Introduction of Si/SiO{sub 2} interface states by annealing Ge-implanted films

Journal Article · Fri Oct 15 00:00:00 EDT 2004 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1790579· OSTI ID:20662111

Marstein, E S; Gunnaes, A E; Olsen, A; Finstad, T G; Turan, R; Serincan, U ^[1]

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1. Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Olso (Norway)

Nanocrystals embedded in SiO{sub 2} films are the subject of a number of recent works, mainly because of their potential usefulness in the fabrication of optoelectronic devices and nanocrystal memory structures. One interesting method for the fabrication of such nanocrystals is the ion implantation of segregating species into SiO{sub 2} films followed by heat treatment in order to induce nanocrystal formation. This method is both relatively simple and also compatible with the current MOS (metal-oxide-semiconductor) device technology. An unintentional effect can occur during the fabrication of nanocrystals using this method, namely a significant diffusion of the implanted species during annealing, away from the regions with the highest concentration. The Si/SiO{sub 2} interface can be exposed to this diffusion flux. This can result in an altered interface and have a significant influence on electronic devices. Here, we report on ion implantation of Ge into SiO{sub 2} on Si followed by annealing under conditions, resulting in Ge accumulation at the Si/SiO{sub 2} interface as determined by secondary-ion mass spectroscopy analysis, transmission electron microscopy with energy dispersive analysis of x-rays, and Rutherford backscattering spectrometry. The accumulation of Ge at the Si/SiO{sub 2} interface has also been reported before. The resulting effect on the electronic structure of the interface is a priori unknown. We have fabricated MOS capacitors on the sample structures and their capacitance-voltage characteristics were measured and analyzed. We measure an interface state density around 1x10{sup 12} cm{sup -2}, which is high compared to standard Si MOS devices. We discuss the results in terms of the previous electrical measurements on Ge-oxide interfaces and SiGe interfaces, which also can yield a high interface state density. The specific conditions we report result in a sufficiently low Ge concentration that nanocrystals are not segregated in the SiO{sub 2} film, while Ge still accumulates at the Si/SiO{sub 2} interface after annealing.

• OSTI ID: 20662111
• Journal Information: Journal of Applied Physics, Vol. 96, Issue 8; Other Information: DOI: 10.1063/1.1790579; (c) 2004 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
CAPACITANCE
CAPACITORS
ELECTRONIC EQUIPMENT
ELECTRONIC STRUCTURE
FABRICATION
GERMANIUM IONS
INTERFACES
ION IMPLANTATION
ION MICROPROBE ANALYSIS
MASS SPECTROSCOPY
NANOSTRUCTURES
RUTHERFORD BACKSCATTERING SPECTROSCOPY
SEMICONDUCTOR MATERIALS
SILICON
SILICON OXIDES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
VACUUM COATING
X RADIATION