Methods for bringing the time dependence of photocurrent resistor to the shape of the optical pulses’ intensity, the repetition frequency of which is higher than the boundary frequency of the photodetector

Abstract

Background. he dependences of the light intensity on time and the photocurrent flowing in the resistor are generally described by various functions. Methods have been studied for obtaining the time dependence of the intensity of light pulses of arbitrary shape, following with a frequency ω, from the time dependence of the photocurrent in the presence of recombination of charge carriers on the surface of the semiconductor. Materials and methods. The results were obtained based on a study of the kinetics of photoconductivity of a resistor for linear and quadratic recombination laws in the bulk of a semiconductor. The diffusion of nonequilibrium charge carriers to the surfaces of the photoresistor with their subsequent surface recombination is taken into account. The first method is based on the use of the photocurrent differentiation operation. The second method allows you to restore the intensity of an optical pulse of an arbitrary shape from the amplitudes of the harmonics of the expansion of the function that specifies the dependence of the current on time in a Fourier series. Results and conclusions. Nonlinear, frequency and phase distortions in the region of high frequencies are small. The proposed methods are valid when the inequality ωτ≥1 (τ is the effective lifetime of the main charge carriers) is fulfilled.

Keywords

• photoconductivity kinetics
• generation rate
• recombination rate
• nonlinear distortions
• surface recombination