I 摘要 石墨烯作为一种单层碳原子材料，可以表现出超高的载流子迁移率。CVD 是最适合工业化生产石墨烯的方法，但面临一个技术瓶颈就是如何无损、可重复 地转移到其他衬底之上。电化学鼓泡法转移石墨烯成本低，环保，具有较高应用 价值，但目前仍有损坏大、重复性差之弱点。本报告系统研究了其机理，提出了 氢离子和水正面穿透 PMMA 是造成石墨烯破损主要原因的看法，并相应设计了 新的空气阻挡层的新方法，果然观察到了一定的质量提高和重复性提高。 石墨烯场效应晶体管 GFET，在高频电路、探测器等方面应用前景广阔。而 制备高性能 GFET，在石墨烯上制备高 k 介质层（如氧化铝）的工艺就显得十分 重要。然而目前在石墨烯表面制备氧化铝薄膜的工艺，例如原子层沉积、物理气 相沉积等，工艺复杂，投资大，且原子层沉积法很难再石墨烯表面成核。因此， 本文在研究鼓泡法机理并取得技术进步之后，继而进行了鼓泡法转移石墨烯表面 CLD 氧化铝可行性研究。 氧化铝具有良好且稳定的物理、化学特性，在光电子学、固体电子学、微机 电系统（MEMS）等方面得到大规模运用。传统制备的氧化物薄膜的办法，投资 大、设备复杂、工艺难以控制。1988 年 Hirotsugu Nagayama 等人首次发表运用 化学液相沉积 Chemical Liquid Phase Deposition( CLD )制备氧化硅薄膜的方法。 2004 年 Sun 等人提出用无氟 CLD 法在 GaAs 表面制备氧化铝薄膜的工艺，之后 Basu 等人相继运用 CLD 法-在 GaN，AlGaAs/InGaAs 表面生长氧化铝薄膜。化 学液相法具有设备简单，投资小，生长薄膜均匀等优点。 本文具体内容如下： 1、提出传统电化学鼓泡法转移石墨烯的工艺中，氢离子和水正面穿透 PMMA 是造成石墨烯破损主要原因的看法； 2、在传统的电化学鼓泡法的设计基础上，提出了用密闭空腔来阻挡溶液中 的水和 H + 离子透过 PMMA，进而透过石墨烯的转移方案，避免了透过的水和 H + 离子在石墨烯的上下表面生成 H 2 气泡从而使石墨烯产生破洞、褶皱和断裂。 对转移后的石墨烯进行的拉曼光谱、扫描电镜、原子力显微镜以及电子迁移率检 测，证明了转移后的石墨烯拥有较高的质量。说明此方法一定程度上提高了工艺 的重复性和可靠性，在工业上进行大面积石墨烯转移方面具有应用前景。 3、探究化学液相法在未经处理的石墨烯表面淀积氧化铝薄膜的可行性。以北京工业大学工学硕士学位报告 II 十八水和硫酸铝与碳酸氢钠为原料配制生长液，保持水浴 30℃淀积若干小时， 通过光学显微镜观测形貌，并测量器导电性。实验结果表面，石墨烯表面没有 Al(OH) 3 基团附着，以硫酸铝和氢氧化钠为原料的化学液相法很难在未经处理的 石墨烯表面淀积氧化铝薄膜。因此，除非对石墨烯进行表面改性，否则 CLD 氧 化铝在鼓泡法转移的石墨烯表面生长难以成核，不具备可行性。 4、采用化学液相法在 N 型砷化镓表面成功生长氧化铝薄膜，生长液粒度分 析结果显示，在生长液中 Al(OH) 3 胶体已经形成；光学显微镜、扫描电镜观测到 薄膜表面呈现小颗粒聚集，提出化学液相沉积法淀积氧化铝薄膜的机理有可能为 胶体沉聚。 关键词：氧化铝薄膜，化学液相沉积，石墨烯，密闭空腔阻挡层，电化学鼓泡法Abstract III Abstract Graphene is a single layer material consists of carbon atoms, and the carrier of which can move near the velocity of light. Thus graphene exhibits ultra-high carrier mobilities. CVD is the most industrialized production methods for graphene, but it faced a bottleneck that how transferred onto another substrate destructively and repeatedly. Electrochemical bubbling transfer is environmentally friendly, but there are still big damage, poor reproducibility of weakness. This paper systematically studied the mechanism proposed positive hydrogen ions and water penetration PMMA is mainly due to damage caused by graphene views and designs a new method of new air barrier, and she observed a certain quality and increase repeat improved. Graphene’s good electrical properties have been utilized in graphene field-effect transistors(GFETs), which have broad application prospects in high-frequency circuits, detectors, etc. Growth of high-k dielectric layer on the graphene is very important for high-performance GFET. However, current processes of growing alumina film on graphene surface, such as atomic layer deposition, physical vapor deposition, etc., were not perfect, which introduced damages to graphene structure. Alumina has a good and stable physical and chemical properties, thus it has been applied in large scale in optoelectronics, solid state electronics, micro-electromechanical systems (MEMS) and so on. Conventional oxide film preparation methods require significant investment and complex equipment, which are difficult to control. In 1988, Nagayama first published the process of chemical liquid deposition(CLD) to grow silicon oxide film. In 2004, Sun et.al proposed a fluorin-free CLD process to grow alumina film on GaAs surface. After that, Basu succeeded in growing alumina film on GaN substrate using the CLD method. CLD process has various advantages, such as low investment, and good film uniformity. However, previous studies did not give clear evidence to elaborate CLD process mechanism. Details are as follows: 1. Proposed a view that hydrogen ions and water pass through PMMA are main causes of graphene damages of conventional electrochemical bubbling transfer process;北京工业大学工学硕士学位报告 IV 2. Achieved innovative results in graphene transfer process. the scheme of using polytetrafluoroethylene (PTFE) film as a stopping layer to avoid the water and H + permeate PMMA has been designed. Compared with the scheme which only use polyethylene terephthalate (PET) frame as the graphene’s support layer, the quality of graphene transferred by PTFE-assisted is better obviously, which was demonstrated by the result of Raman spectroscopy, SEM,AFM and electron mobility. 3. Attempted to use CLD process to deposit Al 2 O 3 on graphene. Observed the film with an optical microscope, and measured the conductivity. Experiment results the indicated that there’s no Al(OH) 3 groups attached to graphene surface, and CLD process is difficult to deposit aluminum oxide film on untreated graphene. 4. Analyzed the particle size distribution of fresh growth solution, and observed the alumina film on the GaAs substrate with optical microscope and SEM. The results indicates that Al (OH) 3 colloid has been formed in the growth solution, and CLD process is a physical absorption process of Al(OH) 3 groups rather than ion chemical reaction process. Keywords: thin Al 2 O 3 films, chemical liquid phase deposition(CLD), graphene, encapsulated air gap, stopping layer, electrochemical bubbling transfer目 录 V 目 录 摘要................................................................................................................................ I Abstract.......................................................................................................................III 目 录...........................................................................................................................V 第 1 章 绪论..................................................................................................................1 1.1 引言.....................................................................................................................1 1.2 石墨烯简介.........................................................................................................2 1.3 氧化铝薄膜的基本结构与性质.........................................................................3 1.4 氧化铝薄膜的应用前景.....................................................................................5 1.4.1 光学领域的应用..........................................................................................5 1.4.2 微电子领域的应用......................................................................................5 1.4.3 机械领域的应用..........................................................................................6 1.5 石墨烯场晶体管（GFET）简介.......................................................................6 1.6 性能表征手段.....................................................................................................8 1.6.1 光学显微镜..................................................................................................8 1.6.2 扫描电子显微镜 SEM.................................................................................8 1.6.3 拉曼光谱......................................................................................................8 1.6.4 原子力显微镜 AFM.....................................................................................9 1.6.5 粒度分析仪..................................................................................................9 1.7 报告主要研究内容.............................................................................................9 第 2 章 石墨烯的制备与转移....................................................................................11 2.1 石墨烯的制备方法...........................................................................................11 2.1.1 物理法........................................................................................................11 2.1.2 化学法........................................................................................................12 2.1.3 制备石墨烯的其他方法............................................................................14北京工业大学工学硕士学位报告 VI 2.2 CVD 石墨烯的常规转移工艺 ..........................................................................14 2.1.1 干法转移....................................................................................................14 2.1.2 腐蚀基底法................................................................................................15 2.3 电化学鼓泡法转移石墨烯...............................................................................16 2.4 本章小结...........................................................................................................17 第 3 章 密闭空腔阻挡层电化学鼓泡法转移石墨烯................................................19 3.1 设计思路的提出...............................................................................................19 3.2 实验方法...........................................................................................................20 3.2.1 实验试剂、装置及样品............................................................................20 3.2.2 改进的石墨烯上层支撑结构....................................................................21 3.2.3 实验步骤....................................................................................................23 3.3 结果及表征.......................................................................................................24 3.3.1 鼓泡分离时间............................................................................................24 3.3.2 光学显微镜与扫描电镜............................................................................25 3.3.3 拉曼光谱....................................................................................................26 3.3.4 原子力显微镜............................................................................................27 3.3.5 载流子迁移率............................................................................................27 3.4 本章小结...........................................................................................................29 第 4 章 氧化铝的制备................................................................................................31 4.1 氧化铝的常用制备方法...................................................................................31 4.1.1 气相法........................................................................................................31 4.1.2 液相法........................................................................................................33 4.1.3 固相法........................................................................................................35 4.2 石墨烯表面氧化铝薄膜常用制备方法...........................................................36 4.2.1 物理组装法................................................................................................37 4.2.2 物理气相沉积法........................................................................................37目 录 VII 4.2.3 原子层沉积法............................................................................................37 4.3 本章小结...........................................................................................................39 第 5 章 化学液相法淀积氧化铝薄膜........................................................................41 5.1 实验装置、样品与试剂...................................................................................41 5.2 淀积微观机制的提出.......................................................................................42 5.3 实验结果与表征...............................................................................................43 5.4 本章小结...........................................................................................................45 第 6 章 石墨烯上 CLD 氧化铝薄膜探究..................................................................47 6.1 石墨烯的制备与转移.......................................................................................47 6.2 工艺方法与步骤...............................................................................................47 6.3 实验结果与分析...............................................................................................48 6.4 CLD 法在石墨烯表面淀积氧化铝薄膜的新设想...........................................49 6.5 本章小结...........................................................................................................49 结论..............................................................................................................................51