AC and dielectric properties of thermally evaporated p-type (Sb2Te3)70 (Bi2Te3)30 thin films

Thin films of (Sb2Te3)70 (Bi2Te3)30 were prepared by thermal evaporation. The composition of the film was confirmed by energy dispersive analysis (EDAX). X-ray diffraction studies showed that the film was polycrystalline with grain size of 4.39 Å and with a preferred orientation in the (0 1 5) directions. Al/((Sb2Te3)70 (Bi2Te3)30)/Al (MSM) thin film capacitors are formed and its AC and dielectric studies were carried out using a digital LCR metre at various frequencies (12 Hz–100 kHz) and temperatures (303–483 K). The dielectric constant for a film of thickness 3000 Å was found to be 86 for 1 kHz at room temperature. The temperature coefficient of capacitance (TCC) and temperature coefficient of permittivity (TCP) were estimated as 684 and 1409 ppm/K for 10 kHz at 303 K, respectively. The activation energy was estimated as 1.190 eV for frequency of 100 kHz at 303 K. The AC conductivity of the films was found to be a hopping mechanism.