Gallium nitride materials and methods associated with the same
Semiconductor materials including a gallium nitride material region and methods associated with such structures are provided. The semiconductor structures include a strain-absorbing layer formed within the structure. The strain-absorbing layer may be formed between the substrate (e.g., a silicon substrate) and an overlying layer. It may be preferable for the strain-absorbing layer to be very thin, have an amorphous structure and be formed of a silicon nitride-based material. The strain-absorbing layer may reduce the number of misfit dislocations formed in the overlying layer (e.g., a nitride-based material layer) which limits formation of other types of defects in other overlying layers (e.g., gallium nitride material region), amongst other advantages. Thus, the presence of the strain-absorbing layer may improve the quality of the gallium nitride material region which can lead to improved device performance.
1. A method of forming a semiconductor structure comprising:
forming an amorphous strain-absorbing layer on an entire top surface of a non-nitride material of a semiconductor substrate by nitridating the entire top surface, wherein said amorphous strain-absorbing layer does not include gallium;
forming a nitride-based material layer using a vertical growth process, wherein the amorphous strain-absorbing layer separates the semiconductor substrate and the nitride-based material layer at all points with the amorphous strain-absorbing layer being directly on the non-nitride material of the semiconductor substrate and the nitride-based material layer being directly on the strain-absorbing layer, wherein said semiconductor substrate is a non-nitride material-based substrate, wherein the misfit dislocation density in the nitride-based material layer is less than about 10 10 defects/cm 2 .
2. The method of claim 1 , wherein the semiconductor substrate is substantially planar.
3. The method of claim 1 , wherein the semiconductor substrate is silicon.
4. The method of claim 1 , wherein the strain-absorbing layer comprises a silicon nitride-based material.
5. The method of claim 4 , wherein the strain-absorbing layer is formed by exposing a silicon substrate to a gaseous source of nitrogen.
6. The method of claim 1 , wherein the nitride-based material layer is a single crystal.
7. The method of claim 1 , comprising forming the nitride-based material layer at temperatures of greater than about 700° C.
8. The method of claim 1 , wherein the nitride-based material layer comprises an aluminum nitride-based material.
9. The method of claim 1 , wherein the nitride-based material layer has an epitaxial relationship with the semiconductor substrate.
10. The method of claim 1 , wherein the nitride-based material layer comprises a gallium nitride material alloy.
11. The method of claim 1 , wherein the nitride-based material layer has a thickness of less than 100 Angstroms.
12. The method of claim 1 , wherein the nitride-based material layer has a thickness of greater than 10 Angstroms.
13. The method of claim 1 , further comprising forming a gallium nitride material region over the nitride-based material layer.
14. The method of claim 1 , wherein the misfit dislocation density in the nitride-based material layer is less than about 10 5 detects/cm 2 .
15. The method of claim 1 , wherein the semiconductor substrate comprises a different material than the nitride-based material layer.
16. The method of claim 1 , wherein the semiconductor substrate has a different crystal structure than the nitride-based material layer.
17. The method of claim 1 , wherein the amorphous strain-absorbing layer is formed in a growth step.
18. The method of claim 1 , comprising forming a continuous amorphous strain-absorbing layer on the semiconductor substrate.