Study And Preparation Of Porous Silicon/Tungsten Oxide Nanowires Gas Sensor

Since the20th century, the overwhelming progress of human race not only fetcheda technological revolution and added comfort to livings, but unfortunately damaged theecosystem by propelling more toxic gases into the environment. NO2is one suchexample. So far, a variety of gas sensitive materials have been developed. Tungstenoxide is considered as one of the most promising materials in the field of gas sensormaterials. And porous silicon (PS) is a new type sensitive material which can work inroom temperature, and it is compatible with the integrated circuit. Based on the aboveback ground, the synthesis and performance of a tungsten oxide nanowires/poroussilicon hybrid structure was studied in this article.Porous silicon (PS) layers were obtained by electrochemical dissolution in adouble-tank cell on the surface of the single-crystalline silicon substrate. Then themetallic tungsten films were deposited on PS by means of DC magnetron sputteringprocess. The tungsten oxide nanowires were synthesized directly by heating thesputtered tungsten film on PS layer inside a tubular furnace. The samples were anealedby conventional annealing and rapid annealing treatment. The morphology, phasestructure, and crystallinity of the samples were investigated by using field emissionscanning electron microscopy (FESEM), X-ray diffractometer (XRD), and highresolution transmission electron microscopy (HRTEM). The NO2gas sensingcapabilities of different samples were investigated.The result indicates that sputtering time of tungsten film, temperature, time andatmosphere of the heat treatment all played roles to the synthsis of tungsten oxidenanowires. The sputtering time of tungsten film determined the thick of tungsten film,and the thicker the film, the more easily nanowires gown. Howerver, there was a oxidelayer under the nanowires which remained without changing into nanowires. Thetungsten oxide nanowires could be synthsised only when the heat treatment was in acertain range, the heat treatment was in a short time, the ratio of argon and oxygen wasbelow a certain percentage. Comparative gas sensing results indicated that the sensorthat wasbased onthetungstenoxidenanowiresexhibited a much higher sensitivitythanthat based onthe PS and pureWO3nanowires in detecting NO2gas at roomtemperature.The samples were oxided by the annealing. And the sensitivity of samples wereimproved.