Ballistic electron emission microscopy and spectroscopy: Recent results and related techniques

Abstract

Interfaces play a central role in determining properties of optical and electronic devices. Many mature techniques exist for surface characterization, providing a great deal of detailed, local information. Interface methods with equivalent capabilities have not developed as fully, due primarily to the inaccessibility of buried interfaces to traditional surface sensitive probes. Ballistic electron emission microscopy (BEEM) is a class of microscopies and spectroscopies that uses energetic electrons injected by a scanning tunneling microscopy tip as a probe of subsurface electronic structure. This article reviews the growth of BEEM methods and summarizes recent areas of investigation using these techniques. Research areas span a range of materials, such as metals, semiconductors, insulators, magnetic materials, and organic layers, as well as a variety of physical properties that include interface barrier height, hot-carrier scattering, interface heterogeneity, magnetic domain structure, and electronic band structure.