the concave portion are arranged so as to overlap in the light extraction side surface of the semiconductor layer structure 2. The light transmissive member 5 is provided on the surface of the group III element-containing region 8 exposed from the p-side ohmic electrode 31 as indicated by hatching in FIG. 1B.
Hereinafter, each member will be described in detail. The same members can be used in the second to fourth embodiments.

(Light transmission member 5)
FIG. 1C shows an enlarged view of the vicinity of the light transmitting member 5. A convex portion 5a is provided on the surface of the light transmissive member 5, and a concave portion 5b is provided at the interface between the light transmissive member 5 and the group III element-containing region 8. The light from the light emitting region is suitably diffusely reflected and refracted to generate light. The light can enter the transmissive member. The incident light is preferably captured in a region between the convex portion on the light extraction side surface of the light transmitting member facing the concave portion, and the surface, for example, the light transmitting member 5 and a protective film described later on Light is preferably extracted out of the member, particularly from the projections, by irregular reflection and refraction suitable at the interface with air and sealing resin.

As shown in FIG. 1C, the height of the convex portion 5a of the light transmitting member 5 surface and h _1, when the depth of the interface of the recess 5b of the group III element-containing region 8 and the light transmitting member 5 and h _2, With the structure in which the height h ₁ of the convex portion 5 a and the depth h _{2 of the} concave portion 5 b are substantially equal, the light incident on the light transmitting member 5 can be extracted efficiently.

  Further, the depth of the recess 5 b provided at the interface between the light transmitting member 5 and the group III element-containing region 8 is determined in consideration of the influence on the device operation, and is preferably shallower than the light emitting region 7. Specifically, in the case of the structure having the first conductive type semiconductor layer between the light emitting region and the surface, the concave portion is formed in the first conductive type semiconductor layer, and between the light emitting region and the surface. In the case where the group III element-containing region 8, which is a region of the above, has a plurality of layers, it is preferable that the concave portion 5 b be the same as or shallower than the outermost layer. As shown in FIG. 1 (FIG. 1C), the recess 5b of the semiconductor layer structure has a shape that is recessed in the semiconductor layer structure, specifically, the first conductive provided on the light extraction side of the light emitting region. An electrode is provided in the mold semiconductor layer, and the electrode is formed in a shape as if entering the inside of the electrode formation surface. In this way, when the interface protruding from the electrode forming surface toward the light emitting region is formed, the electrode forming region is a light shielding region with respect to light extraction, and the covering region of the light transmitting member is a light extraction window portion. In addition, the light traveling to the electrode formation region is preferably captured and taken out to the outside at the interface protruding inward. On the other hand, the convex portion 5a of the semiconductor layer structure is formed in a shape that is located above the electrode formation surface, and thus an interface protruding from the electrode formation surface to the light extraction side is formed suitably. External retrieval is performed.

In addition, the distance between the light emitting region, the covering region, and the electrode forming region, for example, in the structure having the electrode forming region in the first conductivity type semiconductor layer, the remaining film thickness due to the recess is preferably the electrode formation as described above. The area is enlarged, and the remaining film thickness and the area between the recess / covering area and the light emitting area can be used for functions such as current diffusion.
The concave portion and the covering region may reach and penetrate the light emitting region. For example, the first conductive semiconductor on the light extraction side has a structure including first and second conductive type semiconductor layers sandwiching the light emitting region. If the layer is removed, device leakage may be a problem. On the other hand, in the structure of FIG. 1 and the example of the nitride semiconductor, the first conductivity type p-type layer is a covering region that hardly diffuses current. Alternatively, a current blocking structure in which a coating region is provided on the surface of the second conductivity type semiconductor layer (n-type layer) can also be used.

The light transmitting member can be formed on at least a part of the surface of the group III element-containing region. For example, as shown in FIG. 1B, the surface of the group III element-containing region 8 exposed from the p-side ohmic electrode 31 It is preferable to form a film so that the light transmitting member 5 is formed so as to cover the entire surface, and the covered region is preferably an electrode exposed region.
As shown in FIG. 1C, the film-shaped light transmitting member 5 includes a thick film portion of the convex portion 5a and a thin film portion that is thinner than the thick film portion and is adjacent to the thick film portion. An uneven structure is formed on the surface. The ratio d ₂ / d ₁ between the film thickness d ₂ of the thin film portion and the film thickness d ₁ of the thick film portion can be, for example, 1/7 or more and 5/6 or less. Note that the film thickness ratio d ₂ / d ₁ between the thin film portion and the thick film portion may be constant or not constant within the surface, for example, may vary within the above range. As shown in FIG. 1C, the light-transmitting member film may have a form in which convex parts 5a and concave parts are provided adjacent to each other, for example, an alternating form. The part 70 or the form in which the concave part is distributed may be used, and it is preferable that the convex part and the concave part of the semiconductor layer structure opposite to the convex part are separated from each other in the light extraction surface. As seen in FIG. 1, it is preferable that the concave portion on the surface of the light transmitting member 5 is arranged on the convex portion of the group III element-containing region 8 so as to overlap in the plane of the semiconductor layer structure 2, specifically, The film-like light transmitting member surface and the semiconductor layer structure surface each have a concavo-convex structure, and a convex portion facing each concave portion is arranged. In this case, the convex portions at the interface between the light transmitting member 5 and the group III element-containing region 8 and the convex portions on the surface of the light transmitting member 5 are alternately arranged in the surface of the semiconductor layer structure 2. By having the convex part of the semiconductor layer structure in the thin film part, the light transmitting member can be suitably transmitted.

As shown in the example of FIG. 1, in the structure in which the electrode formation region and the covering region are provided on the surface of the first conductive semiconductor layer on the light extraction side of the light emitting region, light shielding is performed when the electrode is not a translucent conductive film. It becomes a structure which each functions as a part and a window part. In the case of a translucent electrode, as shown in FIG. 1, the electrode forming region is made wider than the covering region, and when the electrode is a light shielding region as shown in FIG. Make it wider than the area. In addition to the electrode forming region and the covering region, for example, a semiconductor layer exposed region and a protective film covering region may be provided separately, and the light extraction side surface of the semiconductor structure facing the light emitting region in the electrode forming region and the covering region. Is preferably configured. The form in which the covering region is provided outside the light emitting region will be described in the second embodiment and later.
Specifically, the light transmitting member is provided on the surface of the group III element-containing region exposed from the electrode or the insulating film.
The cross-sectional shape of the convex portion on the surface of the light transmissive member and the concave portion at the interface between the light transmissive member and the group III element-containing region is preferably a curved shape such as a sine wave. The light extraction efficiency is higher than that of such a cornered shape.

  As the material of the light transmitting member 5, a material that can transmit light from the light emitting region 7 is selected, and at least the same group III element as that contained in the group III element containing region 8, specifically a group III element containing region The constituent elements of the semiconductor layer are used. Specifically, it is an oxide of a group III element, and preferably a protective film and an insulating oxide film for preventing element leakage. As the group III element, gallium, aluminum, and indium are more preferable because they can easily form a light-transmitting film or an insulating film. Further, when the group III element-containing region 8 contains a plurality of group III elements, specifically, a mixed crystal of a plurality of group III elements, the light transmitting member 5 having a plurality of group III elements is similarly used. For example, when AlGaN is used as the group III element-containing region, a light transmissive member containing Al and Ga is preferable. Furthermore, as will be described later, when a method for oxidizing a group III element-containing region is selected as a method for forming a light transmitting member, a light transmitting member containing a group III element common to the group III element-containing region is easily formed. In particular, a plurality of common Group III elements are preferred.

As shown in FIG. 2, a protective film 20 having a material different from that of the light transmissive member may be provided on the light transmissive member 5. The protective film 20 can be formed on the exposed surface of the semiconductor layer structure and electrodes in the same manner as a normal protective film. The specific protective film 20 has a composition different from that of the light transmitting member 5, and examples of the material thereof include SiO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , and ZrO _2. Etc. Further, a material that is transparent to light from the light emitting region 7 is preferable. For example, SiO ₂ or Ta ₂ O ₅ for ultraviolet light, and SiO ₂ or Nb ₂ O for blue light. ₅ etc. are mentioned. The protective film 20 formed on the light transmissive member 5 can have a structure having convex portions similar to those of the light transmissive member 5 on the surface thereof. Moreover, since the protective film 20 depends on the surface shape of the layer below it, the protective film 20 and the convex portions on the surface of the light transmitting member 5 are opposed to each other, that is, the convex portions on the surface of the protective film 20 and the light transmitting member. 5 It can be set as the structure arrange | positioned so that the convex part of the surface may overlap in the semiconductor layer structure 2 surface.
Further, as will be described later, when the light transmission member 5 can be formed by causing the light emitting region 7 to emit light, by forming the protective film 20 on the light transmission member 5, the light transmission member 5 can be isolated from the outside air. 20 growth can be stopped.
(Growth substrate 1)

The growth substrate 1 may be any substrate that can grow the semiconductor layer structure 2, for example, sapphire, spinel (insulation such as MgAl ₂ O ₄₎ whose main surface is any one of the C-plane, R-plane, and A-plane. Substrate), SiC, Si, and an oxide substrate lattice-matched with a nitride semiconductor.

(Semiconductor layer structure 2)
The semiconductor layer structure 2 has at least a light emitting region 7 and a group III element-containing region 8 provided on the surface side. Specifically, the light emitting region and the first conductivity type semiconductor layer on the light extraction side thereof, Has a second conductivity type semiconductor layer opposite thereto. As a layer constituting the semiconductor layer structure 2, various semiconductors having a group III element such as GaN and GaAs can be used, and various structures can be taken depending on the type of element. Although the composition of the semiconductor layer is not particularly limited in the present invention, for example, a gallium nitride compound semiconductor such as In _x Al _y Ga _1-xy N (0 ≦ x, 0 ≦ y, x + y ≦ 1) Are preferably used. The layer structure includes a homo structure, a hetero structure or a double hetero structure having a MIS junction, a PIN junction or a PN junction. The semiconductor layer can be formed by a known technique such as MOVPE (metal organic chemical vapor deposition), HVPE, MBE, or the like. Further, the thickness of the semiconductor layer is not particularly limited, and various thicknesses can be applied. Further, each semiconductor and each conductivity type layer may have a single layer structure, a laminated structure of layers having different compositions and film thicknesses, a superlattice structure, or the like.

(Light emitting area 7)
The light emitting region 7 may be any region that can emit light. In the present embodiment, a light emitting layer is used as the light emitting region 7. In particular, a structure having a light emitting layer having a single quantum well structure or a multiple quantum well structure formed in a thin film in which a quantum effect is generated is preferable because an element with high light emission efficiency can be obtained.

(Group III element-containing region 8)
The group III element-containing region 8 is a semiconductor containing at least a group III element and is provided on the light extraction surface of the semiconductor layer structure 2. The group III element contained is preferably one used as a semiconductor material such as gallium, aluminum, or indium, and the same group III element is also included in the light transmitting member 5. In the present embodiment, a p-type semiconductor layer is used as the group III element-containing region 8, but various semiconductor layers can be used regardless of the conductivity type as long as it is the outermost layer of the semiconductor layer structure. When the group III element-containing region is provided on the light extraction surface side of the light emitting region, the light output can be improved efficiently, which is preferable. The semiconductor layer constituting the group III element-containing region 8 is preferably a group III-V compound semiconductor layer, such as a GaN layer or an AlGaN layer, which is a semiconductor light emitting device that emits light in the ultraviolet region. In this case, an AlGaN layer that absorbs less ultraviolet light than the GaN layer is preferable.

(Manufacturing method of the light transmissive member 5)
The light transmitting member 5 and the concave portion of the semiconductor layer structure, and the concave / convex structure thereof, are processed by lift-off, etching, or the like, for example, a concave portion or a concave / convex structure is formed in the semiconductor, and light is applied to the surface. The transmissive member and the film can be formed by forming a convex portion facing the semiconductor concave portion. Further, when the light transmissive member 5 is formed by the method described below, the convex portion of the light transmissive member facing the semiconductor concave portion can be suitably formed as compared with the case of processing by etching or the like.

First, a semiconductor layer structure 2 including an n-type semiconductor layer 6, a light-emitting layer as a light-emitting region 7, and a p-type semiconductor layer as a group III element-containing region 8 is formed on the growth substrate 1. Then, the p-side ohmic electrode 31 and the p-side pad electrode 32 are formed, and the n-electrode 4 is formed on the n-type semiconductor layer 6 exposed by removing a part of the group III element-containing region 8 and the light emitting region 7.
Next, with the surface of the group III element-containing region 8 exposed, a current is passed through the semiconductor light-emitting element in an oxygen-containing atmosphere to cause the light-emitting layer that is the light-emitting region 7 to emit light. When the light emitting layer is allowed to emit light and observed after a certain period of time, the surface of the group III element-containing region 8 exposed from the p-side ohmic electrode 31 has a group III element common to the group III element-containing region 8. As shown to 1A-C, the light transmissive member 5 which has a convex part and a recessed part is formed.

  According to such a method, the light transmitting member 5 is formed by oxidizing the surface side of the semiconductor layer structure 2, that is, the surface of the group III element-containing region 8, and a part of the group III element-containing region 8 is formed. Obtained in an erosive shape. Thereby, the light transmissive member which has the same group III element as a group III element containing area | region can be obtained. The progress of oxidation of the group III element-containing region 8 is usually non-uniform in the plane of the semiconductor layer structure 2, and the oxidized group III element-containing region 8 has a larger volume than before the oxidation, so that light transmission is possible. The convex portion on the surface of the member 5 and the concave portion at the interface between the light transmitting member 5 and the group III element-containing region 8 are aligned and overlapped in the plane of the semiconductor layer structure 2, and the convex portion of the light transmitting member A structure opposite to the semiconductor recess can be formed. Since the light transmission member 5 is generated from the group III element-containing region 8 in an in-plane non-uniform state, the light transmitting member 5 starts to be formed in an island shape on a part of the surface of the group III element-containing region 8 and further grows. The film grows so as to cover the entire exposed surface of the group III element-containing region 8.

  The generation of the light transmissive member 5 is mainly formed depending on the light emission time. For example, when a current of 700 mA is passed at room temperature, the formation of the light transmissive member 5 can be confirmed from about 100 to 200 hours, The higher the temperature during formation, the shorter the formation time. The environmental temperature at the time of formation is preferably at least lower than the temperature at the time of forming the semiconductor layer structure 2, more preferably 100 ° C. or less, and further about room temperature, which is preferable in terms of mass productivity.

  As will be described later, when the temperature in the vicinity of the group III element-containing region 8 is approximately the same, the light-transmitting member 5 can be formed by emitting light, and the light-transmitting member 5 cannot be formed if stored without emitting light. It is considered that the oxidation of the group III element-containing region 8 is promoted by the light from the region 7. Such a light emitting region 7 preferably emits light in the ultraviolet region. In this case, if the group III element-containing region 8 is an AlGaN layer, absorption of light in the ultraviolet region can be relatively reduced. Further, it is considered that the light transmitting member 5 can be formed by irradiating the same light from the outside of the semiconductor light emitting element using a light emitting device such as a laser. However, it is preferable to emit light from the light emitting region 7 because light with a high light density can be easily irradiated and an increase in temperature of the element can be suppressed.

<Embodiment 2>
3A and 3B are a cross-sectional view and a plan view showing the semiconductor light emitting device according to the second embodiment. In this example, an n-type semiconductor layer as a group III element-containing region 38 is formed on the growth substrate 1, and A semiconductor layer structure 33 having an active layer and a p-type semiconductor layer 30 is provided as the light emitting region 37, and a p-side ohmic electrode 31 and a p-side pad electrode 32 are provided on the p-type semiconductor layer 30 as p-electrodes. The n-electrode 4 is provided on the surface of the group III element-containing region 38. A light transmissive member 35 is provided on the surface of the group III element-containing region 38 exposed from the n electrode 4, and the light transmissive member 35 is exposed to the group III element exposed from the n electrode 4, as indicated by hatching in FIG. 3B. It is provided on the surface of the containing region 38.

As shown in FIGS. 3A and 3B, the electrode formation region spaced from the light emitting region on the light extraction surface side of the semiconductor structure, the electrode formation surface side of the structure in which the electrodes of the first and second conductivity type layers are provided on the same surface An exposed portion is provided, and a covered region of the light transmitting member is formed in the exposed portion. In this form, the light extraction effect is lower than the form in which the covering region is provided on the light extraction side surface of the light emitting region as in the first embodiment, but on the other hand, compared to the electrode formation region of the light emitting region, Since the influence on the light emitting structure is small, the electrode formation region can be reduced and the covering region can be increased. Specifically, since the light transmission member 35 is formed on the surface of the n-type semiconductor layer, the p-side ohmic electrode 31 can be formed on almost the entire surface of the p-type semiconductor layer.
At this time, preferably, if a covering region is provided between the electrode formation region of the exposed portion and the light emitting region within the light extraction side surface of the semiconductor structure, the light traveling to the above-described electrode and further the light in the vicinity of the light emitting region are suitable. Can be taken out. In addition, the form in which the electrode region is provided between the covering region and the light emitting region, and further, the covering region of the light transmitting member is provided in the outer peripheral portion of the light emitting region and the exposed portion of the outer edge portion of the element, thereby increasing the covering area. In addition, light that travels outside the element active region and reflects off the end face of the element can be preferably extracted. Similarly, in the form provided at the outer edge in the light emitting region as in the first embodiment, similarly, light at the end of the light emitting region, specifically, the end with the exposed portion is preferably extracted. Can do. Moreover, it can be made to function as an insulating protective film for preventing element leakage in each outer edge portion and outer peripheral portion by the covering region.

<Embodiment 3>
FIG. 4 is a sectional view showing a semiconductor light emitting element according to the third embodiment. In the semiconductor light emitting device shown in FIG. 4, an n-type semiconductor layer as the first group III element-containing region 401, an active layer as the light emitting region 47, and a second group III element containing region 402 are formed on the growth substrate 1. A semiconductor layer structure 42 having a p-type semiconductor layer is provided, and a p-side ohmic electrode 31 and a p-side pad electrode 32 are provided as p-electrodes on the second group III element-containing region 402, An n-electrode 4 is provided on the surface of the group III element-containing region 401. A light transmission member 45 is provided on the surfaces of the first and second group III element-containing regions 401 and 402 exposed from each electrode. As described above, the light transmitting member 45 can be provided on the surface of each semiconductor layer by using the n-type semiconductor layer and the p-type semiconductor layer as the first and second group III element-containing regions 401 and 402.

<Embodiment 4>
5A and 5B are a cross-sectional view and a top view showing the semiconductor light emitting element according to the fourth embodiment. In the semiconductor light emitting device shown in FIGS. 5A and 5B, the semiconductor layer structure 52 is bonded on the conductive support substrate 11 via the conductive layer 13, the p-electrode 53, and the insulating film 12. The semiconductor layer structure 52 includes, in order from the support substrate 11 side, a p-type semiconductor layer 56, a light-emitting layer as the light-emitting region 57, and an n-type semiconductor layer as the group III element-containing region 58. The p-electrode 53 is ohmically connected to the p-type semiconductor layer 56 and can be electrically connected to the outside through the conductive layer 13 and the support substrate 11. An insulating film 12 is formed around the p-electrode 53. On the other hand, an n-electrode 54 is formed on the surface of the group III element-containing region 58, and a light transmission member 55 is further formed. In FIG. 5B, the light transmission member 55 is provided on almost the entire surface of the group III element-containing region 58 exposed from the n-electrode 54.

  As shown in FIGS. 5A and 5B, when the n-electrode 54 and the p-electrode 53 are a semiconductor light emitting device having a semiconductor layer structure 52 sandwiched from above and below, a light transmitting member is formed on the surface on the light extraction side. , Can effectively improve the light output. Further, in a nitride semiconductor, the current is more easily spread in the n-type layer than in the p-type layer, so that the n-type semiconductor layer is provided on the light extraction side as in the present embodiment. The area of the electrode can be reduced. Thus, by reducing the electrode area on the surface of the group III element-containing region, the light transmitting member can be formed in a wider range, and the light output can be improved efficiently.

  As described above, unlike the first to third embodiments, the light extraction side surface does not have the electrode formation exposed portion of the second conductivity type semiconductor layer, so that the entire surface of the semiconductor layer structure is a light emitting region. It has become. On the other hand, in this example, the electrode of the first conductivity type semiconductor layer on the light extraction side surface is a light-shielding electrode and a semiconductor layer having high current diffusivity, so that the window region of the electrode exposure is more than the electrode formation region. The window area can be suitably used as a covering area.

The semiconductor light emitting device of this embodiment can be obtained, for example, as follows.
First, an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer are sequentially stacked on the surface of the growth substrate to form a semiconductor layer structure 52, and a p-electrode 53 is formed on the p-type semiconductor layer. An insulating film 12 such as SiO ₂ is formed around the p electrode 53, and a first conductive layer is formed so as to cover the p electrode 53 and the insulating film 12.
Next, a conductive support substrate 11 made of CuW or the like having a second conductive layer formed on the surface is prepared, and is supported on the semiconductor layer structure 52 so that the first conductive layer and the second conductive layer face each other. The substrate 11 is heated and pressed, for example, 150 ° C. to 350 ° C., and the bonded portion is used as the conductive layer 13.
Next, the growth substrate is peeled off, the n-side surface of the semiconductor layer structure 52 is polished to expose the n-type semiconductor layer functioning as the group III element-containing region 58, and then the n-electrode 54 is formed. Next, the light emitting element is separated into chips by dicing. Thereby, the semiconductor layer structure 52 is laminated on the support substrate 11, and a semiconductor light emitting device having a structure in which the n electrode 54 and the p electrode 53 sandwich the semiconductor layer structure 52 from above and below can be obtained.

Then, a light transmitting member 55 is formed on the surface of the group III element-containing region 58 exposed from the n-electrode 54, and the convex portion on the surface of the light transmitting member 55 and the interface between the light transmitting member 55 and the group III element containing region 58 are formed. A semiconductor light emitting device as shown in FIGS. 5A and 5B can be obtained by disposing the recess so as to overlap in the plane of the semiconductor layer structure 52.
In addition, according to such a method, the semiconductor layer structure 52 and the support substrate 11 are bonded by forming the first conductive layer and the second conductive layer and performing heat-pressure contact. The temperature is preferably lower than the temperature of the heating and pressure welding, for example, 350 ° C. or lower, more preferably 150 ° C. or lower. Thereby, the adhesiveness of the semiconductor layer structure 52 and the support substrate 11 can be kept high.

  Examples according to the present invention are shown below. However, the present invention is not limited to the following examples. The first embodiment will be described with reference to FIGS.

In the semiconductor light emitting device according to Example 1, a buffer layer made of GaN and a non-doped GaN layer are stacked on a sapphire substrate 1 (not shown), and an n-type semiconductor layer 6 is made of Si-doped GaN thereon. an n-type contact layer, an n-type superlattice layer in which GaN and InGaN are alternately stacked 10 times, and a light emitting layer 7 having a multiple quantum well structure in which GaN and InGaN are alternately stacked 3 to 6 times as a light emitting region 7 Group-element-containing region 8, as a p-type semiconductor layer, an Mg-doped p-type superlattice layer in which AlGaN and InGaN layers are alternately laminated 10 times, and an Mg-doped GaN p-type contact layer are laminated in this order. .
A part of the n-type contact layer is removed and exposed, and an n-electrode 4 containing W, Pt, and Au is formed there. The p-type contact layer has a p-side ohmic electrode 31 made of ITO as a p-electrode. , W, Pt, and Au are formed, and the light transmission member 5 containing gallium oxide is formed on the surface exposed from the p-side ohmic electrode. A convex portion 5a is provided on the surface of the light transmissive member 5, and a concave portion 5b is provided at the interface between the light transmissive member 5 and the p-type contact layer. The convex portion 5a and the concave portion 5b are provided in the plane of the semiconductor layer structure 2. They are arranged so as to overlap.

  The semiconductor light emitting device according to Example 1 and the semiconductor light emitting device of Comparative Example 1 similar to Example 1 except that no light transmitting member is provided on the surface of the p-type contact layer are allowed to emit light, and light output is improved. In comparison, Example 1 can achieve higher light output than Comparative Example 1. Similarly, the light output of the semiconductor light emitting device as shown in FIG. 3A and FIG. 3B is slightly lower than that in Example 1 and the p-side ITO electrode having the same area except that it is provided on the n-type contact layer surface. It can be higher than that of Comparative Example 1, and can be further increased by increasing the p-side ITO electrode area. Similarly, the light output of the semiconductor light emitting device as shown in FIG. 4 is higher than that of Comparative Example 1 except that it is provided on the surfaces of both the p-type contact layer and the n-type contact layer, and the p-side ITO electrode has the same area. In some cases, it can be higher than the example of FIG. 1 and the example of FIG.

  In Example 2, the present invention is applied to a semiconductor light emitting device having an emission wavelength of 365 nm, and a semiconductor light emitting device having a structure shown in FIGS. 5A and 5B is manufactured.

First, using a substrate made of sapphire (C-plane) as a growth substrate, a buffer layer made of GaN is grown on the substrate to a thickness of about 200 mm, and a high-temperature grown nitride semiconductor made of undoped GaN is grown to a thickness of 4 μm. As an n-type layer that partially becomes a group III element-containing region 58, an Si-doped n-type Al _0.07 Ga _0.93 N n-type contact layer is 1.8 μm, and a light-emitting region is Si-doped Al _0.1. A Ga _0.9 N barrier layer (200 Å) and a plurality of In _0.02 Ga _0.98 N well layers (150 Å) thereon are stacked to form a light emitting layer having a multiple quantum well structure (MQW), a p-type semiconductor As the layer 56, a Mg-doped Al _0.3 Ga _0.7 N p-type cladding layer of 200 μm, an Al _0.07 Ga _0.93 N layer of 0.1 μm, and an Mg-doped Al _0.07 Ga _0.93 Each p-type contact layer of N is stacked at 0.02 μm and grown. After completion of the growth, the wafer is annealed in a reaction vessel in a nitrogen atmosphere, the resistance of the p-type semiconductor layer 56 is further reduced, and a multilayer p-electrode 53 made of Rh—Ir—Pt is formed on the p-type contact layer. Thereafter, after annealing, SiO _{2 of the} insulating film 12 is formed to a thickness of 0.4 μm on the exposed surface of the p-electrode 53, and Ti—Pt—Au—Sn—Au (thickness 200 nm−) is formed thereon as a first metal layer. 300 nm-300 nm-3000 nm-100 nm), a conductive support substrate 11 made of a composite of Cu and W is used, and Ti—Pt—Pd (film) is formed on the surface of the support substrate 11 as a second metal layer. (Thickness 200 nm-300 nm-1200 nm). Next, in a state where the first metal layer and the second metal layer are opposed to each other, the heater temperature is press-pressed at 280 ° C. to be heat-pressed and diffused to form the conductive layer 13. Next, after removing the sapphire substrate by laser irradiation, the exposed buffer layer and high-temperature growth layer are polished, and further polished to the n-type contact layer to expose the AlGaN layer of the n-type contact layer. Next, a multilayer electrode made of Ti—Al—Ni—Au is formed on the n-type contact layer to form an n electrode 54. Thereafter, an electrode for bonding to the package is formed on the back surface of the support substrate 11, and the elements are separated by dicing.

  With the surface of the n-type contact layer exposed, a current of 700 mA is passed through the semiconductor light emitting element in a nitrogen atmosphere containing oxygen at room temperature to cause the light emitting layer to emit light, thereby forming the light transmitting member 55. The light emitting layer emits light having a peak wavelength of 365 nm, and when observed after 180 hours, it is confirmed that the light transmitting member 55 containing gallium oxide is formed on the surface of the n-type contact layer exposed from the n-electrode 54. it can. The light transmitting member 55 has a convex portion on the surface thereof, the n-type contact layer has a concave portion at the interface with the light transmitting member 55, the convex portion on the surface of the light transmitting member 55, the light transmitting member 55 and the n-type contact. The concave portion at the interface with the layer is arranged so as to overlap in the plane of the semiconductor layer structure 52. Further, when observing after 800 hours, the light transmissive member 55 grown so as to cover almost the entire exposed surface of the n-type contact layer can be confirmed, and the result after 2000 hours is compared with that after 800 hours. Then, in the observation of the light emitting state of the semiconductor light emitting element from the light transmitting member 55 side, the light is brighter after 2000 hours than when 800 hours have passed. This is presumably because the light transmitting member 55 has grown over time.

Further, as Comparative Example 2, a semiconductor light emitting device is fabricated in the same manner as in Example 2 except that after the device is separated and SiO ₂ is formed as a protective film on the exposed surface of the n-type contact layer, light is emitted thereafter. That is, Example 2 and Comparative Example 2 differ in that the surface of the n-type contact layer is exposed or SiO ₂ is provided at the start of light emission.
FIG. 6 shows the transition of the light output of the semiconductor light emitting devices of Example 2 and Comparative Example 2 over time. In FIG. 6, the horizontal axis represents time, the vertical axis represents light output, the black square represents Example 2, and the black triangle represents Comparative Example 2. Light output at 0 hours, 100 hours, 180 hours, and 300 hours. Respectively. The optical output shows the initial output at 0 hours, and after 100 hours, the relative values when the initial output is 100 are shown as values multiplied by the initial output. As shown in FIG. 6, the light output of the semiconductor light emitting device of Comparative Example 2 decreases as time passes. On the other hand, in the case of the semiconductor light emitting device of Example 2, the light output from Comparative Example 2 is 0 hours. However, since the light transmission member 55 grows as time passes, the light output increases, and shows a higher value than that of Comparative Example 2 after 180 hours. Furthermore, when 300 hours have elapsed, the light output of the semiconductor light emitting device of Example 2 is about 7% higher than that of Comparative Example 2.
Thus, by forming the light transmission member 55 as in the semiconductor light emitting element of Example 2, it is possible to obtain a higher output element than Comparative Example 2 in which the SiO ₂ protective film is formed.

In Example 2, the light-transmitting member 55 was formed under the conditions of 60 ° C. and 90% high-temperature and high-humidity, and the light-emitting layer was allowed to emit light. It can be confirmed that the brightness is brighter than that at the same time. This is presumably because the formation of the light transmitting member 55 was promoted by emitting light under high temperature and high humidity conditions.
When light is continuously emitted under high-temperature and high-humidity conditions and observed around 800 hours, the light-transmitting member 55 grown in a film shape so as to cover the surface of the n-type contact layer can be confirmed. When a part of the cross section of the light transmission member 55 is photographed using the STEM, an STEM image as shown in FIG. 7A is obtained. In FIG. 7A, the lower black layer is an n-type contact layer, and the upper layer is a light transmitting member. The convex portion on the surface of the light transmitting member and the concave portion at the interface between the light transmitting member and the n-type contact layer are arranged so as to overlap in the plane. The film thickness of the light transmitting member is about 30 to 190 nm, and the film thickness ratio between the adjacent thick film portion and thin film portion is about 1/7 to 5/6. When the light transmission member is analyzed by STEM-EDS, Ga, O, and Al are detected, and it can be confirmed that a light transmission member containing Ga and Al is formed as a group III element common to the n-type contact layer. FIG. 7B schematically shows the arrangement of the convex portions 70 on the surface of the light transmitting member 75 according to the present embodiment. As shown in FIG. 7B, the convex portions 70 on the surface of the light transmitting member 75 are irregularly arranged with different sizes, and the interval is about several μm. The film thickness of the light transmission member 75 in the portion where the convex portion 70 is formed is thicker than other adjacent portions.

  Further, in Example 2, when the light-emitting layer was made to emit light at the environmental temperature of −30 ° C. when the light transmissive member 55 was formed, the light output is slightly lower than that of Comparative Example 2 after about 180 hours. Around the time, the light output is higher than that of Comparative Example 2, and the formation of the light transmitting member 55 can be confirmed on the surface of the n-type contact layer.

Further, after separating the elements, the semiconductor light emitting element of Comparative Example 3 is manufactured in the same manner as in Example 2 except that the semiconductor light emitting element is stored at an environmental temperature of 125 ° C. without flowing current. When observed after 1000 hours with storage, no light transmitting member can be confirmed on the surface of the n-type contact layer of the semiconductor light emitting device of Comparative Example 3. Since the temperature of the surface of the n-type contact layer when forming the light transmitting member 55 in Example 2 is room temperature, it is considered that the temperature is about the same as or lower than the environmental temperature of 125 ° C. in Comparative Example 3. By making the light emitting layer emit light as described above, the oxidation of the surface of the group III element-containing region 58 can be promoted, and the light transmitting member 55 can be formed. Further, when a similar semiconductor light emitting device is manufactured except that an SiO ₂ protective film is formed so as to cover the light transmitting member 55 after 1000 hours have elapsed, the light transmitting member 55 covered with the protective film may emit light further. You can see that it doesn't grow.

It is a schematic sectional drawing which shows the cross section between an example of the semiconductor light-emitting device which concerns on Embodiment 1 of this invention, and the arrow of FIG. 1B. 1B is a schematic plan view of the semiconductor light emitting device shown in FIG. 1A. FIG. It is a schematic sectional drawing which expands and demonstrates the light transmission member 5 vicinity of the semiconductor light-emitting device shown to FIG. 1A. It is a schematic sectional drawing which shows an example of another semiconductor light-emitting device concerning Embodiment 1 of this invention. It is a schematic sectional drawing which shows the example of the semiconductor light-emitting device concerning Embodiment 2 of this invention, and the cross section between the arrows of FIG. 3B. FIG. 3B is a schematic plan view of the semiconductor light emitting element shown in FIG. 3A. It is a schematic sectional drawing which shows an example of the semiconductor light-emitting device concerning Embodiment 3 of this invention. It is a schematic sectional drawing which shows the cross section between the arrows of FIG. 5B as an example of the semiconductor light emitting element according to Embodiment 4 of the present invention. FIG. 5B is a schematic plan view of the semiconductor light emitting element shown in FIG. 5A. 6 is a graph showing a relationship between time and light output of semiconductor light emitting devices according to Example 2 and Comparative Example 2. 4 is a cross-sectional STEM image of a semiconductor light emitting element according to Example 2. FIG. 10 is a schematic diagram showing the arrangement of convex portions 70 on the surface of a light transmitting member 75 according to Example 2. It is a schematic sectional drawing which shows the semiconductor light-emitting device of a prior art example.

Explanation of symbols

2, 33, 42, 52 Semiconductor layer structure 31 p-side ohmic electrode, 32 p-side pad electrode 4, 54 n-electrode 5, 35, 45 Light transmissive member 5a Convex part 5b Concave part 6 n-type semiconductor layers 7, 37, 47, 57 Light emitting region 8, 38, 58 Group III element-containing region 11 Support substrate 12 Insulating film 13 Conductive layer 20 Protective film 30, 56 p-type semiconductor layer 401 First group III element-containing region 402 Second group III element-containing Region 53 p-electrode 81 substrate, 82 n-type GaN layer, 83 InGaN light-emitting layer, 84 p-type GaN layer, 86 bonding electrode, 87 current blocking layer, 88 p-side translucent electrode

Claims (8)

Sequentially through the p-electrode on a conductive support substrate, and a p-type semiconductor layer, a semiconductor layer structure having a light-emitting region is a light emitting layer, and the group III element-containing region is a n-type semiconductor layer, a
An n-electrode provided on the light extraction side surface of the group III element-containing region;
Provided substantially on the entire surface, the group III element-containing refractive index than region rather low, and 30 to the thickness of the light extraction side surface of the group III element-containing region exposed from the n-electrode into a plurality of windows-like A film-like light transmitting member having a thickness of about 190 nm ,
The light transmitting member includes a group III element common to the group III element-containing region, and has a convex portion on the light extraction side surface,
The group III element-containing region has a recess at the interface with the light transmitting member,
A semiconductor light emitting device in which the convex portion and the concave portion are arranged so as to overlap in the plane of the semiconductor layer structure.   The semiconductor light emitting element according to claim 1, wherein the light transmitting member is an insulating film of an oxide of the group III element. The recess of the semiconductor structure, the n electrode than is formed the III light extraction side surface of the element-containing region, the semiconductor light emitting device according to claim 1 or 2, wherein a shape that is indented to the light emitting region side. Before Symbol thickness of the n-type semiconductor layer, from the light transmitting member is formed region, the semiconductor light emitting element of the n-electrode is formed region is large claim 3. The light transmitting member has a concavo-convex structure on the light extraction surface, according to claim 1-4 comprising more thick film portion of the convex portion, and the thin film portion of the recess in the convex-concave structure adjacent to the thick portion, the The semiconductor light-emitting device according to any one of the above. The group III element common to the said light transmissive member and a group III element containing area | region is a semiconductor light-emitting device of any one of Claims 1-5 selected from the group which consists of gallium, aluminum, or indium. The semiconductor layer structure is made of a nitride semiconductor,
To the light transmitting member, the semiconductor light-emitting device according to any one of claims 1 to 6, the insulating protective film is provided with a material different from that of the light transmitting member. The light transmitting member includes a concavo-convex structure having a plurality of the convex portions on the light extraction side surface, and the protective film is disposed to face the convex portions and the concave portions of the concavo-convex structure, and is provided on the light extraction side surface. The semiconductor light emitting element according to claim 7 , comprising an uneven surface having a portion and a recess.

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