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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.

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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

The evolution of sheet resistance with time of Si nanomembranes in dry air. After two surface modifications, VH and HF etching. (a) 220 nm. (b) 28 nm. The sheet resistance is lower for thicker NMs.
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Figure 1: The evolution of sheet resistance with time of Si nanomembranes in dry air. After two surface modifications, VH and HF etching. (a) 220 nm. (b) 28 nm. The sheet resistance is lower for thicker NMs.

Mentions: As mentioned above, the NM thicknesses chosen for these measurements provide total dopant sheet charge densities differing by about one order of magnitude for the same bulk dopant concentration. The thicker membrane should thus have lower resistance. Figure 1 shows a summary of the evolution of sheet resistance with time. The gray bar on top of each panel is the range of sheet resistance measured for the NM with an oxidized surface; no time dependence is measured nor expected. For oxide termination, the sheet resistance for the thinner NM is much higher, as predicted.


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)

The evolution of sheet resistance with time of Si nanomembranes in dry air. After two surface modifications, VH and HF etching. (a) 220 nm. (b) 28 nm. The sheet resistance is lower for thicker NMs.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: The evolution of sheet resistance with time of Si nanomembranes in dry air. After two surface modifications, VH and HF etching. (a) 220 nm. (b) 28 nm. The sheet resistance is lower for thicker NMs.
Mentions: As mentioned above, the NM thicknesses chosen for these measurements provide total dopant sheet charge densities differing by about one order of magnitude for the same bulk dopant concentration. The thicker membrane should thus have lower resistance. Figure 1 shows a summary of the evolution of sheet resistance with time. The gray bar on top of each panel is the range of sheet resistance measured for the NM with an oxidized surface; no time dependence is measured nor expected. For oxide termination, the sheet resistance for the thinner NM is much higher, as predicted.

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