Atomic resolution electronic structure in silicon-based semiconductors

Abstract

An experimental method for obtaining conduction band electronic structure from the silicon L2,3 absorption edge is reviewed. The method uses Spatially Resolved Electron Energy Loss Spectroscopy in conjunction with a field emission Scanning Transmission Electron Microscope. The best spectroscopic resolution obtained is 160 meV with an energy scale accuracy of ±20 meV using 120keV electrons. The spectroscopy is combined with High Angle Annular Dark Field imaging with a 0.2-nm diameter probe to obtain nearly atomic resolution point spectroscopic analyses. Atomic bonding at a Si/SiO2 interface, conduction bandstructure in the relaxed GexSi1-x alloy system and conduction band offsets in nanometer thick strained quantum wells have been obtained. Future work aims at relating defect electronic structure with directly obtained electronic structure.