Silicon nanowires terminated with methyl functionalities exhibit stronger Si–C bonds than equivalent 2D surfaces

Bashouti, Muhammad Y.; Paska, Yair; Puniredd, Sreenivasa Reddy; Stelzner, Thomas; Christiansen, Silke; Haick, Hossam

doi:10.1039/b820559k

Cited by 77 publications

(64 citation statements)

References 21 publications

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“…Figure 2 shows X‐ray photoelectron spectroscopy (XPS) data from the C1s emission region of molecule‐terminated 2D Si(111) samples, fitted to three peaks: CSi at 284.11 ± 0.02 eV, CC at 285.20 ± 0.02 eV, and CO at 286.69 ± 0.02 eV. The peaks were typically adjusted to produce fits that minimized the difference between the full width at half‐maximum (FWHM) 29–32. The center‐to‐center distances were fixed at 1.10 ± 0.10 eV between the CSi and the CC emissions and at 2.60 ± 0.10 eV between the CO and the CSi emissions.…”

Section: Resultsmentioning

confidence: 99%

“…Si NWs tend to form a layer of SiO 2 with thickness 1–2 nm under ambient conditions, and subsequent HF treatment can be used to remove this oxide layer. Different Si surface treatments can be performed and it is also energetically favorable to passivate Si NW surfaces with organic functionalities 29–32. However, the electrical effects of surface chemical modification of Si NW electronic structure have not been systematically investigated.…”

Section: Introductionmentioning

confidence: 99%

“…Here we report on an approach to fine tune the conductivity of Si NW FETs through surface modification by chlorination/alkylation functionalization procedure 29–32, 34, 35. In this approach, the amorphous SiO 2 coating is first etched away by exposing Si NWs to buffered HF to form H‐terminated surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Tuning the Electrical Properties of Si Nanowire Field‐Effect Transistors by Molecular Engineering

Bashouti¹,

Tung²,

Haick³

2009

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Exposed facets of n-type silicon nanowires (Si NWs) fabricated by a top-down approach are successfully terminated with different organic functionalities, including 1,3-dioxan-2-ethyl, butyl, allyl, and propyl-alcohol, using a two-step chlorination/alkylation method. X-ray photoemission spectroscopy and spectroscopic ellipsometry establish the bonding and the coverage of these molecular layers. Field-effect transistors fabricated from these Si NWs displayed characteristics that depended critically on the type of molecular termination. Without molecules the source-drain conduction is unable to be turned off by negative gate voltages as large as -20 V. Upon adsorption of organic molecules there is an observed increase in the "on" current at large positive gate voltages and also a reduction, by several orders of magnitude, of the "off" current at large negative gate voltages. The zero-gate voltage transconductance of molecule-terminated Si NW correlates with the type of organic molecule. Adsorption of butyl and 1,3-dioxan-2-ethyl molecules improves the channel conductance over that of the original SiO(2)-Si NW, while adsorption of molecules with propyl-alcohol leads to a reduction. It is shown that a simple assumption based on the possible creation of surface states alongside the attachment of molecules may lead to a qualitative explanation of these electrical characteristics. The possibility and potential implications of modifying semiconductor devices by tuning the distribution of surface states via the functionality of attached molecules are discussed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tuning the Electrical Properties of Si Nanowire Field‐Effect Transistors by Molecular Engineering

Bashouti¹,

Tung²,

Haick³

2009

Small

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“…Because of the high surface to volume ratio, Si NWs’ properties depend firmly on their surface conditions and surface terminations, in particular. The oxidation of Si NWs, when exposed to ambient air, is believed to have a detrimental effect on their electrical properties due to the low quality of the oxide, giving rise to the uncontrolled interface states and enhanced carrier recombination rates [2]. This necessitates protection of Si NWs’ surfaces against oxidation via termination by various chemical moieties (i.e., alkyls and alkenyls) [3,4].…”

Section: Introductionmentioning

confidence: 99%

Kinetic study of H-terminated silicon nanowires oxidation in very first stages

et al. 2013

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Oxidation of silicon nanowires (Si NWs) is an undesirable phenomenon that has a detrimental effect on their electronic properties. To prevent oxidation of Si NWs, a deeper understanding of the oxidation reaction kinetics is necessary. In the current work, we study the oxidation kinetics of hydrogen-terminated Si NWs (H-Si NWs) as the starting surfaces for molecular functionalization of Si surfaces. H-Si NWs of 85-nm average diameter were annealed at various temperatures from 50°C to 400°C, in short-time spans ranging from 5 to 60 min. At high temperatures (T ≥ 200°C), oxidation was found to be dominated by the oxide growth site formation (made up of silicon suboxides) and subsequent silicon oxide self-limitation. Si-Si backbond oxidation and Si-H surface bond propagation dominated the process at lower temperatures (T < 200°C).

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“…This effect is enhanced in thin NWs and, as described in our previous report, nanoparticles can accelerate the oxidation on NWs [45]. The higher stability of the 2D(111) relative to the 2D(100) structure is understandable since it naturally has a 15-20% higher coverage than the 2D(100) case [46].…”

Section: Integration Of Hybrid Si Nw Into Solar Cellsmentioning

confidence: 75%

A Non-Oxidative Approach Towards Hybrid Silicon Nanowire- Based Solar Cell Heterojunctions

Bashouti¹,

Ristein²,

Haick³

et al. 2014

Hybrid Materials

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A general method for the non-oxidative termination of silicon nanowires (Si NWs) is reviewed. Oxide-free Si NW have been successfully alkylated in the lab using a two-step chlorination/alkylation process. The distinctive properties of the resulting Si NW have been taken advantage of by integrating the Si NWs into functional devices such as solar cells. Moreover, molecularly terminated Si NWs exhibit lower defect density emissions than unmodified Si NWs. This, in part, explains the better performance of the molecularly terminated Si NW-based solar cells. Solar cells that use organic-inorganic hybrid Si NWs as absorbers show an increased open-circuit voltage (V

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Silicon nanowires terminated with methyl functionalities exhibit stronger Si–C bonds than equivalent 2D surfaces

Cited by 77 publications

References 21 publications

Tuning the Electrical Properties of Si Nanowire Field‐Effect Transistors by Molecular Engineering

Tuning the Electrical Properties of Si Nanowire Field‐Effect Transistors by Molecular Engineering

Kinetic study of H-terminated silicon nanowires oxidation in very first stages

A Non-Oxidative Approach Towards Hybrid Silicon Nanowire- Based Solar Cell Heterojunctions

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