Valeriy G. Voevodin

Deep levels of antisite defects clusters in ZnGeP2

On the basis of the methods of pseudopotential and large unit cell the research of deep lev- els of point and cluster defects in ZnGeP 2 (ZGP) was carried out. It was shown that owing to lowering of the crystal lattice symmetry localised states of point defects in the ternary compound essentially differ from such states in its binary analogue GaP. Small quasicubic antisite defects clusters reduce the value of band gap, but render weak influence on the probability of optical transitions. But both single and the cluster antisite defects cause large modifications in deep levels of another point defects closed to them. On an example of phosphorus vacancy it was shown that intensive optical transitions with small energies can appear and cause an absorption in near IR – range because of antisite defects effect.

Annealing of Some II-IV-V2 Crystals in the Vapor of Volatile Constituents

Abstract : Experiments on annealing of CdGeAs2-, CdSnAs2- and ZnGeP2-crystals in the vapor of volatile constituents were carried out. Conductivity and Hall effect measurements were performed to characterize the modification of electrical properties, caused by the interaction of the crystal with the gas phase during annealing. Literature data and the results of the present work are discussed based on the results of a quasi-chemical analysis. This yielded that the results of annealing depends essentially on both the conditions of the experiment and the initial imperfection of the crystal. The most probable native structural defects becoming apparent under the annealing were the following: for CdSnAs2 - Sn(sub Cd), V(sub As); for CdGeAs2 - V(sub As, V(sub cd), Cd(sub Ge), Ge(sub Cd); for CdSiAs2 - Si(sub As), V(sub As); for CdSiP2 - V(sub Cd), V(sub p); for ZnGeP2 - Zn(sub Ge), Ge(sub Zn), V(sub Zn), V(sub p); and for ZnSnP2 - Zn(sub Sn), Sn(sub Zn), V(sub Zn), V(sub p).

Doping of ternary compounds CdGeAs2 and CdSnAs2 by impurities of I, II and III groups

Abstract Research in doping processes of ternary chalcopyrites A 2 B 4 C 2 5 is of primary interest for several reasons. First of all, a study of the dependencies of ‘the properties of crystal vs. the concentration of impurity in melt’ decides a fundamental problem. It is a check on the theory of ordering of a crystal structure for some specifically defined values of dopant concentration leading to a possible phase transformation caused by the self-organization of large-scale fluctuations in a melt. On the other hand, it is necessary also for practical tasks—for example, obtaining high-resistance CdGeAs 2 -crystals for use in nonlinear optics. In the present work data on electrical activity and on an effect in the electrophysical properties of ternary semiconductors CdGeAs 2 and CdSnAs 2 are obtained for dopants of Au, Cu, Zn, In, Sc and Gd in CdGeAs 2 and for Au, Cu and In in CdSnAs 2 , added to a melt during synthesis or recrystallization of a material.