Fabrication and electrical properties of ultra‐thin silicon nanowires

Abstract

Ultra thin (8 nm) silicon nanowires have been fabricated by Atomic Force Microscopy (AFM) lithography on an insulator layer starting from Silicon On Insulator (SOI) substrates. Electrical measurements reveal a high sensitivity of the electron transport in these ultra thin wires to the charge trapping on the Si/SiO2 interface states. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Chemical functionalisation of silicon and germanium nanowires

“…Consequently, the nanowires displayed a 3-fold greater resistance to re-oxidation when exposed to ambient conditions. The Si nanowires also showed higher stability compared to 2D Si (111) surfaces, despite having a lower surface coverage. Haick and co-workers further observed the Table 1 Bifunctional cross-linker molecules used for Si nanowire functionalisation rate of alkylation to be greater for Si nanowires.…”

“…Ge forms stable oxides in the 2+ (GeO) and 4+ (GeO 2 ), oxidation states, the latter of which is water soluble. Schmeisser 32 was the first to carry out synchrotron studies of oxidised Ge (100) and (111) surfaces and found the presence of all four Ge oxidation states. The oxidation behaviour of Ge is strongly dependant on the oxidative environment and is influenced by illumination conditions and crystal orientation.…”

“…36,45 However, organic functionalisation layers on Ge nanowires do possess greater stability than bulk Ge. Alkyl functionalised Ge (111) surfaces were found to be stable for up to 5 days, 77 while thiol-functionalised Ge(111) surfaces were only stable for 12 h. 107 In contrast, alkylation by hydrogermylation and thiolation of Ge nanowires resulted in oxide-free surfaces up to 1 month of ambient exposure. 79 Furthermore, thiol passivation layers on Ge nanowires were observed to be more stable than monolayers prepared by Grignard reaction, 51,80 however the opposite trend was observed on planar surfaces.…”

“…Interface states have been shown to effectively deplete an ultra thin (8 nm) Si nanowire, demonstrating the need for effective surface passivation. 111 Haick et al 112 compared the electrical properties of oxidised, H-terminated and CH 3 -terminated Si nanowires and found that H-Si and CH 3 -Si nanowires exhibited a 4-and 7-fold increase in conductance, respectively, relative to oxidised Si nanowires. On exposure to air, the average conductance of H-modified nanowires continuously decreased with the mobility reduced from 123 cm 2 V À1 s À1 to 87 cm 2 V À1 s À1 after 672 h of ambient exposure.…”

Surface modification of semiconducting silicon nanowires for biosensing applications

“…Furthermore, by controlling SiNW surface functionalization, it is also possible to inhibit non-specifi c interactions, improve blood circulation (PEG-spacer) and increase electrical properties (defect passivation). 16,25,[27][28][29][30][31] …”