Amorphous Ge quantum dots embedded in SiO{sub 2} formed by low energy ion implantation

Journal Article · Sun Jun 15 00:00:00 EDT 2008 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2927254· OSTI ID:21137365

Zhao, J P ^[1]; Huang, D X; Jacobson, A J ^[1]; Chen, Z Y; Makarenkov, B ^[2]; Chu, W K ^[1]; Bahrim, B ^[3]; Rabalais, J W ^[2]

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1. Texas Center for Superconductivity, University of Houston, Houston, Texas 77204 (United States)
2. Department of Chemistry, University of Houston, Houston, Texas 77204 (United States)
3. Department of Chemistry and Physics, Lamar University, Beaumont, Texas 77710 (United States)

Under ultrahigh vacuum conditions, extremely small Ge nanodots embedded in SiO{sub 2}, i.e., Ge-SiO{sub 2} quantum dot composites, have been formed by ion implantation of {sup 74}Ge{sup +} isotope into (0001) Z-cut quartz at a low kinetic energy of 9 keV using varying implantation temperatures. Transmission electron microscopy (TEM) images and micro-Raman scattering show that amorphous Ge nanodots are formed at all temperatures. The formation of amorphous Ge nanodots is different from reported crystalline Ge nanodot formation by high energy ion implantation followed by a necessary high temperature annealing process. At room temperature, a confined spatial distribution of the amorphous Ge nanodots can be obtained. Ge inward diffusion was found to be significantly enhanced by a synergetic effect of high implantation temperature and preferential sputtering of surface oxygen, which induced a much wider and deeper Ge nanodot distribution at elevated implantation temperature. The bimodal size distribution that is often observed in high energy implantation was not observed in the present study. Cross-sectional TEM observation and the depth profile of Ge atoms in SiO{sub 2} obtained from x-ray photoelectron spectra revealed a critical Ge concentration for observable amorphous nanodot formation. The mechanism of formation of amorphous Ge nanodots and the change in spatial distribution with implantation temperature are discussed.

• OSTI ID: 21137365
• Journal Information: Journal of Applied Physics, Vol. 103, Issue 12; Other Information: DOI: 10.1063/1.2927254; (c) 2008 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
ANNEALING
COMPOSITE MATERIALS
GERMANIUM 74
GERMANIUM IONS
ION IMPLANTATION
KINETIC ENERGY
OXYGEN
QUANTUM DOTS
QUARTZ
RAMAN EFFECT
RAMAN SPECTRA
SEMICONDUCTOR MATERIALS
SILICON OXIDES
SPATIAL DISTRIBUTION
SPUTTERING
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TRANSMISSION ELECTRON MICROSCOPY
X-RAY PHOTOELECTRON SPECTROSCOPY