Semiconductor nano-wire antenna solar cells and detectors

Abstract

Patterning planar photo-absorbing materials into arrays of nanowires is demonstrated as a method for increasing the total photon absorption in a given thickness of absorbing material. Such a method can provide faster, cheaper, and more efficient photo-detectors and solar cells. A thin nanowire can absorb many more photons than expected from the size of the nanowire. The reason for this effect is that such nanowires support cylindrical particle resonances which can collect photons from an area larger than the physical cross-section of the wire. These resonances are sometimes referred to as Mie resonances or Leaky Mode Resonances (LMRs). The nanowires can have various cross section shapes, such as square, circle, rectangle, triangle, etc.

1 . Apparatus for absorbing solar radiation, the apparatus comprising:
 a substrate; and   an array of two or more semiconductor nano-wires disposed laterally on the substrate;   wherein the array has one or more array resonances of optical absorption;   wherein each of the array resonances arises from a corresponding leaky mode resonance of one or more of the nano-wires;   wherein each of the leaky mode resonances has a corresponding spectral absorption peak;   wherein one or more dimensions of the nano-wires are selected such that a selected one of the spectral absorption peaks is substantially at 500 nm.   
     
     
         2 . The apparatus of  claim 1 , wherein the selected spectral absorption peak is in a range between 475 nm and 525 nm. 
     
     
         3 . The apparatus of  claim 1 , wherein the selected spectral absorption peak corresponds to a leaky mode resonance that is a TE   01   or a TM   11   resonance. 
     
     
         4 . The apparatus of  claim 1 , wherein a cross-section shape of the nano-wires is selected from the group consisting of circle, square, rectangle, ellipse, triangle, and hexagon. 
     
     
         5 . The apparatus of  claim 1 , wherein a diameter of the nano-wires is in a range from 10 nm to 3000 nm. 
     
     
         6 . The apparatus of  claim 1 , wherein the semiconductor nano-wires include a single-crystalline, polycrystalline, or amorphous material selected from the group consisting of: Si, CdTe, GaAs, CuInGeSe, copper-zinc-tin-sulfur (CZTS) compositions, and Ge. 
     
     
         7 . The apparatus of  claim 1 , wherein a spacing of the nano-wires in the array is in a range from 10 nm to 500 nm. 
     
     
         8 . The apparatus of  claim 1 , further comprising two terminals connected to the apparatus such that electrical power can be extracted from the terminals when the apparatus is illuminated. 
     
     
         9 . The apparatus of  claim 8 , wherein current carriers generated in the nano-wires by optical absorption travel toward the electrodes in a vertical direction, relative to the substrate. 
     
     
         10 . The apparatus of  claim 1 , further comprising an array of concentrator lenses disposed to focus incident radiation onto the nano-wires. 
     
     
         11 . The apparatus of  claim 1 , wherein the array of two or more semiconductor nano-wires is an aperiodic array. 
     
     
         12 . The apparatus of  claim 1 , wherein the array of two or more semiconductor nano-wires is a substantially periodic array. 
     
     
         13 . A method for absorbing electromagnetic radiation having an incident radiation spectrum with a spectral intensity peak, the method comprising:
 providing an array of two or more semiconductor nano-wires disposed laterally on a substrate;   wherein the array has one or more array resonances of optical absorption;   wherein each of the array resonances arises from a corresponding leaky mode resonance of one or more of the nano-wires;   wherein each of the leaky mode resonances has a corresponding spectral absorption peak;   wherein one or more dimensions of the nano-wires are selected such that one of the spectral absorption peaks is substantially spectrally aligned with the spectral intensity peak.   
     
     
         14 . A method for solar energy collection comprising the method of  claim 13 . 
     
     
         15 . A method for photodetection comprising the method of  claim 13 . 
     
     
         16 . A method for photocatalysis comprising the method of  claim 13 . 
     
     
         17 . A method for imaging comprising the method of  claim 13 .