All-(111) Surface Silicon Nanowires: Selective Functionalization for Biosensing Applications

Abstract

We demonstrate the utilization of selective functionalization of carbon-silicon (C-Si) alkyl and alkenyl monolayers covalently linked to all-(111) surface silicon nanowire (Si-NW) biosensors. Terminal amine groups on the functional monolayer surfaces were used for conjugation of biotin n-hydroxysuccinimide ester. The selective functionalization is demonstrated by contact angle, X-ray photoelectron spectroscopy (XPS), and high-resolution scanning electron microscopy (HRSEM) of 5 nm diameter thiolated Au nanoparticles linked with streptavidin and conjugated to the biotinylated all-(111) surface Si-NWs. Electrical measurements of monolayer passivated Si-NWs show improved device behavior and performance. Furthermore, an analytical model is presented to demonstrate the improvement in detection sensitivity of the alkyl and alkenyl passivated all-(111) Si-NW biosensors compared to conventional nanowire biosensor geometries and silicon dioxide passivation layers as well as interface design and electrical biasing guidelines for depletion-mode sensors.

Influence of Conductivity and Dielectric Constant of Water–Dioxane Mixtures on the Electrical Response of SiNW-Based FETs

“…Most of the work focuses on different aspects of device fabrication and on (potential) sensor applications for the label-free detection of (bio)chemical species [1–4]. Studies on (bio)chemical sensing typically require (bio)chemical modification of the nanowire surface [5].…”

Sum frequency generation spectroscopy study of hydrogenated stepped Si(111) surfaces made by molecular hydrogen exposure

“…In this research, step structures and dihydride orientation on vicinal Si(111) surfaces with 9.5 o miscut angle toward [ ̅ ̅ ] direction are studied with hydrogen molecular adsorption in a UHV chamber with negligible influence from water. Here we note that stepped Si(111) are promising substrates for quantum dots and nanowires growth due to their active sites, and they are worth characterizing [11,12]. 3 The detailed structure of Si(111) surfaces with a miscut angle of 9.5 o toward [ ̅ ̅ ] direction was described by other groups [5,13].…”

Silicon nanowire-transistor biosensor for study of molecule-molecule interactions

“…Therefore, an SiNW-selective modification methodology is urgently desirable. Several approaches, such as photolithography (Stern et al 2007b), electrostatic attraction (Naujoks and Stemmer 2003), microcontact printing (Renault et al 2002), and incomplete chemical etching (Masood et al 2010), have been employed to decorate nanowire surface by focusing on the sensing area.…”