Photoluminescence of site-selectively Zn-doped CuGaS2/GaP epitaxial layers Original Research Article

Photoluminescence properties of site-selectively Zn-doped CuGaS2 layers grown on GaP substrates under completely and partially separated alternate source feeding (i.e. alternate feeding of simultaneous metal sources and H2S) condition are discussed in terms of conduction type of the grown layers. The photoluminescence appearing in these samples is compared with those in an undoped layer and nonsite-selectively Zn-doped bulk crystals. Layers with n-type conduction exhibit a donor–acceptor pair type emission at around 2.31 eV at low temperatures, while layers with p-type conduction do a broad emission at around 2.21 eV. These emissions were reported to appear in nonsite-selectively Zn-doped bulk crystals. From comparison with the result of bulk crystals, the appearance of these emissions in n- and p-type layers is shown to be consistent with formation of ZnCu for n-type samples and ZnGa for p-type samples. In addition, for n-type layers a characteristic bound exciton line seems to appear at 2.475 eV at low temperatures.