Advancements in Light Management for Thin-Film Space Photovoltaics

This work studies the integration of textured back surface reflectors (BSR) in 600 nm-thick InGaAs solar cells to improve radiation tolerance and maintain efficiency in inverted metamorphic (IMM) solar cells. Current enhancement is demonstrated in the InGaAs solar cells with textured BSRs compared to a similar device with an absorbing BSR. The textured BSRs consist of wet-chemical maskless etching and in situ texturing during epitaxial growth. The textured layers achieve higher surface roughness than the pre-textured surface, indicating extended photon scattering. The device characterization emphasizes the impact of free-carrier absorption in the backside textured layers, mainly evident within the Al0.25Ga0.75As maskless BSR solar cell, which has a high p-type doping concentration. All devices had similar fill factor and V-OC near 74% and 0.57 V, respectively, indicating no negative influence on electrical performance from the texture development. Reducing parasitic absorption in the AlGaAs textured layer and back mirror will enhance the current collection and render a platform for thin-film bottom InGaAs subcells with textured BSR to successfully improve radiation tolerance and sustain IMM device performance.