Group III nitride compound semiconductor device

1. A method of manufacturing a group III nitride compound semiconductor device comprising a substrate, buffer layers disposed on the substrate, and a group III nitride compound semiconductor layer disposed on the top layer of the buffer layers, the method comprising:

forming a first buffer layer on the substrate, the first buffer layer comprising a transition metal nitride; and

forming a second buffer layer on the first buffer layer, the second buffer layer comprising a nitride of gallium and a transition metal.

2. The method of claim 1 , wherein the transition metal comprises at least one element selected from the group consisting of titanium, zirconium, hafnium, and tantalum.

3. The method of claim 1 , further comprising forming a third buffer layer on the second buffer layer, the third buffer layer being interposed between the second buffer layer and the group III nitride compound semiconductor layer, wherein the third buffer layer comprises GaN.

4. The method of claim 1 , wherein the first buffer layer comprises TiN, and the second buffer comprises (Ti, Ga)N.

5. The method of claim 1 , wherein the first buffer layer comprises a TiN layer formed from a metal-organic titanium source selected from tetrakis-diethylamino-titanium (TDEAT), tetrakis-dimethylamino-titanium (TDMAT), titanium isopropoxide (TTIP), and titanium tetrachloride (TiCl 4 ).

6. The method of claim 1 , wherein the second buffer layer comprises a (Ti, Ga)N layer formed from a metal-organic titanium source selected from tetrakis-diethylamino-titanium (TDEAT), tetrakis-dimethylamino-titanium (TDMAT), titanium isopropoxide (TTIP), and titanium tetrachloride (TiCl 4 ).

7. The method of claim 1 , wherein the substrate comprises a material selected from the group of sapphire, silicon carbide, gallium nitride, gallium phosphide, and gallium arsenide.

8. The method of claim 3 , wherein the first buffer layer has a thickness ranging from 20 Å to 100 Å, the second buffer layer has a thickness ranging from 50 Å to 100 Å, and the third buffer layer has a thickness ranging from 200 Å to 300 Å.

9. The method of claim 4 , wherein the (Ti, Ga)N comprises a Ti 2 GaN phase.

10. A method of manufacturing a group III nitride compound semiconductor device comprising a substrate, buffer layers disposed on the substrate, and a group III nitride compound semiconductor layer disposed on the top layer of the buffer layers, the method comprising:

forming a first buffer layer on the substrate, the first buffer layer comprising a transition metal nitride;

forming a second buffer layer on the first buffer layer, the second buffer layer comprising a nitride of gallium and a transition metal; and

forming a third buffer layer comprising GaN, the third buffer layer being interposed between the second buffer layer and the group III nitride compound semiconductor layer,

wherein the transition metal comprises at least one element selected from the group consisting of titanium, zirconium, hafnium, and tantalum.

11. The method of claim 10 , wherein the first buffer layer has a thickness ranging from 20 Å to 100 Å, the second buffer layer has a thickness ranging 50 Å from 100 Å, and the third buffer layer has a thickness ranging from 200 Å to 300 Å.

12. The method of claim 10 , wherein the first buffer layer comprises TiN, and the second buffer layer comprises (Ti, Ga)N.

13. The method of claim 10 , wherein the first buffer layer comprises a TiN layer formed from a metal-organic titanium source selected from tetrakis-diethylamino-titanium (TDEAT), tetrakis-dimethylamino-titanium (TDMAT), titanium isopropoxide (TTIP), and titanium tetrachloride (TiCl 4 ).

14. The method of claim 10 , wherein the second buffer layer comprises a (Ti, Ga)N layer formed from a metal-organic titanium source selected from tetrakis-diethylamino-titanium (TDEAT), tetrakis-dimethylamino-titanium (TDMAT), titanium isopropoxide (TTIP), and titanium tetrachloride (TiCl 4 ).

15. The method of claim 10 , wherein the substrate comprises a material selected from the group of sapphire, silicon carbide, gallium nitride, gallium phosphide, and gallium arsenide.

16. The method of claim 10 , wherein the substrate has a hexagonal crystal structure.

17. The method of claim 12 , wherein the (Ti, Ga)N comprises a Ti 2 GaN phase.