The electrical properties of CdTe films of different preparation conditions in correlation with microstructure changes

Polycrystalline films of CdTe have been thermally deposited on glass substrates. Using the Van der Pauw technique, the dark resistivities have been measured at different temperatures (298-523 K). The resistivity, rho, was found to decrease markedly in the range of thickness less than 400 nm and was then subjected to a slight decrease at larger thicknesses. The behaviour was found to fit properly with the Fuchs and Sondheimer relation with parameters rho = 4.39 x 10(5) Omega cm and mean free path, I = 734 nm. Raising the substrate temperature and decreasing the deposition rate were found to increase the resistivity monotonically. Annealing the prepared films caused a significant decrease in the resistivity particularly for films of small thicknesses (t < 500 nm). The log rho vs. 1/T curves showed three distinct regions at high, low and sufficiently low temperature regions with decreasing activation energies, 0.39 eV, 0.29 eV and 0.19 eV respectively. The data obtained at higher regions has been analysed in accordance with Seto model. Attribution of the film resistivity variation to microstructure changes of the films are discussed.