Giant resonant enhancement of the nonstationary holographic currents in an alternating electric field

Abstract

We report the resonant excitation of the nonstationary holographic currents in photoconductive crystals placed in a sinusoidal electric field. The analysis of the effect is performed for the simplest model of a semiconductor with monopolar photoconductivity. We demonstrate that the frequency transfer function of the effect has a maximum at ${\ensuremath{\omega}}_{r}\ensuremath{\simeq}K\ensuremath{\mu}{E}_{0}$ originating from the resonant excitation of photoconductivity gratings. The dependences of the holographic current amplitude versus effective value of the ac electric field ${E}_{0},$ spatial frequency of the interference pattern K, and light intensity ${I}_{0}$ are measured in the photorefractive n-type ${\mathrm{Bi}}_{12}{\mathrm{SiO}}_{20}$ crystal. The drift mobility of electrons is estimated from the position of the resonant peak on the frequency transfer function of the effect: $\ensuremath{\mu}=0.13--0.8{\mathrm{cm}}^{2}/\mathrm{V}\mathrm{}\mathrm{s}.$ The advantages of the photocurrent generation in ac fields are pointed out, and possible practical applications of the effect are discussed.