| AVS 55th International Symposium & Exhibition | |
| Surface Science | Thursday Sessions |
| Session SS1-ThM |
| Session: | Growth and Etching on Surfaces |
| Presenter: | J.D. Wnuk, Johns Hopkins University |
| Authors: | J.D. Wnuk, Johns Hopkins University J.M. Gorham, Johns Hopkins University W.F. Van Dorp, Rutgers, the State University of New Jersey C.W. Hagen, Delft University of Technology, The Netherlands T.E. Madey, Rutgers, the State University of New Jersey D.H. Fairbrother, Johns Hopkins University |
| Correspondent: | Click to Email |
Electron beam induced deposition (EBID) of volatile organometallic precursors has emerged as an effective and versatile route to creating 2-D and 3-D metallic nanostructures. In an effort to better elucidate the process by which these structures are formed, we have studied the effect of low energy (500eV) electrons on sub-monolayer coverages of methylcyclopentadienylplatinum(IV)-trimethyl (MeCpPtMe3) adsorbed onto gold substrates in situ under ultra-high vacuum conditions using a combination of mass spectrometry, reflection absorption infrared spectroscopy (RAIRS) and x-ray photoelectron spectroscopy (XPS). Electron beam irradiation produces a carbonaceous film that contains Pt atoms in an oxidation state which is intermediate between metallic Pt and the parent Pt(IV) species. XPS analysis of the Pt(4f) region indicates that the conversion of Pt species follows first order kinetics, with a rate constant proportional to the target current. Electron stimulated decomposition of adsorbed MeCpPt(IV)Me3 is also accompanied by the evolution of gas phase methane and hydrogen as well as the loss of the C-H bonds associated with the parent MeCpPt(IV)Me3 compound. The kinetics of methane and hydrogen production and the loss of C-H groups from the adsorbate layer can all be described by first order kinetics, with calculated reaction cross-sections comparable to the XPS-measured value. In conjunction, XPS, RAIRS and MS data suggests that a single electron event is responsible for decomposition of the parent compound and the formation of the platinum containing carbonaceous film. Electron beam irradiation also results in a reproducible change in the film’s Pt/C ratio, whose magnitude is consistent with the idea that electron beam decomposition is initiated by a single Pt-CH3 bond cleavage event. The average cross-section for the electron stimulated decomposition of adsorbed MeCpPt(IV)Me3 via the different pathways at a specific electron beam energy of 500 eV is measured to be 1.5x10-16 cm-2. Results from this study, carried out under well-defined reaction conditions where changes in the gas phase composition and the film’s surface composition can be monitored simultaneously, provide new insights into the EBID process.