Oxides with Thin Metallic Layers as Transparent Ohmic Contacts for P-Type and N-Type Gallium Nitride

Patent metadata

Field	Value
Publication number	US-2016013367-A1
Application number	US-201414330616-A
Country	US
Kind code	A1
Filing date	Jul 14, 2014
Priority date	Jul 14, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

Transparent conductive layers usable as ohmic contacts for III-V semiconductors with work functions between 4.1 and 4.7 eV are formed by annealing layers of transparent oxide with thin (0.1-5 nm) layers of conductive metal. When the layers interdiffuse during the annealing, some of the conductive metal atoms remain free to reduce resistivity and others oxidize to reduce optical absorption. Examples of the transparent oxides include indium-tin oxide, zinc oxide, and aluminum zinc oxide with up to 5 wt % Al. Examples of the metals include aluminum and titanium. The work function of the transparent conductive layer can be tuned to match the contacted semiconductor by adjusting the ratio of metal to transparent oxide.

First claim

What is claimed is:

1 . An optoelectronic device, comprising:
a transparent conductive layer in direct contact with a III-V semiconductor region on a substrate; wherein the transparent conductive layer comprises an oxide of a first metal and wherein the transparent conductive oxide further comprises a second metal.

2 . The device of claim 1 , wherein a work function of the transparent conductive layer matches a work function of the III-V semiconductor within±0.2 eV.

3 . The device of claim 1 , wherein the second metal comprises aluminum or titanium.

4 . The device of claim 1 , wherein the oxide of the first metal comprises indium tin oxide.

5 . The device of claim 4 , wherein the indium tin oxide comprises about 90 wt % indium oxide and about 10 wt % tin oxide.

6 . The device of claim 1 , wherein the oxide of the first metal comprises zinc oxide.

7 . The device of claim 6 , wherein the oxide comprises aluminum zinc oxide having 0.1-5 wt % aluminum or indium zinc oxide having 0.1-5 wt % indium.

8 . The device of claim 1 , wherein the oxide of the first metal further comprises an oxide of the second metal.

9 . The device of claim 1 , wherein the transparent conductive layer comprises a layer of the second metal in contact with a surface of the III-V semiconductor region.

10 . The device of claim 1 , wherein the transparent conductive layer further comprises a plurality of layers of the second metal; and wherein each of the plurality of layers of the second metal has a thickness between about 1 and about 10 monolayers.

11 . The device of claim 1 , wherein the transparent conductive layer has a thickness between about 50 nm and about 100 nm.

12 . The device of claim 1 , wherein the transparent conductive layer is at least 30% crystalline.

13 . The device of claim 1 , wherein the III-V semiconductor region comprises gallium nitride.

14 . The device of claim 1 , wherein the transparent conductive layer comprises substitutional defects.

15 . The device of claim 1 , wherein a specific contact resistivity of an interface between the transparent conductive layer and the III-V semiconductor surface is less than about 0.005 Ω-cm 2 .

16 . A method of forming a transparent conductive layer of an optoelectronic device, the method comprising:
forming a first metal layer of a thickness between about 0.1 nm and about 5 nm over a substrate; forming a first oxide layer in contact with the first metal layer; and annealing the substrate; and wherein the first metal layer or the first oxide layer is in contact with a III-V semiconductor surface.

17 . The method of claim 16 , further comprising forming a second metal layer or a second oxide layer before the annealing, wherein the second metal layer or the second oxide layer becomes part of the transparent conductive layer after the annealing.

18 . The method of claim 16 , wherein the forming of the first metal layer or the forming of the first oxide layer comprises physical vapor deposition or atomic layer deposition.

19 . The method of claim 16 , wherein the forming of the first metal layer or the forming of the first oxide layer occurs at a substrate temperature between about 20 C and about 30 C in an argon ambient with or without 1-5 vol % oxygen gas.

20 . The method of claim 16 , wherein the annealing occurs at a temperature between about 350 C and about 650 C for between about 3 minutes and 10 minutes in a nitrogen gas ambient.

Assignees

• Intermolecular Inc

Inventors

• Hu Jianhua
• Hsu Heng-Kai
• Le Minh Huu
• Nijhawan Sandeep
• Sapirman Teresa B

Classifications

• H10H20/032

  of electrodes · CPC title

• H10H20/825

  containing nitrogen, e.g. GaN · CPC title

• H10H20/0137

  the light-emitting regions comprising nitride materials · CPC title

• H10H20/01

  Manufacture or treatment · CPC title

• H10H20/833 Primary

  Transparent materials · CPC title