Silicon nanowires as chemical sensors

... dramatically decrease even at room temperature. This phenomenon serves as the basis for a new kind of sensor based on silicon nanowires. The sensor, made by a bundle of etched silicon nanowires, is ... China Abstract Chemical sensitivity of silicon nanowires bundles has been studied. Upon exposure to ammonia gas and water vapor, the electrical resistance of the HF-etched relativ...

Ngày tải lên: 16/03/2014, 15:08

... target temperature was 1100–1400 °C and the nanowires growth temperature was selected as 900–1100 °C. In general, when using pure Fe metal as a catalyst for the growth of silicon nanowires, almost all ... on. Many efforts have been made to prepare silicon nanowires (SiNWs) by different methods, such as laser ablation [6,7], thermal evaporation deposition [8], chemical vapor dep...

Ngày tải lên: 16/03/2014, 15:06

... pressure in the tube was pumped down to 4 Â 10 À3 Torr, argon was fed into the tube as a protective gas and the furnace temperature was increased to 1100°C for 6 h. 1100°C was used as the annealing ... annealed nanowires were the same as the as- grown SiNWs. However, the density of defects inside the an- nealed nanowires decreased signi®cantly. Fig. 2A shows the HRTEM image of a t...

Ngày tải lên: 16/03/2014, 15:03

... 2003 Abstract Carbon-assisted synthesis of silicon nanowires has been accomplished with silicon powders as well as solid sub- strates. The method involves heating an intimate mixture of silicon powder ... powders. In procedure (iii), a silicon substrate was used as the source of silicon. The Si(1 0 0) substrates were cleaned by ultrasonication in distilled water. Amorphous ca...

Ngày tải lên: 16/03/2014, 15:04

... deposition was as high as 1100°C, the carbon layers bucked openly to form many feather-like carbon sheets sprouting from the surface of the nanowires. A mixture of large carbon sheets and b-SiC nanowires ... ®lament was placed between these two RF electrodes. The distance between the substrate and the ®lament could be adjusted. The as- grown SiNWs were put on a silicon sheet as a...

Ngày tải lên: 16/03/2014, 15:04

... single-crystal Si nanowires in a SiCl 4 -based chemical vapour deposition process. The growth rates were higher with Pt than with Au under all processing conditions. The activation energy was measured as 80 ... All rights reserved. 1. Introduction Silicon (Si) nanowires have novel properties as well as comple- mentary metal oxide semiconductor (CMOS) compatibility. As such, th...

Ngày tải lên: 16/03/2014, 15:05

... Si nanowires 12 , however, such a photoluminescence from the a-SiNWs was ascribed as arising from defect centers in the amorphous SiO x layer sheathing the nanowires as well. The silicon nanowires ... that the nanowires are completely amorphous. wx In the case of oven-laser ablation 7 , the silicon source for SiNW growth was supplied from the vapor phase in which the atomic Si...

Ngày tải lên: 16/03/2014, 15:05

... vertically aligned amorphous silicon nanowires on Au±Pd co-deposition silicon oxide substrate by thermal chemical vapor deposition using SiH 4 gas at 800°C. The diameter of silicon nanowires is in the ... crystalline state silicon nanowires with a thin oxide outer layer. Amorphous state silicon nanowires have been reported very slightly. Recently, Yan et al. [16] have prep...

Ngày tải lên: 16/03/2014, 15:05

... and hydrogen ions react with silicon oxide to form carbon oxide and silicon car- bide. The carbon oxide gas was pumped out while silicon carbide remained on the silicon nanowire. Fig. 2b shows ... previously observed silicon oxide layer covering the silicon nanowire has been removed after the coating of the silicon carbide. It is of particular interest that the undesirable oxide...

Ngày tải lên: 16/03/2014, 15:05

... is the formation of a sucient amount of silicon atoms and/or silicon oxide clusters in gas phase from the target powders of silicon or silicon oxide by laser ablation or high temperature evaporation. ... sucient silicon atoms from the gas phase, precipitation of silicon nanowires from the droplet can be induced. Based on a systematic analysis of the growth mechanism of semi-co...

Ngày tải lên: 16/03/2014, 15:06