Photoconductance and photoresponse of layer compound photodetectors in the UV-visible region

In this study, a number of photoconductive photodetectors made from GaSe1-xSx (0 <= x <= 1) series layered semiconductors are presented, which are suitable for the detection of energies in the range of visible to ultraviolet (UV). Each photodetector consists of a gallium chalcogenide photoconductor and an electronic amplifier, forming an optical sensor unit covering the energy spectrum range from red (2 eV) to UV (similar to 5 eV). Spectral photoconductances of the GaSe1-xSx series layers with x=0, 0.1, 0.2, 0.3, 0.4, and 1 are characterized using photoconductivity measurements in the energy range of 2-4 eV, and the results of these measurements are analyzed. Photoluminescence and piezoreflectance measurements are carried out to identify the band-edge transitions of the layered GaSe1-xSx (0 <= x <= 1) compounds. From experimental analysis the transition origins of the band-edge transitions are clarified. The functional performance of three selective sensor units of GaSe, GaS, and two-color GaS/GaSe is tested using the spectral measurements of a xenon arc lamp. The emission line features from the xenon arc lamp are clearly resolved in the detection spectra of the sensor units. The results show a good functional performance of these layer compound photodetectors.