Electrical properties of gamma-In2Se3 layers synthesized by solid state reaction between In and Se thin films

In2Se3 layers were obtained by solid state reaction induced by annealing between the In and Se constituents sequentially deposited in thin film form. The annealing is carried out under a selenium atmosphere which allows polycrystalline films of the gamma-In2Se3 phase to be obtained. Conductivity measurements show that five different behaviours are encountered depending on the history of the sample. After X-ray diffraction and X-ray photoelectron spectroscopy measurements, the different behaviours are interpreted in terms of crystalline quality and contamination of the layer with oxygen and/or carbon. The conductivity is controlled by grain boundaries. When some contamination (intentional or otherwise) occurs, the properties of the grain boundary are modified, which explains the different behaviours of the layers.