Nano scale phase separation in Au-Ge system on ultra clean Si(100) surfaces

Journal Article · Tue May 15 00:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4721666· OSTI ID:22038965

Rath, A; Dash, J K; Juluri, R R; Satyam, P V ^[1]; Schowalter, Marco; Mueller, Knut; Rosenauer, A ^[2]

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1. Institute of Physics, Sachivalaya Marg, Bhubaneswar-751005 (India)
2. Institute of Solid State Physics, University of Bremen, D-28359 Bremen (Germany)

We report on the phase separation in Au-Ge system leading to the formation of lobe-lobe (bi-lobed) Au-Ge nanostructures under ultra high vacuum (UHV) conditions ({approx_equal}3 x 10{sup -10} mbar) on clean Si(100) surfaces. For this study, {approx_equal}2.0 nm thick Au samples were grown on the substrate surface by molecular beam epitaxy. Thermal annealing was carried out inside the UHV chamber at temperature {approx_equal}500 deg. C and following this, nearly square shaped Au{sub x}Si{sub 1-x} nano structures of average length {approx_equal}48 nm were formed. A {approx_equal}2 nm Ge film was further deposited on the above surface while the substrate was kept at a temperature of {approx_equal}500 deg. C. Well ordered Au-Ge nanostructures where Au and Ge residing side by side (lobe-lobe structures) were formed. In our systematic studies, we show that, gold-silicide nanoalloy formation at the substrate (Si) surface is necessary for forming phase separated Au-Ge bilobed nanostructures. These results show that the Au-Ge bonding is unstable in nature. Electron microscopy (TEM, STEM-EDS, SEM) studies were carried out to determine the structure of Au-Ge nano systems. Rutherford backscattering spectrometry measurements show gold inter-diffusion into substrate while it is absent for Ge.

• OSTI ID: 22038965
• Journal Information: Journal of Applied Physics, Vol. 111, Issue 10; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
77 NANOSCIENCE AND NANOTECHNOLOGY
ANNEALING
CHEMICAL ANALYSIS
CRYSTAL GROWTH
DIFFUSION
FILMS
GERMANIUM
GOLD
GOLD SILICIDES
LAYERS
MOLECULAR BEAM EPITAXY
NANOSTRUCTURES
RUTHERFORD BACKSCATTERING SPECTROSCOPY
SCANNING ELECTRON MICROSCOPY
SUBSTRATES
SURFACES
TRANSMISSION ELECTRON MICROSCOPY