Development of prototype devices based on ZnO nanorods

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Fang, F.; Kennedy, J.V.; Futter, R.J.; Markwitz, A. 2010 Development of prototype devices based on ZnO nanorods Lower Hutt, N.Z.: GNS Science. GNS Science report 2010/25 25 p.


Abstract: Recently, one-dimensional (1D) nanostructures such as wires, rods, belts and tubes have became the focus of intensive research owing to their unique applications in mesoscopic physics and fabrication of nanoscale devices. Among them, zinc oxide (ZnO) nanomaterials with 1D structures, such as nanowires or nanorods, are especially attractive due to their tunable electronic and optoelectronic properties. ZnO nanorods were synthesized successfully by arc discharge method at GNS Science. Prototype devices based on as-synthesized ZnO nanorods were constructed with the addition of phoymeric film-forming agent which assisted with construction of the conducting networks among ZnO nanorods. UV sensing properties of a ZnO nanorods prototype device has been analyzed. The results indicate a UV-sensitive photoconduction in our device. Annealing in air at 200 ºC for 30 minutes increases the conductivity of the sensor. After annealing, the photocurrent of the sensors increased by nearly four orders of magnitude from 2.7 x 10-10 A to 1.0 x 10-6 A at 18 V under 340 nm UV illumination. The UV response of the ZnO nanorods sensor is attributed to adsorption and photodesorption of ambient gas molecules. UV sensing properties of ZnO nanorods prototype device have also been analyzed in this work. High sensitivity and recovery have been found in the humidity sensing investigation. The resistance of the ZnO nanorods sensor device reduced by approximately five orders of magnitude (1011-106), from 4.35 x 1011 in dry air (7 % relative humidity) to about 4.95 x 106 in 95 % relative humidity air. The ZnO nanorods sensor device has long-term reusable stability when exposes to water in open air. ZnO is one of the earliest discovered and the most widely applied oxide gas sensing materials due to its high mobility of conduction electrons, good chemical and thermal stability under the operating conditions of sensors. The present work was undertaken to investigate the gas sensing behaviour of ZnO nanorods prepared by arc discharge method. Gas sensing properties at proper temperature were studied. The ultimate objective of this study is to explore the sensing properties of prototype device based on ZnO nanorods synthesized by arc discharge method at GNS Science. (auth)