ELECTRICAL, THERMAL AND OPTICAL-PROPERTIES OF SE75GE7SB18

Electrical, thermal and optical properties of Se75Ge7Sb18 in bulk and thin film form were studied. X-ray diffraction patterns indicate that the bulk sample and the prepared films at room temperature had amorphous structure. The dc electrical conductivity and the thermal conductivity of Se75Ge7Sb18 were measured at room temperature and at elevated temperatures up to the glass transition temperature (T(g)). The conduction activation energy DELTA-E was determined. Switching and memory effects have been studied. The threshold switching voltage, V(th), was found to increase linearly with the film thickness. Moreover, V(th) decreases exponentially with temperature. The obtained data were analysed using the thermal model for switching processes. The optical constants (refractive index n and absorption index k) of Se75Ge7Sb18 thin films were determined in the spectral range of 0.4-1.2-mu-m. The absorption coefficient (alpha) of this system was also determined. Analysis of the absorption spectrum reveals indirect optical transitions. The corresponding forbidden-band width was determined. Its value is approximately twice the conduction activation energy.