Reducing leakage current in semiconductor devices

1. A semiconductor device, comprising:

a first semiconductor region that is a silicon region;

a second semiconductor region comprising a nitride semiconductor material, the second semiconductor region being formed over the silicon region;

first and second terminals of the semiconductor device over the second semiconductor region; and

at least one p-n junction formed in the silicon region between the first and second terminals, the at least one p-n junction being configured to reduce lateral current flow in the silicon region between the first and second terminals.

2. The semiconductor device of claim 1 , wherein the at least one p-n junction comprises a first p-n junction that extends in a direction perpendicular to an interface between the silicon region and the second semiconductor region.

3. The semiconductor device of claim 1 , wherein a third terminal is formed in the silicon region and the at least one p-n junction is further configured to reduce current flow between the third terminal and the first terminal.

4. The semiconductor device of claim 1 , wherein the silicon region is at least a portion of a substrate, the substrate being a bulk semiconductor substrate or a semiconductor-on insulator-substrate.

5. The semiconductor device of claim 1 , wherein the at least one p-n junction extends to an interface between the silicon region and the second semiconductor region.

6. The semiconductor device of claim 1 , wherein the at least one p-n junction is configured to reduce current flow in the silicon region along a direction perpendicular to the interface between the silicon region and the second semiconductor region.

7. The semiconductor device of claim 1 , wherein a p-type region and an n-type region form the at least one p-n junction.

8. The semiconductor device of claim 7 , wherein the p-type region and the n-type region are arranged as stripes.

9. The semiconductor device of claim 1 , wherein the at least one p-n junction comprises a plurality of p-n junctions.

10. The semiconductor device of claim 1 , wherein the semiconductor device is a transistor, wherein the first terminal is a drain terminal of the transistor, and wherein the second terminal is a source terminal of the transistor.

11. A semiconductor device, comprising:

a silicon region;

semiconductor pillars disposed over the silicon region between first and second terminals of the semiconductor device;

an insulating region between the semiconductor pillars to reduce leakage current between the semiconductor pillars; and

a semiconductor region comprising a nitride semiconductor material, the semiconductor region being formed over the semiconductor pillars.

12. The semiconductor device of claim 11 , wherein the insulating region comprises a dielectric material.

13. The semiconductor device of claim 12 , wherein the dielectric material comprises a dielectric fluid.

14. The semiconductor device of claim 12 , wherein the dielectric material comprises at least one of AN, SiN, SiC, polycrystalline diamond, SiO 2 , or another dielectric material with a critical electric field higher than 30 kV/cm.

15. The semiconductor device of claim 11 , wherein the semiconductor pillars comprise silicon.

16. The semiconductor device of claim 11 , wherein adjacent semiconductor pillars are separated from one another by no more than 20 μm.