Imaging defects and dopants

Abstract

The electrical properties of semiconductor materials are, to a large degree, governed by defects and dopant atoms incorporated during growth and production processes. Unfortunately, direct experimental access to such bulk point defects is very difficult. In recent years, however, scanning tunneling microscopy has developed into an ideal tool for the investigation of individual bulk defects and dopant atoms in semiconductors. This technique allows not only atomically resolved imaging of individual defects and dopant atoms, but also detailed determination of nanoscale electronic as well as structural properties and their concentrations. This provides new access to the physical mechanisms involved in the incorporation and interaction of defects and dopant atoms in semiconductors, leading eventually to an atomic level understanding of materials’ properties.With the invention of the transistor, a revolution in the development of semiconductor-based electronic devices began. However, even in the very early stages, the importance of defects and dopant atoms became obvious. In fact, if one incorporates the right defects and dopant atoms into semiconductor materials, one can tune their electrical properties such that optimal device characteristics are achieved. Unfortunately, counteractive defects are often also formed unintentionally during semiconductor<@> <@$p>processing, leading to unfavorable electronic properties. Considerable research efforts have, therefore, focused on understanding the nanoscale physics that governs the formation of point defects, the incorporation behavior of impurities, and their respective electronic properties.