Group III-N nanowire transistors
A group III-N nanowire is disposed on a substrate. A longitudinal length of the nanowire is defined into a channel region of a first group III-N material, a source region electrically coupled with a first end of the channel region, and a drain region electrically coupled with a second end of the channel region. A second group III-N material on the first group III-N material serves as a charge inducing layer, and/or barrier layer on surfaces of nanowire. A gate insulator and/or gate conductor coaxially wraps completely around the nanowire within the channel region. Drain and source contacts may similarly coaxially wrap completely around the drain and source regions.
1. A semiconductor structure, comprising:
a nanowire disposed above a substrate, wherein a longitudinal length of the nanowire comprises:
a channel region of a group III -N material;
a source region electrically coupled with a first end of the channel region; and
a drain region electrically coupled with a second end of the channel region;
a gate stack comprising a gate insulator and a gate conductor coaxially wrapping completely around the channel region of the nanowire; and
a semiconductor material beneath the source region and the drain region of the nanowire, wherein the semiconductor material is not included beneath the channel region of the nanowire.
2. The semiconductor structure of claim 1 , further comprising:
a source contact on the source region of the nanowire and on the semiconductor material beneath the source region of the nanowire; and
a drain contact on the drain region of the nanowire and on the semiconductor material beneath the drain region of the nanowire.
3. The semiconductor structure of claim 1 , further comprising:
a second group III-N material disposed between the group III-N material and the gate stack along at least a portion of the channel region of the nanowire, wherein the second group III-N material is different than the group III-N material of the channel region of the nanowire.
4. The semiconductor structure of claim 3 , wherein the second group III-N material is to provide a back barrier with a heterojunction formed along a first surface of the nanowire, and to induce a 2DEG within the channel region the nanowire with a heterojunction along a second surface of the nanowire.
5. The semiconductor structure of claim 1 , wherein the group III-N material of the channel region of the nanowire has a wurtzite crystal structure.
6. The semiconductor structure of claim 1 , further comprising:
an extrinsic drain region comprising a second group III-N material separating the drain region from the channel region of the nanowire, wherein the second group III-N material is different than the group III-N material of the channel region of the nanowire.
7. The semiconductor structure of claim 6 , wherein the second group III-N material has a larger bandgap than that of the group III-N material.
8. The semiconductor structure of claim 1 , wherein the semiconductor material has a lower bandgap than that of the group III-N material.
9. The semiconductor structure of claim 1 , wherein the semiconductor material has a larger bandgap than that of the group III-N material.
10. The semiconductor structure of claim 1 , wherein the group III-N material consists essentially of GaN, or consists essentially of InN, or consists essentially of Al x In 1-x N, where x is less than 1, or consists essentially of Al x Ga 1-x N, where x is less than 1, and wherein the semiconductor material comprises AlN, GaN, InN, Al z In 1-z N, or Al z Ga 1-z N, where z is different than x.
11. A method of fabricating a semiconductor structure, the method comprising:
forming a first semiconductor material on a second semiconductor material above a substrate, wherein the first semiconductor material comprises a group III-N material;
forming a fin from the first semiconductor material and the second semiconductor material;
forming an insulating layer over the fin;
forming a gate trench in the insulating layer;
removing the second semiconductor material from portions of the fin exposed by the gate trench to provide a nanowire having a channel region comprising the group III-N material;
forming a gate stack comprising a gate insulator and a gate conductor coaxially wrapping completely around the channel region of the nanowire;
subsequent to forming the gate stack, removing remaining portions of the insulating layer to expose a source region electrically coupled with a first end of the channel region of the nanowire and to expose a drain region electrically coupled with a second end of the channel region of the nanowire, wherein the second semiconductor material is beneath the source and drain regions of the nanowire.
12. The method of claim 11 , further comprising:
forming a source contact on the source region of the nanowire and on the second semiconductor material beneath the source region of the nanowire; and
forming a drain contact on the drain region of the nanowire and on the second semiconductor material beneath the drain region of the nanowire.
13. The method of claim 11 , further comprising:
forming a second group III-N material between the group III-N material and the gate stack along at least a portion of the channel region of the nanowire, wherein the second group III-N material is different than the group III-N material of the channel region of the nanowire.
14. The method of claim 13 , wherein the second group III-N material is to provide a back barrier with a heterojunction formed along a first surface of the nanowire, and to induce a 2DEG within the channel region the nanowire with a heterojunction along a second surface of the nanowire.
15. The method of claim 11 , wherein the group III-N material of the channel region of the nanowire has a wurtzite crystal structure.
16. The method of claim 11 , further comprising:
forming an extrinsic drain region comprising a second group III-N material separating the drain region from the channel region of the nanowire, wherein the second group III-N material is different than the group III-N material of the channel region of the nanowire.
17. The method of claim 16 , wherein the second group III-N material has a larger bandgap than that of the group III-N material.
18. The method of claim 11 , wherein the second semiconductor material has a lower bandgap than that of the group III-N material.
19. The method of claim 11 , wherein the second semiconductor material has a larger bandgap than that of the group III-N material.
20. The method of claim 11 , wherein the group III-N material consists essentially of GaN, or consists essentially of InN, or consists essentially of Al x In 1-x N, where x is less than 1, or consists essentially of Al x Ga 1-x N, where x is less than 1, and wherein the second semiconductor material comprises AlN, GaN, InN, Al z In 1-z N, or Al z Ga 1-z N, where z is different than x.