Continuous-wave laser annealing of Si-rich oxide: A microscopic picture of macroscopic Si-SiO{sub 2} phase separation

Journal Article · Wed Dec 15 00:00:00 EST 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3520673· OSTI ID:21537995

Khriachtchev, Leonid; Nikitin, Timur; Raesaenen, Markku; Domanskaya, Alexandra ^[1]; Boninelli, Simona; Iacona, Fabio ^[2]; Engdahl, Anders ^[3]; Juhanoja, Jyrki ^[4]; Novikov, Sergei ^[5]

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1. Laboratory of Physical Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 (Finland)
2. MATIS IMM CNR, Via Santa Sofia 64, I-95123 Catania (Italy)
3. MAX-lab, Lund University, P.O. Box 118, 22100 Lund (Sweden)
4. Top Analytica, Ruukinkatu 4, FIN-20540 Turku (Finland)
5. Electron Physics Laboratory, Aalto University, P.O. Box 3000, FIN-02015 HUT (Finland)

We report on the first observation of the macroscopic (long-range) Si-SiO{sub 2} phase separation in Si-rich oxide SiO{sub x}(x<2) obtained by continuous-wave laser annealing of free-standing SiO{sub x} films. The effect is analyzed by a unique combination of microscopic methods (Raman, transmission, photoluminescence, and infrared spectroscopy, transmission electron microscopy, electron energy loss spectroscopy, and x-ray photoelectron spectroscopy). Three regions can be distinguished on a SiO{sub x} free-standing film after 488 nm laser annealing at intensities above {approx}10{sup 4} W cm{sup -2}: central spot, ring around the central spot, and pristine film outside the irradiated area. In the pristine SiO{sub x} material, small Si nanocrystals (Si-nc) (diameters of a few nanometer) are surrounded by SiO{sub 2} with an addition of residual suboxides, the Si-nc being produced by annealing at 1100 deg. C in a furnace. The central spot of the laser-annealed area (up to {approx}30 {mu}m wide in these experiments) is practically free of Si excess and mainly consists of amorphous SiO{sub 2}. The ring around the central spot contains large spherical Si-nc (diameters up to {approx}100 nm) embedded in amorphous SiO{sub 2} without the presence of suboxides. Laser-induced temperatures in the structurally modified regions presumably exceed the Si melting temperature. The macroscopic Si-SiO{sub 2} phase separation is connected with extensive diffusion in temperature gradient leading to the Si concentration gradient. The present work demonstrates the advantages of high spatial resolution for analysis in materials research.

• OSTI ID: 21537995
• Journal Information: Journal of Applied Physics, Vol. 108, Issue 12; Other Information: DOI: 10.1063/1.3520673; (c) 2010 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTROSCOPY
AMORPHOUS STATE
ANNEALING
BEAMS
DIFFUSION
ENERGY-LOSS SPECTROSCOPY
FILMS
INFRARED SPECTRA
LASER RADIATION
MELTING POINTS
NANOSTRUCTURES
PHOTOLUMINESCENCE
RAMAN SPECTRA
SILICON
SILICON OXIDES
SPATIAL RESOLUTION
TEMPERATURE GRADIENTS
TRANSMISSION
TRANSMISSION ELECTRON MICROSCOPY
X-RAY PHOTOELECTRON SPECTROSCOPY
CHALCOGENIDES
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ELEMENTS
EMISSION
HEAT TREATMENTS
LUMINESCENCE
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PHOTON EMISSION
PHYSICAL PROPERTIES
RADIATIONS
RESOLUTION
SEMIMETALS
SILICON COMPOUNDS
SPECTRA
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE