Distribution of tellurium in melt-grown ZnSe(Te) crystals

Abstract The properties of semiconductor scintillation crystals are largely determined by the presence and distribution of the activator dopant. Influence of growth technological parameters (overheating Δ T , inert gas pressure P , crystallization rate V k ) upon distribution of tellurium dopant was studied for ZnSe(Te) crystals grown by Bridgman technique in compression furnaces. Values of the “apparent” distribution coefficient of tellurium ( k Te ) over crystal length were shown to be dependent on Δ T and the related value of charge carry-over (Δ m / m 0 ). It was established that at Δ m / m 0 =12%, K Te =1; at Δ m / m 0 K Te m / m 0 >12%, K >1. This relationship is explained by assuming a competition between two processes affecting the distribution coefficient of tellurium: movement to the tail part in accordance with the phase diagram of the ZnSe–ZnTe pseudobinary system and thermal desorption of ZnTe due to its high volatility. Conditions required for preparation of ZnSe(Te) crystals of highly uniform composition are determined.