Papers

ICMCTF2007 Session H4-1: The Atomistics of Thin Film Growth: Computational and Experimental Studies

Monday, April 23, 2007 10:00 AM in Room Tiki Pavilion

Monday Morning

Start	Invited?	Item
10:00 AM		H4-1-1 Kinetic Measurements During the Nucleation and Growth of Si and Ge Nanowires F. Ross, S. Kodamabaka, J. Tersoff, M.C. Reuter, J.B. Hannon, R.M. Tromp (IBM T.J. Watson Research Center) By carrying out chemical vapour deposition of semiconductors, such as GaAs, InAs, GaP, InP, Si and Ge, in the presence of small particles of a catalytic material, usually Au, it is possible to grow columnar structures which may be many microns long and below 100nm in diameter. Such nanowires or whiskers have interesting electrical and optoelectronic properties, and have already been incorporated into functional devices. Even more applications can be envisaged if the nanowires could be grown epitaxially at precise locations over an entire wafer. In this presentation we will discuss the growth of epitaxial nanowires in Si and Ge, focusing on the kinetic processes that influence the nucleation and final shape of the structures. The nanowires were grown in an environmental TEM, which has capabilities both for evaporating Au onto a clean Si substrate, and for introducing the CVD precursor gases (disilane and digermane) while the sample remains under observation. These in situ video rate observations allow us to measure nanowire growth rates, observe nucleation events, examine the catalyst particles directly, and determine the effects of changes in the environment on the shapes of the wires. We will focus in particular on the factors that affect wire shape and the reliability of wire nucleation, and we will consider ways in which wire structures may be tailored for particular applications.
10:40 AM		H4-1-3 Exploring Magnetic Nanostructures by Spin Polarized Low Energy Electron Microscopy A. Schmid (Lawrence Berkeley National Laboratory) We use in-situ microscopy to observe deposition and growth of nanoscale materials while, simultaneously, imaging their magnetic structure. We illuminate sample surfaces with a spin-polarized beam of electrons and observe spin-dependent electron reflection to form images. The images contain information on sample structure as well as electronic and magnetic properties. This is interesting, both to shed light on basic magnetic phenomena and because the properties of small magnetic domains are potentially useful to enable miniaturization of spin-based devices. Several examples including self-assembled magnetic nanodots, self-organized nanowire arrays, and epitaxial multilayer structures will be discussed to show how SPLEEM can be used to study magnetism in low-dimensional systems.