Advances in control of doping and lifetime in single-crystal and polycrystalline CdTe

We demonstrate the controlled alteration of bulk defects in CdTe single crystals and polycrystalline films to achieve high bulk minority-carrier lifetime and p-type doping. Low-temperature photoluminescence measurements confirm that bulk defect chemistry is altered by inserting intentional extrinsic dopants. Group I dopants such as copper display a tradeoff where increased doping decreases lifetime. By incorporating a Group V dopant source such as phosphorus, bulk lifetime values of 20-40 ns with acceptor density values of 0.7-1.0×10¹⁶ cm^-3 are obtained in single and polycrystalline CdTe crystals. This exceptional combination of long lifetime and high p-type doping in a manufacturable material provides a path to increase open-circuit voltage, fill factor, and efficiency in CdTe photovoltaic devices.