Multi-junction photovoltaic device and fabrication method

Abstract

A method of forming a photovoltaic device that includes bonding a substrate to a germanium-containing semiconductor layer with a stressor layer, wherein the stressor layer cleaves the germanium-containing semiconductor layer. At least one semiconductor layer is formed on a cleaved surface of the germanium-containing semiconductor layer that is opposite the conductivity type of the germanium-containing semiconductor layer to provide a first solar cell. The first solar cell absorbs a first range of wavelengths. At least one second solar cell may be formed on the first solar cell, wherein the at least one second solar cell is composed of at least one semiconductor material to absorb a second range of wavelengths that is different than the first range wavelengths absorbed by the first solar cell.

1 . A method of forming a photovoltaic device comprising:
 joining a substrate to a germanium-containing semiconductor layer with a stressor layer, wherein the stressor layer cleaves the germanium-containing semiconductor layer;   forming at least one semiconductor layer on a cleaved surface of the germanium-containing semiconductor layer, wherein the at least one semiconductor layer has a conductivity type that is opposite the conductivity type of the germanium-containing semiconductor layer to provide a first solar cell that absorbs a first range of wavelengths; and   forming at least one second solar cell on the first solar cell, wherein the at least one second solar cell is comprised of at least one semiconductor material to absorb a second range of wavelengths that is different than the first range of wavelengths absorbed by the first solar cell.   
     
     
         2 . The method of  claim 1 , wherein the stressor layer is a metal layer, and the substrate is composed of a flexible polymer, a flexible metal foil, or a thin flexible sheet of glass. 
     
     
         3 . The method of  claim 2 , wherein the bonding of the substrate to the germanium-containing semiconductor layer comprises depositing the metal layer on the substrate. 
     
     
         4 . The method of  claim 1 , wherein the stressor layer is heated to effectuate a cleaving stress on the germanium-containing semiconductor layer, wherein in response to the cleaving stress the germanium-containing semiconductor layer is fractured so that a first portion of the germanium containing semiconductor layer is connected to the substrate through at least the stressor layer, and a second portion of the germanium-containing semiconductor layer is removed. 
     
     
         5 . The method of  claim 1 , wherein the at least one of a passivation layer, transparent conductivity material layer, n-type conductivity semiconductor layer, p-type conductivity semiconductor layer and intrinsic semiconductor layer is present between the germanium-containing layer and the stressor layer. 
     
     
         6 . The method of  claim 1 , wherein the forming of the at least one semiconductor layer on a cleaved surface of the germanium-containing semiconductor layer comprises an epitaxial growth process. 
     
     
         7 . The method of  claim 1 , wherein the at least one semiconductor layer comprises Si, SiGe, SiC, SiGeC and a combination thereof. 
     
     
         8 . The method of  claim 1  further comprising forming a tunneling layer on the cleaved surface of the germanium-containing semiconductor layer, wherein the tunneling layer comprises at least one of a metal layer, transparent conductive material, a semiconductor junction or a combination thereof. 
     
     
         9 . The method of  claim 8 , wherein prior to forming the tunneling layer, an intrinsic semiconductor layer is formed on the at least one semiconductor layer that is present on the cleaved surface of the germanium containing semiconductor layer. 
     
     
         10 . The method of  claim 1 , wherein the forming of the at least one second solar cell comprises forming a p-i-n junction of hydrogenated amorphous silicon, hydrogenated amorphous silicon carbide, hydrogenated amorphous silicon-germanium, hydrogenated nano/microcrystalline Si, or a combination thereof. 
     
     
         11 . The method of  claim 10 , wherein the forming of the at least one second solar cell comprises a first p-i-n junction of hydrogenated amorphous silicon germanium present on the first solar cell, and a second p-i-n junction of hydrogenated amorphous silicon comprising carbon present on the first solar cell. 
     
     
         12 . The method of  claim 10 , wherein the forming of the at least one second solar cell comprises a first p-i-n junction of hydrogenated crystalline silicon on the first solar cell, a second p-i-n junction of hydrogenated amorphous silicon germanium present on the first solar cell, and a third p-i-n junction of hydrogenated amorphous silicon comprising carbon present on the second solar cell. 
     
     
         13 . The method of  claim 10 , wherein the forming of the at least one second solar cell comprises a first p-i-n junction of hydrogenated amorphous silicon-germanium on the first solar cell, a second p-i-n junction of p-i-n junction of hydrogenated amorphous silicon comprising carbon on the first solar cell, and a third p-i-n junction of hydrogenated amorphous silicon-carbide present on the second solar cell. 
     
     
         14 . The method of  claim 10 , wherein the forming of the at least one second solar cell comprises a first p-i-n junction of hydrogenated crystalline silicon on the first solar cell, a second p-i-n junction of hydrogenated amorphous silicon which may contain carbon on the first solar cell, and a third p-i-n junction of hydrogenated amorphous silicon-carbide present on the second solar cell. 
     
     
         15 - 24 . (canceled)