Photoconductivity of Semiconductor Materials at Low Temperatures

We have extended the technique based on a whispering gallery mode disk dielectric resonator (WGM DDR) to study the changes of photoconductivity of low-loss semiconductors under the optical radiation at low temperatures in the millimeter waveband. For this purpose the cryodielectrometer was modified, and a set of DDRs made from semiconductor materials as Si:Au, InP etc. was investigated at dark and light illumination conditions. Peculiarities of variation of resonance frequency and Q-factor of DDR under illumination by laser sources of three different optical wavelength are shown. Preliminary results have shown the possibility of implementation of WGM DDR technique for study of photoconductivity properties of high-resistance semiconductors at low temperatures in the millimeter waveband.