Amorphous HgCdTe thin films were deposited on quartz substrate by RF magnetron sputtering technique. The modulated photocurrent(MPC) of amorphous HgCdTe thin films has been investigated as a function of temperature T, the excitation light intensity F, and applied electric fields E B . The results indicated that the modulated photocurrent show an activated behavior in the range of 80K-300K. The activated energy ΔE ap of the modulated photocurrent was found to strongly depend on temperature, whereas it is nearly independent of the applied electric field. The exponent γ in the power law relationship (I p ∝F γ ) between excitation light intensity F and modulated photocurrent of amorphous HgCdTe thin films was obtained at different temperature. The γ depends strongly on the temperature T, but it is independence of applied electric fields E B . The values of exponent γ of amorphous HgCdTe thin films lie between 0.5 and 1.0. The results indicated a continuous distribution of localized states exists in amorphous HgCdTe thin films.
This paper reports the dark conductivity and photoconductivity of amorphous Hg 0:78 Cd 0:22 Te thin films deposited on an Al 2 O 3 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. The -product is low in the range of 10 11 -10 9 cm 2 /V, which indicates that some defect states exist in the amorphous thin films.
The relationship between the dark conductivity (σ d ) and temperature (T) of amorphous HgCdTe films has been investigated at 80-300 K. The measurement of σ d as a function of T indicates the presence of four distinct regions: (I)
The persistent photoconductivity (PPC) of amorphous Hg0.78Cd0.22Te: In films has been studied under illumination by super-bandgap light (a He-Ne laser, hv = 1.96 eV, 30 mW/cm2) and sub-bandgap light (1000 K Blackbody source, the largest photon energies hvp = 0.42 eV, 8.9 mW/cm2) in the range of 80-300 K. The persistent photoconductivity effect increases with increase in illumination intensity and illumination time. However, it decreases with increase in working temperature. The non-exponential decay of photoconductivity implies the presence of continuous distribution of defect states in amorphous Hg0.78Cd0.22Te: In films. These results indicate that the decay of photoconductivity is not governed by the carrier trapped in the intrinsic defects, but it may be due to light-induced defects under light illumination.
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