Complex chalcogenides as highly-polarizable semiconductors*

Ternary sulfides and selenides in the distorted-perovskite and related structures (“complex chalcogenides”) are predicted to be semiconductors with band gap in the visible-to-infrared, and may be useful for optical, electronic, and energy conversion technologies. The crystal structures familiar to complex oxides, together with larger chalcogenide anions, suggest that complex chalcogenides will be highly polarizable semiconductors.

We will report theoretical and experimental progress towards establishing the fundamentals of highly-polarizable complex chalcogenide semiconductors. We use computational thermodynamics to predict the phase diagrams for select materials, highlighting windows of equilibrium between solid and vapor phases – relevant to growing films by molecular beam epitaxy (MBE). We then report on progress towards MBE growth of complex chalcogenide films, focusing on control of H₂S and H₂Se gas precursors. We will also report experimental results on complex chalcogenides in the Ba-Zr-S system, including time-resolved photoluminescence suggesting slow minority carrier recombination, and impedance spectroscopy providing evidence of highly-polarizable materials with band gap below 2 eV.