The structure, composition, and chemical state of the surface of wire-like silicon nanocrystal grown by self-organization technology

Abstract

The surfaces of wire-like silicon crystals grown by self-organization processes are characterized using electron microscopy of high resolution, scanning tunnelling microscopy, x-ray microprobe analysis, secondary-ion mass spectroscopy, and Auger electron spectroscopy. The results obtained have shown that the upper layer of each microcrystal is a nanoporous envelope. The composition of the envelope is in general similar to the composition of the bulk part of the crystal but with some differences: the density of the matter - due to the porous nature of the envelope - is much smaller, and the density of metal impurities is slightly increased on the external surface. More striking was the fact that the external surface of the envelope is passive under exposure to oxygen. In Auger spectra of crystals stored in open air for several years, only the LVV and KLL peaks that are specific to the atomically clean silicon surface were observed.