A narrow-bandwidth hydrogenated amorphous silicon (a-Si : H) photodetector with a basic structure of Al/n+-i-p+-i-n-i-p-i-n+/ITO/glass has been investigated. The spectral response of this new photodetector was found to be affected by the absorption coefficient of a-Si:H material, surface recombination current, device layer thicknesses, and applied bias. The spectral response of this device reveals a measured minimum FWHM of 58 nm at zero volt bias. The peak wavelength in the visible spectrum can be shifted from 400 nm (purple) to 550 nm (green) by decreasing the bias voltage from 5 to 0 V. The optoelectronic characteristics of this photodetector fit theoretically using suitable quantitative estimates.
