heterostructure 篇一：TMDs带隙 篇二：什么是MB、GB、TS、AS芯片 什么是MB、GB、TS、AS芯片 一．MB芯片定义与特点 定义﹕MB 芯片﹕Metal Bonding (金属粘着〕芯片﹔该芯片属于UEC 的专利产品 特点﹕ 1: 采纳高散热系数的材料---Si 作为衬底、散热简单 ThermalConductivity GaAs:46W/m-K GaP:77W/m-K Si:125～150W/m-K Cupper:300~400W/m-k SiC:490W/m-K 2﹕通过金属层来接合(wafer bonding)磊晶层和衬底，同时反射光子，幸免衬底的汲取 3: 导电的Si 衬底取代GaAs 衬底，具备良好的热传导实力(导热系数相差3~4 倍)，更适应于高驱动电流领域 4: 底部金属反射层、有利于光度的提升及散热 5: 尺寸可加大、应用于High power 领域、eg : 42mil MB 二、定义﹕GB 芯片﹕Glue Bonding (粘着结合〕芯片﹔该芯片属于UEC 的专利产品 特点﹕ 1﹕透亮的蓝宝石衬底取代吸光的GaAs衬底、其出光功率是传统AS (Absorbable structure)芯片的2倍以上、蓝宝石衬底类似TS芯片的GaP衬底。
2﹕芯片四面发光、具有精彩的Pattern 3﹕亮度方面、其整体亮度已超过TS芯片的水准(8.6mil) 4﹕双电极构造、其耐高电流方面要稍差于TS单电极芯片 三、TS芯片定义和特点 定义﹕TS 芯片﹕ transparent structure(透亮衬底)芯片、该芯片属于HP 的专利产品 特点﹕ 1.芯片工艺制作困难、远高于AS LED 2. 信任性卓越 3.透亮的GaP衬底、不汲取光、亮度高 4.应用广泛 四、AS芯片定义和特点 定义﹕AS 芯片﹕Absorbable structure (汲取衬底〕芯片﹔经过近四十年的开展努力、{词语被屏蔽}LED光电业界对于该类型芯片的研发﹑生产﹑销售处于成熟的阶段、各大公司在此方面的研发水平根本处于同一水准、差距不大. 大陆芯片制造业起步较晚、其亮度及牢靠度与业界还有必须的差距、在这里我们所谈的AS芯片、特指UEC的AS芯片、eg: 712SOL-VR, 709SOL-VR, 712SYM-VR,709SYM-VR 等 特点﹕ 1. 四元芯片、采纳 MOVPE工艺制备、亮度相对于常规芯片要亮 2. 信任性优良 3. 应用广泛 发光二极管芯片材料磊晶种类 1、LPE：LiquidPhaseEpitaxy(液相磊晶法)GaP/GaP 2、VPE：VaporPhaseEpitaxy(气相磊晶法)GaAsP/GaAs 3、MOVPE：MetalOrganicVaporPhaseEpitaxy(有机金属气相磊晶法)AlGaInP、GaN 4、SH：GaAlAs/GaAsSingleHeterostructure(单异型构造)GaAlAs/GaAs 5、DH：GaAlAs/GaAsDoubleHeterostructure，(双异型构造)GaAlAs/GaAs 6、DDH：GaAlAs/GaAlAsDoubleHeterostructure，(双异型构造)GaAlAs/GaAlAs 篇三：Terahertz semiconductor Terahertz semiconductor-heterostructure laser Semiconductor devices have become indispensable for generating electromagnetic radiation in everyday applications. Visible and infrared diode lasers are at the core of information technology, and at the other end of the spectrum, microwave and radio-frequency emitters enable wireless communications. But the terahertz region (1–10 THz; 1 THz = 1012 Hz) between these ranges has remained largely underdeveloped, despite the identification of various possible applications—for example, chemical detection, astronomy and medical imaging. Progress in this area has been hampered by the lack of compact, low-consumption, solid-state terahertz sources. Here we report a monolithic terahertz injection laser that is based on interminiband transitions in the conduction band of a semiconductor (GaAs/AlGaAs) heterostructure. The prototype demonstrated emits a single mode at 4.4 THz, and already shows high output powers of more than 2 mW with low threshold current densities of about a few hundred A cm-2 up to 50 K. These results are very promising for extending the present laser concept to continuous-wave and high-temperature operation, which would lead to implementation in practical photonic systems. In conventional semiconductor lasers, light is generated by the radiative recombination of conduction band electrons with valence band holes across the bandgap of the active material; in contrast, electrons in a quantum-cascade laser propagate through a potential staircase of coupled quantum wells, where the conduction band is split by quantum confinement into a number of distinct sub-bands10. By choice of layer thickness and applied electric field, lifetimes and tunnelling probabilities of each level are engineered in order to obtain population inversion between two sub-bands in a series of identical repeat units. Injector/collector structures connect these active regions, allowing electrical transport through injection of carriers into the upper laser level, and extraction of carriers from the lower laser level. The radiation frequency is determined by the energy spacing of the lasing sub-bands, allowing in principle operation at arbitrarily long wavelengths. The quantum-cascade scheme has thus long been the preferred choice in many attempts to fabricate a terahertz semiconductor laser. Although electroluminescent devices have been reported by several groups, laser action has been shown only at much shorter wavelengths15, 16. In fact, above the forbidden phonon band of the material, direct electron–longitudinal optical (LO) phonon scattering processes can be conveniently used to achieve large population inversions16. Furthermore, an additional problematic issue for the terahertz range stems from the fact that conventional laser waveguides are not suitable, owing to large free-carrier absorption losses and practical limitations on the thickness of epilayer growth. As in all lasers, efficient depletion of the lower level is essential, and long lifetimes of the upper level are highly desirable. Up until now, proposed terahertz quantum-cascade designs focused mainly on the latter aspect. To this end, structures have featured narrow injec。