Epitaxial lift off in inverted metamorphic multijunction solar cells

摘要

The present disclosure provides a process for manufacturing a solar cell by selectively freeing an epitaxial layer from a single crystal substrate upon which it was grown. In some embodiments the process includes, among other things, providing a first substrate; depositing a separation layer on said first substrate; depositing on said separation layer a sequence of layers of semiconductor material forming a solar cell; mounting and bonding a flexible support on top of the sequence of layers; etching said separation layer while applying an agitating action to the etchant solution so as to remove said flexible support with said epitaxial layer from said first substrate.

主权项

1. A method for manufacturing a solar cell using a process for selectively freeing an epitaxial layer from a single crystal substrate upon which it was grown, comprising:
providing a first substrate of gallium arsenide; depositing a separation layer on said first substrate; depositing on the separation layer a sequence of epitaxial layers of semiconductor material forming a solar cell including: forming over the separation layer an upper first solar subcell having a first band gap and including a semiconductor contact layer; forming over said first solar subcell a middle second solar subcell having a second band gap smaller than said first band gap; forming a graded interlayer over said second solar subcell; and forming over said graded interlayer a lower third solar subcell having a fourth band gap smaller than said second band gap such that said third subcell is lattice mismatched with respect to said second subcell; mounting the first substrate and the sequence of epitaxial layers of semiconductor material on a flexible film; mechanically holding said first substrate against a bottom support of an etching apparatus; attaching a connecting link element that connects at least two opposed points on the periphery of the flexible film to an upper portion of the etching apparatus; introducing said solar cell having said flexible film bonded thereon into an etchant environment in said etching apparatus; etching said separation layer while applying mechanical tension to said connecting link element so as to remove said flexible film with said epitaxial layers from said first substrate; attaching the flexible film directly to a surrogate substrate by an electrostatic technique; depositing a contact metal layer over the semiconductor contact layer; lithographically processing the contact metal layer to form grid lines; attaching a cover glass over the grid lines; and removing the surrogate substrate.