Epitaxial Lift-Off of Single-Junction GaAs Solar Cells Grown Via Hydride Vapor Phase Epitaxy

Hydride vapor phase epitaxy (HVPE) is attracting attention as a technology for reducing the epitaxial cost of III-V solar cells. To further reduce manufacturing costs, it is effective to combine HVPE with substrate-reuse technology using epitaxial lift-off (ELO). However, ELO of solar cells grown via HVPE has not yet been demonstrated. Although Al(Ga)As is typically used as the release layer for the ELO process, there is a difficulty in growing Al-containing materials on HVPE because aluminum monochloride reacts with the reactor. Here, we present the growth of AlAs via HVPE using aluminum trichloride generated by the reaction between Al metal and HCl gas at a temperature of 500 °C. The AlAs layer grown via HVPE exhibits sufficient crystal quality to achieve the ELO process. We obtained a conversion efficiency of 21.63% for a HVPE-grown GaAs single-junction solar cell peeled off from a GaAs substrate. This performance is almost similar to that of HVPE-grown solar cells on GaAs substrates without ELO.