Investigation of physical properties of quaternary AgGa _o.5In_o.5Te₂ thin films deposited by thermal evaporation

The aim of this study is to understand the structural, optical and photo-electrical properties of the quaternary chalcogenide AgGa _0.5In_0.5Te₂ thin films deposited onto the glass substrates by thermal evaporation of the single crystalline powder. Energy dispersive X-ray analysis (EDXA) showed remarkable change in atomic percentage of the constituent elements after annealing. The X-ray diffraction (XRD) of the films below the annealing temperature of 300°C indicated the polycrystalline structure with co-existence of AgGaTe₂ and AgGa_0.5In _0.5Te₂ phases. However, the single phase of AgGa _0.5In_0.5Te₂ chalcopyrite structure was obtained at the annealing of 300 °C. The band gap values were calculated in between 1.05 and 1.37 eV depending on annealing temperature. The temperature dependent photoconductivity was measured under different illumination intensity. The nature of existing trap levels were studied by measuring the variation of photocurrent as a function of illumination intensity. The analysis showed that AgGa_0.5In_0.5Te₂ thin film changes its behavior from the sublinear to supralinear photoconductivity after annealing.