Pulsed selective area lateral epitaxy for growth of III-nitride materials over non-polar and semi-polar substrates
An epitaxy procedure for growing extremely low defect density non-polar and semi-polar III-nitride layers over a base layer, and the resulting structures, is generally described. In particular, a pulsed selective area lateral overgrowth of a group III nitride layer can be achieved on a non-polar and semi-polar base layer. By utilizing the novel P-MOCVD or PALE and lateral over growth over selected area, very high lateral growth conditions can be achieved at relatively lower growth temperature which does not affect the III-N surfaces.
1. A method of growing a non-polar group III nitride layer on a base layer, the method comprising:
masking the base layer with a first dielectric layer, wherein the first dielectric layer is located on select areas of the base layer such that a portion of the base layer is exposed;
growing a mushroom-shaped PLOG group III nitride layer via pulse lateral overgrowth epitaxy on the portion of the base layer that is exposed, wherein the PLOG group III nitride layer grows over a portion of the first dielectric layer;
masking the mushroom-shaped PLOG group III nitride layer with a second dielectric layer, wherein each side of the mushroom-shaped PLOG group III nitride layer remains exposed; and
growing a nonpolar group III nitride layer from each exposed side of the mushroom-shaped PLOG group III nitride layer, wherein the nonpolar group III nitride layer is grown by pulsing a nitrogen source and a group III metal source.
2. The method as in claim 1 , wherein the first dielectric layer masking the base layer is grown by pulsing a silicon source and an oxygen source.
3. The method as in claim 1 , wherein the second dielectric layer masking the mushroom-shaped PLOG group III nitride layer is grown by pulsing a silicon source and an oxygen source.
4. The method as in claim 1 , wherein the mushroom-shaped PLOG group III nitride layer is grown by pulsing a nitrogen source and a group III metal source.
5. The method as in claim 1 , wherein the PLOG group III nitride layer comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦1 and 0<x+y≦1.
6. The method as in claim 1 , wherein the base layer comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦1 and 0<x+y≦1.
7. The method as in claim 1 , wherein the nonpolar group III nitride layer comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦1 and 0<x+y≦1.
8. The method as in claim 1 , wherein the base layer overlays a buffer layer and a substrate.
9. The method as in claim 8 , wherein the buffer layer is deposited as a Al x In y Ga 1-x-y N/Al r In s Ga (1-r-s) N short period super lattice, wherein 0≦x≦1, 0≦y≦1, 0<x+y≦1, 0<r≦1, 0≦s≦1 and 0<r+s≦1, and wherein x and r are different and y and s are different.
10. The method as in claim 1 , wherein the nonpolar group III nitride layer is grown by sequentially pulsing a nitrogen source and a group III metal source.
11. A non-polar substrate formed according to the method of claim 1 .
12. A non-polar substrate comprising
a non-polar material;
a buffer layer overlying the non-polar material;
a group III nitride base layer overlying the buffer layer, wherein the group III nitride base comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦1 and 0<x+y≦1;
a first dielectric layer masking a portion of the group III nitride base layer, wherein a portion of the group ill nitride base layer remains unmasked;
a mushroom-shaped PLOG group III nitride layer grown on the unmasked portion of the group III nitride base layer, wherein the mushroom-shaped PLOG group III nitride layer overgrows a portion of the first dielectric layer;
a second dielectric layer masking the mushroom-shaped PLOG group III nitride layer, wherein each side of the mushroom-shaped PLOG group III nitride layer remains unmasked; and
a nonpolar group III nitride layer overlying exposed portions of the first dielectric layer and the second dielectric layer, wherein the nonpolar group III nitride layer is grown out of each unmasked side of the mushroom-shaped PLOG group III nitride layer by pulsing a nitrogen source and a group III metal source.
13. The non-polar substrate as in claim 12 , wherein a cavity is defined between exposed portions of the first dielectric and the nonpolar group III nitride layer.
14. The non-polar substrate as in claim 12 , wherein the nonpolar group III nitride layer comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦1 and 0<x+y≦1.
15. The non-polar substrate as in claim 12 , wherein the non-polar material comprises sapphire.
16. The non-polar substrate as in claim 12 , wherein the nonpolar group III nitride layer is grown by sequentially pulsing a nitrogen source and a group III metal source.
17. A semipolar substrate comprising
a semi-polar material;
a buffer layer overlying the semi-polar material;
a group III nitride base layer overlying the buffer layer, wherein the group III nitride base comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦1 and 0<x+y≦1;
a first dielectric layer masking a portion of the group III nitride base layer, wherein a portion of the group III nitride base layer remains unmasked;
a mushroom-shaped PLOG group III nitride layer grown on the unmasked portion of the group III nitride base layer, wherein the mushroom-shaped PLOG group III nitride layer overgrows a portion of the first dielectric layer;
a second dielectric layer masking the mushroom-shaped PLOG group III nitride layer, wherein each side of the mushroom-shaped PLOG group III nitride layer remains unmasked; and
a semi-polar group III nitride layer overlying exposed portions of the first dielectric layer and the second dielectric layer, wherein the semi-polar group III nitride layer is grown out of each unmasked side of the mushroom-shaped PLOG group III nitride layer by pulsing a nitrogen source and a group III metal source.
18. The semi-polar substrate as in claim 17 , wherein a cavity is defined between exposed portions of the first dielectric and the semi-polar group III nitride layer.
19. The semi-polar substrate as in claim 17 , wherein the semi-polar group III nitride layer comprises Al x In y Ga 1-x-y N, wherein 0≦x≦1, 0≦y≦1 and 0<x+y≦1.
20. The semi-polar substrate as in claim 17 , wherein the semi-polar group III nitride layer is grown by sequentially pulsing a nitrogen source and a group III metal source.