Three-dimensional thin-film solar cells

1. A method for manufacturing a three-dimensional monocrystalline silicon thin-film solar cell, comprising:

forming a three-dimensional thin-film monocrystalline silicon solar cell substrate having an area measuring at least 125 mm×125 mm and having a first set and a second set of structural surface topography features:

said first set of said structural surface topography features positioned at predetermined locations on said three-dimensional monocrystalline silicon thin-film solar cell substrate and comprising a plurality of discrete and isolated hexagonal prism cavities having a central axis positioned substantially perpendicular to the light capturing surface of said three-dimensional monocrystalline silicon thin-film solar cell substrate, said discrete and isolated hexagonal prism cavities associated with a first set of geometrical aspect ratios and dimensions comprising a ratio between height and hexagonal diagonal dimension approximately in the range of 0.5 to 5.0; and

said second set of said structural surface topography features positioned at predetermined locations on said three-dimensional monocrystalline silicon thin-film solar cell substrate and comprising a plurality of interconnected continuous cavity boundary sidewalls defining said plurality of discrete and isolated hexagonal prism cavities thereby constructing said three-dimensional monocrystalline silicon thin-film solar cell substrate as a free-standing, self-supporting substrate, said second set of structural surface topography features associated with a second set of geometrical aspect ratios and dimensions comprising cavity boundary sidewall widths ranging approximately between 2 to 30 microns on the light capturing side of said three-dimensional monocrystalline silicon thin-film solar cell substrate;

said three-dimensional monocrystalline silicon thin-film solar cell substrate, said first set of said structural surface topography features, and said second set of said structural surface topography features cooperating to comprise a free-standing, self-supporting three-dimensional monocrystalline silicon thin-film solar cell with sufficient mechanical rigidity for reduced cell breakage rate in a solar cell production factory;

said three-dimensional thin-film monocrystalline silicon solar cell substrate formed by the steps of:

forming a sacrificial porous silicon layer on a reusable monocrystalline silicon template, said reusable monocrystalline silicon template comprising a template substrate, said template substrate comprising a plurality of discrete and isolated hexagonal posts having a central axis positioned substantially perpendicular to a surface of said reusable template and a plurality of interconnected continuous trenches interspersed among and bordering said plurality of discrete and isolated hexagonal posts;

subsequently depositing an in-situ doped monocrystalline silicon layer doped with a first dopant and having a thickness in the range of approximately 1 to 30 microns using an epitaxial silicon growth process; and

releasing said monocrystalline silicon layer from said reusable monocrystalline silicon template at said sacrificial porous silicon layer;

subsequently performing the following processing steps on said three-dimensional monocrystalline silicon thin-film solar cell substrate released from said reusable monocrystalline silicon template, the steps comprising:

doping select portions of said three-dimensional monocrystalline silicon thin-film solar cell substrate with a second dopant of polarity similar to said first dopant, said doping forming doped base regions;

doping select portions of said three-dimensional monocrystalline silicon thin-film solar cell substrate with a third dopant of opposite polarity to said first dopant, said doping forming doped emitter regions,

at least a portion of at least one of said steps of forming doped base regions and forming doped emitter regions using a thermal anneal process at a temperature of 800°-950° C.; and

forming emitter metallization regions and base metallization regions.

2. The method for manufacturing a three-dimensional monocrystalline silicon thin-film solar cell of claim 1 , wherein said first set of geometrical aspect ratios and dimensions comprise a ratio between height and hexagonal diagonal dimension approximately in the range of 1 to 3.

3. The method for manufacturing a three-dimensional monocrystalline silicon thin-film solar cell of claim 1 , wherein said cavity boundary sidewall widths range at least approximately between 2 to 10 microns.

4. The method for manufacturing a three-dimensional monocrystalline silicon thin-film solar cell of claim 1 , wherein said emitter regions are positioned on the light capturing surface of said sidewalls.