Abstract
Detailed structural data of the {′113} interstitial defect or the rod-like defect in Si and Ge have been given based on firm experimental evidence by high-resolution transmission electron microscopy (HRTEM). We have found line interstitial defect structures, in which a few chains of additional (interstitial) atoms in the 〈110〉 direction are inserted in a perfect crystal without dangling bonds in the {′110} cross-section. We have also found various kinds of atomic steps, whose ledges are parallel to the [1&1bar;0] direction, in the extremely extended {′113} planar defect. The HRTEM images of a bend of a {′113} planar defect have been also presented. The interstitial defect structures mentioned above have been determined by HRTEM with image simulation. Based on the experimental evidence, we have shown that the observed structures such as the extremely extended part on {′113}, the bend, the steps and the disturbed structure in which the hexagonal structure with stacking faults exists have been consistently reproduced by successive nucleation of the line interstitial defect structure. In this context, we have concluded that various disturbed structures are growth faults during developing of the planar {′113} defect, rather than due to the formation of the hexagonal phase. We have shown transmission electron diffraction (TED) patterns from a single (113) defect, and optical diffraction pattern (Fourier transform) of a HRTEM image of a {′113} defect. The TED patterns taken with various incident beam directions including the plan-view incidence have shown extra spots from the defect. The extinction of the extra spots has been also found in the pattern taken with the {′001} incidence. The location of the extra spots and the extinction have been consistently explained based on the planar {′113} defect model which was determined from the HRTEM observation before. Furthermore, electron diffraction intensity has been simulated based on the atomic model. Simulated electron diffraction has reproduced well the characteristic intensity distribution from the defect. The reliability factor has been estimated in the plan view pattern to be 0·30. There has been less experimental information regarding self-interstitials in Si and Ge than vacancies and impurities. We emphasize that a series of our papers are the first elaborated transmission electron microscopy and diffraction studies combined with theoretical calculation that determine without doubt the agglomerate structures of self-interstitial atoms in Si and Ge at atomic level.
