A shallow state in molecular beam epitaxial grown CuGaSe2 film detectable by 1.62 eV photoluminescence

Cu-rich CuGaSe2 films grown on [001] oriented GaAs substrates by molecular beam epitaxy show a remarkable low temperature photoluminescence emission peaked at 1.620 eV. This emission can be attributed to a free-to-bound recombination accompanying a donor-to-acceptor pair recombination. The ionization energies of these states are found to be 3.4 and 108 meV, respectively, via temperature dependent photoluminescence. The 108 meV state is attributed to a donor and the 3.4 meV state to an acceptor state observed. (C) 1997 American Institute of Physics.