PHOTOELECTRONIC PROPERTIES OF THE GAAS, SI EPITAXIAL LAYERS ON THE GAAS SUBSTRATE

Surface photovoltage spectroscopy (SPS) with a modified Kelvin method and photoconductivity (PC) measurements have been carried out for epit axial GaAs-GaAs:Si layers deposited by a MOCVD method on the semi-insu lated GaAs substrate compensated with chromium. The substrate orientat ion was (100). The silicon concentration in the doped epitaxial layer amounted to 5.4 x 10(16) cm(-3). The measurements were carried out at a temperature of 83 K. The existence of three types of doping levels i n the bulk with energies E(1) = 0.83 eV, E(2) = 1.17 eV and E(3) = 1.4 3 eV below the bottom of the conduction band, and two types of surface levels with energies E(t4) = 0.05 eV and E(t5) = 0.19 eV, also below the bottom of the conduction band, have been stated. The value of the surface voltage barrier V-s(o) = 0.22 eV at 83 K has been measured and the influence of the photoadsorption of the rest gases in the measuri ng chamber on ifs height has been investigated. The energy of the band gap at 83 K, equal to 1.51 eV, and its temperature coefficient alpha = 3.3 x 10(-4) eV/K, have been determined.