AVS 47th International Symposium
    Processing at the Nanoscale/NANO 6 Wednesday Sessions
       Session NS+NANO6-WeA

Paper NS+NANO6-WeA10
Ion Implanted Contacts to Nanostructures and Metallic Monolayers on Clean Surfaces

Wednesday, October 4, 2000, 5:00 pm, Room 302

Session: Nanoscale Modification of Materials
Presenter: J.W. Nolan, University of Nottingham, UK
Authors: J.W. Nolan, University of Nottingham, UK
B.N. Cotier, University of Nottingham, UK
M.J. Butcher, University of Nottingham, UK
P.H. Beton, University of Nottingham, UK
P. Moriarty, University of Nottingham, UK
M.R.C. Hunt, University of Nottingham, UK
A. Neumann, University of Nottingham, UK
V.R. Dhanak, Daresbury Laboratory, UK
A. Gundlach, Edinburgh University, UK
S. Thoms, University of Glasgow, UK
Correspondent: Click to Email
Ion implanted (As) contact tracks with separations of order 200nm and depths ~20nm are formed in p-Si/SiO2 wafers. These tracks are investigated using scanning tunnelling microscopy (STM) in an ultra-high vacuum environment following removal of the SiO2 layer using a combination of wet etching and high temperature vacuum annealing in the range 600-1000oC. The ion implanted regions are activated by this anneal and are slightly depressed (by ~5nm) as compared with the surrounding surface but co-exist with the Si(100)-2x1 and Si(111)-7x7 surface. Core level photoemission studies of control samples which have been uniformly implanted show that As desorbs from the near surface region for temperatures >900oC, the temperature at which the oxide layer is thermally desorbed, but this leads to an insignificant change in resistance of the tracks. The ion implanted regions form high impedance reverse biased p/n junctions with a p-type substrate and adjacent implanted tracks may be shorted by the deposition of thin metallic films. The shorting resistance of these structures has been measured using an in-situ electrical prober and results are correlated with the morphology of the metallic layer. For samples annealed below 900oC the oxide layer is not desorbed and a shorting resistance ~20kOhms is observed for a Ag film of thickness 0.5nm. At higher annealing temperatures this shorting resistance is much higher due in part to As desorption and in part the island morphology of the Ag film. The process is compatible with H termination and de-passivation and we report results on metallic adsorption on depassivated wires ~1-5nm wide.