Transmission electron microscopy of interfaces in III–V compound semiconductors

Abstract

This paper presents a review of the applications of transmission-electron-microscopy (TEM) analytical techniques to the study of several types of interfaces in III–V compound semiconductor structures. The TEM techniques for analysis of lattice mismatched interfaces are briefly discussed since they are straightforward for most III–V compounds. New techniques for analyzing interface roughness and interface diffusion on an atomic scale are presented. The study of interface structures on such a fine scale is made possible by optimizing the diffraction effects between interfaces and the electron beam. By combining the excellent control of the molecular-beam-epitaxy deposition technique to fabricate ’’interface superlattices’’ with high-resolution dark-field and lattice-imaging TEM techniques, the interface roughness between ultrathin GaAs and AlAs films have been analyzed on an atomic scale. Interdiffusion at GaAs and AlAs interfaces is also discussed, and two methods which make use of ’’interface superlattices’’ are presented. They allow for rapid and precise measurements of diffusion profiles and diffusion length as small as 2.83 Å for this system. The TEM techniques discussed in this paper are applicable to other types of semiconductor structures providing they can be made into ultrathin superlattices.