Mercury cadmium telluride films were grown by the RF magnetron sputtering technique at different sputtering powers.In experiment,X-ray diffraction(XRD) and atomic force microscopy(AFM) have been used to characterize the microstructure of HgCdTe films.The experimental results showed that when the growth power increased,the growth rate of HgCdTe films increased;when the growth power was less than 30 W,the HgCdTe film deposited by RF magnetron sputtering was amorphous;when the growth power was more than 30 W,the films exhibited polycrystalline structure.Films deposited at different growth rates were found to have characteristically different formations and surface morphologies;as observed through AFM,the surface morphology is composed of longitudinal islands forming a maze-like pattern in the high deposition rate.AFM analysis also illustrated that a significant reduction in the areal density of large islands and characteristically smoother films was achieved using a low deposition rate.
This paper reports the dark conductivity and photoconductivity of amorphous Hg0.78Cd0.22Te thin films deposited on an Al2O3 substrate by RF magnetron sputtering.It is determined that dark conduction activation energy is 0.417 eV for the as-grown sample.Thermal quenching is absent for the as-grown sample during the testing temperature zone,but the reverse is true for the polycrystalline sample.Photosensitivity shows the maximum at 240 K for amorphous thin films,while it is higher for the as-grown sample than for polycrystalline thin films in the range from 170 to 300 K.The recombination mechanism is the monomolecular recombination process at room temperature,which is different from the low temperature range.Theμτ-product is low in the range of 10-11-10-9 cm2/V,which indicates that some defect states exist in the amorphous thin films.
