Properties and modelling of InGaN for high temperature photovoltaics

In this work we present the temperature-dependent electrical properties of undoped, n-type, and p-type InGaN layers and p-type superlattices at temperatures up to 200 °C. The analysis takes into account contributions from underlying GaN buffer layers and piezoelectric polarization at the GaN-InGaN interface. P-type InGaN-GaN superlattices show much greater conductivity than p-GaN, but less change relative to room temperature than p-GaN. In light of these results, InGaN photovoltaic performance has been modeled from room temperature to 200 °C for bandgaps between 2.2 and 1.8 eV. For these bandgaps, the efficiency of p-i-n solar cells is projected to drop around 30% at 200 °C relative to the efficiency at 25 °C.