Semiconductor devices with integrated hole collectors
Transistor devices which include semiconductor layers with integrated hole collector regions are described. The hole collector regions are configured to collect holes generated in the transistor device during operation and transport them away from the active regions of the device. The hole collector regions can be electrically connected or coupled to the source, the drain, or a field plate of the device. The hole collector regions can be doped, for example p-type or nominally p-type, and can be capable of conducting holes but not electrons.
1. A transistor device, comprising:
a source, a gate, and a drain;
a semiconductor material which includes a gate region between the source and the drain;
a plurality of channel access regions in the semiconductor material between the source and the gate, and between the drain and the gate, respectively;
a channel in the semiconductor material;
an insulating material over the semiconductor material, the insulating material having a first portion over the gate region and a second portion over at least one of the plurality of channel access regions, a thickness of the first portion being less than a thickness of the second portion; and
one or more hole collector regions at least partially in the gate region of the semiconductor material, the one or more hole collector regions extending through the channel and forming a break in the channel; wherein
the one or more hole collector regions are configured to conduct substantial hole current but not substantial electron current during operation of the transistor device; and
the insulating material is between the gate and the semiconductor material and prevents the gate from contacting the semiconductor material in the gate region.
2. The transistor device of claim 1 , wherein the first portion of the insulating material is sufficiently thin to allow holes generated during device operation to be collected by the gate.
3. The transistor device of claim 1 , wherein the first portion of the insulating material is sufficiently thin to allow holes generated during device operation to be transported out of the semiconductor material through the gate.
4. The transistor device of claim 1 , wherein the device includes at least two hole collector regions in the gate region of the semiconductor material.
5. The transistor device of claim 1 , wherein the hole collector region contains dopants.
6. The transistor device of claim 5 , wherein the dopants are selected from the group consisting of Mg, Al, and Fe.
7. The transistor device of claim 1 , wherein the device is a III-N transistor.
8. The transistor device of claim 1 , wherein the device is a high-voltage device.
9. The transistor device of claim 1 , wherein the device is a field-effect transistor.
10. The transistor device of claim 1 , wherein the insulating material comprises a first insulating material layer and a second insulating material layer.
11. The transistor device of claim 10 , wherein the second portion of the insulating material includes both the first and second insulating material layers, and the first portion of the insulating material includes the first insulating material layer but not the second insulating material layer.
12. The transistor device of claim 1 , wherein the insulating material is over an entirety of the one or more hole collector regions.
13. The transistor device of claim 1 , wherein the maximum hole current density that the one or more hole collector regions are configured to conduct is at least 100 times the maximum electron current density that the one or more hole collector regions are configured to conduct.
14. A transistor device, comprising:
an electrode;
a semiconductor material which includes a gate region between two channel access regions;
a channel in the semiconductor material;
an insulating material over the semiconductor material; and
a hole collector region in the semiconductor material below the electrode, the hole collector region extending through the channel and forming a break in the channel; wherein
the hole collector region is configured to conduct substantial hole current but not substantial electron current during operation of the transistor device;
the insulating material is between the electrode and the hole collector region and prevents the electrode from contacting the hole collector region; and
at least a portion of the insulating material that is between the electrode and the hole collector region is sufficiently thin to allow holes generated during device operation to be collected by the electrode.
15. The transistor device of claim 14 , wherein the portion of the insulating material that is between the electrode and the hole collector region is sufficiently thin to allow holes generated during device operation to be transported out of the semiconductor material through the electrode.
16. The transistor device of claim 14 , wherein the electrode is a gate, and the transistor further comprises a source and a drain.
17. The transistor device of claim 16 , wherein the portion of the insulating material that is between the electrode and the hole collector region is a first portion, the insulating material comprising a second portion between the gate and the drain, wherein the first portion is thinner than the second portion.
18. The transistor device of claim 14 , wherein the insulating material prevents the electrode from contacting the semiconductor material.
19. The transistor device of claim 14 , wherein the semiconductor material includes a III-N material.
20. The transistor device of claim 14 , wherein the hole collector region contains dopants.
21. The transistor device of claim 20 , wherein the dopants are selected from the group consisting of Mg, Al, and Fe.
22. A method of forming a transistor device, comprising:
providing a III-N semiconductor material having a channel therein;
forming a source, a gate, and a drain on the III-N semiconductor material, wherein the III-N semiconductor material includes a gate region between the source and the drain and a plurality of channel access regions between the source and the gate, and between the drain and the gate, respectively;
doping a portion of the III-N semiconductor material, wherein the doped portion comprises one or more hole collector regions, the one or more hole collector regions being at least partially in the gate region, the one or more hole collector regions extending through the channel to form a break in the channel, the one or more hole collector regions being configured to conduct substantial hole current but not substantial electron current during operation of the transistor device; and
forming an insulating material over the III-N semiconductor material, the insulating material having a first portion over the gate region and a second portion over at least one of the plurality of channel access regions, a thickness of the first portion being less than a thickness of the second portion; wherein
the insulating material is between the gate and the III-N semiconductor material and prevents the gate from contacting the semiconductor material in the gate region.
23. The method of claim 22 , wherein the doping comprises ion implantation of dopants.
24. The method of claim 23 , wherein the dopants are selected from the group consisting of Mg, Al, and Fe.