Bismuth-Induced Layer-by-Layer Growth in the Homoepitaxial Growth of Fe(100)
- PDF / 250,956 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 83 Downloads / 165 Views
W4.5.1
Bismuth-Induced Layer-by-Layer Growth in the Homoepitaxial Growth of Fe(100) Masao Kamiko, Hiroaki Chihaya, Hiroyuki Mizuno, Junhua Xu1, Isao Kojima1, and Ryoichi Yamamoto Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, JAPAN. 1 National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 5, Higashi 1-1, Tsukuba, Ibaraki 305-8565, JAPAN ABSTRACT We have investigated the effect of Bi on the homoepitaxial growth of Fe(100) by means of reflection high-energy electron diffraction (RHEED). It was clearly found that Bi induces layer-by-layer growth of Fe on Fe(100)-c(2×2)O reconstruction surface. The result of the dependence of the growth behavior as a function of Bi layer thickness suggests that there is optimum amount of Bi surfactant layer that induces the smoother layer-by-layer growth. A strong surface segregation of Bi was found at the top of surface and acts as a surfactant by promoting the interlayer transport. INTRODUCTION Surfactant epitaxy has been known as a useful method for changing the thin film growth mode from 3D-island formation to layer-by-layer growth [1]. Although heteroepitaxial systems with surfactant are of greater interest for electronic devices, the understanding of surfactant effects in heteroepitaxy is more complicated than that of homoepitaxy because of strain induced by lattice mismatch or surface energy difference between film and substrate. Therefore, homoepitaxial systems are ideally suited to investigate the effect of surfactants on kinetics of the growth. The surfactant atoms must float up to the surface. In other words, it should be more stable on the surface than in the bulk. Mae et al. investigated how the surfactant atoms segregate on the surface by computer simulations [2]. The calculations have indicated that the most important characteristic of the surfactant is a larger atomic radius than that of film and substrate atoms, and it is favorable for the surfactant to have smaller surface energy than that of the film and the substrate elements and to be immiscible with them. Bi has a much smaller surface energy and a much larger atomic radius compared to Fe, and also does not alloy with Fe up to 271.4˚C. From these reasons, Bi is a good candidate as surfactant atoms in the homoepitaxial growth of Fe. In this paper, we report the influence of the Bi surfactant on the homoepitaxial growth of Fe(100). EXPERIMANTAL DETAILS Molecular beam epitaxy (MBE) experiments have been carried out. The base pressure was 10-10 Torr range and the pressure during deposition did not exceed 5×10-9 Torr. Fe(100) surfaces were fabricated by evaporating Fe on MgO(100) single crystals. The substrates of MgO(100) single crystal were cleaned by heating at 850˚C for 10min. Fe buffer layers of 100Å were deposited at 200˚C and were then annealed at 850˚C for 30 min.
W4.5.2
RHEED intensity measurements were performed during deposition of Fe on Fe. The growth temperature was varied from room temperatu
Data Loading...
