Charge transport mechanism of Al/Bi2Te3/Al thin film devices

Results of dielectric and conduction properties of vacuum evaporated Bi2Te3 thin film capacitors (Al/Bi2Te3/Al) have been reported in the frequency range 12 Hz to 100 kHz at various temperatures (303–423 K). The variation of capacitance and dielectric constant was found to be temperature and frequency dependent. The capacitance of the film decrease with increasing temperature which may be due to the expansion of the lattice and also due to the excitation of charge carriers at the sites of imperfection. The dielectric constant decreases with frequency at all temperature. This can be attributed to an interfacial polarization caused by space charge. The prevailing ac conduction mechanism in these films is hopping type. The activation energies were evaluated for various thicknesses and it is found to be 0.016 and 0.014 eV for the frequencies 200 Hz and 1 kHz, respectively.