POINT DEFECT CLUSTERS IN PbTe:In. A.K. Tkalich^_a), K.D. Chtcherbatchev^_a) and V.P. Zlomanov^_b). ^_a)Moscow Institute of Steel and Alloys, Moscow, Russia; ^_b)Moscow State University, Moscow, Russia

The asymptotic X-ray diffuse scattering (AXRDS) has been used to characterize the point defect structure in Pb^_1-xIn^_xTe (x=0.01) single crystals doped above the point of hole compensation x~0.004. From the AXRDS intensity profile (Fig.1) taken along the diffraction vector near to (400) reciprocal lattice point on a triple-crystal diffractometer, it is evident that there are microdefects (the submicron point defects clusters) of both vacancionic (at q<0) and interstitial (at q>0) type. Herewith, the concentration of the former is greater than that of the latter. The typical size of microdefects is approximately of ~0.01-0.1 um. The interstitial microdefects are supposedly formed from the Te interstitials created during the post-crystallization cooling cycle due to the decomposition of solid solution enriched with Te, while the vacancionic microdefects should contain the In impurity atoms and vacancies of lead.

The role of the In impurity and native point defects in the effect of Fermi level pinning is discussed taking into account our recent photoemission data on In states in PbTe.

Fig.1 (400) AXRDS intensity profile in PbTe:In. I - intensity, q - deviation from the diffraction vector.