Influence of surface properties on the electrical conductivity of silicon nanomembranes
1 University of Wisconsin-Madison, Madison WI 53706, USA
2 School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
Nanoscale Research Letters 2011, 6:402 doi:10.1186/1556-276X-6-402Published: 31 May 2011
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