Modification of photoelectric and electrical properties of III-V semiconductors by pulsed laser irradiation

Abstract

The effect of nanosecond ruby laser pulses on the photoelectric and electrical properties of GaAs and InSb single crystals with different pre-treated surfaces was studied. The photoconductivity, surface recombination rate and electrical resistivity of the samples have been analysed before and after irradiation with laser pulses characterized by a wide range of energy densites. An increase in the photoconductivity and decrease in the surface recombination rate of the investigated crystals was attributed to cleaning of the crystal surface and to the laser-stimulated desorption and segregation of electrically active defects at sinks. A considerable reduction in the resistivity of GaAs and a shift of the maximum and of the red edge of the photoconductivity specrtrum of InSb crystals toward shorter wavelengths were observed after irradiation with laser pulses of energy density above the melting threshold. The reasons for the found phenomena have been determined and the mechanism of the action of laser-induced stress and shock waves on the structure and properties of the crystals has been discussed.