Einfluß der Transportkinetik auf die Kristallisation von AIIBIVC-Verbindungen beim Gasphasentransport

The reported investigation intended to find tendencies in the influence of thermal and chemical conditions of chemical transport reactions on the growth of ZnSiP₂ and ZnSiAs₂ crystals. A more favourable crystallisation with less intergrowth is proved, if transport gases of the same system — as e.g. ZnCl₂ or SiCl₄ — is used instead of PbCl₂ and TeCl₄. — Depending on the concentration of the transporting medium the largest amount of crystals with lengths of more than 5 mm coincides with the point of lowest transport rate. The number of crystal defects increases with the dimensions of the crystals. — From the experimental results a hypothesis for explaining the locally different growth of crystals of ternary compounds is presented.     

Beitrag zur Kristallisation von ZnSiP2 aus der Gasphase

The influence of thermal conditions on the synthesis and crystallinity of ZnSiP₂ is investigated. Extensive measurements lead to statements on the axial and radial distribution of temperature in the apparatus and in the reaction vessel. The axial temperature gradient in the crystallization room equals some 3 deg/cm, whereas in the ampoule a radial gradient of 4 to 5 deg/cm is ruling. — At different temperature differences the thermal conditions of deposition of ZnSiP₂ are discussed, and it is found that ΔT should not fall below a minimum value of 15 deg, if ZnSiP₂ is to be produced by means of gas phase transport in a finite period of time. — In a full discussion the characteristic transport effects are explained. — Condensation of ZnP₂ at the end of the ampoule and by secondary transport caused by local temperature and concentration gradients in the crystallization room are stated to be responsible for different concentration profiles, for the phases present and for the crystallinity depending on the place of crystallization. — Hints for favourable variants of growing are given.     

Herstellung und ausgewählte physikalische Eigenschaften von ZnSiP2

Undoped ZnSiP₂ crystals grown by different methods (vapour phase transport, solution growth) show in part considerable differences in their physical properties. The connections between growth, quality of the basic materials and the physical properties of ZnSiP₂ will be shown. Measurements of Hall effect, resistivity, luminescence and backscattering of protons yielded informations about the perfection and homogenity of the crystals and about the impurities and recombination centres characteristically for the various growth methods. The influence of doping by different elements on the properties of solution grown ZnSiP₂ crystals was investigated.