InP Solar Cell on Porous Silicon for Improved Solar Energy Conversion

Brimrose Corporation has developed a novel low-temperature and low energy ion-beam assisted growth process for minimizing the problems and improving the quality of the hetero epitaxial films of III-V compound semiconductors on foreign substrates such as silicon, germanium, etc. The improvement in the quality of hetero epitaxial InP/Si films will be achieved by using this novel low temperature growth technique in conjunction with the surface modified silicon substrate. Briefly porous silicon substrate and Brimrose Corporation's low energy hydrogen beam assisted low temperature growth process will be used to improve the InP epitaxial films quality and thereby the solar energy conversion efficiency. Phase I technical objective is to demonstrate that InP epilayer grown on porous silicon substrates will have substantially improved material characteristics than the InP epilayers grown by state of the art MBE and MOCVD growth processes. An InP solar cell on porous silicon will be fabricated, tested and a sample will be provided to BMDO. Phase II objective, initially, is to optimize the process, improve the material properties. During Phase II Brimrose will back coat the InP/porous silicon solar cell with epitaxial GaSb and boost the solar cell efficiency to above 30-35%. The attractive features of this growth technique will be the low V/III ratio, efficient usage of costly metalorganics, improved material properties, high yield, low cost, very thin SLS layers that may need to filter out dislocations due to the use of porous silicon substrates and low temperatures involved.