High electron mobility transistor and method of manufacturing the same

1. A high electron mobility transistor comprising:

a channel layer comprising a 2-dimensional electron gas (2DEG);

a barrier layer on the channel layer and comprising first regions and a second region, the first regions on portions of the channel layer and configured to induce the 2DEG of a first density in the portions of the channel layer, and the second region on other portions of the channel layer and configured to induce the 2DEG of a second density different from the first density in the other portions of the channel layer;

source and drain electrodes on the barrier layer; and

a gate electrode on the barrier layer between the source and drain electrodes,

the first regions including a first edge region and a second edge region opposite each other with the second region in between,

the first edge region and the second edge region corresponding respectively to both a first end and a second end of a surface of the channel layer crossing the gate electrode in plan view, wherein

the barrier layer includes recesses in the first edge region and the second edge region,

a thickness of the barrier layer in the recesses is greater than 0 nm and less than a thickness of the barrier layer in the second region,

a portion of the gate electrode vertically overlapping the recesses is closer to the surface of the channel layer than a part of the gate electrode over the second region of the barrier layer,

the second region is not recessed,

the source electrode and the drain electrode each have a longest dimension that extends parallel to each other in a first direction,

the gate electrode has a longest dimension that extends in the first direction parallel to the longest dimension of each of the source electrode and drain electrode, and

the first edge region and the second edge region are separated from each other in the first direction by the second region.

2. The high electron mobility transistor of claim 1 , wherein the first density of the 2DEG is less than the second density of the 2DEG.

3. The high electron mobility transistor of claim 1 , further comprising:

an insulating film between the barrier layer and the gate electrode.

4. The high electron mobility transistor of claim 1 , further comprising:

a depletion formation layer between the barrier layer and the gate electrode, wherein

the depletion formation layer is configured to form a depletion region in the 2DEG.

5. The high electron mobility transistor of claim 1 , wherein the recesses have a depth greater than 0 nm and less than 100 nm.

6. The high electron mobility transistor of claim 1 , wherein a depth of the recesses is the same as the thickness of the barrier layer in the recesses.

7. The high electron mobility transistor of claim 1 , wherein the recesses have a width that is the same as a width of the gate electrode.

8. The high electron mobility transistor of claim 1 , wherein a shape of the recesses is configured to simultaneously form a channel in a first region of the channel layer and a second region of the channel layer in response to applying a same threshold voltage to the gate electrode, the recesses overlap the first region of the channel layer in the plan view, and the second region of the channel layer overlaps the second region of the barrier layer in the plan view.

9. The high electron mobility transistor of claim 1 , wherein the first edge region and the second edge region of the barrier layer are regions doped with anions.

10. The high electron mobility transistor of claim 9 , wherein the anions comprise any one of fluorine ions F − and oxygen ions O 2− .

11. The high electron mobility transistor of claim 1 , wherein the barrier layer comprises any one of AlGaN, AlInN, InGaN, AlN, and AlInGaN.

12. A high electron mobility transistor comprising:

a channel layer comprising a 2-dimensional electron gas (2DEC);

a barrier layer on the channel layer and comprising first regions and a second region, the first regions on portions of the channel layer and configured to induce the 2DEC of a first day density in the portions of the channel layer, and the second region on other portions of the channel layer and configured to induce the 2DEC of a second density different from the first density in the other portions of the channel layer;

source and drain electrodes on the barrier layer;

a gate electrode on the barrier layer between the source and drain electrodes; and

a depletion formation layer between the barrier layer and the gate electrode,

the first regions including a first edge region and a second edge region opposite each other with the second region in between,

the first edge region and the second edge region corresponding respectively to both a first end and a second end of a surface of the channel layer crossing the gate electrode in plan view, wherein

the barrier layer includes recesses in the first edge region and the second edge region,

a thickness of the barrier layer in the recesses is greater than 0 nm and less than a thickness of the barrier layer in the second region,

a portion of the gate electrode vertically overlapping the recesses is closer to the surface of the channel layer than a part of the gate electrode over the second region of the barrier layer,

the depletion formation layer is configured to form a depletion region in the 2DEC, and

the depletion formation layer comprises a p-type Group III-V nitride semiconductor.

13. The high electron mobility transistor of claim 12 , wherein

the source and drain electrodes extend parallel to each other in a first direction, and

the gate electrode extends in the first direction parallel to the source and drain electrodes.

14. The high electron mobility transistor of claim 13 , wherein, in the plan view, both ends of the gate electrode extend away from the channel layer in the first direction.

15. The high electron mobility transistor of claim 13 , wherein

the gate electrode comprises protrusions at both ends thereof extending in the first direction.

16. The high electron mobility transistor of claim 15 , wherein

the barrier layer comprises second protrusions extending in the first direction, and

the second protrusions correspond to the protrusions of the gate electrode.

17. A method of manufacturing a high electron mobility transistor comprising:

forming a barrier layer on a channel layer;

forming first regions and a second region of the barrier layer, the first regions configured to induce a 2DEG of a first density in portions of the channel layer and the second region configured to induce a 2DEG of a second density different from the first density in other portions of the channel layer;

forming source and drain electrodes on the barrier layer; and

forming a gate electrode on the barrier layer between the source and drain electrodes,

the first regions including a first edge region and a second edge region opposite each other with the second region in between, the first edge region and the second edge region corresponding respectively to both a first end and a second end of a surface of the channel layer crossing the gate electrode in plan view, wherein

the forming the first regions and the second region on the barrier layer comprises forming recesses in the first edge region and the second edge region of the barrier layer such that a thickness of the barrier layer in the recesses is greater than 0 nm and less than a thickness of the barrier layer in the second region,

the gate electrode is formed on the barrier layer so a portion of the gate electrode vertically overlapping the recesses is closer to the surface of the channel layer than a part of the gate electrode over the second region of the barrier layer,

the second region is not recessed,

the source electrode and the drain electrode each have a longest dimension that extends parallel to each other in a first direction,

the gate electrode has a longest dimension that extends in the first direction parallel to the longest dimension of each of the source electrode and drain electrode, and

the first edge region and the second edge region are separated from each other in the first direction by the second region.

18. The method of claim 17 , further comprising:

forming an insulating film between the barrier layer and the gate electrode.

19. The method of claim 17 , further comprising:

forming a depletion formation layer on the barrier layer to form a depletion region in the 2DEG in the barrier layer.

20. The method of claim 19 , further comprising:

forming an insulating film on the depletion formation layer;

forming a hole in the insulating film by patterning portions of the insulating film; and

forming the gate electrode on the insulating film to cover the hole.

21. The method of claim 17 , wherein the gate electrode, the source electrode, and drain electrode are formed to extend parallel to each other in a first direction.

22. The method of claim 21 , wherein, in the plan view, both ends of the gate electrode extend away from the channel layer in the first direction.

23. The method of claim 17 , wherein the forming the first regions and the second region on the barrier layer further comprises forming a recess in portions of the barrier layer between the first edge region and the second edge region.

24. The method of claim 17 , wherein the forming the first regions and the second region on the barrier layer comprises doping anions at both ends of a surface of the gate electrode contacting the channel layer.