SEMICONDUCTOR MATERIAL, METHOD OF MAKING THE SAME, AND SEMICONDUCTOR DEVICE

• US 20110001127A1
• Filed: 12/17/2008
• Published: 01/06/2011
• Est. Priority Date: 12/27/2007
• Status: Active Grant

• Current Assignee: Dowa Electronics Materials Co. Ltd. (DOWA Holdings Company Limited), Nagoya Institute of Technology
• Original Assignee: Dowa Electronics Materials Co. Ltd. (DOWA Holdings Company Limited), Nagoya Institute of Technology
• Inventors: Egawa, Takashi, Shimizu, Jo, Ito, Tsuneo, Sakamoto, Ryo
• Granted Patent: US 8,344,356 B2
• Time in Patent Office: Days
• US Class Current: 257/22
• CPC Class Codes: H01L 21/02381 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02507 Alternating layers, e.g. superlattice
• CPC Class Codes: H01L 21/0251 Graded layers
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 29/155 Comprising only semiconductor materials H01L29/154 takes precedence
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer

Abstract

A semiconductor material is provided comprising: a composition graded layer, formed on a Si substrate or an interlayer formed thereon, comprising a composition of Al_XGa_1-XN graded such that a content ratio of Al in the composition decreases continuously or discontinuously in a crystal growing direction; a superlattice composite layer, formed on the composition graded layer, comprising a high Al-containing layer comprising a composition of Al_YGa_1-YN and a low Al-containing layer comprising a composition of Al_ZGa_1-ZN that are laminated alternately; and a nitride semiconductor layer formed on the superlattice composite layer.

Claims

1. A semiconductor material comprising:

a composition graded layer, formed on a Si substrate or an interlayer formed on the Si substrate, comprising a composition of Al_XGa_1-XN graded such that a content ratio of Al in the composition decreases continuously or discontinuously in a crystal growing direction;

a superlattice composite layer, formed on the composition graded layer, comprising a high-Al-containing layer comprising a composition of Al_YGa_1-YN (0.5≦

Y≦

1) and a low Al-containing layer comprising a composition Al_ZGa_1-ZN (0≦

Z≦

0.5) that are laminated alternately; and

a nitride semiconductor layer formed on the superlattice composite layer.

2. The semiconductor material according to claim 1, wherein the superlattice composite layer comprises an AlN layer (Y=1) as the high Al-containing layer and an Al_ZGa_1-ZN layer (0≦

Z≦

0.3) as the low Al-containing layer.

3. The semiconductor material according to claim 1, wherein a total number of the high Al-containing layer and the low Al-containing layer is 2 to 100 in the superlattice composite layer.

4. The semiconductor material according to claim 1, wherein the superlattice composite layer comprises the high Al-containing layer as a bottom layer thereof and the low Al-containing layer as a top layer.

5. The semiconductor material according to claim 1, wherein, in the graded layer, a value of X in Al_XGa_1-XN is in a range of 0.5 to 1 at a lower surface in contact with the Si substrate or the interlayer and in a range of 0 to 0.5 at an upper surface in contact with the superlattice composite layer.

6. The semiconductor material according to claim 1, wherein the nitride semiconductor layer is a GaN layer.

7. The semiconductor material according to claim 6, wherein a pit density of the GaN layer is 1000 pits/cm² or less.

8. A semiconductor device produced by using the semiconductor material according to claim 1 provided with an electrode.

9. A method of making a semiconductor material comprising:

forming a composition graded layer, on a Si substrate or an interlayer formed on the Si substrate, comprising a composition of Al_XGa_1-XN graded such that a content ratio of Al in the composition decreases continuously or discontinuously in a crystal growing direction

forming a superlattice composite layer, on the composition graded layer, comprising a high Al-containing layer comprising a composition of Al_YGa_1-YN (0.5≦

Y≦

1) and a low Al-containing layer comprising a composition Al_ZGa_1-ZN (0≦

Z≦

0.5) that are laminated alternately; and

forming a nitride semiconductor layer on the superlattice composite layer.

10. The method of making the semiconductor material according to claim 9, wherein a process to form the superlattice composite layer is to form an AlN layer as the high Al-containing layer and to form an Al_ZGa_1-ZN layer (0≦

Z≦

0.3) as the low Al-containing layer.

11. The method of making the semiconductor material according to claim 9, wherein the process to form the superlattice composite layer is to laminate the high Al-containing layer and the low Al-containing layer such that a total number thereof is 2 to 100.