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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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Tapping-mode AFM images of a 1 μm × 1 μm area on the sample with NCs below the 50-nm silicon cap: (a) amplitude, (b) phase.
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Figure 3: Tapping-mode AFM images of a 1 μm × 1 μm area on the sample with NCs below the 50-nm silicon cap: (a) amplitude, (b) phase.

Mentions: Tapping-mode AFM amplitude and phase images of the samples with NCs near the surface are shown in Figure 3a,b, respectively. The tapping-mode AFM amplitude (Figure 3a) is not sensitive to the CrSi2 NCs. Several bigger NCs appear in the phase image (Figure 3b). We suppose that it is due to the electrical interaction of NCs with the vibrating scanning tip. The phase of the vibration changes, but does not cause energy dissipation, interpreted as height in the amplitude image. Some spherical protrusions appear with a diameter of about 90 nm and a height of 12 nm in the amplitude. The morphology measured in contact-mode does not show these large protrusions. The difference can be an effect of the pressure of the tip in contact-mode and the possible wear of the sample, since repeated scans over the imaged areas has shown visible degradation of the surface. However, we suppose that these protrusions are mainly due to areas with large NC density in the cap, resulting in virtual height increase in tapping-mode amplitude image.


Microscopic study of electrical properties of CrSi2 nanocrystals in silicon.

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

Tapping-mode AFM images of a 1 μm × 1 μm area on the sample with NCs below the 50-nm silicon cap: (a) amplitude, (b) phase.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Tapping-mode AFM images of a 1 μm × 1 μm area on the sample with NCs below the 50-nm silicon cap: (a) amplitude, (b) phase.
Mentions: Tapping-mode AFM amplitude and phase images of the samples with NCs near the surface are shown in Figure 3a,b, respectively. The tapping-mode AFM amplitude (Figure 3a) is not sensitive to the CrSi2 NCs. Several bigger NCs appear in the phase image (Figure 3b). We suppose that it is due to the electrical interaction of NCs with the vibrating scanning tip. The phase of the vibration changes, but does not cause energy dissipation, interpreted as height in the amplitude image. Some spherical protrusions appear with a diameter of about 90 nm and a height of 12 nm in the amplitude. The morphology measured in contact-mode does not show these large protrusions. The difference can be an effect of the pressure of the tip in contact-mode and the possible wear of the sample, since repeated scans over the imaged areas has shown visible degradation of the surface. However, we suppose that these protrusions are mainly due to areas with large NC density in the cap, resulting in virtual height increase in tapping-mode amplitude image.

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