Scanning tunneling microscopy/scanning tunneling spectroscopy observation of step structures of Si (001) and (111) surfaces

Abstract

The step-edge structures of the Si (001) and (111) surfaces roughened by heating at 1300 °C were studied utilizing the scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). The bunches of 7–8 double layer steps and the 200–300 Å wide terraces were observed on the Si (111) surface. An unexpected finding is the interminglement of single and double atomic layer steps on the vicinal Si (001) surfaces tilted to any orientation. The double layer steps split into two single layer steps at the kink sites of the step edge. The dimer rows on the lower terraces shift in the direction of the rotation of the vicinal surface around the normal axis of the surface. The tunneling spectra at the single step exhibits several peaks at the sample bias voltages 0.6, −0.6, −1.4, −1.7, −2.1, and −2.4 V. The peaks at −1.4 and −1.7 V are found to be particularly sharp and high at the step edge.