Tuning structural, electrical, and optical properties of oxide alloys : ZnO_1-xSe_x

Previously we showed that it is possible to narrow the band gap of zinc oxide from 3.3 to ∼2 eV through the addition of Se. Here, we use thin film samples of ZnO_1-xSe_x grown by pulsed laser deposition to describe in detail the effect of growth parameters (temperature, pressure, and fluence) on the chemistry, structure, and optoelectronic properties of oxide alloys. We analyze the influences of temperature, laser fluence, and pressure during growth on the structure and composition of the films and define the parameter space in which homogeneous ZnO_1-xSe_x alloy films can in fact be synthesized. Electronic transport in films grown under different conditions was characterized by resistivity, thermopower, and Hall effect measurements. We discuss how the electron affinity and native defects in polycrystalline oxide alloys enable reasonable mobilities (∼15 cm ²/Vs) relative to their single crystalline counterparts. Finally, we elaborate on the model of optical structure in ZnO_1-xSe_x and discuss the dependence of optical properties on growth temperature and fluence. © 2012 American Institute of Physics.