A high-efficiency GaAlAs double-heterostructure photovoltaic detector

Abstract

An antireflection-coated GaAlAs double-heterostructure photovoltaic detector is described whose extrinsic power conversion efficiency is 56% when used with a focused 8075-μm wavelength laser beam. This, to our knowledge, is the highest photovoltaic efficiency yet reported. A partially reflective rear contact provides extrinsic quantum efficiencies exceeding 0.90 with a relatively thin active region. By restricting the diameter of this contact to 50 μm and using high dopings to reduce series resistance, open-circuit voltages of 1.15 V and fill factors up to 0.84 are obtained. The series resistance was 3.0 Ω, with 1.0 Ω being attributable to the contacts.