Light source assembly, optical sensor assembly, and method of manufacturing a cell of the same

1. A light source assembly comprising:

a plurality of cells, each of which including

a transistor including a drain region, and

a light source comprising a first light source layer formed in a hole of a substrate, a light-generating layer, and a second light source layer, the first light source layer comprising a first sidewall and a second sidewall opposite to the first sidewall, wherein the drain region of the transistor is in contact with the first sidewall of the first light source layer and not in contact with the second sidewall of the first light source layer, and serves as a cathode of the light source; and

a driving circuit configured to drive each of the plurality of cells.

2. The light source assembly of claim 1 , wherein:

the transistor further includes a source region and an electrode over the source region; and

the drain region of the transistor is free of an electrode.

3. An optical sensor cell comprising:

a transistor over a substrate and including a drain region;

a light source over the substrate, coupled to the transistor, configured to emit light, wherein the drain region of the transistor serves as a cathode of the light source; and

an optical sensor over the substrate and configured to detect the light,

wherein the substrate includes a first well region and a second well region that has a different conductivity type than the first well region,

the transistor is over the first well region of the substrate, and

the optical sensor is over the second well region of the substrate.

4. The optical sensor cell of claim 3 , wherein:

the light source is over the first well region of the substrate.

5. The optical sensor cell of claim 3 , wherein the light source is between the transistor and the optical sensor.

6. The optical sensor cell of claim 3 , wherein the optical sensor includes

a first optical sensor region, and

a second optical sensor region having a different conductivity type than the first optical sensor region and disposed between the light source and the first optical sensor region.

7. The optical sensor cell of claim 6 , wherein the optical sensor further includes an intrinsic optical sensor region over the substrate and the second optical sensor region is in the intrinsic optical sensor region.

8. The optical sensor cell of claim 3 , wherein:

the optical sensor includes a first optical sensor region and a second optical sensor region that has a different conductivity type than the first optical sensor region; and

at least one of the first and second optical sensor regions has a top surface substantially coplanar with a top surface of the substrate.

9. The optical sensor cell of claim 3 , further comprising an isolation region over the substrate and between the light source and the optical sensor.

10. The optical sensor cell of claim 3 , further comprising a light reflecting layer over a top surface of the light source.

11. The optical sensor cell of claim 3 , wherein the light source includes a light source layer, the optical sensor includes an optical sensor region, and a top surface of the light source layer is above a top surface of the optical sensor region.

12. The optical sensor cell of claim 3 , wherein the transistor includes a source/drain region and the optical sensor includes an optical sensor region that has a substantially same dopant concentration as the source/drain region.

13. A method comprising:

simultaneously forming first and second holes in a substrate;

growing a III-V compound semiconductor in the first hole and forming a light source over the substrate; and

depositing a dielectric material in the second hole and forming an optical sensor over the substrate after forming the light source.

14. The method of claim 13 , further comprising forming a light reflecting layer over the light source.

15. The method of claim 13 , further comprising:

forming a first optical sensor region of the optical sensor over the substrate; and

forming an intrinsic optical sensor region of the optical sensor such that the intrinsic optical sensor region is between the light source and the first optical sensor region.

16. The method of claim 13 , further comprising:

forming an intrinsic optical sensor region of the optical sensor over the substrate; and

forming an isolation region between the light source and the intrinsic optical sensor region.