Growth and optimization by post-annealing of chalcopyrite CuAlS compound

The chalcopyrite CuAlS2 compound was grown from stoichiometric melt by horizontal Bridgman method. The obtained ingots were crushed finely and annealed at different temperatures from 800 deg C to 1100 deg C under a gas mixture of 5% N2/H2 atmosphere. X-ray diffraction and Raman spectroscopy were used to investigate the layer microstructures, as well as their lattice vibration spectra. The layers were characterized by scanning electron microscopy (SEM) and the compositional analyses were done by energy dispersive X-ray microanalysis (EDX). Raman measurements of the as made powder indicated seven prominent peaks at 205, 250, 290, 340, 369, 418 and 457 cm-1 with large intensity at 457 cm-1. The peaks at 205, 250, 340 and 457 cm-1 were ascribed to B2 modes while the peaks 369 and 418 cm-1 were ascribed to E modes. The peak at 290 cm-1 may be assigned to the A1 mode. After annealing, the Raman features become better and phonon mode at 290 cm-1 looks more distinct. The stoichiometric CuAlS2 compound was obtained when the sample was annealed at 900 deg C.