Silicon Nanowires:  Preparation, Device Fabrication, and Transport Properties

Abstract

The preparation of 20 ± 5 nm diameter Si nanowires and the electrical characterization of Si nanowire devices are presented. The nanowires were grown at 450−500 °C on solid substrates via the vapor−liquid−solid mechanism using Au or Zn nucleation catalysts and SiH4 as the silicon source. The wires were investigated by high-resolution transmission electron microscopy. Two types of wires were found, as characterized by different growth directions (〈111̄〉 and 〈211〉). Several types of devices, including crossed nanowire devices, four- and six-terminal devices, and three-terminal (gated) devices, were fabricated. For certain devices, various electrode compositions were also studied. The measured resistivity of these nanowires was separated from the contact resistance and could be varied from >105 Ω cm to ∼10-3 Ω cm. The wide variation in resistivity was related to the nature of the electrical contact to the wires (Schottky or Ohmic) and to the doping level of the wires. Doping of the nanowires was performed by the thermal diffusion of metal catalyst into the nanowires at 750−850 °C. Au nucleated nanowires exhibited resistivity values much lower than those of similarly treated Zn nucleated nanowires. This result is attributed to the much larger relative solid solubility of gold in silicon.

Metallic and Semimetallic Silicon⟨100⟩Nanowires

“…Indeed, typical concentrations for attaining the measured SiNWs conductance [21,22] may well mean that no donor/acceptor is actually present in nm-wide SiNWs. Some of these measurements show that conductance is larger than expected for doped SiNW [21] and the authors suggest that surface states may 2 be responsible for the measured conduction.…”

“…Iso-surfaces of wave-function amplitude have been plotted on the SiNW atomic structure, showing that Bloch states originate on the facet dangling bonds. Figure (3 Conductance through thin SiNWs remains a difficult issue [21]. The way SiNWs bind to metal electrodes is complex and crucial for determining the actual conductance of SiNWbased devices.…”

Pt/CdTe/Pt asymmetric nano-Schottky diodes from colloidal quantum dots

“…36,37 Another mechanism which is responsible for asymmetry nature of I-V curve is tunneling current which becomes the dominating component under the reverse bias and especially in low dimension systems. 38,39 So, the observation of asymmetry in I-V curve in the present nano-Pt/CdTe QDs/Pt Schottky device could be due to the combining effect of size distribution in QDs and tunneling current.…”

Gate bias-dependent junction characteristics of silicon nanowires suspended between polysilicon electrodes

“…Nanowires (NWs) can act as electrodes in future integrated nanocircuits, as actuators, and as a model system in the study of the size effects on the intrinsic material properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. One of the most promising application areas for NWs is in biological systems, which consist of a myriad of highly interactive and complex interconnections and pathways operating at various length and time scales [1].…”