Tunable properties of wide-band gap p-type BaCu(Ch1 − xChx′)F (Ch = S, Se, Te) thin-film solid solutions

Thin-film solid solutions of BaCu(Ch_1 − xCh_x′)F (Ch, Ch′ = S, Se, or Te) wide-band gap p-type semiconductors are obtained by pulsed laser deposition at elevated substrate temperatures from alternating layers of BaCuChF and BaCuCh′F. Adjusting the thickness of the component layers varies the relative chalcogen content, which allows tunability of the film transparency and results in a conductivity change of more than three orders of magnitude. The tunability of the physical properties makes these chalcogen-based semiconductors potentially useful for optoelectronics applications. Lattice parameters of BaCuChF calculated using density functional theory agree with those previously reported for the powders. Deviations from Vegard's law are observed in BaCu(S_1 − xSe_x)F thin films with large sulfur content.