Molecular Adsorption Kinetics of a Single Gold Nanowire Chemical Sensor and the Effects of Thermal Annealing

• Main Authors: Huang, Hsiao-Chien, 黃小倩
• Other Authors: Lin, Heh-Nan
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/28735102260059170322

碩士 === 國立清華大學 === 材料科學工程學系 === 99 === In this work, we have fabricated a resistive-type single nanowire chemical sensor based on a single gold nanowire connected with titanium electrodes by a combination of atomic force microscopy nanolithography and conventional photolithography. In-situ measurement of the resistance increase of the gold nanowire due to the chemical adsorption of alkanethiolate molecules onto the nanowire in alcohol has been conducted. The effect of gold nanowire thickness on resistance increase upon chemisorptions has been studied. Furthermore, the effect of thermal annealing of the nanowire on the resistance increase upon chemisorption has also been investigated. The fabricated gold nanowires have a length of 10 μm and widths of 70 to 100 nm. With a nanowire thickness range of 5 to 46 nm, it is found that the relationship between the resistance increase and the nanowire thickness can be roughly described by a constant plus an exponential decay with the constant equal to around 8%. A resistance increase as high as 27% has been obtained from a 5 nm thick nanowire. Furthermore, the adsorption kinetics has been analyzed and can be well-described by a first order Langmuir equation. The adsorption constant obskincreases with increasing thickness as well. For the effect of thermal annealing on the resistance increase after chemisorption, it is found that resistance increases of annealed gold nanowires after chemisorptions are about 11% to 47% higher than those without annealing at the same thickness. This result is consistent with reports in the literature that the resistance increase is proportional to the surface roughness. As the thermal annealing increases the surface roughness of a nanowire, more adsorption sites are available and consequently the resistance increase is higher.