Photovoltaic Cells for Very High Altitude Very Long Endurance Solar Aircraft

The significance of the innovation in this Phase II SBIR is the development of a low cost, lightweight epitaxial lift-off (ELO) process for large improvements in the power/weight ratio in solar cell devices. This effort will advance solar cell development by decreasing the weight while maintaining the efficiency performance of the solar cell. The innovation of this work is based upon the complete removal of the GaAs substrate from the epitaxial layers while maintaining the performance of the solar cell device and the re-usage of the GaAs substrate. Development efforts will focus on the manufacturability of the ELO process towards increasing the throughput and device yield. This effort will concentrate on the development of large scale plating which plays a critical role in the ELO process. Initial work will be on 4-inch GaAs substrates and will be subsequently transferred to 6-inch GaAs substrates since this provides a significant increase in throughput for material growth and device processing. The goal is to achieve an overall solar cell device yield of at least 85%.