Growth and stoichiometry of THM-bulk single crystals of CuAlSe2

The purpose of this study is to investigate the growth condition of high-quality CuAlSe2 single crystal by using traveling heater method (THM). Both stoichiometric and CuSe2-rich CuAlSe2 polycrystals are synthesized by the reaction of constituent elements at 1050 degreesC, which is by 67 degreesC lower than the melting point. All the grown crystals by THM using In solvent and both those of stoichiometric and Cu,Se-rich feed crystals are found to be chemically stable and to have excellent stoichiometric composition in the form of CuAl1-xInxSe2 alloy crystals (Cu: Al + In: Se = 1: 1 : 2). On the other hand, only 3-5% Cu2Se-rich crystals grown by Bridgman method are found to be stable, in accordance with the reported result in literatures. It may be considered that In substitution for original Al sites plays a role to stabilize, otherwise chemically unstable, I-III-VI2 stoichiometric chalcopyrite phase. An excitonic blue photoluminescence is found for the first time in the bulk single crystal only for the THM crystals using 5% CU2Se-rich feed crystals. (C) 2002 Elsevier Science B.V. All rights reserved.