Preparation and properties of Ag(AlxGa1-x)S-2 crystals by iodine transportmethod

The growth of chalcopyrite Ag(AlxGa1-x)S-2 crystals is demonstrated in the entire alloy composition range using the conventional iodine transport meth od. The composition of the grown crystals corresponds to that of starting m aterials. With increasing x, lattice constants decrease, following Vegard's law. The vibration modes for Raman scattering lines al-e assigned on the b asis of the reported AgGaS2 data. The compositional dependence of the A(1) mode spectrum is discussed in comparison with that for Cu-III-VI2 compounds . Two bands observed in photoluminescence excitation spectra for a dominant ly deep emission at 77 K correspond to band-to-band transitions, which are related to the uppermost valence band and the lower two closed valence band s. The changes in photon energies of these photoluminescence excitation ban ds indicate an increase in the energy gap from 2.7 eV to approximately 3.6 eV with x. The spectral broadening of the A(1) mode line and the two photol uminescence excitation bands around x = 0.5 is considered to be due to the clustering effect.