He Li, Johansson Jonas, Murayama Mitsuhiro, Hull Robert
Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22904, USA.
Nanotechnology. 2008 Nov 5;19(44):445610. doi: 10.1088/0957-4484/19/44/445610. Epub 2008 Oct 2.
A novel method of indirect deposition by means of a focused ion beam (FIB) is utilized to develop metal/insulator/semiconductor nanowire core-shell structures. This method is based upon depositing an annular pattern centered on a nanowire, with secondary deposition then coating the wire. Typical cross-sectional deposition area increments as a function of ion doses are 1.3 × 10(-2) µm(2) nC(-1) for Pt and 3.5 × 10(-2) µm(2) nC(-1) for SiO(2). The structures are examined with a transmission electron microscope (TEM) using a new nanowire TEM sample preparation method that allows direct examinations of individually selected core-shell nanowires fabricated under different indirect FIB deposition conditions. Elemental analyses by means of energy dispersive x-ray spectroscopy and electron energy filtered TEM imaging verify the deposition of SiO(2) and Pt layers. Relatively uniform Pt and SiO(2) coatings on individual GaP nanowires can be achieved with overall thickness deviation of about 10% for deposition up to 25-30 nm thick Pt or SiO(2) shells. It should be possible to extend this approach to any nanowire/nanotube system, and to a wide range of coatings in any desired layer sequences.
一种利用聚焦离子束（FIB）进行间接沉积的新方法被用于制备金属/绝缘体/半导体纳米线核壳结构。该方法基于在纳米线上沉积一个环形图案，然后进行二次沉积以覆盖该线。对于铂，典型的横截面沉积面积随离子剂量的增加量为1.3×10⁻² 微米²/纳库仑，对于二氧化硅为3.5×10⁻² 微米²/纳库仑。使用一种新的纳米线透射电子显微镜（TEM）样品制备方法对这些结构进行检查，该方法允许直接检查在不同间接FIB沉积条件下制备的单个选定的核壳纳米线。通过能量色散X射线光谱和电子能量过滤TEM成像进行的元素分析验证了二氧化硅和铂层的沉积。对于厚度达25 - 30纳米的铂或二氧化硅壳层的沉积，在单个磷化镓纳米线上可以实现相对均匀的铂和二氧化硅涂层，总体厚度偏差约为10%。应该有可能将这种方法扩展到任何纳米线/纳米管系统，并扩展到任何所需层序列的广泛涂层。
