ZnSe single crystals of good quality have been grown from the vapour p
hase by dissociative sublimation in sealed ampoules. Under p(min) cond
itions, maximum transport rates have been measured. The grown crystals
had convex growth faces. However, the majority of runs in this catego
ry yielded relatively poor quality boules. As the vapour approaches co
nditions for depositing nearly stoichiometric solid ZnSe, at decreasin
g growth rates, large strain-free single crystals without twinning and
morphological instability were successfully grown. Additional critica
l parameters which contribute to this behaviour are growth temperature
, temperature gradient and temperature difference between source and c
rystal.