Patent ID: 9741880
Date: 2017-08-22
CPC Classifications: H01L,Y02E

Claim:
1. A method for forming a photovoltaic device, comprising: forming a plurality of pillar structures in a substrate; forming a first electrode layer on the pillar structures; forming a continuous photovoltaic stack including an N-type layer, a P-type layer and an intrinsic layer on the first electrode layer; depositing a second electrode layer over the photovoltaic stack such that air gaps occur in the second electrode layer between the pillar structures, wherein the air gaps extend in a stack direction for a majority of the height of the pillar structures and wherein only a single air gap is formed between each set of adjacent pillar structures; further depositing the second electrode layer to enclose the air gaps in the second electrode layer, wherein the enclosed air gaps extend in a stack direction for a majority of the height of the pillar structures; and wet etching the second electrode layer to reduce the second electrode layer and to form a three-dimensional electrode over the photovoltaic stack.