發(fā)布時(shí)間：2018-02-04 03:18

  本文關(guān)鍵詞： ZnO納米線 Pd表面修飾 Mo膜包覆 氣敏傳感器 場(chǎng)致電子發(fā)射　出處：《深圳大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：一維ZnO納米材料具有尖端小尺寸效應(yīng)、表面效應(yīng),因而具有優(yōu)異的電學(xué)、光學(xué)性能等,近年來得到廣泛關(guān)注。本文首先采用電阻式熱蒸發(fā)法、脈沖激光沉積法(PLD)分別在單晶Si襯底上沉積Au薄膜、ZnO晶種層薄膜;然后采用化學(xué)氣相沉積法(CVD)在上述襯底上生長了ZnO納米線陣列,并研究了不同生長條件對(duì)ZnO納米線陣列形貌、結(jié)構(gòu)的影響;最后對(duì)ZnO納米線陣列在氣敏傳感器及場(chǎng)致電子發(fā)射(FEE)領(lǐng)域的應(yīng)用進(jìn)行了初步研究,得到如下結(jié)果:Au膜襯底上ZnO納米線陣列的生長。采用電阻式熱蒸發(fā)法在Si襯底上沉積不同厚度(0.5,1.0,2.5,5 nm)的Au膜,采用CVD法在上述襯底上生長了ZnO納米線陣列,結(jié)果顯示:納米線呈現(xiàn)底端較粗、上端較細(xì)的分級(jí)結(jié)構(gòu);這些納米線長14μm,底端直徑約300~500 nm;隨Au膜厚度增加,Au催化劑液滴尺寸和數(shù)量增加,在納米線底部形成了ZnO納米片結(jié)構(gòu),從而降低了納米線面密度;ZnO晶種層薄膜襯底上ZnO納米線垂直陣列的生長。采用PLD法在SiO2/Si襯底上沉積了厚度約250 nm的ZnO晶種層薄膜,采用CVD方法生長了大面積、直徑均一的ZnO納米線垂直陣列,結(jié)果顯示:隨生長溫度提高,納米線直徑由100~200 nm增至400~600 nm,長度由12μm增至51μm,而面密度則由4.34×108根/cm2減至2.60×107根/cm2;我們將納米線上述變化的原因歸結(jié)如下:生長溫度的提高使得吸附于襯底表面的Zn原子遷移能增大,導(dǎo)致相同面積襯底上Zn/ZnOx合金液滴直徑逐漸增加、數(shù)量減少;Pd納米顆粒表面修飾ZnO納米線陣列的氣敏性能研究。在ZnO晶種層薄膜襯底上生長的ZnO納米線垂直陣列,經(jīng)不同濺射時(shí)間(0,5,10,30 s)金屬Pd納米顆粒表面修飾后氣敏測(cè)試結(jié)果顯示:所有器件的最佳工作溫度均為260℃;濺射時(shí)間為10s時(shí),納米線表面的Pd納米顆粒尺寸較小同時(shí)數(shù)量較多,導(dǎo)致器件具有最佳響應(yīng)度5.12;器件對(duì)乙醇具有較好的選擇性;器件穩(wěn)定性誤差值小于2.1%,響應(yīng)-恢復(fù)時(shí)間分別為7 s和95 s。經(jīng)Pd納米顆粒表面修飾后,ZnO納米線陣列氣敏性能的提升原因如下:表面的Pd納米顆粒增大了納米線表面吸附面積,同時(shí)催化和激活更多的氧離子吸附在納米線表面,結(jié)果導(dǎo)致納米線的電阻較大提高;金屬M(fèi)o包覆ZnO納米線陣列的FEE性能研究。采用磁控濺射法在不同厚度Au薄膜(0.5,1.0,2.5 nm)上生長的ZnO納米線的表面進(jìn)行Mo膜包覆,包覆后納米線的直徑約200 nm;包覆的Mo膜呈現(xiàn)多晶結(jié)構(gòu),厚度約50 nm。Mo膜包覆后,三個(gè)樣品均展現(xiàn)出較好的場(chǎng)發(fā)射電流密度穩(wěn)定性,開啟場(chǎng)強(qiáng)和閾值場(chǎng)強(qiáng)分別為7.80、7.29、10.90 V/μm和12.15、11.20、15.35 V/μm;場(chǎng)增強(qiáng)因子分別為959、807、461;隨Au膜厚度增加,場(chǎng)發(fā)射像中心亮斑數(shù)量減少。Mo膜的包覆導(dǎo)致了納米線的彎曲和折斷,從而增大了納米線上部的電子發(fā)射尺寸,降低了納米線的面密度,并最終導(dǎo)致了上述場(chǎng)發(fā)射性能的變化。
[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，

本文編號(hào)：1489164