Large (up to 60 mm in diameter) untwinned ZnSe single crystals have be
en grown in sealed quartz ampoules by seeded physical vapour transport
and seeded chemical vapour transport with hydrogen. The dependence of
structure perfection on the seed quality and its orientation, the sou
rce design, the gas filling of the growth ampoule and the temperature
regime was researched. Selective chemical etching topography, X-ray di
ffraction rocking curve and cathodoluminescence studies are presented
to characterize grown crystals. The influence of oxygen impurity on cr
ystal emission and weakening of this influence in crystals grown in hy
drogen was found. The results of crystal annealing in Zn vapour and Zn
melt are discussed.