The composition of the vapor phase upon evaporation of a mechanical mixture of cadmium and zinc selenotelluride powders

The effect temperature has on the composition of a vapor phase passed through a thermal field after the evaporation of a mechanical mixture of the powders of cadmium and zinc selenotelluride is studied. It is found that the composition of the vapor phase can be changed throughout the range of concentrations by varying the temperature. The results of the study are satisfactorily explained by the effect temperature has on the particle distribution function in correspondence to the weights of the molecules constituting the mixture. There were virtually no molecules of the evaporated substance in the vapor phase, which consisted of diatomic molecules of the elements of Group VX compounds and metal atoms. This means that with the evaporation of mechanical mixtures of CdTe and CdSe powders, the vapor phase in the evaporator contains only Cd, Se2, and Te2 molecules, while mixtures of ZnTe and ZnSe powders contain Zn, Se2 and Te2 molecules. Despite the similarity between the components’ heats of sublimation, their concentrations over the powdermixture did not correspond to the composition of the powder mixture, since compounds A2B6 sublimate incongruently. Coming from the evaporator, the vapor phase entered the thermal field and was condensed onto a substrate at room temperature at its outlet. As follows from the composition of the substrate films, the vapor phase at the outlet was enriched with the light component Se, compared to the powder mixture. By virtue of the law of the conservation of mass, the vapor phase was therefore enriched with the heavy component Te at the inlet to the thermal field. Our results show that the thermal field controls the composition of the vapor phase by changing the particle distribution function according to the weight of the molecules constituting the mixture. The temperature dependences of the composition of the vapor phase are presented for several mechanical mixtures of the powders of (CdSe)x (CdTe)1-x and (ZnSe)x (ZnTe)1-x, where x = 0.45-0.90.