HREM of Edge-on Interfaces and Defects

The latest generation of intermediate-voltage high-resolution electron microscopes (HREMs) offer the exciting prospect of resolution limits of 2A or better [1,2]. Moreover, under certain well-defined conditions, it is even possible to deduce useful structural details down to small fractions of this limit [3–5], and some limited chemical information can also be extracted. In this paper, the potentialities and limitations of the high-resolution technique will be considered, with particular reference to edge-on interfaces and defects in various elemental and compound semiconductors. Specific examples described include: i the identification of crystal polarity in -orientated sphalerite materials; ii intensity variations across GaAs/Ga1-xAlxAs interfaces; iii stacking fault symmetry and dislocations; iv refinement of the diamond platelet defect; v distinguishing shuffle and glide models for the Si 30° partial dislocation. Prospects and practical problems associated with the HREM technique, as it applies to imaging semiconductors, are briefly discussed.