Photoelectronic properties of LPE GaAs : Cu

The photoelectronic properties of liquid-phase epitaxial GaAs : Cu, either grown from a Ga melt with Cu impurity added or with incorporation of Cu by diffusion after growth, have been investigated through measurements of photocapacitance; conductivity in light and dark as a function of photon energy, light intensity, and temperature; thermal and optical quenching of photoconductivity; thermally stimulated conductivity; and photoluminescence. When Cu is present in the growth melt, the electron density in the resulting LPE GaAs layer is increased; when Cu is diffused into a grown layer, it behaves as a conventional acceptor and converts the layers to high-resistivity p-type conductivity. A Cu-related center with energy level about 0.43 eV above the valence band, electron-capture cross section of 10−21 cm2, and hole-capture cross section of 10−16 cm2 is observed in the layers produced with Cu in the melt by spectral response of photocapacitance and photocapacitance decay, and in the layers with diffused Cu by thermal and optical quenching of photoconductivity, spectral response of photoconductivity, and thermally stimulated conductivity. Six other levels, three of them electron traps and three of them hole traps, are also observed and described.