Mol ecular Beam Epitaxy of Cu 2 O Heterostructures for Photovoltaics

Cu2O is a p-type semiconductor that has demonstrated attractive photovoltaic properties, but its efficiencies have been limited by surface instability and lack of high quality thin films. In this work, plasma-assisted molecular beam epitaxy is used to precisely control film orientation and interface chemistry of Cu2O heterostructures. Thin films of Cu2O are deposited by MBE onto thin films of Pt and Au sputtered on MgO single crystal substrates. This heterostructure configuration provides a path for an all-epitaxial thin film Cu2O solar cell, which can serve as a top cell in a tandem structure with a crystalline Si bottom cell. Index Terms — Cuprous oxide, molecular beam epitaxy, heteroepitaxy, photovoltaic.