Photodetecting and light-emitting devices based on two-dimensional materials

Two-dimensional(2D) materials, e.g., graphene, transition metal dichalcogenides(TMDs), and black phosphorus(BP), have demonstrated fascinating electrical and optical characteristics and exhibited great potential in optoelectronic applications. High-performance and multifunctional devices were achieved by employing diverse designs, such as hybrid systems with nanostructured materials, bulk semiconductors and organics, forming 2D heterostructures. In this review,we mainly discuss the recent progress of 2D materials in high-responsive photodetectors, light-emitting devices and single photon emitters. Hybrid systems and van der Waals heterostructure-based devices are emphasized, which exhibit great potential in state-of-the-art applications.     

拓扑量子材料光电探测器研究进展

物质拓扑态的发现是近年来凝聚态物理和材料科学的重大突破.由于存在不同于常规半导体的特殊拓扑量子态(如狄拉克费米子、外尔费米子、马约拉纳费米子等),拓扑量子材料通常能表现出一些新颖的物理特性(如量子反常霍尔效应、三维量子霍尔效应、零带隙的拓扑态、超高的载流子迁移率等),因而在低能耗电子器件和宽光谱光电探测器件领域具有重要...     

Graphene integrated photodetectors and opto-electronic devices — a review

Graphene and other two-dimensional materials have recently emerged as promising candidates for next-generation,high-performance photonics. In this paper, the progress of research into photodetectors and other electro-optical devices based on graphene integrated silicon photonics is briefly reviewed. We discuss the performance metrics, photo-response mechanisms, and experimental results of the latest graphene photodetectors integrated with silicon photonics. We also lay out the unavoidable performance trade-offs in meeting the requirements of various applications. In addition, we describe other opto-electronic devices based on this idea. Integrating two-dimensional materials with a silicon platform provides new opportunities in advanced integrated photonics.     

Magnetic two-dimensional van der Waals materials forspintronic devices

Magnetic two-dimensional (2D) van der Waals (vdWs) materials and their heterostructures attract increasing attention in the spintronics community due to their various degrees of freedom such as spin, charge, and energy valley, which may stimulate potential applications in the field of low-power and high-speed spintronic devices in the future. This review begins with introducing the long-range magnetic order in 2D vdWs materials and the recent progress of tunning their properties by electrostatic doping and stress. Next, the proximity-effect, current-induced magnetization switching, and the related spintronic devices (such as magnetic tunnel junctions and spin valves) based on magnetic 2D vdWs materials are presented. Finally, the development trend of magnetic 2D vdWs materials is discussed. This review provides comprehensive understandings for the development of novel spintronic applications based on magnetic 2D vdWs materials.     

Recent progress on two-dimensional neuromorphic devices and artificial neural network

Mimicking biological synapses with microelectronic devices is widely considered as the first step in hardware building artificial neuromorphic networks, which is also the basis of brain-inspired neuromorphic computing. Numerous artificial neurons and synapses making up an artificial neuromorphic network have been gained wide attention due to their powerful and efficient data processing capabilities. Recently, artificial synapses, especially memristor-type and transistor-type synapses based on multifarious two-dimensional (2D) materials have been paid much attention. The unique properties of 2D materials make devices perform well in learning ability and power efficiency when mimicking synaptic behaviors, which highlights the feasibility of 2D neuromorphic devices in constructing artificial neuromorphic networks. Herein, the basic structures and principles of biological synapses are introduced, and the definitions of synaptic behaviors in synaptic electronic devices are discussed. Then, the progress of 2D memristor-type and transistor-type neuromorphic devices involving their device architecture, neuromorphic operational mechanism, and promising applications is reviewed. Finally, the future challenges of artificial synaptic devices based on 2D materials are discussed briefly.     

二维原子层谷电子学材料和器件

人为操控电子的内禀自由度是现代电子器件的核心和关键.如今电子的电荷和自旋自由度已经被广泛地应用于逻辑计算与信息存储.以二维过渡金属硫属化合物为代表的二维原子层材料由于其具有独特的谷自由度和优异的物理性质,成为了新型谷电子学器件研究的优选材料体系.本文介绍了能谷的基本概念、谷材料的基本物理性质、谷效应的调控和谷电子学器件...     

Epitaxy of III-nitrides on two-dimensional materials and its applications

III-nitride semiconductor materials have excellent optoelectronic properties, mechanical properties, and chemical stability, which have important applications in the field of optoelectronics and microelectronics. Two-dimensional (2D) materials have been widely focused in recent years due to their peculiar properties. With the property of weak bonding between layers of 2D materials, the growth of III-nitrides on 2D materials has been proposed to solve the mismatch problem caused by heterogeneous epitaxy and to develop substrate stripping techniques to obtain high-quality, low-cost nitride materials for high-quality nitride devices and their extension in the field of flexible devices. In this progress report, the main methods for the preparation of 2D materials, and the recent progress and applications of different techniques for the growth of III-nitrides based on 2D materials are reviewed.     

Field-effect transistors based on two-dimensional materials for logic applications

Field-effect transistors （FETs） for logic applications, graphene and MoS2, are discussed. These materials have based on two representative two-dimensional （2D） materials, drastically different properties and require different consider- ations. The unique band structure of graphene necessitates engineering of the Dirac point, including the opening of the bandgap, the doping and the interface, before the graphene can be used in logic applications. On the other hand, MoS2 is a semiconductor, and its electron transport depends heavily on the surface properties, the number of layers, and the carrier density. Finally, we discuss the prospects for the future developments in 2D material transistors.     

Deep-ultraviolet and visible dual-band photodetectors by integrating Chlorin e6 with Ga_2O_3

Gallium oxide(Ga_2O_3) is a promising material for deep-ultraviolet(DUV) detection. In this work, Chlorin e6(Ce6)has been integrated with Ga_2O_3 to achieve a DUV and visible dual-band photodetector, which can achieve multiple target information and improve the recognition rate. The photodetector shows two separate response bands at 268 nm and 456 nm.The DUV response band has a responsivity of 9.63 A/W with a full width at half maximum(FWHM) of 54.5 nm; the visible response band has a responsivity of 1.17 A/W with an FWHM of 45.3 nm. This work may provide a simple way to design and fabricate photodetectors with dual-band response.     

二维原子晶体的低电压扫描透射电子显微学研究

二维原子晶体材料,如石墨烯和过渡金属硫族化合物等,具有不同于其块体的独特性能,有望在二维半导体器件中得到广泛应用.晶体中的结构缺陷对材料的物理化学性能有直接的影响,因此研究结构缺陷和局域物性之间的关联是当前二维原子晶体研究中的重要内容,需要高空间分辨率的结构研究手段.由于绝大部分二维原子晶体在高能量高剂量的电子束辐照下容易发生结构损伤,利用电子显微方法对二维原子晶体缺陷的研究面临诸多挑战.低电压球差校正扫描透射电子显微(STEM)技术的发展,一个主要目标就是希望在不损伤结构的前提下对二维原子晶体的本征结构缺陷进行研究.在STEM下,多种不同的信号能够被同步采集,包括原子序数衬度高分辨像和电子能量损失谱等,是表征二维原子晶体缺陷的有力工具,不但能对材料的本征结构进行单原子尺度的成像和能谱分析,还能记录材料结构的动态变化.通过调节电子束加速电压和电子辐照剂量,扫描透射电子显微镜也可以作为电子刻蚀二维原子晶体材料的平台,用于加工新型纳米结构以及探索新型二维原子晶体的原位制备.本综述主要以本课题组在石墨烯和二维过渡金属硫族化合物体系的研究为例,介绍低电压扫描透射电子显微学在二维原子晶体材料研究中的实际应用.     

有机双光子吸收材料的研究进展

本文综述了具有优异双光子吸收/双光子荧光性质的有机功能材料的研究工作和成果。近年来,有机材料凭借其出众的性质、丰富的种类、多重功能性以及快速的非线性光学响应引起国际科学和技术界的极大兴趣。文章介绍了测量材料的非线性光学性质和超快响应的实验方法,它们已被广泛应用于有机材料的研究工作,并且取得了重大的进展。本文描述了对偶极、四极、多枝结构、大环结构以及聚合物等有机材料的非线性光学性质和超快光学响应的研究结果。基于有机材料的迷人性质,具有优异非线性光学性质和超快响应的有机材料将会在很多领域显示出巨大的应用潜力。     

Recent advances in two-dimensional layered and non-layered materials hybrid heterostructures

With the development of Moore's law, the future trend of devices will inevitably be shrinking and integration to further achieve size reduction. The emergence of new two-dimensional non-layered materials (2DNLMs) not only enriches the 2D material family to meet future development, but also stimulates the global enthusiasm for basic research and application technologies in the 2D field. Van der Waals (vdW) heterostructures, in which two-dimensional layered materials (2DLMs) are physically stacked layer by layer, can also occur between 2DLMs and 2DNLMs hybrid heterostructures, providing an alternative platform for nanoelectronics and optoelectronic applications. Here, we outline the recent developments of 2DLMs/2DNLMs hybrid heterostructures, with particular emphasis on major advances in synthetic methods and applications. And the categories and crystal structures of 2DLMs and 2DNLMs are also shown. We highlight some promising applications of the heterostructures in electronics, optoelectronics, and catalysis. Finally, we provide conclusions and future prospects in the 2D materials field.     

新型二维材料在固体激光器中的应用研究进展

本文主要介绍了二维可饱和吸收体材料在固体激光器中的应用与研究进展。简要介绍了新型二维材料的性质和优点。以石墨烯、拓扑绝缘体、过渡金属硫化物和黑磷等新型二维材料为例分析了它们在固体激光器中实现调Q或锁模的过程,展示了二维材料在脉冲固体激光研究中的重要应用前景。二维材料与固体激光器的结合,可进一步推进二维材料的研究,有望开发出大量新型固体激光器件并且作为基础光源应用于多个领域,推动相关领域的发展。     

Toward high-performance two-dimensional black phosphorus electronic and optoelectronic devices

Recently, black phosphorus(BP) has joined the two-dimensional material family as a promising candidate for electronic and photonic applications due to its moderate bandgap, high carrier mobility, and unusual in-plane anisotropy. Here,we review recent progress in BP-based devices, such as field-effect transistors, contact resistance, quantum transport, stability, photodetector, heterostructure, and in-plane anisotropy. We also give our perspectives on future BP research directions.     

Recent development and status of magnetoelectric materials and devices

The magnetoelectric (ME) materials and related devices have been attracting increasing research attention over the last few years. They exhibit strong ME coupling effect at room temperature, and electric field control of magnetization or magnetic field control of ferroelectric polarization can be achieved. The ME coupling effect brings novel functionalities to develop ultra-fast, low-power, and miniaturized electronics. Recent progress shows the performance of ME materials is further improved and the materials are used to develop many new types of electronics such as high-speed memory, radio frequency resonator, compact ME antenna, and weak magnetic field sensor. In this review, we present the overview in those fields with emphasis on both the opportunities and challenges for the application of ME materials and devices in the cutting-edge technologies.     

二维材料类脑器件

研究类脑器件是构建一个能够与大脑相媲美的类脑信息处理系统的重要基础。二维材料凭借优异的电学与光电特性、可多自由度调控以及可三维垂直集成等优势,为设计多功能的类脑器件提供了丰富的材料和机制选择。文章围绕二维材料及异质结类脑器件的设计展开,通过总结最近的重要研究进展,探究该领域未来可能面临的机遇与挑战。     

二维材料的新奇物理及异质结的能带调控

以石墨烯为代表的层状材料具备显著区别于三维材料的新奇物理特性。更为重要的是,原子级平整的二维材料使得科学家们可以将不同的二维材料通过堆垛或者把相同的二维材料通过堆垛加扭转构成范德瓦耳斯异质结。通过层间耦合作用,可对异质结的能带结构和物理性质进行有效调控,从而衍生出单个二维材料所不具备的新奇物性。范德瓦耳斯异质结的能带调控极大地拓宽了二维材料的科学研究和应用前景。     

二维材料及其异质结的声子物理研究

声子是固体最重要的元激发之一,是理解材料摩尔热容、德拜温度以及热膨胀系数等热力学性质的基础,同时电声子相互作用也决定了固体的电导和超导等特性。拉曼光谱是表征固体声子物理的重要实验手段,不仅能表征材料的结构和质量,还能提供材料声子性质、电子能带结构、电声耦合等信息。文章将拉曼光谱应用于二维材料及其范德瓦尔斯异质结的声子物理研究。先简单介绍二维材料的层间振动声子模式和层内振动声子模式,其中层间振动声子模式的频率可用线性链模型来计算,而强度则可用层间键极化率模型来解释;同类层内振动声子模式的Davydov劈裂峰之间的频率差异可用范德瓦尔斯模型拟合。随后,将这些模型推广到二维范德瓦尔斯异质结中,以转角多层石墨烯、MoS₂/石墨烯和hBN/WS₂为例介绍了范德瓦尔斯异质结的声子谱,阐述如何应用线性链模型和经典键极化率模型计算层间振动模的频率和强度,并由此给出二维范德瓦尔斯异质结的界面耦合强度和各层间呼吸模的电声耦合强度等重要参数。     

弛豫铁电体的键能与配位数模型

基于一定浓度的杂质会在钛酸钡型铁电体中导致键能与配位数的高斯型分布原理,利用键能与配位数起伏模型导出了介电峰温与测量频率的关系.当键能和配位数的相对起伏接近时,其关系呈现出一般弛豫铁电体所普遍具有的Vogel-Fulcher函数形式,且冻结温度仅与键能的相对起伏和激活能有关.并由此解释了低掺杂浓度下杂质均匀分布导致弥散性的机理和超过临界浓度时的弛豫铁电性的机理.同时提出,杂质替代对畴的形成和生长所产生的强烈抑制作用及微畴化是实现键能起伏与配位数起伏一致的来源.     

Different angle-resolved polarization configurations of Raman spectroscopy: A case on the basal and edge plane of two-dimensional materials

Angle-resolved polarized Raman(ARPR) spectroscopy can be utilized to assign the Raman modes based on crystal symmetry and Raman selection rules and also to characterize the crystallographic orientation of anisotropic materials.However, polarized Raman measurements can be implemented by several different configurations and thus lead to different results. In this work, we systematically analyze three typical polarization configurations: 1) to change the polarization of the incident laser, 2) to rotate the sample, and 3) to set a half-wave plate in the common optical path of incident laser and scattered Raman signal to simultaneously vary their polarization directions. We provide a general approach of polarization analysis on the Raman intensity under the three polarization configurations and demonstrate that the latter two cases are equivalent to each other. Because the basal plane of highly ordered pyrolytic graphite(HOPG) exhibits isotropic feature and its edge plane is highly anisotropic, HOPG can be treated as a modelling system to study ARPR spectroscopy of twodimensional materials on their basal and edge planes. Therefore, we verify the ARPR behaviors of HOPG on its basal and edge planes at three different polarization configurations. The orientation direction of HOPG edge plane can be accurately determined by the angle-resolved polarization-dependent G mode intensity without rotating sample, which shows potential application for orientation determination of other anisotropic and vertically standing two-dimensional materials and other materials.