Plan-view Si(111) samples for surface science and TEM studies

Abstract

Versatile Si(111) samples consisting of both, Si bulk material for various surface science studies and thin Si films for transmission electron microscopy (TEM) studies were prepared using a combination of mechanical and chemical treatments. The bulk and surface quality of these samples was controlled by different experimental techniques. In-situ low-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM) have been performed under UHV conditions to characterize surface properties of the thick parts as well as of the thin films. Ex-situ X-ray topography and TEM have been used to analyse the quality of the bulk material. The preparation method described below enables us to use the same specimen in its whole, first in surface science experiments, e.g. formation and characterization of a metal/Si interface under UHV, and subsequently in TEM, without further sample preparation in a non-destructive and complementary way. In addition, the samples proved to an interesting new type of specimen as far as the study of vicinal Si(111) surfaces is concerned. A remarkable morphology was found on the treated rear side. During sample preparation the Si(111) planes are cut under continuously changing polar angles in all azimuthal directions. The result is a dimple consisting of a large number of vicinal (111) surfaces with varying polar and azimuthal misorientations. An UHV heat treatment of these samples leads to the build-up of (111)-oriented terraces separated by step bunches. All terraces are reconstructed in the 7 × 7 periodicity.