A Comparison of DC and Modulated Photocurrent in Chalcogenide Glasses

A comparison of DC and frequency modulated photocurrent measurements in amorphous (a-) Se, a-As2Se3, and a-As2Te3 chalcogenide thin films are carried out at room temperature. Current-voltage I-V characteristics are examined and series resistances are determined under dark and different light intensities. The exponent v in the power-law relationship, I-ph similar to G(v) between generation rate, G, and photocurrent, I-ph, are calculated at different applied voltages and modulation frequencies. The small v values are obtained for DC applied voltages (25-500 V), but high v values are found for various modulation frequencies (500-3950 Hz). We report that v is almost independent of applied voltage and modulation frequency within the experimental uncertainty, but it strongly depends on sample characteristics. The results are also compared in detail and interpreted for all three-type samples.