1.Binary Pt-Si nanostructures prepared by focused electron-beam-induced deposition.
Winhold M1, Schwalb CH, Porrati F, Sachser R, Frangakis AS, Kämpken B, Terfort A, Auner N, Huth M. ACS Nano. 2011 Dec 27;5(12):9675-81. doi: 10.1021/nn203134a. Epub 2011 Nov 29.
Binary systems of Pt-Si are prepared by electron-beam-induced deposition using the two precursors, trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPt(Me)(3)) and neopentasilane (Si(SiH(3))(4)), simultaneously. By varying the relative flux of the two precursors during deposition, we are able to study composites containing platinum and silicon in different ratios by means of energy-dispersive X-ray spectroscopy, atomic force microscopy, electrical transport measurements, and transmission electron microscopy. The results show strong evidence for the formation of a binary, metastable Pt(2)Si(3) phase, leading to a maximum in the conductivity for a Si/Pt ratio of 3:2.
2.Gas phase low energy electron induced decomposition of the focused electron beam induced deposition (FEBID) precursor trimethyl (methylcyclopentadienyl) platinum(IV) (MeCpPtMe3).
Engmann S1, Stano M, Matejčík S, Ingólfsson O. Phys Chem Chem Phys. 2012 Nov 14;14(42):14611-8. doi: 10.1039/c2cp42637d. Epub 2012 Oct 2.
Relative cross sections for dissociative electron attachment (DEA) and dissociative ionization (DI) of the FEBID precursor, trimethyl (methylcyclopentadienyl) platinum(iv), MeCpPtMe(3), are presented. The most pronounced DEA process is the loss of one methyl radical, while the loss of two or three methyl groups along with hydrogen is the main pathway in DI. Further fragments are formed in DEA and through DI by more complex rearrangement reactions but complete dissociation to bare Pt(-) in DEA or Pt(+) in DI is minor. The transient negative ion (TNI) formation in DEA is discussed and fragmentation mechanisms are proposed for individual processes. From the thermodynamics of the DEA processes we derive a lower limit for the electron affinity of the MeCpPtMe(2) radical (1.7 eV). Appearance energies (AE) of MeCpPtMe(3)(+) (7.7 eV) and Pt(+) (18.6 eV) formation through electron impact ionisation (EI) and through DI, respectively, are determined.
3.Structural investigation of Ru/Pt nanocomposite films prepared by plasma-enhanced atomic layer depositions.
Kawasaki M1, Hsiao CN2, Yang JR3, Shiojiri M4. Micron. 2015 Jul;74:8-14. doi: 10.1016/j.micron.2015.03.012. Epub 2015 Apr 5.
We have fabricated Ru and Pt nanocomposite films using plasma-enhanced atomic layer deposition (PE-ALD), and characterized their structure by means of analytical electron microscopy. Pt and Ru were deposited in Ar/O(2) plasma using trimethyl(methylcyclopentadienyl) platinum(IV) and bis(cyclopentadienyl)Ru(II) or bis(ethylcyclopentadienyl)Ru(II) as precursors, respectively. The resistivity of a Pt film deposited on a Si substrate at 300°C was 16.2μΩcm, and that of a Ru film was as low as 11μΩcm, showing the film to be metallic and not oxidized. It was revealed that the film prepared by successive PE-ALDs of Pt and Ru on a thin amorphous carbon substrate for electron microscopy analysis is a nanocomposite of Ru ribbons and PtRu (7:3) alloy ribbons with 2-3 nm in width. The Ru ribbon comprised small particles with poor crystallinity of the hcp A3 structure and the PtRu ribbon comprised crystallites with good crystallinity of the fcc Al structure.
4.Synthesis of nanowires via helium and neon focused ion beam induced deposition with the gas field ion microscope.
Wu HM1, Stern LA, Chen JH, Huth M, Schwalb CH, Winhold M, Porrati F, Gonzalez CM, Timilsina R, Rack PD. Nanotechnology. 2013 May 3;24(17):175302. doi: 10.1088/0957-4484/24/17/175302. Epub 2013 Apr 3.
The ion beam induced nanoscale synthesis of platinum nanowires using the trimethyl (methylcyclopentadienyl)platinum(IV) (MeCpPt(IV)Me3) precursor is investigated using helium and neon ion beams in the gas field ion microscope. The He(+) beam induced deposition resembles material deposited by electron beam induced deposition with very small platinum nanocrystallites suspended in a carbonaceous matrix. The He(+) deposited material composition was estimated to be 16% Pt in a matrix of amorphous carbon with a large room-temperature resistivity (∼3.5 × 10(4)-2.2 × 10(5) μΩ cm) and temperature-dependent transport behavior consistent with a granular material in the weak intergrain tunnel coupling regime. The Ne(+) deposited material has comparable composition (17%), however a much lower room-temperature resistivity (∼600-3.0 × 10(3) μΩ cm) and temperature-dependent electrical behavior representative of strong intergrain coupling. The Ne(+) deposited nanostructure has larger platinum nanoparticles and is rationalized via Monte Carlo ion-solid simulations which show that the neon energy density deposited during growth is much larger due to the smaller ion range and is dominated by nuclear stopping relative to helium which has a larger range and is dominated by electronic stopping.