Via-hole fabrication for III-V triple-junction solar cells

Abstract

Backside contact technology for InGaP/GaAs/InGaAs inverted metamorphic (IMM) triple junction solar cells is a potential avenue for achieving significant improvements in solar cell efficiency. To implement such a backside contact technology in IMM triple-junction III-V solar cells, through-cell via-hole fabrication is a key fabrication process. To address this challenge, a three-step etching process has been developed for via-hole fabrication. The etching process includes two Cl2/Ar inductively coupled plasma reactive ion etching steps, followed by a selective wet etch to form via-holes with excellent sidewall anisotropy and etch morphology. The process enables fabrication of backside contact photovoltaic cells for improved efficiency.