Electrical and optical properties of amorphous Te40As38Ge10Si12 thin films

Electrical, optical and structural, properties, of Te40As38Ge10Si10 thin films were studied. X-ray diffraction patterns indicate that these films are in an amorphous state. The dark electrical resistivity of Te40As38Ge10Si12 films was measured at room temperature and at elevated temperature. The thermal activation energy ΔE was determined. The optical constants (refractive index n and absorption index k) of such films were determined in the spectral range of 0.5-2.0 μm. The absorption coefficient (α) of this system was determined using the known equation α = 4πk/λ. The refractive index n has anomalous behaviour near the absorption edge. Analysis of the absorption spectrum reveals indirect optical transitions. The corresponding forbidden-band width was determined. Its value is approximately twice the thermal activation energy.