Investigation of grown ZnS film on HgCdTe substrate for passivation of infrared photodetector

Zinc sulfide (ZnS) thin films were developed on the mercury cadmium telluride (HgCdTe) substrate using the thermal evaporation technique and investigated with X-ray diffraction, energy dispersive analysis of X-rays, atomic force microscopy (AFM) and capacitance-voltage (C-V). The obtained results confirm that the films have a cubic zinc-blend structure with (111) preferred orientation and nearly stoichiometric composition. The AFM measurement reveals that the film is uniform, densely packed and has a smooth surface or very low roughness. The C-V measurement of a ZnS/HgCdTe based metal-insulator-semiconductor device provides the utility of ZnS thin film as a passivation layer for the HgCdTe substrate. The evaluated fixed-charge density, slow state density and fast state density of the device are 4.98 × 1010 cm−2, 4.22 × 1010 cm−2 and 5.32 × 1011 cm−2 eV−1, respectively. Thus, the grown ZnS thin film could be used as a suitable passivation agent in HgCdTe-based infrared detector fabrication.