用633nm的激光器监控峰值波长为 530nm的AlGaN/GaN DBR的生长

本文从理论和实验上研究了用633nm激光器干涉仪监控峰值反射波长为530nm的1/4光学厚度的AlGaN/GaN 分布布拉格反射器（DBR）的生长。首先采用传输矩阵法从理论上研究了不同周期厚度的AlGaN/GaN DBR的实时反射率随DBR生长厚度的变化。接着采用金属有机化合物气相外延法生长了两个与模拟结构相同的DBR样品。仿真结果和实验结果表明能够从DBR实时反射率随生长厚度变化的曲线形状判断DBR的结构参数。最后通过激光干涉仪实时监控生长了DBR发光二极管,光致发光实验证明DBR对发光二极管出射光的加强作用在期望波长范围内。     

AlGaN /GaN分布布拉格反射镜的设计与表征

设计了反射中心波长为500nm的Al0.3Ga0.7N/GaN和AlN/GaN两种分布布拉格反射镜（DBR）,并采用光学传递矩阵方法对其光谱反射率进行了理论上的模拟.采用金属有机物化学气相淀积（MOCVD）技术在蓝宝石衬底上制备了样品.实际测量的样品反射谱中有明显的反射峰,但峰值波长与理论设计有偏差,峰值反射率也比理论设计值偏低.SEM和AFM测量结果表明：这是由生长层厚与设计的偏差和界面不平整引起的.     

LED芯片DBR反射镜优化设计

讨论了反射镜反射率对LED光提取效率的影响,并基于芯片与封装协同设计的原理,针对蓝光和黄光波段,通过TFcalc膜系仿真软件设计和优化了分布式布拉格反射镜(DBR)膜系。仿真结果表明,单堆栈DBR结构最大反射带宽为134nm,而双堆栈DBR结构最大反射带宽可拓展至216nm。利用参考波长红移的方式,可以缓解DBR反射特性随入射角度增加而出现的反射谱线蓝移现象。金属增强型DBR结构能够减小反射偏振效应,提高反射带宽和平均反射率,并能够减小DBR厚度,从而显著改善芯片的散热性能。     

宽反射角DBR红光发光二极管

对用于提高AlGaInP红光发光二极管出光效率的传统DBR进行了分析,用MOCVD生长了包含对垂直入射光反射的DBR和对斜入射光反射的DBR复合在一起的红光LED,在20 mA注入电流下,LED的峰值波长为630 nm,轴向光强达到137 mcd,输出光功率为2.32 mW.与常规的LED相比,光强和输出光功率有很大的提高.     

高亮度AlGaInP红光发光二极管

对用于提高AlGaInP红光发光二极管(LED)出光效率的分布布拉格反射镜(DBR)和增透膜进行了分析,用金属有机物化学气相沉积(MOCVD)生长了包含DBR和增透膜的LED,在20 mA注入电流下,LED的峰值波长为623 nm,光强达到200 mcd,输出光功率为2.14 mW.与常规的LED相比,光强和输出光功率有很大的提高.     

高亮度AIGalnP红光发光二极管

对用于提高AlGaInP红光发光二极管(LED)出光效率的分布布拉格反射镜(DBR)和增透膜进行了分析,用金属有机物化学气相沉积(MOCVD)生长了包含DBR和增透膜的LED,在20mA注入电流下,LED的峰值波长为623nm,光强达到200mcd,输出光功率为2.14mW。与常规的LED相比,光强和输出光功率有很大的提高。     

Fabrication and property analysis of AIGalnP red light LED with high bright

The LED with DBR and enhancing transmission film was grown by MOCVD. At 20 mA DC injection current, the LED peak wavelength was 623 nm, the light intensity was 200 mcd, and the output light power was 2.14 mW. The light intensity and output light power have been improved than traditional LED.     

复合布拉格反射镜高亮度AlGaInP发光二极管

采用光学薄膜理论中干涉矩阵模型计算了峰值波长为630nm的AlGaInP红光LED的Al0.6Ga0.4As/AlAs材料的常规DBR和复合DBR的反射谱特性,用LP-MOCVD方法生长了模拟设计的DBR结构,测量了其白光反射谱,实验与模拟结果基本符合.制备了采用Al0.6Ga0.4As/AlAs复合DBR的LED器件,未封装输出光功率为2.3mW,外量子效率为5.6%,发光效率可达12 lm/W,比常规DBR器件提高了35%.验证了复合DBR与常规DBR相比,可以大幅度提高AlGaInP红光LED的出光效率.     

Wide reflected angle DBR red light LED

The coupled DBR LED with one DBR for reflecting normal incidence light and the other for reflecting inclined incidence light has been grown by MOCVD. For improving the conventional DBR which was used to increase light extraction efficiency in AlGaInP red light LED is analyzed. At 20 mA Dc injection current, the LED peak wave length is 630 nm, and the light intensity of on axis is 137 mcd. The output light power is 2.32 mW. The light intensity and output light power have been improved compared with the conventional LEDs.     

全反射镜结构对AlGaInP发光二极管发光效率的影响

采用计算机模拟的方法,计算了SiO2/Al,ITO/Al,SiO2/Au和ITO/Au全方位反射镜结构和分布式布拉格反射镜的反射特性.用PECVD和溅射设备制作了Glass/SiO2/Au结构,用LP-MOCVD生长了DBR结构,并测量了其反射特性,实验与模拟结果基本吻合.从模拟和实验的结果得到,SiO2/Au ODR结构在波长为630nm的垂直入射光下反射率很高,达到91%以上.对于不同角度的入射光,SiO2/Au在20°～85°都有很高的反射率,远高于DBR结构的反射率.在实际器件测试中,ODR结构的AlGaInP红光LED比无DBR结构的LED提高了115%,比DBR结构的LED提高了28%.这说明,ODR结构与DBR结构相比可以大幅提高红光LED的出光效率.     

MOCVD生长双有源区AlGaInP发光二极管

设计并用金属有机物化学气相沉积方法生长了双有源区AlGaInP发光二极管,该发光二极管的两个AlGaInP有源区用高掺杂的反偏隧道结连接.双有源区发光二极管在20 mA注入电流下,主波长为623 nm,峰值波长为633 nm,电压为4.16 V,光强为163 mcd.     

AlGaAs／AlAs体系DBR的MOCVD生长及表征

设计并利用MOCVD在（311）GaAs衬底上生长了12．5个周期的Al0．6Ga0．4As／AlAs黄绿光分布式Bragg反射（DBR）体系，测量了白光反光谱及其外延片峰值波长分布，反射率90％以上，波长不均匀性在1．0％以下；利用了X射线双晶衍射对其进行结构表征，580nm波长DBR结构周期为84．5nm。     

材料结构对AlGaN基分布布拉格反射镜特性的影响

采用低压MOCVD技术生长了AlGaN／GaN、AlGaN／AlN等多种交替生长结构的半导体多层膜分布布拉格反射镜（DBR）。利用X射线衍射、扫描电子显微镜（SEM）、原子力显微镜（AFM）等测量手段对材料的物理特性进行了分析表征。结果表明，材料结构对DBR的性能影响很大。通过材料的优化生长，获得了反射率高达93.5％、中心波长和发射率都接近理论值的AlGaN／AlNDBR材料。     

MOCVD在位监测技术及其在VCSEL研制中的应用

使用MOCVD技术生长了 980nmVCSEL ,在GaAs/AlGaAsDBR对的生长过程中通过相干反射率测量方法实现了在位监测和实时校正生长。白光反射谱测量结果表明通过上述手段准确控制了外延层的光学厚度。外延生长结束后 ,制备了 980nmVCSEL ,器件在室温下连续工作 ,输出功率为 7.1mW ,激射波长为 974nm ,斜率效率为 0 .4 6 2mW/mA。     

Determination of the direction of piezoelectric field in InGaN/GaN multiple quantum-well structures grown by metal-organic chemical vapor deposition

The direction of the piezoelectric field in InGaN/GaN multiple quantum-well (MQW) structures grown by metal-organic vapor deposition (MOCVD) was determined using excitation-power-density variable photoluminescence (PL). By comparing the excitation-power-density dependence of the shift of the PL peak and the change of the full-width at half-maximum (FWHM) of the peak from an InGaN/GaN MQW structure and an InGaN MQW-based light-emitting diode (LED), the piezoelectric field in the InGaN/GaN MQW structures was unambiguously determined to be pointing toward the substrate. This result helps to identify the surface polarity of the LED wafer as Ga-faced.     

Vertical cavity surface-emitting laser with an AlGaAs/AlAs Braggreflector

The letter elucidates the room temperature pulsed operation of a vertical cavity surface-emitting laser with an electrically conductive AlGaAs/AlAs distributed Bragg reflector (DBR). The maximum reflectivity of a DBR grown by MOCVD was 96% at 0.88 μm wavelength. The threshold current of 30 μm diameter devices was 200 mA under room temperature pulsed condition, which is the lowest value for such a broad area structure     

具有ODR结构的高压倒装氮化镓基发光二极管

通过在传统ITO+DBR膜系结构基础上令电极金属与DBR层形成ODR(全角反射镜)膜系结构的方法,设计并制备了具有ODR结构的高压倒装氮化镓基发光二极管,有效提高了LED芯片的光效。ODR结构由DBR(分布布拉格反射镜)层上联接芯粒的电极金属和DBR层组成,经过理论分析和计算,与传统ITO+DBR结构器件相比,在400～550nm波长范围、全角度入射时平均反射率Rave从86.25%提升到了96.71%。实验制备了传统ITO+DBR结构和ODR结构的3颗芯粒串联的高压倒装氮化镓基LED器件,尺寸为0.2mm×0.66mm,ODR结构器件的有效反射结构面积增加了4.8%,饱和电流增加了12mA,用3030支架封装后在30mA的测试电流下,电压降低了0.163V,辐射功率提升了3.78%,在显色指数均为71时光效提升了5.42%。     

Fabrication of Microcavity Light-Emitting Diodes Using Highly Reflective AlN–GaN and Ta2O 5–SiO2 Distributed Bragg Mirrors

We report the fabrication of microcavity light-emitting diodes (MCLEDs) with high reflectivity and crack-free AlN-GaN distributed Bragg reflector (DBR). The 5lambda microcavity structure consists of an n-type GaN, ten pairs InGaN-GaN multiple quantum wells and p-type GaN sandwiched between the hybrid cavity mode of an AlN-GaN and a Ta₂O₅-SiO₂ DBR. The AlN-GaN DBR has 29 periods with insertion of six AlN-GaN superlattice layers showing a crack-free surface morphology and a high peak reflectivity of 99.4% with a stopband of 21 nm. The output power of MCLED is about 11 W at an injection current of 7 mA. The electroluminescence has a polarization property with a degree of polarization of about 51%.     

P—type AlAs／[GaAs／AlAs]Semiconductor／Superlattice DBR Grown by MBE

A p-type AlAs(70.2 nm)/16.5 period [GaAs(3 nm)/AlAs(0.7 nm)] semiconductor/superlatice distributed Bragg reflector (DBR) has been grown on n +-GaAs(100) substrate by V80H molecular beam epitaxy system. Experimental reflection spectrum shows that its central wavelength is 820 nm, with the peak reflectivity for 10-pair DBR of as high as 96 %, and the reflection bandwidth of as wide as 90 nm. We formed a 20×20 μm 2 square mesa to measure the series resistance using wet chemical etching. From the measurement result, the series resistance of about 50 Ω is obtained at a moderate doping (3×10 18 cm -3 ). Finally, the dependence of the resistance of the DBR on the temperature is analyzed. From the experimental result, it is found that the mechanism of the low series resistance of this kind of DBR may increase the tunneling current in the semiconductor/superlattice mirror structure, which will result in a decrease in series resistance.     

一种微腔有机发光二极管的设计与性能研究

设计了PPV为发光层、Ag和DBR为上下反射镜、结构为Glass/DBR/ITO/PPV/Ag的微腔有机发光二极管。应用特征矩阵法,系统地研究了DBR和银镜的性质对器件性能的影响。结果表明:1)当金属厚度较小时,随着厚度的增加,器件的反射峰值不断增加并且蓝移,但是当厚度达到100 nm后,再增加厚度反射谱基本上没变化;2)随着DBR周期数的增加,器件的反射谱峰值不断增大,峰值半宽度不断变窄。3)器件的EL谱的峰值随着金属反射率的增加不断增大,而随着DBR反射率的增加是先增加后减小的。并给出了不同条件下DBR的最优化选择依据。