Variation of electrical transport properties and thermoelectric figure of merit with thickness in 1% excess Te-doped Pb<inf>0.2</inf>Sn<inf>0.8</inf>Te thin films

Pb0.2Sn0.8Te thin films of different thicknesses have been deposited on glass substrates by flash evaporation. Electrical resistivity and thermoelectric power measurements have been carried out in the temperature range 300-500 K as a function of film thickness. The thickness dependence of the electrical resistivity and thermoelectric power observed has been explained using the effective mean free path model of classical size effect theory. The thermoelectric power factor was calculated from the measured values of electrical resistivity and thermoelectric power. The thermoelectric power factor is found to be dependent on thickness and temperature. By taking thermal conductivity values from the literature, the thermoelectric figure of merit was also calculated and it was found that this too was dependent on the temperature and thickness.