ABSTRACT
For elemental semiconductors, VA and Ai are sometimes denoted V and I. In compound semiconductors, we find two kinds of each of these defects (Figure 2.1). In GaAs, for example, a gallium vacancy is denoted VGa while an arsenic vacancy is VAs. In addition, there is a new kind of defect, the antisite (e.g., a gallium atom residing on an arsenic site, GaAs, or an arsenic atom sitting on a gallium site, AsGa). Deviations from exact stoichiometry may lead to large concentrations of interstitials and antisites of the excess constituent.
