Substrates for High-Efficiency Thin-Film Solar Cells Based on Crystalline Templates

Abstract

A three-dimensional thin-film semiconductor substrate having a plurality of ridges on the surface of the semiconductor substrate which define a base opening of an inverted pyramidal cavity and walls defining the inverted pyramidal cavity is provided. And a fabrication method for a 3-D TFSS by forming a porous silicon layer on a silicon template having a top surface aligned along a (100) crystallographic orientation plane of the silicon template and a plurality of walls each aligned along a (111) crystallographic orientation plane of the silicon template and forming an inverted pyramidal cavity. The porous silicon layer forms substantially conformal on the silicon template. Then forming a substantially conformal epitaxial silicon layer on the porous silicon layer and releasing the epitaxial silicon layer from the silicon template.

Description

[0001]This application claims the benefit of provisional patent application 61 / 114,378 filed on Nov. 13, 2008, which is hereby incorporated by reference.FIELD[0002]This disclosure relates in general to the field of photovoltaics and solar cells, and more particularly to semiconductor substrates and methods for making semiconductor substrates for use in manufacturing three-dimensional thin-film solar cells.DESCRIPTION OF THE RELATED ART[0003]Current methods for manufacturing a three-dimensional thin-film solar cell (3-D TFSC) include forming a 3-Dimensional thin-film silicon substrate (3-D TFSS) using a silicon template. The template may comprise a plurality of posts and a plurality of trenches between said a plurality of posts. The 3-D TFSS may then be formed by forming a sacrificial layer on the template, subsequently depositing a semiconductor layer, selective etching the sacrificial layer and releasing the semiconductor layer from the template. More specifically, the said semicon...

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Benefits of technology

[0007]Therefore a need has arisen for a three-dimensional thin-film substrate which provides fabrication process improvements and manufacturing costs reductions for forming a three-dimensional thin-film solar cell (3-D TFSC). In acco

Problems solved by technology

These processes are often costly and difficult.

Also, flat thin-film silicon substrates may have reduced mean optical path length which reduces IR absorption and results in reduced cell quantum efficiency.

And flat thin-film crystalline silicon substrates may

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