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Influence of surface properties on the electrical conductivity of silicon nanomembranes.

Zhao X, Scott SA, Huang M, Peng W, Kiefer AM, Flack FS, Savage DE, Lagally MG - Nanoscale Res Lett (2011)

Bottom Line: Two surface modifications, vacuum hydrogenation (VH) and hydrofluoric acid (HF) cleaning, of silicon nanomembranes (SiNMs) that nominally have the same effect, the hydrogen termination of the surface, are compared.Re-oxidation rates after these treatments also differ.We pinpoint the likely cause of the differences.PACS: 73.63.-b, 62.23.Kn, 73.40.Ty.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Wisconsin-Madison, Madison WI 53706, USA. lagally@engr.wisc.edu.

ABSTRACT
Because of the large surface-to-volume ratio, the conductivity of semiconductor nanostructures is very sensitive to surface chemical and structural conditions. Two surface modifications, vacuum hydrogenation (VH) and hydrofluoric acid (HF) cleaning, of silicon nanomembranes (SiNMs) that nominally have the same effect, the hydrogen termination of the surface, are compared. The sheet resistance of the SiNMs, measured by the van der Pauw method, shows that HF etching produces at least an order of magnitude larger drop in sheet resistance than that caused by VH treatment, relative to the very high sheet resistance of samples terminated with native oxide. Re-oxidation rates after these treatments also differ. X-ray photoelectron spectroscopy measurements are consistent with the electrical-conductivity results. We pinpoint the likely cause of the differences.PACS: 73.63.-b, 62.23.Kn, 73.40.Ty.

No MeSH data available.


Related in: MedlinePlus

XPS spectra of samples treated by the two surface modifications after 20-min exposure to air. Take-off angle is 45°, pass energy is 89.45 eV. The unlabeled peak is the O Auger line.
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Figure 3: XPS spectra of samples treated by the two surface modifications after 20-min exposure to air. Take-off angle is 45°, pass energy is 89.45 eV. The unlabeled peak is the O Auger line.

Mentions: It is known that after dosing with hydrogen under vacuum, the surface is purely H-terminated [16,21], while after HF treatment and DI water rinse, the surface is H-terminated with trace amounts of OH and F [12,14,23]. Figure 3 shows XPS spectra of 220-nm SiNMs treated by the two surface modifications after 20-min exposure to air. The samples treated with HF show a F 1s core level peak, confirming that the HF treatment leaves F ions on the surface [14], a feature that is absent in the VH-terminated sample. Comparison of the O1s peak for the H-terminated samples with the O1s peak from the sample with a native oxide confirms that the native oxide was removed after both H surface modifications.


Influence of surface properties on the electrical conductivity of silicon nanomembranes.

Zhao X, Scott SA, Huang M, Peng W, Kiefer AM, Flack FS, Savage DE, Lagally MG - Nanoscale Res Lett (2011)

XPS spectra of samples treated by the two surface modifications after 20-min exposure to air. Take-off angle is 45°, pass energy is 89.45 eV. The unlabeled peak is the O Auger line.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211497&req=5

Figure 3: XPS spectra of samples treated by the two surface modifications after 20-min exposure to air. Take-off angle is 45°, pass energy is 89.45 eV. The unlabeled peak is the O Auger line.
Mentions: It is known that after dosing with hydrogen under vacuum, the surface is purely H-terminated [16,21], while after HF treatment and DI water rinse, the surface is H-terminated with trace amounts of OH and F [12,14,23]. Figure 3 shows XPS spectra of 220-nm SiNMs treated by the two surface modifications after 20-min exposure to air. The samples treated with HF show a F 1s core level peak, confirming that the HF treatment leaves F ions on the surface [14], a feature that is absent in the VH-terminated sample. Comparison of the O1s peak for the H-terminated samples with the O1s peak from the sample with a native oxide confirms that the native oxide was removed after both H surface modifications.

Bottom Line: Two surface modifications, vacuum hydrogenation (VH) and hydrofluoric acid (HF) cleaning, of silicon nanomembranes (SiNMs) that nominally have the same effect, the hydrogen termination of the surface, are compared.Re-oxidation rates after these treatments also differ.We pinpoint the likely cause of the differences.PACS: 73.63.-b, 62.23.Kn, 73.40.Ty.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Wisconsin-Madison, Madison WI 53706, USA. lagally@engr.wisc.edu.

ABSTRACT
Because of the large surface-to-volume ratio, the conductivity of semiconductor nanostructures is very sensitive to surface chemical and structural conditions. Two surface modifications, vacuum hydrogenation (VH) and hydrofluoric acid (HF) cleaning, of silicon nanomembranes (SiNMs) that nominally have the same effect, the hydrogen termination of the surface, are compared. The sheet resistance of the SiNMs, measured by the van der Pauw method, shows that HF etching produces at least an order of magnitude larger drop in sheet resistance than that caused by VH treatment, relative to the very high sheet resistance of samples terminated with native oxide. Re-oxidation rates after these treatments also differ. X-ray photoelectron spectroscopy measurements are consistent with the electrical-conductivity results. We pinpoint the likely cause of the differences.PACS: 73.63.-b, 62.23.Kn, 73.40.Ty.

No MeSH data available.


Related in: MedlinePlus