Light Wavelength Effects on Performance of a-Si:H PIN Photodiodes

Abstract

ABSTRACTLight effects on the performance of the a-Si:H PIN photodiode has been studied. The leakage current-voltage and capacitance-voltage curves under the red, green and blue light illuminations were measured. The apparent charge storage density in the negative voltage range was quantified from the capacitance-voltage curve; charges in the positive voltage range were estimated from the leakage current-voltage curve. A comparison of charge storage capacities of diodes with different intrinsic layer thicknesses is also presented. The diode under the long wavelength light illumination condition stored more charges than that under the short wavelength light illumination condition because the former could penetrate the intrinsic a-Si:H layer deeper than the latter could. The leakage current and charge storage capacity of the diode are determined by the generation of electron-hole pairs, the depletion of charges in the intrinsic layer, and the supply of charges from the electrodes. The number of incident photons is critical to the process.