Comparison of different passivation layers for GaInAs solar cells grown by solid-source molecular beam epitaxy

• The effect of the passivation material on the solar cell performance was studied. • All growths were conducted using a solid-source MBE system. • The quality of MBE-grown GaInAs/InP heterostructures was improved. • The cell with InP window and AlInAs BSF showed the highest V OC of 394 mV. • The obtained V OC is the highest value ever achieved in an MBE-grown GaInAs solar cell. Ga 0.47 In 0.53 As solar cells with a 0.74 eV bandgap were grown by solid-source molecular beam epitaxy (MBE) using different passivation layer combinations. Al 0.48 In 0.52 As (hereafter, AlInAs) and InP with 1.50 and 1.35 eV bandgaps, respectively, are promising candidates for use as passivation layers. Since As 2 and P 2 are used in GaInAs/InP heteroepitaxy, the effect of exposing the InP and GaInAs surfaces to As 2 and P 2 fluxes was evaluated before the GaInAs solar cell growth to improve the heterointerface quality. It was found that an exposure time of 10s was sufficient to obtain clean heterointerfaces by minimizing the As–P exchange reaction on each surface. Regarding the solar cell performance, by implementing an InP window and AlInAs back-surface field layers on a GaInAs solar cell, the recombination at both the front and rear surface can be effectively reduced. Consequently, 13.04% conversion efficiency with a 394 mV open-circuit voltage was obtained. This is the highest efficiency ever achieved in an MBE-grown GaInAs solar cell on InP.