ABSTRACT
Crystals of CuGaSe2 were grown by chemical vapor transport (CVT) with iodine as transport agent and by horizontal gradient freeze. Using CVT flat crystals of dimensions 50×l5×2mm3 were obtained. CuGaSe2 ingots crystallized from the melt in glassy carbon boats exhibited single crystalline grains of 12×5×5mm3. Thermo-gravimetric measurements have shown that CuGaSe2 is thermally stable under CVT conditions (ΔT=820 − 750°C). However, this chalcopyrite thermally decomposes at 1000°C into solid Cu2Se and volatile Ga2Se and Se2. Therefore, an additional Ga2Se3 source was introduced in the melt growth experiments and hold at 700°C during crystallization. The crystallized ingot exhibited an uniform composition over the whole length. This observation is in contradiction to the established phase diagram proposing a peritectic melting point. Preliminary own differential thermal analyses (DTA) in the join Cu2Se – Ga2Se3 allows the conclusion that CuGaSe2 has a congruent melting point at 1094°C.
