Zinc oxide crystals were grown on the sapphire substrates in silica glass ampoules by Chemical Vapour Transport and Contactless Growth Method. The temperature field configuration and geometrical dimensions which were formerly applied to PVT contactless growth of other zinc and cadmium based II-VI compounds [1] and lead based IV-VI semiconductor compounds appeared to be appropriate for growth of ZnO by CVT. Hydrogen, bromine and chlorine were used as the transport agents, depending on the doping element (As, Cr, Cu) introduced to the crystal. Additional gases (N2, Ar) and additional Zn were used in order to improve the transport and growth conditions. It appears, that the best growth conditions are obtained in hydrogen atmosphere, keeping the Zn partial pressure close to pressure of hydrogen. Due to changes of the hydrogen pressure during growth, also the partial pressure of the zinc must be changed. Synchronization of these changes remains the main problem in our growth system.
[1] K.Grasza, W.Palosz, Crys.Res.Technol. 34(1999)565
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