Polarization induced doped transistor
A nitride-based field effect transistor (FET) comprises a compositionally graded and polarization induced doped p-layer underlying at least one gate contact and a compositionally graded and doped n-channel underlying a source contact. The n-channel is converted from the p-layer to the n-channel by ion implantation, a buffer underlies the doped p-layer and the n-channel, and a drain underlies the buffer.
1. A III-V Nitride-based field effect transistor (FET) comprising:
a compositionally graded and polarization doped p-layer underlying at least one of a source, drain, gate, or body contact;
a compositionally graded and doped n-channel underlying at least one of the source or gate contact, wherein the n-channel is converted from the p-layer to the n-channel by ion implantation;
a drift region underlying the doped p-layer and the n-channel;
a n+region underlying the drift region; and
a drain underlying the n+region.
2. A field effect transistor as defined in claim 1 , wherein the n-channel is converted via ion implantation of silicon.
3. A field effect transistor as defined in claim 1 wherein the drift region is a doped n-layer.
4. A field effect transistor as defined in claim 3 , wherein the drift region is a doped n-layer comprising GaN.
5. A field effect transistor as defined in claim 1 , wherein the p-layer comprises AlGaN.
6. A field effect transistor as defined in claim 1 , wherein the transistor forms a vertical junction field effect transistor.
7. A field effect transistor as defined in claim 1 further comprising a substrate between the buffer and the drain.
8. A field effect transistor as defined in claim 7 , wherein the substrate is GaN.
9. A metal-oxide semiconductor field effect transistor (MOSFET) comprising:
a compositionally graded AlGaN epitaxial structure;
an n-channel formed in the upper portion of the epitaxial structure via ion implantation;
a pair of n+regions formed in the upper portion of the epitaxial structure laterally displaced on either side of the n-channel, wherein the n+regions are formed via at least one of ion implantation or regrowth;
a p doped region formed in the upper portion of the epitaxial structure laterally displaced on either side of the n+regions and in ohmic contact with a p layer;
an AlGaN top barrier, a gate contact overlaying the n-channel;
a source overlaying at least a portion of the upper portion of the epitaxial structure; and
a drain underlying at least a portion of a lower portion of the epitaxial structure.
10. A metal-oxide semiconductor field effect transistor as defined in claim 9 , wherein the n-channel is formed via ion implantation of silicon.
11. A metal-oxide semiconductor field effect transistor as defined in claim 9 , wherein the n-channel comprises AlGaN.
12. A metal-oxide semiconductor field effect transistor as defined in claim 9 , wherein the lower portion of the epitaxial structure comprises GaN.
13. A metal-oxide semiconductor field effect transistor as defined in claim 9 , further comprising edge terminations on each side of the epitaxial structure.
14. A metal-oxide semiconductor field effect transistor as defined in claim 12 , wherein the edge termination is formed via isolation ion implantation.
15. A metal-oxide semiconductor heterostructure field effect transistor comprising:
an AlGaN compositionally graded pGaN layer;
a GaN channel overlaying the pGaN layer;
at least two n-doped regions formed in the upper portion of the GaN channel laterally displaced from one another;
at least one p-doped region formed in the upper portion of the GaN channel in ohmic contact with the graded pGaN layer;
a gate dielectric and a gate contact overlaying the GaN channel;
a source overlaying at least a portion of one of the n-doped regions; and
a drain overlaying at least a portion of the other of the n-doped region.
16. A field effect transistor as defined in claim 1 , wherein the compositionally graded and doped n-channel is graded in the different direction from the p-layer.
17. A field effect transistor as defined in claim 1 , wherein the compositionally graded and doped n-channel is adjacent to the p-layer.
18. A field effect transistor as defined in claim 17 , where the compositional grading is equal at the juncture between the n and p layer.
19. A field effect transistor as defined in claim 1 , wherein the graded and doped n-channel comprises compositionally graded AlGaN.
20. A field effect transistor as defined in claim 4 , wherein the drift region is a doped n-layer further comprising linearly graded n-type AlGaN.
21. A metal-oxide semiconductor field effect transistor as defined in claim 12 , wherein the lower portion of the epitaxial structure further comprises linearly composition graded doped n-type AlGaN.