ZnO纳米线阵列的制备及其气敏、场发射性能研究

发布时间：2018-02-04 03:18

  本文关键词： ZnO纳米线 Pd表面修饰 Mo膜包覆 气敏传感器 场致电子发射　出处：《深圳大学》2017年硕士论文　论文类型：学位论文

【摘要】：一维ZnO纳米材料具有尖端小尺寸效应、表面效应,因而具有优异的电学、光学性能等,近年来得到广泛关注。本文首先采用电阻式热蒸发法、脉冲激光沉积法(PLD)分别在单晶Si衬底上沉积Au薄膜、ZnO晶种层薄膜;然后采用化学气相沉积法(CVD)在上述衬底上生长了ZnO纳米线阵列,并研究了不同生长条件对ZnO纳米线阵列形貌、结构的影响;最后对ZnO纳米线阵列在气敏传感器及场致电子发射(FEE)领域的应用进行了初步研究,得到如下结果:Au膜衬底上ZnO纳米线阵列的生长。采用电阻式热蒸发法在Si衬底上沉积不同厚度(0.5,1.0,2.5,5 nm)的Au膜,采用CVD法在上述衬底上生长了ZnO纳米线阵列,结果显示:纳米线呈现底端较粗、上端较细的分级结构;这些纳米线长14μm,底端直径约300~500 nm;随Au膜厚度增加,Au催化剂液滴尺寸和数量增加,在纳米线底部形成了ZnO纳米片结构,从而降低了纳米线面密度;ZnO晶种层薄膜衬底上ZnO纳米线垂直阵列的生长。采用PLD法在SiO2/Si衬底上沉积了厚度约250 nm的ZnO晶种层薄膜,采用CVD方法生长了大面积、直径均一的ZnO纳米线垂直阵列,结果显示:随生长温度提高,纳米线直径由100~200 nm增至400~600 nm,长度由12μm增至51μm,而面密度则由4.34×108根/cm2减至2.60×107根/cm2;我们将纳米线上述变化的原因归结如下:生长温度的提高使得吸附于衬底表面的Zn原子迁移能增大,导致相同面积衬底上Zn/ZnOx合金液滴直径逐渐增加、数量减少;Pd纳米颗粒表面修饰ZnO纳米线阵列的气敏性能研究。在ZnO晶种层薄膜衬底上生长的ZnO纳米线垂直阵列,经不同溅射时间(0,5,10,30 s)金属Pd纳米颗粒表面修饰后气敏测试结果显示:所有器件的最佳工作温度均为260℃;溅射时间为10s时,纳米线表面的Pd纳米颗粒尺寸较小同时数量较多,导致器件具有最佳响应度5.12;器件对乙醇具有较好的选择性;器件稳定性误差值小于2.1%,响应-恢复时间分别为7 s和95 s。经Pd纳米颗粒表面修饰后,ZnO纳米线阵列气敏性能的提升原因如下:表面的Pd纳米颗粒增大了纳米线表面吸附面积,同时催化和激活更多的氧离子吸附在纳米线表面,结果导致纳米线的电阻较大提高;金属Mo包覆ZnO纳米线阵列的FEE性能研究。采用磁控溅射法在不同厚度Au薄膜(0.5,1.0,2.5 nm)上生长的ZnO纳米线的表面进行Mo膜包覆,包覆后纳米线的直径约200 nm;包覆的Mo膜呈现多晶结构,厚度约50 nm。Mo膜包覆后,三个样品均展现出较好的场发射电流密度稳定性,开启场强和阈值场强分别为7.80、7.29、10.90 V/μm和12.15、11.20、15.35 V/μm;场增强因子分别为959、807、461;随Au膜厚度增加,场发射像中心亮斑数量减少。Mo膜的包覆导致了纳米线的弯曲和折断,从而增大了纳米线上部的电子发射尺寸,降低了纳米线的面密度,并最终导致了上述场发射性能的变化。
[Abstract]:One-dimensional ZnO nanomaterials have many advantages such as small scale effect and surface effect, so they have excellent electrical and optical properties. In this paper, resistive thermal evaporation method is firstly used. Au thin films and ZnO seed layer films were deposited on single crystal Si substrates by pulsed laser deposition (PLD). Then the ZnO nanowire arrays were grown on the above substrates by chemical vapor deposition (CVD), and the effects of different growth conditions on the morphology and structure of ZnO nanowire arrays were studied. Finally, the application of ZnO nanowire array in gas sensor and field emission field was studied. The results obtained are as follows: the growth of ZnO nanowire arrays on the Si substrate is obtained. The au films of different thickness (0.51.0 ~ 2.5nm) have been deposited on Si substrates by resistive thermal evaporation. The ZnO nanowire array was grown on the substrate by CVD method. The results show that the nanowires have a coarse bottom end and a fine hierarchical structure at the upper end. The length of these nanowires is 14 渭 m and the diameter of the bottom end is about 300 ~ 500 nm. With the increase of au film thickness, the size and number of au catalyst droplets increase, and the structure of ZnO nanowires is formed at the bottom of nanowires, which reduces the surface density of nanowires. The growth of ZnO nanowire vertical array on ZnO seeded film substrates. ZnO seed layer films with a thickness of about 250nm were deposited on SiO2/Si substrates by PLD method. A large area and uniform diameter ZnO nanowire vertical array was grown by CVD method. The results show that the growth temperature increases with the growth temperature. The diameter of nanowires increased from 100 nm to 600 nm, and the length of nanowires increased from 12 渭 m to 51 渭 m. The surface density decreased from 4.34 脳 10 ~ 8 / cm ~ 2 to 2.60 脳 10 ~ 7 / cm ~ 2; The reasons for the above changes are summarized as follows: the increase of growth temperature increases the migration energy of Zn atoms adsorbed on the substrate surface. As a result, the diameter of Zn/ZnOx alloy droplets on the same area of substrate increases gradually and the number of droplets decreases. The gas sensing properties of ZnO nanowire arrays modified with PD nanoparticles were investigated. The ZnO nanowire vertical arrays grown on the substrate of ZnO seed layer films were deposited at different sputtering times. 30 s) after surface modification of metal PD nanoparticles, the results of gas sensing test show that the optimum operating temperature of all devices is 260 鈩，

本文编号：1489164