THE INFLUENCE OF PEIERLS RELIEF ON LOW-TEMPERATURE PLASTICITY OF CDTESINGLE-CRYSTALS

The following was investigated on CdTe single crystals: the kinetics o f spontaneous elongation of dislocation arms arising near the indentor impression on the (111) face at room temperature; the kinetics of str ess relaxation in the early stages of deformation in the vicinity of t he yield point at 200, 225, 250, 273 and 300 K; the temperature depend ence of the yield point in the temperature range 200-300 K. The experi mental data for the temperature dependence of macroscopic plasticity p arameters are well described by the model of dislocation movement in t he Peierls relief by the kink pair mechanism for the case of low effec tive stresses tau when the equation for the average dislocation veloc ity is v approximately exp[-H(kp)(tau)/kT] with the activation enthal py H(kp) = 2H(k) - 2alpha(tau)1/2. According to our estimates, the pa rameters of the theory have the following values: enthalpy of kink pai r formation 2H(k) = 0.6 eV, alpha = 10(-23) N1/2 m2, and Peierls stres s tau(p) = 21 MPa. To explain the temperature dependence of the yield point we suppose that it is determined not only by the natural contrib ution tau(T) but also by the temperature dependence of internal stres ses tau(i)(T). The empirical values of tau(i)(T) obtained in the tempe rature region studied can be assigned to development of the superjogs structure on dislocations. The average distance between the superjogs impenetrable to kinks is estimated to be L less-than-or-equal-to 10 mu m. The process of dislocation arm elongation can be described by the e mpirical formula l(t,P) approximately P1/3t1/3 (P is the indentation l oad, t is time). This dependence follows from the assumption that the velocity of a single dislocation in an array can be described by the e quation v approximately (tau)m exp(- H-0/kT) at m = 1.