Obtaining Bulk Electronic Structure with Atomic Resolution Using Spatially Resolved Electron Energy Loss Spectroscopy

Abstract

Recently, it has been shown that higher performance within the silicon-based technology can be obtained by using Si-Ge alloys in both strained and unstrained configurations. For instance, very high electron mobilities can be obtained in a strained Si quantum well structure formed by CVD deposition of Si on a relaxed Ge30Si70 substrate. [1] In addition, there remains the more difficult goal of obtaining optically active device structures within the Si-based technology. [2] In each of these cases, the relevant electronic structure of the device is completely dependent on the local structure, composition, and strain within a few Angstrom units of an internal interface. In the past, electron microscopy has been very successful at determining the local structure of buried interfaces and defects, but has not provided a good tool for measurement of either the bonding or the electronic structure in the same areas. Spatially Resolved EELS has therefore been devised as a technique to obtain the bulk electronic structure in a way that is compatible with electron microscopy so that direct comparisons can be made between electronic and atomic structure.