Photoelectrical and electrical properties of polycrystalline CdxHg1-xTe layers on GaAs substrates

Temperature dependences of electrical conductivity, concentration, and mobi lity of electrons, as well as photoconductivity spectra and conductivity-il lumination characteristics of Cd0.8Hg0.2Te polycrystalline layers grown on GaAs substrates are studied. The features of charge transport and photocond uctivity of CdxHg1-xTe/CdTe/GaAs structures are discussed. It is establishe d that a high photoconductivity at a temperature of 300 K and a jump in con ductivity-illumination characteristics at high levels of excitation are cau sed by the influence of electrically active grain boundaries, which produce the potential barriers for the drift and recombination of charge carriers. It is shown within the framework of the semiconductor barrier model with a random potential relief pattern that, for high levels of excitation by the radiation pulses of ruby or neodymium lasers, the height of potential barr iers at the grain boundaries lowers due to screening by nonequilibrium carr iers. (C) 2000 MAIK "Nauka/Interperiodica".