Patent ID: 9373741
Filing Date: 2016-06-21
CPC Classification: H01L,Y02E

Claim Text:
1. A photovoltaic device comprising: an upper cell that absorbs a first range of wavelengths of light, wherein said upper cell has a topmost surface that is in direct contact with a transparent conductive material layer, and a bottommost surface that is in direct contact with a topmost surface of a tunneling layer; and a bottom cell that absorbs a second range of wavelengths, wherein a topmost surface of said bottom cell is in direct contact with a bottommost surface of said tunneling layer, and wherein the bottom cell includes a heterojunction comprising a crystalline germanium (Ge) containing layer and a silicon (Si) containing layer having a larger band gap than that of the crystalline germanium (Ge) containing layer, wherein said crystalline germanium (Ge) containing layer comprises a first portion and a second portion, wherein the second portion is planar with a horizontal surface, wherein said first portion comprises a nanowire having a width and a length and an aspect ratio, wherein the length of the nanowire extends vertically upward in a first direction perpendicular to said a horizontal surface of said second portion, and wherein said silicon (Si) containing layer is in direct contact with an entire outermost surface of said nanowire; and wherein said first portion and said second portion of the crystalline germanium (Ge) containing layer is doped with an n-type or p-type dopant to provide a first conductivity type, and the silicon (Si) containing layer is doped with an n-type or p-type dopant to provide a second conductivity type that is opposite the first conductivity type.