Nanostructured devices

Abstract

A photovoltaic device is provided. It comprises at least two electrical contacts, p type dopants and n type dopants. It also comprises a bulk region and nanowires in an aligned array which contact the bulk region. All nanowires in the array have one predominant type of dopant, n or p, and at least a portion of the bulk region also comprises that predominant type of dopant. The portion of the bulk region comprising the predominant type of dopant typically contacts the nanowire array. The photovoltaic devices' p-n junction would then be found in the bulk region. The photovoltaic devices would commonly comprise silicon.

1 . A device comprising two or more electrical contacts suitable for connection of the device to external circuitry, a substrate, a collection of nanowires partially covering the substrate, and a thin film covering portions of the substrate not covered by nanowires of the collection but located between nanowires of the collection, wherein the thin film comprises a metal and forms part of one of the two or more electrical contacts. 
     
     
         2 . The device of  claim 1 , wherein the device operates as a photovoltaic cell or a light emitting diode. 
     
     
         3 . The device of  claim 1 , wherein the thin film is continuous. 
     
     
         4 . The device of  claim 1 , wherein the thin film is at least about 50 nm below the top of the nanowires. 
     
     
         5 . The device of  claim 4 , wherein the thin film is at least about 100 nm below the top of the nanowires. 
     
     
         6 . The device of  claim 5 , wherein the thin film is at least about 200 nm below the top of the nanowires. 
     
     
         7 . The device of  claim 1 , wherein the thin film comprises silver. 
     
     
         8 . The device of  claim 1 , wherein the substrate comprises silicon. 
     
     
         9 . The device of  claim 1 , wherein the nanowires comprise silicon. 
     
     
         10 . The device of  claim 1 , wherein the nanowires are integral with the substrate. 
     
     
         11 . A photovoltaic device comprising:
 (a) a crystalline semiconductor substrate comprising:
 (1) a bottom n-doped region; and 
 (2) a top p-doped region adjacent to and in direct physical contact with the n-doped region, 
   
       wherein the n-doped region and the p-doped region form a p-n junction within the bulk of the crystalline semiconductor substrate, and the top p-doped region contains p-dopant throughout the entirety of the top p-doped region; and
 (b) a p-doped nanostructure in direct physical contact with the top p-doped region of the crystalline semiconductor substrate, 
 
       wherein the p-n junction is located at least about 30 nm from the bottom of the p-doped nanostructure. 
     
     
         12 . The device of  claim 11 , wherein the height of nanostructure above the crystalline semiconductor substrate is no more than about 1 μm. 
     
     
         13 . The device of  claim 12 , wherein the height of nanostructure above the crystalline semiconductor substrate is no more than about 0.5 μm. 
     
     
         14 . The device of  claim 11 , wherein the p-doped nanostructure comprises a plurality of protrusions. 
     
     
         15 . A photovoltaic device comprising:
 (a) a crystalline semiconductor substrate comprising:
 (1) a bottom p-doped region; and 
 (2) a top n-doped region adjacent to and in direct physical contact with the p-doped region, 
   
       wherein the n-doped region and the p-doped region form a p-n junction within the bulk of the crystalline semiconductor substrate, and the top n-doped region contains n-dopant throughout the entirety of the top n-doped region; and
 (b) an n-doped nanostructure in direct physical contact with the top n-doped region of the crystalline semiconductor substrate, 
 
       wherein the p-n junction is located at least about 30 nm from the bottom of the n-doped nanostructure. 
     
     
         16 . The device of  claim 15 , wherein the height of nanostructure above the crystalline semiconductor substrate is no more than about 1 μm. 
     
     
         17 . The device of  claim 16 , wherein the height of nanostructure above the crystalline semiconductor substrate is no more than about 0.5 μm. 
     
     
         18 . The device of  claim 15 , wherein the n-doped nanostructure comprises a plurality of protrusions.