Observation of surface reconstruction on silicon above 800 °C using the STM

Abstract

AN understanding of the kinetics of structural phase transitions in crystalline, semiconducting thin films is important for the control of film growth in techniques such as molecular-beam epitaxy, as well as in applications of such films at high temperatures. Electron diffraction techniques (LEED and RHEED) have been applied to the study of high-temperature surface reconstruction, but although these can detect changes in surface periodicity, they do not permit atomic-scale resolution of the nucleation and growth processes. The scanning tunnelling microscope (STM) provides an alternative tool to investigate changes of this sort, but high-temperature observations have been hampered by problems of thermal drift. Here we report our success in overcoming these problems and thus in obtaining atomic-resolution STM images of the 1 × 1 → 7 × 7 surface reconstruction of a silicon thin film at about 860 °C. Step formation and migration are clearly visible in these images.