Conduction studies on ZnTe thin films

摘要

Zinc Telluride (ZnTe) is a II-VI compound semiconductor with zinc-blende Structure. Due to its wide, direct band gap, ZnTe is of considerable interest for potential application in optoelectronic devices. It has been extensively studied for application as back contact for CdTe in CdTe/CdS heterojunction solar cells. The ZnTe thin film was deposited onto well-cleaned glass substrate in between aluminium electrodes to form the MSM structure under the vacuum of 10-5 Torr. The thickness of the film was measured by multiple beam interferometer (MBI) technique. From X-ray analysis, it has been found that ZnTe thin film possesses crystalline structure. The transport mechanism in these films under a.c. fields was studied in the frequency range 12 Hz to 100 kHz, at different temperatures (303-483 K). The dependence of capacitance and loss factor on frequency, for different temperatures was investigated and results are discussed. The process of a. c. conduction has been explained on the basis of hopping conduction mechanism. The dielectric constant (epsilon'), temperature co-efficient of capacitance (TCC) and temperature co-efficient of permitivity (TCP) were estimated The dependences of activation energy on frequency and thickness were also studied.