Seeded vapour-phase free growth of ZnSe single crystals in the [100]direction

Seeded vapour-phase free growth of ZnSe single crystals at T-g = 1100-1250 degrees C in [100] direction was studied. The [100] growth process was found to be more sensitive to the temperature profile in a furnace than the [111] direction. The problem that seed attachment to a support pedestal is followed by a generation of high dislocation density was solved by use of a reverse temperature gradient along the axis of the furnace between the seed and the pedestal and by optical monitoring of the attachment process during the growth. Seeds with dislocation density of 10(4)-10(5) cm(-2) and 2-4 cm(2) area selected from single crystals grown in [111] direction were used for the first growth processes in [100] direction. To increase the diameter of the grown crystals, a tangential growth regime was developed. Twin free ZnSe single crystals of 51 mm diameter and of 15 mm height were grown in helium. The average dislocation density was about 10(4) cm(-2) and the full-width at half-maximum (FWHM) of the X-ray rocking curve was as small as 16 arcsec. (C) 1998 Elsevier Science B.V. All rights reserved.