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Microscopic study of electrical properties of CrSi2 nanocrystals in silicon.

Dózsa L, Lányi S, Raineri V, Giannazzo F, Galkin NG - Nanoscale Res Lett (2011)

Bottom Line: Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface.The electrical interaction of the vibrating scanning tip results in virtual deformation of the surface.SCM has revealed NCs deep below the surface not seen by AFM.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Institute for Technical Physics and Materials Science, P, O, Box 49, H-1525 Budapest, Hungary. dozsa@mfa.kfki.hu.

ABSTRACT
Semiconducting CrSi2 nanocrystallites (NCs) were grown by reactive deposition epitaxy of Cr onto n-type silicon and covered with a 50-nm epitaxial silicon cap. Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface. The electrical characteristics were investigated in Schottky junctions by current-voltage and capacitance-voltage measurements. Atomic force microscopy (AFM), conductive AFM and scanning probe capacitance microscopy (SCM) were applied to reveal morphology and local electrical properties. The scanning probe methods yielded specific information, and tapping-mode AFM has shown up to 13-nm-high large-area protrusions not seen in the contact-mode AFM. The electrical interaction of the vibrating scanning tip results in virtual deformation of the surface. SCM has revealed NCs deep below the surface not seen by AFM. The electrically active probe yielded significantly better spatial resolution than AFM. The conductive AFM measurements have shown that the Cr-related point defects near the surface are responsible for the leakage of the macroscopic Schottky junctions, and also that NCs near the surface are sensitive to the mechanical and electrical stress induced by the scanning probe.

No MeSH data available.


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Contact-mode scanning probe images of a 1 μm × 1 μm area on the samples with NCs 50 nm below the surface. (a). AFM amplitude image. (b). SCM image of the same area.
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Figure 6: Contact-mode scanning probe images of a 1 μm × 1 μm area on the samples with NCs 50 nm below the surface. (a). AFM amplitude image. (b). SCM image of the same area.

Mentions: The contact-mode AFM and SCM images of the sample with NCs at 50-nm depth are shown in Figure 6a,b, respectively. The NCs are hardly visible in AFM, as the sample surface is flat. The NCs are apparent in SCM. The higher conductivity of inclusions increases the locally sensed capacitance, and thus, the difference of electrical properties of silicon and CrSi2 gives a better contrast for the detection of the NCs by scanning tip capacitance sensing. NCs deep below the surface are revealed in SCM images, and are not shown in the morphology measured simultaneously. Deep NC features are generally expected to appear somewhat smeared [10]. A cross section of the SCM image across a NC is shown in Figure 7. The half-width of the peak agrees with the size of the NCs. It shows that the interaction of the charged NC and the measuring tip is strong, which controls the transport, and we assume that the measured capacitance is dominated by the NC-host junction. The measurements indicate that the NCs embedded deep--having electrical characteristics different from the defect-free host--can be detected using the SCM with high resolution.


Microscopic study of electrical properties of CrSi2 nanocrystals in silicon.

Dózsa L, Lányi S, Raineri V, Giannazzo F, Galkin NG - Nanoscale Res Lett (2011)

Contact-mode scanning probe images of a 1 μm × 1 μm area on the samples with NCs 50 nm below the surface. (a). AFM amplitude image. (b). SCM image of the same area.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211265&req=5

Figure 6: Contact-mode scanning probe images of a 1 μm × 1 μm area on the samples with NCs 50 nm below the surface. (a). AFM amplitude image. (b). SCM image of the same area.
Mentions: The contact-mode AFM and SCM images of the sample with NCs at 50-nm depth are shown in Figure 6a,b, respectively. The NCs are hardly visible in AFM, as the sample surface is flat. The NCs are apparent in SCM. The higher conductivity of inclusions increases the locally sensed capacitance, and thus, the difference of electrical properties of silicon and CrSi2 gives a better contrast for the detection of the NCs by scanning tip capacitance sensing. NCs deep below the surface are revealed in SCM images, and are not shown in the morphology measured simultaneously. Deep NC features are generally expected to appear somewhat smeared [10]. A cross section of the SCM image across a NC is shown in Figure 7. The half-width of the peak agrees with the size of the NCs. It shows that the interaction of the charged NC and the measuring tip is strong, which controls the transport, and we assume that the measured capacitance is dominated by the NC-host junction. The measurements indicate that the NCs embedded deep--having electrical characteristics different from the defect-free host--can be detected using the SCM with high resolution.

Bottom Line: Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface.The electrical interaction of the vibrating scanning tip results in virtual deformation of the surface.SCM has revealed NCs deep below the surface not seen by AFM.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Institute for Technical Physics and Materials Science, P, O, Box 49, H-1525 Budapest, Hungary. dozsa@mfa.kfki.hu.

ABSTRACT
Semiconducting CrSi2 nanocrystallites (NCs) were grown by reactive deposition epitaxy of Cr onto n-type silicon and covered with a 50-nm epitaxial silicon cap. Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface. The electrical characteristics were investigated in Schottky junctions by current-voltage and capacitance-voltage measurements. Atomic force microscopy (AFM), conductive AFM and scanning probe capacitance microscopy (SCM) were applied to reveal morphology and local electrical properties. The scanning probe methods yielded specific information, and tapping-mode AFM has shown up to 13-nm-high large-area protrusions not seen in the contact-mode AFM. The electrical interaction of the vibrating scanning tip results in virtual deformation of the surface. SCM has revealed NCs deep below the surface not seen by AFM. The electrically active probe yielded significantly better spatial resolution than AFM. The conductive AFM measurements have shown that the Cr-related point defects near the surface are responsible for the leakage of the macroscopic Schottky junctions, and also that NCs near the surface are sensitive to the mechanical and electrical stress induced by the scanning probe.

No MeSH data available.


Related in: MedlinePlus