PHOTOELECTRICAL PROPERTIES OF SEMICONDUCTOR IN CONTACT WITH GAS-DISCHARGE PLASMA

The plasma contact effect on spectral characteristics of the longitudi nal photoconductivity of GaAs has been investigated in the present pap er. The sample studied was a GaAs:Cr high-resistivity (rho = 10(7) Ohm cm) plate of thickness d = 1 mm and diameter similar to 20 mm. One el ectrode (thin semi-transparent Ni layer) was deposited on the plate su rface, and another electrode (SnO2 film) was separated from the plate surface by the gas discharge air gap. The constant voltage applied to the electrodes was higher than the breakdown voltage. The semiconducto r was illuminated both from the side of the Ni-contact and through pla sma contact. The measured spectral characteristics of photocurrent wer e different in the strong absorption region. When the semiconductor wa s illuminated through plasma contact the photocurrent was 1.5-2 times higher than for the Ni-contact illumination. The observed phenomenon c an be explained by the change of surface recombination velocity of non -equilibrium carriers in the semiconductor due to the bombardment of t he semiconductor surface by plasma.