WO2006009372A1

WO2006009372A1 - Method of controlling the conductivity of n-type nitride semiconductor layer

Info

Publication number: WO2006009372A1
Application number: PCT/KR2005/002287
Authority: WO
Inventors: Tae Kyung Yoo; Soo Kun Jeon
Original assignee: Epivalley Co., Ltd.
Priority date: 2004-07-19
Filing date: 2005-07-16
Publication date: 2006-01-26
Also published as: KR20060007123A

Abstract

The present invention relates to a method of controlling the conductivity of an n-type semiconductor layer which is indispensable in manufacturing a nitride light-emitting device, wherein the n-type nitride layer is formed by alternately depositing an n-type doped In(x)Ga(l-x)N (0<x<1) layer and an undoped GaN layer and the conductivity of the n-type nitride layer is controlled by adjusting the ratios in concentration and thickness between the n-type doped In(x)Ga(l-x)N (0<x<l) layer and the undoped GaN layer.

Description

METHOD OF CONTROLLING THE CONDUCTIVITY OF N- TYPE NITRIDE SEMICONDUCTOR LAYER

Technical Field

[1] The present invention relates to a method of controlling the conductivity of an n- type semiconductor layer which is indispensable in manufacturing a nitride light- emitting device. Background Art

[2] US PAT No. 6,472,689, as shown in Fig. 1, discloses a GaN-based semiconductor light-emitting device comprising an n-type Al(x)Ga(l-x)N (O≤x≤l) semiconductor layer, in which the n-type Al(x)Ga(l-x)N (O≤x≤l) semiconductor layer has a con¬ ductivity increasing in linear proportion to a mixing ratio of a silicon-containing gas and other source material gases.

[3] However, in the GaN-based semiconductor light-emitting device, a large amount of n-type impurities should be added to grow a high concentration n-type nitride layer for forming a route of current applied into the device, which makes it difficult to produce a high quality nitride layer. Disclosure of Invention Technical Problem

[4] Accordingly, the present invention has been made to solve the above-mentioned problem occurring in the prior art, and it is an object of the present invention to provide a high quality n-type nitride layer capable of controlling conductivity by a specific arrangement of an undoped nitride layer and a doped semiconductor layer. Technical Solution

[5] To accomplish the above object, according to the present invention, there is provided a method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device, in which the n-type nitride layer is formed by alternately depositing an n-type doped In(x)Ga(l-x)N (0≤x<l) layer and an undoped GaN layer and the conductivity of the n-type nitride layer is controlled by adjusting the ratios in concentration and thickness between the n-type doped In(x)Ga(l-x)N (0≤x<l) layer and the undoped GaN layer.

[6] Here, the n-type doped In(x)Ga(l-x)N (0≤x<l) layer has preferably an electron concentration of lθ"/cm³ to 10²¹/cm³.

[7] Also, the n-type doped In(x)Ga(l-x)N (0≤x<l) layer has preferably a thickness of lnm to 20nm.

[8] Also, the undoped GaN layer has preferably a base concentration of 10 /cm to 10 /cm .

[9] Also, the undoped GaN layer has preferably a thickness of lnm to 20nm.

[10] Also, a pair of the In(x)Ga(l-x)N (0<x<l) layer and the undoped GaN layer has preferably a thickness of 2nm to 40nm.

[11] Also, the n-type nitride layer has preferably a total thickness of 20nm to 5um.

[12] Also, the n-type dopant is preferably at least one selected from Si, In and Sn.

[13] Also, the present invention provides a method of controlling the conductivity of an n-type nitride layer of a GaN-based semiconductor light-emitting device, in which the n-type nitride layer is formed by repeatedly depositing an undoped GaN layer delta- doped with an n-type dopant and the conductivity of the n-type nitride layer is controlled by adjusting the concentration and time of the delta doping and the thickness of the undoped GaN.

[14] Here, in the delta-doping with an n-type dopant, the electron concentration is

17 ¹^ 00 ¹^ preferably within a range from 10 /cm to 10 /cm . [15] Also, in the delta-doping with an n-type dopant, the doping time is preferably within a range from 0.1 sec to 120 sec. [16] Also, the undoped GaN layer has preferably a base concentration of from 10 /cm

, _{1 r},l7, 3 to 10 /cm .

[17] Also, the n-type nitride layer has preferably a total thickness of 20nm to 5um.

[18] Also, the n-type dopant is preferably at least one selected from Si, In and Sn.

Advantageous Effects

[19] Unlike the previously published method of forming a n-type nitride layer (to provide a desired conductivity by adjusting the mixing ratio of an n-type dopant and source materials), the present invention is directed to a method of forming an n-type nitride layer having a desired conductivity by adjusting the thickness ratio of the doped n-type nitride layer and the undoped nitride layer, or repeatedly performing delta- doping with an n-type dopant between undoped nitride layers, whereby the n-type nitride layer can supply electrons and the undoped nitride layer can recover the layer quality. By the foregoing construction, the present invention can provide a high quality and high conductivity n-type nitride layer and thereby, a high efficiency and high re¬ liability nitride optoelectronic device. Brief Description of the Drawings

[20] Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

[21] Fig. 1 is a view for explanation of US PAT NO. 6,472,689 as a prior art;

[22] Fig. 2 is a view for explanation of an embodiment according to the present invention; and

[23] Fig. 3 is a view for explanation of another embodiment according to the present invention. Mode for the Invention

[24] Now, the present invention will be described in further detail through the following examples.

[25] Embodiment 1

[26] As shown in Fig. 2, a buffer layer 20 is grown on a substrate 10 and an n-type nitride layer 40 is grown on a undoped GaN layer 30. The n-type nitride layer 40 has the following construction. An n-type doped In(x)Ga(l-x)N (0<x<l) layer 41 and an undoped GaN layer 42 are alternately grown to form a cycle. The average conductivity of the cycle is controlled by adjusting the concentration and thickness of the n-type doped In(x)Ga(l-x)N (0<x<l) layer 41 and the thickness of the undoped GaN layer 42. The number of the cycle is adjusted to determine the total thickness of the n-type semi¬ conductor layer. The n-type doped In(x)Ga(l-x)N (0<x<l) layer 41 is grown at 800 to 950°C and the undoped GaN layer 42 is grown at 950 to 1100°C.

[27] By this procedure, the n-type doped In(x)Ga(l-x)N (0<x<l) layer 41 serves to supply electrons to the undoped GaN layer 42 and the undoped GaN layer 42 serves to recover the deteriorated layer quality of the highly doped In(x)Ga(l-x)N (0<x<l) layer 41.

[28] Therefore, a thick, high concentration and high quality n-type nitride layer 40 may be obtained.

[29] Embodiment 2

[30] As shown in Fig. 3, a buffer layer 20 is grown on a substrate 10 and an n-type nitride layer 40 is grown on a undoped GaN layer 30. The n-type nitride layer 40 has the following construction. A delta-doping with an n-type dopant 43 is performed between two undoped GaN layers 42a and 42a to form a cycle. The average con¬ ductivity of the cycle is controlled by adjusting the concentration and time of the delta doping with the n-type dopant 43 and the thickness of the undoped GaN 42a. The number of the cycle is adjusted to determine the total thickness of the n-type semi¬ conductor layer 40.

[31] After the undoped GaN layer 42a is grown, gallium containing gas is cut off. Next, the n-type dopant is introduced to the reactor, and then the undoped GaN layer 42a is grown thereon. Here, the n-type dopant 43 inserted between the undoped GaN layers 42a and 42a functions to supply electrons, thereby forming an n-type conductive layer.

[32] The substrate 10 may be formed of SiC or sapphire, preferably a hetero-substrate of sapphire, though a homo-substrate may be used. [33] The growth of the buffer layer 20 and the undoped GaN 30 is well described in

USA PAT NO. 5,290,393 by Nichia. According to the patent, the Al(x)Ga(l-x)N buffer layer is grown at 200 to 900°C and the Al(x)Ga(l-x)N layer is grown at 900 to

1150°C. [34] Meanwhile, US PAT No. 4,855,249 discloses a method of growing a buffer layer of

AlN. This low temperature buffer layer growth is well known to the art. [35] Korean Patent Application Nos. 2003-52936, 2003-85334, and 2004-46349 by the present inventors disclose methods for growing a buffer layer of SiC or SiCN. These buffer layers may be used in the present invention. [36] According to the present invention, the deposition sequence of the doped layer and the undoped layer can be changed and the first layer and the last layer should not be a pair when they are deposited alternately.

Claims

[1] A method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device, wherein the n-type nitride layer is formed by alternately depositing an n-type doped In(x)Ga(l-x)N (0<x<l) layer and an undoped GaN layer and the conductivity of the n-type nitride layer is controlled by adjusting the ratios in concentration and thickness between the n- type doped In(x)Ga(l-x)N (0<x<l) layer and the undoped GaN layer.

[2] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 1, wherein the n-type doped In(x)Ga(l-x)N (0<x<l) layer has an electron concentration of 10 /cm to 10 / cm³.

[3] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 1, wherein the n-type doped In(x)Ga(l-x)N (0<x<l) layer has a thickness of lnm to 20nm.

[4] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 1, wherein the undoped GaN layer has a base concentration of 10¹⁴/cm³ to 10¹⁷/cm³.

[5] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 1, wherein the undoped GaN layer has a thickness of lnm to 20nm.

[6] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 1, wherein a pair of the In(x)Ga(l-x)N (0<x<l) layer and the undoped GaN layer has a thickness of 2nm to 40nm.

[7] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 1, wherein the n-type nitride layer has a total thickness of 20nm to 5um.

[8] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 1, wherein the n-type dopant is at least one selected from Si, In and Sn.

[9] A method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device, wherein the n-type nitride layer is formed by repeatedly depositing an undoped GaN layer delta-doped with an n- type dopant and the conductivity of the n-type nitride layer is controlled by adjusting the concentration and time of the delta doping and the thickness of the undoped GaN.

[10] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 9, wherein in the delta- doping with an n-type dopant, the electron concentration is within a range from lθ"/cm³ to 10²²/cm³.

[11] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 9, wherein in the delta- doping with an n-type dopant, the doping time is within a range from 0.1 sec to 120 sec.

[12] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 9, wherein the undoped GaN layer has a base concentration of from 10¹⁴/cm³ to 10¹⁷/cm³.

[13] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 9, wherein the n-type nitride layer has a total thickness of 20nm to 5um.

[14] The method of controlling the conductivity of an n-type nitride layer of a GaN- based semiconductor light-emitting device of claim 9, wherein the n-type dopant is at least one selected from Si, In and Sn.