Preparation and surface defect regulation of CdZnTe films based on GaN substrates

High quality polycrystalline CdZnTe (CZT) films were prepared on GaN substrates via close-spaced sublimation (CSS). Au electrodes were deposited on the surface of CZT films to form CZT/Au structure. XRD, SEM, EDAX and UV-Vis spectra were adopted to investigate the structure, composition and morphology of CZT films. XPS and I-V characterizations were used to investigate the surface defects and electrical properties of CZT films. The quantity of the surface defects is decreased with the extended growth times and remains stable when the deposition times exceed 20 min. The minimum resistivity of CZT thick films grown on GaN substrates is 1.12 × 109 Ω-cm, which is about two orders of magnitude higher than that on FTOs. The high resistivity can significantly reduce the leakage currents of CZT films and thus improve the signal-to-noise ratio of the radiation detector based on CZT films.