Photoluminescence and excitation spectra of Cu(AlxGa1−x)S2 films grown by vapor phase epitaxy

Chalcopyrite Cu(AlxGa1−x)S2 alloy films were successfully grown on GaP substrates by vapor phase epitaxy using metallic chlorides (CuCl, GaCl3 and AlCl3) and H2S as source materials. Photoluminescence (PL) spectra of these films taken under a low excitation density using a super high pressure Hg lamp exhibited broad emissions in the orange region. Photoluminescence excitation (PLE) measurements revealed that these broad emissions are effectively excited at the photon energies of A- and the BC-exciton energies. Under the high excitation density using the pulsed XeCl laser, these alloy films showed the exciton related emissions composed of biexciton recombination, exciton-exciton and exciton-carrier scatterings. The influence of the compositional fluctuation was observed on the increase of the full-width at half maximum (FWHM) for the exciton related emission with increase in composition of x.