Arsenic doped Cd-rich CdTe: Equilibrium doping limit and long lifetime for high open-circuit voltage solar cells greater than 900 mV

Abstract

The combination of group-V element doping and Cd-rich composition is the most promising current strategy for maximizing p-type doping while preserving long lifetime. In this study, we carefully measure the equilibrium p-type doping limit for As-doped Cd-rich CdTe single crystals and demonstrate a doping limit in the low 1017 cm-3 range upon slow cooling. We present evidence for self-compensation with rapidly decreasing doping efficiency per added As above 5 × 1016 cm-3, yet we also demonstrate CdTe with >1017 cm-3 hole concentration and bulk lifetime >30 ns. Such crystals allow As-doped CdTe photovoltaic devices with open-circuit voltage exceeding 900 mV.