High-quality II-VI films grown on amorphous substrates using tunable tetradymite templates

We demonstrate the growth of highly oriented CdSe and ZnTe films at ∼300 °C on amorphous substrates such as glass and flexible polyimide using ultrathin tetradymite buffer layers composed of Sb_xBi_2-xTe₃ alloys lattice-matched to the film overgrowth. This leads to significant improvement of the crystallinity, roughness, grain size, and pit density of the II-VI overlayer along with enhancement of the optoelectronic properties. For example, photoluminescence emission is observed at ∼1.74 eV for optimized CdSe films, the same as in a single crystal reference. An in-plane carrier diffusion length of ∼500 nm is inferred from transient optical data. The use of tetradymite buffer layers to control II-VI compound deposition on non-crystalline substrates is a promising route for large area optoelectronic applications such as photovoltaic, light-emission, or infrared detector devices.