Dielectric and transport properties of thin polycrystalline CdTe films

The electrical properties of vacuum-deposited CdTe thin films as functions of temperature, frequency, film thickness and applied field for various substrate temperatures are reported. A detailed examination of these results reveals the presence of an electron trap which is 0.58 eV below the conduction band edge with a density of (5−10) × 1015 cm−3. The position of this trap correlates well with the reports of other investigators for CdTe single crystals and thin films. The dielectric constant evaluated (8.70) at 1 kHz is independent of film thickness. The AC conductivity of these samples investigated is proportional to ωn, a being the angular-frequency and n a temperature-dependent quantity; the value of n decreases with increase in temperature. Analysis of the law-temperature frequency-dependent conductivity indicates that hopping is the dominant mechanism of conduction.