2010年，诺贝尔物理学奖授予石墨烯的发现者Andre Geim和Konstantin Novoselov，他们用最简单的机械剥离的办法将这种在理论上绝对零度时存在的神奇材料在常态下制备出来。自此开启了全世界科学家投身各类二维纳米材料研究的热潮。石墨烯——这种仅由单层碳原子所组成的二维纳米材料，亦可视为准二维的理想电子气体。作为零带隙半导体，其特殊的能带结构使之在电学、光学等多方面具有极其优异的物理和化学性质，被认为是最有希望替代硅基半导体的下一代光电子材料，在理论和实践上都具有极大的研究价值。 过去十年，在石墨烯的研究领域涌现出来诸多卓有成就的开创性工作（第1章）。众多工作中，基于石墨烯的光电子器件的研究主要沿着两个方向发展：一是充分利用石墨烯中超高的载流子迁移率，旨在发展响应速度超快的碳基光电子器件；二是设法提高石墨烯的光吸收率，旨在发展灵敏更高、探测率更高的碳基光电子器件。这两个方面都分别有非常突出的研究成果。但其中存在的问题是：在超快响应的石墨烯光电子器件中，载流子寿命短，使得其响应度并不高；在超高响应（度）的石墨烯光电子器件中，载流子复合慢，又严重影响其响应速度。于是，在进一步发展兼具超敏、超快、超宽带等优良响应特性的石墨烯光电探测器领域，前景可期、道阻且长。 本论文将结合石墨烯和超快离子导体RbAg4I5，探究以离子调控石墨烯中电子输运的方式来实现超敏、超快的光电探测之可行性。文章依次就单层石墨烯（第3章）、多层石墨烯（第4章）、PMMA辅助悬空的石墨烯（第5章）与RbAg4I5薄膜的复合纳米结构展开研究，系统地研究了这类复合纳米结构的制备表征方法和光电响应特性。在实验方面，实现了响应度高（~1 A?W−1）、响应速度快（~102 μs）、量子效率>100%，且可探测光波长范围宽（紫外光—近红外光）的器件性能。在理论方面，提出了以“电子?离子束缚态”（IEBSs）的解离和重复合过程为基本物理图像的光电动力学响应模型，该模型及进一步的修正模型能够成功解释实验现象，依IEBS动力学方程而给出的拟合结果与实验统计数据十分吻合。 综上，石墨烯/RbAg4I5复合纳米结构用于光电探测，虽尚有不足之处，但其展现出的优良响应特性，已具相当的应用潜力。本文为发展石墨烯基光电器件提供了一个新的思路，同时也为进一步探索离子调控型器件提供了一点有意义的参考。
In 2010, the Nobel Prize in Physics was awarded to graphene discoverers Andre Geim and Konstantin Novoselov, who used the simplest mechanical exfoliation method to produce the magic material, which exists at theoretically absolute zero temperature, under normal conditions. Since then, scientists around the world have devoted themselves to the research of various two-dimensional nanomaterials. Graphene, a two-dimensional nanomaterial composed of just one layer of carbon atoms, is an ideal quasi-two-dimensional electronic gas. As a zero-bandgap semiconductor, its special band structure enables it to have extremely excellent physical and chemical properties in electrical, optical, and other aspects, and it is considered as the most promising next-generation photoelectronic material to replace silicon semiconductor, which has great research value in theory and practice. In the past decade, a lot of remarkable work has been done in graphene research (Chapter 1). In many works, the research on graphene-based optoelectronic devices mainly develops in two directions: one is to make full use of the ultra-high carrier mobility in graphene to develop ultra-fast graphene optoelectronic devices; the other is to improve the photoabsorption of graphene, so as to develop graphene photoelectronic devices with higher sensitivity and detectivity. Both two directions have very outstanding research results. However, there are some problems: for the ultra-fast response graphene optoelectronic devices, the carrier life is short, so that its responsivity is not high; for the ultra-high response graphene optoelectronic devices, the carrier recombination is slow, which seriously affects the response speed. Therefore, in the field of further developing graphene photodetectors with excellent response characteristics such as ultra-sensitive, ultra-fast and broadband detection, the prospect can be expected while the journey is long and challengeable. This paper will combine graphene with superionic conductor RbAg4I5 to explore the feasibility of realizing ultra-sensitive and ultra-fast photoelectric detection by means of ion regulation of electron transport in graphene. In this paper, the composite nanostructures based on single-layer graphene (Chapter 3), multi-layer graphene (Chapter 4), PMMA-assisted suspended graphene (Chapter 5) and RbAg4I5 thin films were studied successively, and the preparation and characterization methods of composite nanostructures and their photoresponse characteristics were systematically studied. In aspects of experiment, it realizes the photoelectric performances with high responsivity (~1 A?W−1), fast response speed (~102 μs) and wide detection wavelength range (ultraviolet to near-infrared). In terms of theory, we proposed a photoelectric dynamic response model with the dissociation and recombination process of "electron-ion bound states" (IEBSs) as the basic physical image. The model and the further modified model can successfully explain the experimental phenomena, and the fitting the results given by the dynamic equation are quite coincident with experimental statistical data. In conclusion, although graphene /RbAg4I5 composite nanostructure has some shortcomings in the application of photoelectric detection, its excellent response performance has shown considerable application potential. This provides a new idea for the development of graphene-based optoelectronic devices and a meaningful reference for the further exploration of ion modulated devices.
