石墨烯材料气敏性能及场效应晶体管结构设计研究

发布时间：2018-03-03 05:39

  本文选题：石墨烯材料　切入点：薄膜厚度　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文采用改进Hummers法制备氧化石墨,经超声剥离得到氧化石墨烯(GO);采用旋涂法并通过控制GO水相分散液浓度制备不同厚度GO薄膜;采用热还原法制备不同还原程度的还原氧化石墨烯(r GO)薄膜;采用一步水热复合法制备得到石墨烯-聚苯胺(r GO-PANI)复合材料。利用XRD、FT-IR、Raman、AFM、SEM、TG-DTA和气敏测试系统等对GO、r GO和r GO-PANI的结构、形貌及气敏性能进行表征分析,重点探究GO薄膜厚度、热还原程度及石墨烯与聚苯胺复合质量比对气敏性能的影响,并进一步揭示石墨烯及其复合材料的气敏响应机理。研究结果表明,GO在成膜过程中工艺条件对元件的气敏性能有很大影响。采用旋涂法,随GO水相分散液浓度由1 mg/m L增加到5mg/m L,薄膜的厚度依次为18、35、65、102和139 nm。随着薄膜厚度增大,元件的灵敏度增大,电阻变化的线性关系变差,而响应-恢复时间延长。当薄膜厚度为18 nm时湿敏元件的响应时间2 s,恢复时间8 s,灵敏度可达72.59%。随着还原温度的升高,GO样品含氧官能团逐渐热解消失,所形成的结构向较为有序的类石墨结构转变;无序程度(ID/IG值)先由0.85增大至1.59后再减小至1.41,总体呈现增加趋势;当还原温度≤150℃样品仍表现GO的性质,当还原温度≥250℃时则表现出r GO的性质;还原温度为150、200和350℃时样品分别表现出p型、双极型和n型半导体性质。在室温下,GO及低还原程度的r GO气敏元件对H2表现出较高的响应和灵敏度,灵敏度88.56%,响应时间30 s。r GO-PANI复合材料比单纯的r GO、PANI的气敏性能更加优异,在400 ppm浓度的NH3环境下,r GO、PANI和r GO-PANI-1的灵敏度依次为13.92、41.49和50.26%。响应时间依次为422、296和156 s,恢复时间依次为485、304和214 s;随着复合材料中PANI质量的增加,灵敏度呈现减小趋势,在400 ppm浓度的NH3环境下,复合材料中r GO与PANI的质量比为1:1、1:2和1:3时的灵敏度依次为50.26、44.72和38.90%。目前,常见的石墨烯气体传感器结构有电阻型、场效应晶体管型(FET)、声表面型(SAW)和石英晶体微天平型(QCM),尤其是FET型气体传感器因具备独特的优势而迅速发展。本文对FET型结构设计初步探索,优化设计参数,可为下一步研制集成、小型和智能化的高性能气体传感器提供理论依据和技术指导。
[Abstract]:In this paper, graphite oxide was prepared by modified Hummers method, and graphene oxide was obtained by ultrasonic stripping, and go thin films with different thickness were prepared by spin-coating method and by controlling the concentration of go aqueous dispersion. The reduced graphene oxide (GOR) thin films with different degree of reduction were prepared by thermal reduction method, and the graphene / Polyaniline (GO-PANI) composite materials were prepared by one step hydrothermal recombination method. The structures of GOr go and r GO-PANI were studied by using XRDX FT-IR Ramanine, AFMSEMN TG-DTA and gas sensing test system, etc. The morphology and gas sensing properties were characterized and analyzed. The effects of the thickness of go film, the degree of thermal reduction and the composite mass ratio of graphene to Polyaniline on the gas sensing properties were investigated. The gas sensing response mechanism of graphene and its composites is further revealed. The results show that the process conditions of go have a great influence on the gas sensing properties of the components during the process of film formation. With the increase of go aqueous dispersion concentration from 1 mg/m / L to 5 mg / mL, the thickness of the film is 1835 / 65 / 102 and 139nm / L respectively. With the increase of the thickness of the film, the sensitivity of the component increases and the linear relationship of the resistance changes becomes worse. When the thickness of the film is 18 nm, the response time of the humidity sensor is 2 s, the recovery time is 8 s, and the sensitivity is 72.59. With the increase of the reduction temperature, the oxygen functional groups of the go sample gradually disappear. The resulting structure changed to a more ordered graphite-like structure, the degree of disorder increased from 0.85 to 1.59 and then decreased to 1.41, and the reduction temperature 鈮，

本文编号：1559777