Investigation of Single-Crystal CdSeTe Thin Films Grown by MBE

Polycrystalline CdTe-based thin film solar cells are at the forefront of commercial thin film photovoltaic products. Recent state-of-the-art experimental CdTe cells have introduced a thin p-type poly-CdSeTe layer into the absorber, which has led to increased carrier lifetimes and overall quantum efficiency. However, carrier mobilities in the poly-CdSeTe layer are extremely low, and the impact of Se on dopant activation and defect complexes is poorly understood. Here, Sivananthan Laboratories, as part of the DOE's CdTe Accelerator Consortium (CTAC) program, has grown As doped and undoped single-crystal CdSeTe layers at various Se compositions. Using the single-crystal layers as a model system, we explore the fundamental impact of Se on CdSeTe lattice structure, PL response, bandgap tuning, and As incorporation.