Signal strength enhancement and bandwidth tuning in moving space charge field photodetectors using alternating bias field

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Abstract
Enhancement of the photocurrent density generated by internal moving space charge electric fields in semi-insulating GaAsmultiple quantum wells is observed when the sample is biased with a high speed, zero-mean square waveelectric field which increases the internal space charge electric field strength. Tunability of the space charge field formation time is also demonstrated by adjusting the amplitude of the bias signal. This technique can be used to enhance the sensitivity of optical dopplerfrequency measurements based on moving space charge field effects in photoconductive semiconductors. Electronic tunability of the space charge field formation time also adds versatility in optical power spectrum analysis applications.