Epitaxial lift-off of large-area GaAs multi-junction solar cells for high efficiency clean and portable energy power generation

Epitaxial lift-off (ELO) is a processing technique that enables thin epitaxial layers grown on GaAs substrate to be “peeled off” from the host substrate. The ELO process offers several key advantages for both performance enhancement and cost reduction of III-V electronic and optoelectronic devices. The epitaxial films can be transferred to new support substrates that are thin, flexible, lightweight, and with higher thermal conductivity than the original growth substrate. The GaAs substrate can be reused multiple times without any performance degradation. We have developed an ELO process capable of lifting off large areas of semiconductor material from substrates up to 6 inches in diameter without any degradation of material quality or performance characteristics. Solar cells with a 33% efficiency under 1-sun AM 1.5 and 31% efficiency at 1-sun under AMO were demonstrated using ELO. Production of this technology for fabricating thin, flexible large-area multi-junction solar cell arrays with very high efficiency has been established. Light weight portable solar sheets for remote charging have been produced. Other applications include electric-powered, unmanned aerial vehicles (UAVs), space satellites, and terrestrial solar concentrator systems.