Structure analysis of defects in nanometer space inside a crystal: creation and agglomeration of point defects in Si and Ge revealed by high-resolution electron microscopy.

Abstract

Recent structural studies of point-defect-agglomerates in Si and Ge by high-resolution transmission electron microscopy (HRTEM) are compiled along with some new results. After examining the wave nature of incident electrons on defect formation during HRTEM observation and the correlated recombination of point defects under electron irradiation, we show that HRTEM is the unique means to analyze the atomic structure of small agglomerates of point defects, nanometer in size, inside a crystal. Emphasis is placed on the extension of studies made possible only by the elaborate and crucial structure determination by HRTEM: the mechanism of agglomeration at the atomic level, the extraction of novel unit structures of point defects, and the electronic structure of the agglomerate. Some examples on the subjects are demonstrated in cases of the [113] and [001] defects. The effect of specimen surfaces on structure determination is also discussed. Finally, a development of TEM technique with in-situ optical spectroscopy is described, which is utilized to pursue interaction of point defects under electron irradiation and thus may reinforce HRTEM experiments.