Approach to Defect-Free Lifetime and High Electron Density in CdTe

Achieving simultaneously high carrier density and lifetime is important for II–VI semiconductor-based applications such as photovoltaics and infrared detectors; however, it is a challenging task. In this work, high purity CdTe single crystals doped with indium (In) were grown by vertical Bridgman melt growth under carefully controlled stoichiometry. Two-photon excitation time-resolved photoluminescence was employed to measure bulk recombination lifetime by eliminating surface recombination effects. By adjusting stoichiometry with post growth annealing, high-net free carrier density approaching 10¹⁸ cm⁻³ was achieved simultaneously with lifetime approaching the radiative limit by suppressing non-radiative recombination centers.