Schottky barrier measurement by electron energy loss spectroscopy

Abstract

It is difficult to imagine an electrical property which is more crucial to the success of modern device structures than the Schottky Barrier. In spite of this, the mechanism of barrier formation is still imperfectly understood, because the barrier formation is essentially a result of the details of the micro-structure of the metal/semiconductor interface. High resolution microscopy can obtain the microstructure of small regions of interfaces, but typical tools for measuring electronic structure have been able to measure only the bulk, or average, properties. Recently, scanning tunneling microscopy, using ballistically injected electrons, was used to obtain I-V characteristic of a buried junction. It was possible to image the junction in the plan-view geometry to show how the junction electrical properties change on a scale of 1 nm. These studies showed barrier changes with morphology and promise to provide useful insight into the problem. However, the studies do not obtain electrical properties as a function of distance away from the junction. This information is needed to help understand the underlying physics of the barrier formation. Thus, there is a need for an analytical tool which is compatible with the high resolution TEM imaging of interfaces in the cross-section geometry. Electron energy loss scattering can provide this tool if a small probe and a high energy resolution can be obtained.