Patent ID: 8168465
Filing Date: 2012-05-01
Classification: H01L,Y02E,Y02P,Y10T

Abstract:
1. A method for fabrication of a structure for use in a photovoltaic solar cell, the method comprising: selectively removing material from a monocrystalline silicon wafer to form a reusable monocrystalline silicon template having a top surface aligned along a (100) crystallographic plane of said template and a plurality of walls each aligned along a (111) crystallographic plane of said template, said walls defining a plurality of inverted pyramidal cavities comprising a set of larger inverted pyramidal cavities with an opening size in the range of approximately 10 μm up to 1 mm and a set of smaller inverted pyramidal cavities with an opening size a fraction of said opening size of said larger inverted pyramidal cavities, said set of larger pyramidal cavities and said set of smaller inverted pyramidal cavities arranged in a staggered pattern on said template which limits the length of ridges of said pyramidal cavity openings to less than twice the width of the openings of said larger pyramidal cavities; forming a substantially conformal sacrificial porous silicon layer comprising at least two different porosities coupled to said template; and epitaxially depositing a monocrystalline silicon layer to form a thin-film solar cell substrate on said sacrificial porous silicon layer, said solar cell substrate having a surface topography defined by said inverted pyramidal cavities on said reusable template; said inverted pyramidal cavities on said reusable template ensuring that said solar cell substrate is capable of being detached from said template as a free-standing, self-supporting substrate with sufficient mechanical rigidity for use in a manufacturing environment.