Scanning tunneling mircroscopy and X-ray photoelectron spectroscopy studies of MnSi film and MnSi1.7 nanowires grown on Si substrates

Abstract

Manganese silicides are promising industrial materials in optoelectronics and microelectronics fields. The study of electronic structures of manganese silicide film and nanowires is essential for a deeper understanding of their properties. In this paper, MnSi film and MnSi1.7 nanowires are prepared by molecular beam epitaxy method, and then observed by scanning tunneling microscopy (STM). The Mn 2p and Si 2p of MnSi film and MnSi1.7 nanowires are comprehensively studied using X-ray photoelectron spectroscopy (XPS). The results demonstrate that MnSi film with ～ 0.9 nm high is √3 × √3 reconstruction, and that the MnSi1.7 nanowires are about ～ 3 nm high, 16—18 nm wide and 500—1500 nm long. The binding energies of the Mn 2p1/2 level and Mn 2p3/2 level for MnSi film are 649.7 and 638.7 eV, respectively, which coincide with those of MnSi1.7 nanowires. The Mn 2p3/2 and Mn 2p1/2 peaks which are located at 640—645 eV and ～653.8 eV indicate that an oxide layer formed on the surfaces of film and nanowires because of short-time exposure to the atmosphere. The negative chemical shifts for MnSi film and MnSi1.7 nanowires from Si2p spectra indicate that with the formation of manganese silicides, the chemical state of Si is changed.