中文摘要：

采用纳米球光刻和金属辅助刻蚀法以p型单晶硅片制备了硅纳米线阵列,并以此作为基底,通过溅射不同时长的金属钒薄膜并进行热退火氧化处理,制备出硅纳米线/氧化钒纳米棒复合材料.采用扫描电子显微镜和X射线衍射仪表征了该复合材料的微观特性,结果表明该结构增大了材料的比表面积,有利于气体传感,并且镀膜时间对后续生长的氧化钒纳米棒形貌有明显影响.采用静态配气法在室温下测试了该复合材料对NO_2的气敏性能,气敏测试结果表明沉积钒膜的时间对复合材料的气敏性能影响较大.当选择合适的镀膜时间时,适量氧化钒纳米棒增加了材料表面积并形成大量pn结结构,相比纯硅纳米线对NO_2气体的灵敏度有明显提升,且在室温下表现出优良的选择性.同时,对气敏机理做了定性解释,认为硅纳米线与氧化钒纳米棒之间形成的pn结及能带结构在接触NO_2时的动态变化是其气敏响应提升的主要机制.

英文摘要：

As air pollution is becoming more and more serious in recent years,gas-sensing devices have attracted intensive attention.In particular,NO_2 is one of the most toxic gases in the atmosphere,which tends to produce acid rain and photochemical smog.Thus,there is a strong demand of cheap,reliable and sensitive gas sensors targeting NO_2.Gas sensors fabricated on silicon substrates with room-temperature operation are very promising in power saving,integrated circuit processing and portable detectors.More important,the silicon nanowires（Si NWs）-based devices are compatible with very large scale integration processes and complementary metal oxide semiconductor technologies.In the present work,the novel nanocomposite structure of（Si NWs）/vanadium oxide（V_2O_5） nanorods for NO_2 detection is successfully synthesized.The Si NWs are fabricated by a combination of nanosphere lithography and metal-assisted chemical etching.Vanadium films are deposited on Si NWs by DC magnetron sputtering,and then V_2O_5 nanorods are synthesized with subsequent thermal annealing process for full oxidation in air.The morphology and crystal structure of product obtained are characterized by field-emission scanning electron microscopy and X-ray diffraction.The characterization results indicate that V_2O_5 nanorods are uniformly distributed on the surfaces of Si NWs.The increased specific surface area of Si NWs/V_2O_5 nanocomposite provides more adsorption sites and diffusion conduits for gas molecules.Therefore,the novel structure of the nanocomposite is conducive to gas-sensing.In addition,the sputtering time has an obvious influence on the morphology of vanadium oxide.With the increase of the sputtering time,the specific surface area and the number of p-n heterojunctions formed in the nanocomposite are both less than those of nanocomposite with appropriate sputtering time.The gas-sensing properties are examined by measuring the resistance change towards 0.5–4 ppm NO_2 gas at room temperature by the static volumetric method.Results