Growth and characterization of twin-free ZnSe single crystals by the vertical Bridgman method

The crystallographic characteristics of twin-reduced ZnSe crystals grown by a high-pressure melting method and the approach to stoichiometric growth are given. The crystals were grown by the seeded vertical Bridgman method and gradient freezing with in-situ composition control by a defined Zn source temperature. One inch ZnSe single crystals having twin-reduced parts and an average etch pit density of 2.0 x 10(5) cm(-2) were successfully grown by the seeded Bridgman method. Multi-twin patterns, typically for melt-grown boules, were not detected from the observation by optical microscopy with crossed polaroids and by transmission X-ray topography. The crystallinity of the as-grown crystal was characterized by X-ray rocking curve analysis using a double crystal arrangement. A full width at half maximum of 24 arcsec was detected. The influence of the Zn source on the crystal composition was studied by chemical analysis and photoluminescence.