The Fourier analysis of a-Si:H photodiode transient response

In this paper, color detection based on the transient response of n-i-p a-Si:H photodiodes to light and voltage pulses was described. The responses to a voltage pulse at constant light and to a light pulse at constant reverse bias voltage were also measured. From the measured dark current as well as the photocurrent, which are both proportional to the instantaneous charge change, the charge was calculated using the FFT method. In the case of transient response to light and voltage pulses, the changeable capacitance as a measure of wavelength dependent light absorption is introduced. The obtained results show the charge increment's dependence on wavelength and confirm the p-i-n a-Si:H photodiode as an efficient color detector.