Phase separation in SiGe nanocrystals embedded in SiO{sub 2} matrix during high temperature annealing

Journal Article · Mon Dec 15 04:00:00 EST 2008 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3048543· OSTI ID:21180057

Mogaddam, N A. P.; Turan, R ^[1]; Alagoz, A S ^[1]; Yerci, S ^[1]; Foss, S; Finstad, T G ^[2]

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1. Department of Physics, Middle East Technical University, 06531 Ankara (Turkey)
2. Department of Physics, University of Oslo, Oslo 0316 (Norway)

SiGe nanocrystals have been formed in SiO{sub 2} matrix by cosputtering Si, Ge, and SiO{sub 2} independently on Si substrate. Effects of the annealing time and temperature on structural and compositional properties are studied by transmission electron microscopy, x-ray diffraction (XRD), and Raman spectroscopy measurements. It is observed that Ge-rich Si{sub (1-x)}Ge{sub x} nanocrystals do not hold their compositional uniformity when annealed at high temperatures for enough long time. A segregation process leading to separation of Ge and Si atoms from each other takes place. This process has been evidenced by a double peak formation in the XRD and Raman spectra. We attributed this phase separation to the differences in atomic size, surface energy, and surface diffusion disparity between Si and Ge atoms leading to the formation of nonhomogenous structure consist of a Si-rich SiGe core covered by a Ge-rich SiGe shell. This experimental observation is consistent with the result of reported theoretical and simulation methods.

• OSTI ID: 21180057
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 12 Vol. 104; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
DEPOSITION
GERMANIUM ALLOYS
GERMANIUM SILICIDES
NANOSTRUCTURES
RAMAN SPECTRA
RAMAN SPECTROSCOPY
SEGREGATION
SEMICONDUCTOR MATERIALS
SILICON ALLOYS
SILICON OXIDES
SIMULATION
SPUTTERING
SUBSTRATES
SURFACE ENERGY
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION