Comparative frequency-resolved photoconductivity studies of amorphous semiconductors

Comparative frequency-resolved photoconductivity measurements in amorphous (a-) semiconductors, such as a-Si:H p–i–n junction, a-SiGe:H and a-chalcogenides (a-Se, a-As2Se3, a-As2Te3, a-SeTe, a-As2S3, etc.) are reported. In particular, photoconductivity lifetimes as a function of light intensity and temperature were determined by using the quadrature frequency-resolved spectroscopy method. The activation energies from the temperature-dependent lifetime and photocurrent were determined and compared in different materials. The exponent ν in the power-law relationship (Iph∝Gν) between generating flux and photocurrent was also obtained at different excitation wavelengths. The results were compared with the predictions of multiple-trapping (MT) and distant-pair (DP) models developed for photoconductivity of a-semiconductors at high and low temperatures, respectively.