论文总字数：24098字

摘 要

随着电子产品芯片的高度集成化，电子器件的尺寸不断减小，目前芯片制造工艺所能达到的精度为7 nm的光刻加工技术已经是传统硅材料极限。若器件尺寸继续缩小，则会导致短沟道效应发生，器件的电学性能将严重退化，这使得对新型材料的需求愈加迫切。自从2004年石墨烯从天然石墨材料中通过机械剥离的方法剥离出来，并被证实能在室温条件下稳定存在以来，石墨烯便一直备受各界研究人员的关注和研究。因为石墨烯拥有极高的迁移率以及极低的能耗，这使得石墨烯有望成为在微纳米电子器件领域替代传统的硅材料。除此之外，石墨烯的光学性能和力学性能的优越更是一般的金属或非金属材料所能比拟的，这也更加奠定石墨烯成为未来在航天领域和透明电子材料领域不可或缺的基石。基于石墨烯优良的物理性能和可观的应用前景，对其进行理论上探索和研究就显得更加必要。

目前石墨烯的实验室研究数据表明，在室温条件下可测得的载流子迁移率已经可以达到15000 cm²·V^-1·s^-1（而且在液氦温度条件下的载流子迁移率更是高达250000 cm²·V^-1·s^-1），电导率也高达10⁶ S·m^-1，导电性能远远超过所有的金属导体。由于单层石墨烯为二维材料，其应用于电子器件时须利用其他的金属材料制作电极以实现载流子的注入。但是在石墨烯上蒸镀金电极时，会因工艺的不同导致金电极与石墨烯形成欧姆接触或者肖特基接触，进而影响石墨烯的电流-电压特性。在本论文中，我们通过胶带粘贴解离石墨片的方法获得单层石墨烯，并将获得的单层石墨烯制作为霍尔器件，利用霍尔效应对其载流子浓度和迁移率进行了测量研究。同时，我们还测量并绘制了石墨烯金电极的I-V曲线，对比分析了石墨烯与金电极的肖特基接触和欧姆接触。

关键字：石墨烯 二维材料 机械剥离 量子输运

ABSTRACT

With the high integration of electronic products, the size of electronic devices is decreasing. At present, the precision of 7 nm lithography technology which can be achieved by the chip manufacturing process has been the limit of traditional silicon materials. If the device size continues to shrink, short channel effect will occur, and the electrical performance of the device will be seriously degraded, which makes the demand for new materials more urgent. Since graphene was separated from natural graphite materials by mechanical stripping in 2004 and proved to exist stably at room temperature, graphene has been concerned and studied by researchers from all walks of life. Due to its high mobility and low energy consumption, graphene is expected to replace the traditional silicon materials in the field of micro nano electronic devices. In addition, the optical and mechanical properties of graphene are superior to those of general metal or non-metal materials, which also lays an indispensable foundation for graphene in the future in the field of aerospace and transparent electronic materials. Based on the excellent physical properties and considerable application prospects of graphene, it is more necessary to explore and study the theory of graphene.

At present, the experimental data of graphene show that the carrier mobility measured at room temperature has reached 15000 cm²·v^-1·s^-1 (and the carrier mobility at liquid helium temperature is as high as 250000 cm²·v^-1·s^-1 ), and the conductivity is as high as 10⁶ S·m^-1, which far exceeds all metal conductors. Because single graphene is a two-dimensional material, it is necessary to use other metal materials to make electrodes for carrier injection when it is used in electronic devices. However, when the gold electrode is evaporated on graphene, the ohmic contact or Schottky contact will be formed between the gold electrode and graphene due to different processes, which will affect the current voltage characteristics of graphene. In this thesis, we use tape to paste the dissociated graphene sheet to obtain the graphene monolayer, and use the graphene monolayer as hall element to measure the carrier concentration and mobility. At the same time, the I - U curve of graphene gold electrode is measured and drawn, and the Schottky contact and ohmic contact between graphene and gold electrode are compared and analyzed.

Keywords: graphene; two-dimensional materials; mechanical stripping; quantum transport;

目 录

摘 要 I

ABSTRACT II

第一章 绪论 1

1.1 石墨烯材料 1

1.2 石墨烯的电学性能 2

1.3 石墨烯的光学性能 3

1.4 石墨烯的热学性能 3

1.5 石墨烯的力学性能 4

第二章 石墨烯材料生长与器件制备 5

2.1 石墨烯的生长（制备）方法 5

2.1.1 石墨烯物理制备方法及其改进 5

2.1.2 石墨烯化学制备方法及其改进 6

2.2 器件的制备工艺 7

2.2.1 电子束曝光处理方法 8

2.2.2 紫外光刻加工技术 8

2.3 输运系统 9

2.3.1 电导 10

2.3.2 光电导 10

2.3.3 磁阻效应 10

2.4 单层石墨烯材料样品的制备 11

2.5 紫外光刻制作石墨烯霍尔电极 13

第三章 石墨烯的基本物相表征及量子输运性能研究 14

3.1 石墨烯样品的拉曼表征 14

3.2 石墨烯的载流子浓度和迁移率 14

3.2.1石墨烯的载流子浓度和迁移率计算依据 15

3.2.2 石墨烯样品的载流子浓度和迁移率的数据处理及结果分析 18

3.3 金电极-石墨烯的肖特基接触和欧姆接触 20

第四章 总结与展望 21

4.1 论文工作总结 21

4.2 展望 21

参考文献 23

致 谢 25

第一章 绪论

碳基类材料可以说是固体材料中一类神奇存在的物质，不管是无定形结构的天然炭黑到晶体结构的层状天然石墨的自然存在，还是零维富勒烯^[14]、一维碳纳米管^[15]以及二维石墨烯的的研究发现，无一例外的给材料界带来了一次又一次的惊喜。而石墨烯所具有的特殊的光电特性和极佳的量子运输性能，为人类科技文明的进一步发展带来了福音。

1.1 石墨烯材料

二十一世纪初，随着互联网和电子产品各行业的飞跃性发展，对于有关电子器件材料性能和结构尺寸的要求越来越高。由传统三维材料制成的电子器件随着尺寸的减小逐渐显现出一些量子负效应，慢慢地无法满足行业快速发展需求。石墨烯作为材料界迅速崛起的新型二维材料，其优越的光电特性和极佳的量子运输性能得到了广大研究人员的青睐。

图1.1 石墨烯的结构示意图

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