Solar blind ultra violet (uv) detector and fabrication methods of the same

Abstract

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.

What is claimed is: 
     
         1 . A device comprising:
 a substrate;   a plurality of pixels;   a plurality of nanowires in each of the plurality of pixel;   wherein the plurality of nanowires are configured to detect a UV emitting source without interference from solar radiation.   
     
     
         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 a 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 a 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 a 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.