Growth and Effect of Thermal Annealing for CuInSe2 Single Crystal Thin Film by Hot Wall Epitaxy

Abstract

A stoichiometric mixture of evaporating materials for <TEX>$CuInse_2$</TEX> single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, <TEX>$CuInse_2$</TEX> mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were <TEX>$620^{\circ}C\;and\;410^{\circ}C$</TEX>, respectively. The temperature dependence of the energy band gap of the <TEX>$CuInse_2$</TEX> obtained from the absorption spectra was well described by the Varshni's relation, <TEX>$E_{g}(T)=1.1851 eV - (8.99{\times}10^{-4} eV/K)T^2/(T+153 K)$</TEX>. After the aa-grown <TEX>$CuInse_2$</TEX> single crystal thin films was annealed in Cu-, Se-, and In-atmospheres, the origin of point defects of <TEX>$CuInse_2$</TEX> single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of <TEX>$V_{cu},\;V_{Se},\;Cu_{int},\;and\;Se_{int}$</TEX> obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted <TEX>$CuInse_2$</TEX> single crystal thin films to an optical n-type. Also, we confirmed that In in <TEX>$CuInse_2$</TEX>/GaAs did not form the native defects because In in <TEX>$CuInse_2$</TEX> single crystal thin films existed in the form of stable bonds.