Photoelectrical Properties of Semiconductor in Contact with Gas Discharge Plasma

(Received 30 September 1996, revised 27 January 1997, accepted 11 February 1997)

Abstract
The plasma contact effect on spectral characteristics of the longitudinal photoconductivity of GaAs has been investigated in the present paper. The sample studied was a GaAs:Cr high-resistivity (  cm) plate of thickness d = 1 mm and diameter  mm. One electrode (thin semi-transparent Ni layer) was deposited on the plate surface, and another electrode (SnO ₂ 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 semiconductor was illuminated both from the side of the Ni-contact and through plasma contact. The measured spectral characteristics of photocurrent were different in the strong absorption region. When the semiconductor was illuminated through plasma contact the photocurrent was 1.5-2 times higher than for the Ni-contact illumination. The observed phenomenon can be explained by the change of surface recombination velocity of non-equilibrium carriers in the semiconductor due to the bombardment of the semiconductor surface by plasma.