Sb-doped CuAlO2: Widening of band gap and nonlinear J-E characteristics

The effect of antimony doping on the optical and electrical properties of copper aluminum oxide synthesized by solid state reaction technique was investigated. Formation of single phase CuAlO2 was confirmed by x-ray diffraction studies. Variation of strain, particle size, and preferred orientation of the crystallites with Sb doping concentrations were analyzed by x-ray diffraction. Using the x-ray photoelectron spectroscopy trivalent state of Sb ions was confirmed. A blue shift in the energy band gap with Sb doping was observed, and it was supported by ab initio calculation based on density functional theory. A nonlinear current-voltage characteristic was observed for the Sb-doped CuAlO2 samples whereas the same was linear for the undoped samples. The nonlinearity of the current-voltage characteristics changed significantly at higher temperature, and this behavior was explained.