Solar blind ultra violet (UV) detector and fabrication methods of the same
View Patent ↗Described herein is device configured to be a solar-blind UV detector comprising a substrate; a plurality of pixels; a plurality of nanowires in each of the plurality of pixel, wherein the plurality of nanowires extend essentially perpendicularly from the substrate.
1. A device comprising:
a substrate;
a plurality of pixels;
a plurality of nanowires in each of the plurality of pixel, the nanowires comprising silicon;
wherein the plurality of nanowires extend essentially perpendicularly from the substrate and comprise silicon, and the plurality of nanowires essentially do not absorb radiation except UV radiation with a wavelength in the solar-blind UV region.
2. The device of claim 1 , wherein the plurality of nanowires have an absorptance above 25% for UV light with a wavelength from 0.12 to 0.34 micron.
3. The device of claim 1 , wherein each of the plurality of nanowires comprises a core and a cladding surrounding the core, wherein the core has a higher refractive index than the cladding.
4. The device of claim 1 , wherein each of the plurality of the nanowires comprises a coupler disposed on an end of each of the nanowire away from the substrate, the coupler being functional to guide radiation into the nanowires.
5. The device of claim 1 , wherein the nanowires have a height from about 0.1 μm to about 5 μm; the cladding has a thickness of about 10 nm to about 200 nm.
6. The device of claim 1 , wherein the nanowires have a pitch from about 0.2 μm to about 2 μm.
7. The device of claim 1 , wherein the nanowires detect UV radiation in the solar-blind UV region by converting UV radiation in the solar-blind UV region to an electrical signal.
8. The device of claim 7 , wherein the device further comprises electrical components configured to detect the electrical signal.
9. The device of claim 7 , wherein the device is functional to detect the electrical signal from the nanowires in different pixels separately.
10. The device of claim 1 , wherein each of the nanowires comprises a photodiode or forms a photodiode with the substrate, wherein the photodiode is functional to convert at least a portion of UV radiation in the solar-blind UV region impinged on the nanowires.
11. The device of claim 10 , wherein each of the nanowires comprises
a first heavily doped semiconductor layer,
a lightly doped semiconductor layer or an intrinsic semiconductor layer,
a second heavily doped semiconductor layer, and
a metal silicide layer;
wherein the first heavily doped semiconductor layer is disposed on the lightly doped semiconductor layer or the intrinsic semiconductor layer;
the lightly doped semiconductor layer or the intrinsic semiconductor layer is disposed on the second heavily doped semiconductor layer;
the second heavily doped semiconductor layer is disposed on the metal silicide layer;
the metal silicide layer is disposed on the substrate;
the first heavily doped semiconductor layer is of an opposite type from the second heavily doped semiconductor layer; and
wherein the first heavily doped semiconductor layer, the lightly doped semiconductor layer or the intrinsic semiconductor layer, and the second heavily doped semiconductor layer form the photodiode.
12. The device of claim 11 , wherein the device further comprises a common electrode disposed on and electrically connected to ends of all the nanowires, wherein the common electrode is substantially transparent to UV radiation in the solar-blind UV region.
13. The device of claim 12 , wherein the common electrode is made of graphene.
14. The device of claim 12 , further comprising a metal grid on the common electrode, the metal grid configured to provide mechanical support for the common electrode.
15. The device of claim 10 , wherein each of the nanowires comprises
a core of lightly doped semiconductor,
an intermediate shell of intrinsic semiconductor and
an outer shell of doped semiconductor;
wherein the intermediate shell is conformally disposed over the core;
the outer shell is conformally disposed over the intermediate shell;
the outer shell is of an opposite type from the core; and
the outer shell, the intermediate shell and the core form the photodiode.
16. The device of claim 15 , wherein each nanowire further comprises
a heavily doped semiconductor layer of the same type as the core, and a metal silicide layer;
wherein the heavily doped semiconductor layer and a metal silicide layer are sandwiched between the core and the substrate;
the intermediate shell and the outer shell do not contact the heavily doped semiconductor layer and the metal silicide layer; and
the metal silicide layer is in contact with the substrate and forms electrical contact to the substrate.
17. The device of claim 10 , wherein the photodiode is an avalanche photodiode.
18. The device of claim 1 , wherein space between the nanowires is filled with an oxide layer.
19. A solar-blind image sensor, comprising the device of claim 1 and electronic circuitry functional to detect electrical signals generated by the nanowires of the device.
20. The solar-blind image sensor of claim 19 , wherein the electronic circuitry comprises a high voltage supply.
21. A method of detecting UV radiation, comprising obtaining the device of claim 1 , and detecting UV radiation with the device of claim 1 .
22. The method of claim 21 , wherein UV radiation in the solar-blind UV region.
23. The device of claim 1 , wherein the nanowires have a diameter from about 5 nm to about 30 nm.