Asymmetric band gap junctions in narrow band gap MOSFET

1. A semiconductor device comprising:

one or more fin structures comprising a first material formed on a substrate;

gate, source, and drain regions comprising a second material formed on the substrate;

a first contact insulator layer deposited over the substrate;

wherein a first etching process applied to the substrate removes the first contact insulator to create a trench in the first contact insulator layer that extends to the source region;

a first source material having a first band gap, the first source material being deposited into the trench that extends to the source region such that the source region has a higher resistance to parasitic current flow than the drain region;

a second contact insulator layer that is deposited over the substrate; and

a metalizing material that is deposited over the substrate.

2. The device of claim 1 further comprising a first drain material that is deposited over the drain regions, the first drain material having a second band gap that defines a second band gap that is lower than the first band gap to decrease current flow through the source region compared to the current flow through the drain region.

3. The device of claim 2 , wherein the first drain material is comprised of indium gallium arsenide (InGaAs) with an indium concentration of at least 50%.

4. The device of claim 2 , wherein the indium gallium arsenide is In 0.7 Ga 0.3 As.

5. The device of claim 1 , wherein the first contact insulator layer is comprised of indium aluminum arsenide (InAlAs) or indium phosphide (InP).

6. The device of claim 1 , wherein the second contact insulator layer is comprised of indium aluminum arsenide (InAlAs) or indium phosphide (InP).

7. The device of claim 1 , wherein the fin structure is comprised of indium gallium arsenide (InGaAs) or silicon germanium (SiGe).

8. The device of claim 1 , wherein the fin structure is instead a nanowire.

9. The device of claim 1 , wherein the fin structure is instead a nanosheet.

10. The device of claim 1 , wherein the fin structure is instead a planar device.

11. The device of claim 1 , wherein the fin structure is formed by Aspect Ratio Trapping (ART) or Strain Relaxed Buffer (SRB) processes.

12. The device of claim 1 , wherein the first source material is comprised of indium gallium arsenide (InGaAs) with an indium concentration less than 50%.

13. The device of claim 12 , wherein the indium gallium arsenide is In 0.3 Ga 0.7 As.

14. The device of claim 1 , further comprising the first and/or second contact insulator layers of the substrate being planarized.

15. The device of claim 1 , wherein the substrate is selected from one of the following: monocrystalline silicon, silicon germanium, silicon carbon, and semiconductor on insulator.

16. The device of claim 1 , wherein a top layer of the substrate is Si, SiGe, Group III-V channel material, or other suitable channel materials.

17. The device of claim 16 , wherein the Group III-V channel materials include materials having one or more Group III element and one or more Group V element.

18. The device of claim 17 , wherein the Group III-V channel material is chosen from aluminum gallium arsenide, aluminum gallium nitride, aluminum arsenide, aluminum indium arsenide, aluminum nitride, gallium antimonide, gallium aluminum antimonide, gallium arsenide, gallium arsenide antimonide, gallium nitride, indium antimonide, indium arsenide, indium gallium arsenide, indium gallium arsenide phosphide, indium gallium nitride, indium nitride, indium phosphide and alloy combinations including one or more of the foregoing materials.

19. The device of claim 1 , further comprising a dielectric spacer disposed on the top and sides of the gate stack.

20. The device of claim 1 , wherein the dielectric spacer comprises a low-K dielectric material.