Final Report: A Novel Tandem Homojunction Solar Cell, July 1, 1995 - June 30, 1999

The eventual target material, ZnSnP{sub 2}, was difficult to grow with MBE because of the high phosphorus vapor pressure. We decided to begin by growing a similar material, ZnSnAs{sub 2}, that also has a band gap dependent on the growth temperature that is related to the metal sub lattice site disorder. We were successful at growing and characterizing this material with MBE. Single crystals of a variety of the chalcopyrite materials were also prepared and characterized. The single crystals were used for optical and electronic property comparisons with the MBE and MOMBE grown thin films. Films of ZnSnP{sub 2} were eventually grown using organophosphorus precursors in an MOMBE growth process. This was also described in a published paper. We also completed the most thorough solid state NMR characterization of 11-IV-V{sub 2} chalcopyrite semiconductors yet done. This paper will soon be submitted to ''Chemistry of Materials''. Although we did not succeed in preparing a photovoltaic device we did pioneer new growth methods for preparing epitaxial layers of these materials and were able to obtain acceptable electronic properties from the thin film materials. Five high quality publications and two PhD thesis were also a direct result of this research project