Thermal oxidation of amorphous GaSe thin films

In this work the results of the thermal oxidation of GaSe thin films in air at different temperatures are presented. The structural and morphological characteristics of the thermally annealed products were studied by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The as-deposited GaSe films were amorphous and they transformed into polycrystalline GaSe films with a hexagonal crystal structure at a temperature around 400 °C. Thermal oxidation at 650 °C resulted in the formation of mixed Ga2Se3 and Ga2O3 compounds both in the monoclinic phase. At higher temperatures, Ga2Se3 disappeared and complete oxidation of the initial compound occurred. The optical energy gaps of products were determined at room temperature by transmittance measurements using UV–vis–NIR spectroscopy. ► Thermal oxidation of amorphous GaSe thin films deposited on quartz was studied. ► The oxidation at 400 °C led to the formation of hexagonal GaSe film. ► The oxidation at 650 °C led to the formation of monoclinic Ga2Se3 and Ga2O3 film. ► The oxidation at 900 °C led to the formation of monoclinic Ga2O3 film. ► The band gap increased with increasing temperature of oxidation.