热带雨林灌木丛——CdS可见光催化处理有机污染物CSCD

CdS作为一种重要的II-VI族半导体,可以制成量子点、纳米棒、纳米带、复杂等级结构等多种微纳米材料,在光电转换器件、催化、发光器件、传感器以及荧光标记等不同领域均有广阔的应用前景。CdS的禁带宽度保证了它对可见光的高效吸收,同时复杂的等级结构具有较大的比表面积,因此具有复杂等级结构的CdS可以作为一种重要的可见光催化材料,应用于有机污染物的可见光催化降解。     

宽带半导体材料分子束外延的最新进展

本文评述了分子束外延在以 ZnSe 为代表的宽带半导体材料及其超晶格结构研究中的最新进展。介绍了在晶格匹配和不匹配的衬底上分子束外延生长 ZnSe等Ⅱ-Ⅵ族宽带半导体和有关的材料分析。叙述了在 ZnTe,Zn(S、Se)以及磁性半导体 MnSe 和低磁性半导体 Zn_(1-x)Mn_xSe 上生长 ZnSe 所形成的超晶格和多量子阱结构,并在此基础上说明了一些相关的物理现象。     

激光二极管直接抽运中红外固体激光材料综述

利用激光二极管(LD)直接抽运稀土离子或过渡金属离子的方式产生中红外激光可以大幅度降低系统的复杂程度,提高效率。而找到合适的基质材料和离子能级结构是实现LD直接抽运产生中红外激光的关键。总结了相关研究进展和发展方向,主要包括高功率、高效率、激光二极管直接抽运的过渡金属离子掺杂II-VI族材料激光器和稀土离子掺杂晶体、玻璃、光纤、陶瓷等材料的固态激光器,这些激光器的输出涵盖了2~5μm波段,具有结构简单、成本低等优点。其中过渡金属离子掺杂II-VI族化合物,如Cr:Zn Se/Zn S,具有吸收和发射截面大、室温量子效率高、激发态吸收小等优点;而稀土离子掺杂材料,如Er3+/Tm3+/Ho3+:玻璃,具有能级丰富,可多波长抽运获得多波长发光等优点。通过对稀土离子在不同基质材料中晶格场结构能级调控有望实现波长可控的中红外激光输出。     

Ⅲ-Ⅴ族化合物低维半导体材料制备技术及进展

低维半导体材料特别是Ⅲ -Ⅴ族化合物低维半导体材料日益受到人们的重视和深入的研究。文章回顾和评述了近几年Ⅲ -Ⅴ族化合物低维半导体材料包括量子阱、量子线、量子点的制备技术的进展 ,展望了这些技术在光电子器件等方面的应用前景。     

“宽禁带半导体材料与器件”专题征文通知北大核心

一代材料催生一代器件,引领一代产业。以Ⅲ族氮化物、碳化硅、氧化物半导体等为代表的宽禁带半导体材料是发展高能效的半导体光电子和电力电子器件的核心基础。宽禁带半导体材料与器件围绕国民经济和社会发展的战略性、基础性和前瞻性方向,重点面向固态照明、新型半导体显示、射频电力电子以及光电探测、绿色能源等前沿领域,对于赋能低碳排放的"美丽中国建设"。     

InGaAsP量子阱混合技术理论及模拟研究

本文以品格中原子的扩散理论为基础，分析了四元系InGaAsP半导体材料中Ⅲ、Ⅴ族原子的扩散规律，建立了量子阱和超晶格结构中量子阱混合(QWI)的理论模型，模拟计算了半导体材料中组分浓度与扩散长度的关系，以及应变与扩散长度的关系，计算分析了应变对量子阱带隙、带结构和量子跃迁的影响，获得了一些有价值的结论，为量子阱混合试验和量子阱及超晶格集成器件的开发和研究提供了重要的理论基础。     

宽禁带半导体材料技术

宽禁带半导体材料是一种新型材料,具有禁带宽度大、击穿电场高、热导率高等特点,非常适合于制作抗辐射、高频、大功率和高密度集成电子器件;利用其特有的禁带宽度,还可以制作蓝光、绿光、紫外光器件和光探测器件,能够适应更为苛刻的生存和工作环境。在宽禁带半导体材料中,具有代表性的是碳化硅(SiC)、氮化镓(GaN)、氮化铝(AlN)、金刚石以及氧化锌(ZnO),综合叙述了这些材料的特性、发展现状和趋势;并介绍了SiC、GaN、ZnO材料的应用情况和代表性器件的研究进展。     

北京邮电大学半导体低维量子结构材料研究组

半导体应变异质结构材料,如量子阱、量子线和量子点等在光电材料与器件中发挥着越来越重要的作用,晶格失配导致的应变对材料生长过程、形貌与物理性质具有非常重要的作用,弹性应变场能够改变半导体材料的能带结构,进而影响材料的光学和电学特性以及光电器件的性能。以应变工程为基础的低维量子结构材料的研究已经成为国际半导体材料与器件领域的重要研究方向。北京邮电大学半导体低维量子结构材料研究组在俞重远教授带领下,以连续弹性理论和原子势函数理论为基础,对于自组织量子结构材料的内部应变场、应变能、压电效应、电子与空穴的能级分…     

宽禁带半导体技术

概述 根据半导体材料禁带宽度的不同,可分为宽禁带半导体材料与窄禁带半导体材料.若禁带宽度Eg＜2ev(电子伏特),则称为窄禁带半导体,如锗(Ge)、硅(Si)、砷化镓(GaA s)以及磷化铟(InP);若禁带宽度Eg＞2.0～6.0ev,则称为宽禁带半导体,如碳化硅(SiC)、氮化镓(GaN)、4H碳化硅(4H-SiC)、6H碳化硅(6H-SiC)、氮化铝(AIN)以及氮化镓铝(ALGaN)等.     

量子级联探测器研究进展

综述了基于三大化合物半导体材料(GaAs基、InP基与GaN基)的量子级联探测器(QCD)的进展,对这三种材料体系的QCD的各种技术指标如光电流响应度、电阻、电流-电压特性等做了详细的说明,最后对其他半导体材料及新型结构的QCD做了展望.     

宽禁带半导体关键设备技术及发展

宽禁带半导体设备技术是宽禁带半导体器件的支撑和重要基础。简要介绍了宽禁带半导体器件发展面临的设备问题,重点介绍了碳化硅晶体生长炉、碳化硅外延生长炉、碳化硅离子注入机和氮化镓MOCVD四种制约我国宽禁带半导体器件技术发展的关键设备,指出了宽禁带半导体设备技术的未来发展趋势。     

硅基发光材料研究进展

阐述了等电子杂质、掺Er硅、硅基量子结构(包括量子阱、量子线和量子点)及多孔硅的发光机理,综述了90年代以来a-Si/SiO2、SiGe/Si等Si基异质结构材料的优异特性和诱人的应用前景,着重介绍了能带工程为Si基异质结构带来的新特性、新功能,重点介绍了硅基量子点的制备和发光机理,综述了半导体量子点材料的最新发展动态和发展趋势。     

Nanostructured thin films based on TiO2 and/or SiC for use in photoelectrochemical cells: A review of the material characteristics,synthesis and recent applications

In solar energy harvesting research, there is growing interest in the study of photoelectrochemical (PEC) properties of the following classes of semiconductor materials: metal oxides and silicon-based compounds. The motivation is that such materials are being successfully used as photoelectrode in PEC cells. Special attention has been given to the wide band gap materials. This review discusses, from the material science perspective, the recent literature relating to two wide band gap semiconductor materials: one metal oxide, titanium dioxide (TiO₂), and one silicon-based compound, silicon carbide (SiC). Emphasis is placed on TiO₂ and SiC thin films for PEC applications. Materials characteristics, synthesis methods and recent photocatalytic applications are presented. Finally, the interesting effect of the efficiency increase of PEC devices developed from a hetero-junction of TiO₂ and SiC is discussed.     

基于化学溶液法制备的氧化锌量子点发光二极管研究

氧化锌（ZnO）量子点是一种宽直接带隙半导体纳米颗粒,具有激子束缚能大、绿色环保、量子效应等优点,引起广泛关注。近期,将通过化学溶液法制备的ZnO量子点应用到发光二极管的研究成为热点。文章综述了近几年ZnO量子点发光二极管研究进展,重点介绍了各种结构的ZnO量子点发光二极管最新研究成果,并对ZnO量子点发光二极管的发展趋势进行了展望。     

Engineering Route for Stretchable, 3D Microarchitectures of Wide Bandgap Semiconductors for Biomedical Applications

Wide bandgap (WBG) semiconductors have attracted significant research interest for the development of a broad range of flexible electronic applications, including wearable sensors, soft logical circuits, and long-term implanted neuromodulators. Conventionally, these materials are grown on standard silicon substrates, and then transferred onto soft polymers using mechanical stamping processes. This technique can retain the excellent electrical properties of wide bandgap materials after transfer and enables flexibility; however, most devices are constrained by 2D configurations that exhibit limited mechanical stretchability and morphologies compared with 3D biological systems. Herein, a stamping-free micromachining process is presented to realize, for the first time, 3D flexible and stretchable wide bandgap electronics. The approach applies photolithography on both sides of free-standing nanomembranes, which enables the formation of flexible architectures directly on standard silicon wafers to tailor the optical transparency and mechanical properties of the material. Subsequent detachment of the flexible devices from the support substrate and controlled mechanical buckling transforms the 2D precursors of wide band gap semiconductors into complex 3D mesoscale structures. The ability to fabricate wide band gap materials with 3D architectures that offer device-level stretchability combined with their multi-modal sensing capability will greatly facilitate the establishment of advanced 3D bio-electronics interfaces.     

Research and Development of Electronic and Optoelectronic Materials in China

A review on the research and development of electronic and optoelectronic materials in China, including the main scientific activities in this field, is presented. The state-of-the-arts and prospects of the electronic and optoelectronic materials in China are briefly introduced, such as those of silicon crystals, compound semiconductors, synthetic crystals, especially nonlinear optical crystals and rare-earth permanent magnets materials, etc. , with a greater emphasis on Chinese scientist's contributions to the frontier area of nanomaterials and nanostructures in the past few years. A new concept of the trip chemistry proposed by Dr. Liu Zhongfan from Peking University has also been described. Finally the possible research grants and the national policy to support the scientific research have been discussed.     

Realization of a New Topological Crystalline Insulator and Lifshitz Transition in PbTe

Topological materials boast exotic metallic surface states with linear dispersion and spin‐momentum locking, which makes them potential candidates for dissipationless electronic and spintronic devices. Here, it is theoretically predicted that intrinsic Te antisite defects (Te_Pb) in the narrow‐gap semiconductor PbTe induce a band inversion, turning it into a topological crystalline insulator (TCI). To experimentally verify the exotic properties, Te_Pb antisites are introduced into PbTe crystals via nonstoichiometric growth by molecular beam epitaxy. Semimetallic resistivity and distinct quantum oscillations are observed on the Te_Pb doped PbTe. Most importantly, a π Berry phase is unambiguously revealed by a Landau index analysis, demonstrating the Dirac fermion nature of the topological surface states. The discovered TCI nature in Te_Pb doped PbTe is further explored using magneto‐transport measurements under external pressure, and the theoretical calculations of band structures with applying pressure indicate a pressure‐induced Lifshitz transition. Besides, it is proposed that the contribution of bulk states to transport can be reduced by enlarging the inverted gap with strain.     

Application of Photonic Crystals in Semiconductor Lasers

Photonic crystals(PCs) have attracted much considerable research attention in the past two decades. They are artificially fabricated periodic dielectric structures. The periodic dielectric structures have photonic band gap(PBG) and are referred to as photonic band gap materials. This paper mainly introduces one-dimensional (1-D) and 2D PCs applied in the semiconductor lasers.     

All‐Metallic Vertical Transistors Based on Stacked Dirac Materials

It is an ongoing pursuit to use metal as a channel material in a field effect transistor. All metallic transistor can be fabricated from pristine semimetallic Dirac materials (such as graphene, silicene, and germanene), but the on/off current ratio is very low. In a vertical heterostructure composed by two Dirac materials, the Dirac cones of the two materials survive the weak interlayer van der Waals interaction based on density functional theory method, and electron transport from the Dirac cone of one material to the one of the other material is therefore forbidden without assistance of phonon because of momentum mismatch. First‐principles quantum transport simulations of the all‐metallic vertical Dirac material heterostructure devices confirm the existence of a transport gap of over 0.4 eV, accompanied by a switching ratio of over 10⁴. Such a striking behavior is robust against the relative rotation between the two Dirac materials and can be extended to twisted bilayer graphene. Therefore, all‐metallic junction can be a semiconductor and novel avenue is opened up for Dirac material vertical structures in high‐performance devices without opening their band gaps.     

Photonic band gap of the photonic crystals with chiral and negative-index materials

In this paper, the photonic band gap of photonic crystals with chiral and negative-index materials alternately is investigated. It is shown that this kind of photonic crystal exhibits very wide photonic band gap. The photonic crystals with a defect layer have a narrow defect mode in the band gap, which can be used as a very good filtering material by choosing the parameters of the defect layer properly.