Effect of Sn content on the electrical and optical properties of Ge 1− xSn xSe 3 glasses

Abstract

The effect of Sn impurity on the electrical and optical properties of Ge 1− x Sn x Se 3 films has been studied. The current–voltage characteristics in the off-state and switching phenomenon were investigated in the thin Ge 1− x Sn x Se 3 ( x=0, 0.2, 0.4 and 0.6) films system. Both dynamic and static I– V curves for switching and memory behaviour have been studied. The threshold switching voltage was found to increase linearly with increasing film thickness (250–923.1 nm), while it decreased exponentially with increasing temperature. The conduction activation energy and the pre-exponential factor which appear in the dc conductivity are decreased to x=0.4. Intrinsic defect states induced by Sn impurity were suggested to enhance hopping conduction. At x=0.6, partially crystalline films were formed. The reflectance and the transmission were analysed to measure the optical gap, which decreases as the Sn content increases. The variation of the refractive index and the imaginary part of the dielectric constant with photon energy have been reported. The influence of composition on the investigated parameters is reported and the implications are discussed.