The CuInSe2-CuGaSe2-2CdSe system and crystal growth of the γ-solid solutions

Phase equilibria in the CuInSe2-CuGaSe2-2CdSe system are studied using differential-thermal analysis and phase X-ray diffraction. An isothermal section of the system at 870 K, and phase diagrams of polythermal sections CuInSe2-CuGaSe2 and 'CuCd2InSe4'-CuCd2GaSe4 have been constructed. The 'CuCd2InSe4'-CuCd2GaSe4 section is not quasi-binary and includes two solid solution regions with the wurtzite and sphalerite structure-types. Eleven crystals of the γ-solid solutions with the sphalerite structure-type were grown by the Bridgman technique. The non-quasi-binary nature of the 'CuCd2InSe4'-CuCd2GaSe4 section gives rise to compositional gradients for copper, cadmium, and gallium along the crystal growth direction so that the crystal tip is enriched with CdSe. Band gap of the grown crystals varies from 1.05 eV to ∼1.30 eV.