摘要
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%。
The high-voltage flip-chip(HVFC)GaN light-emitting diodes(LED)with omnidirectional reflector(ODR)structure was optimized on the basis of traditional indium-tin-oxide(ITO)+ distributed bragg Bragg reflector(DBR)structure,thus the luminous efficiency is greatly improved.The ODR structure is composed of the electrode metal and DBR layer connected with core particles on the DBR layer.After theoretical analysis and calculation,it is shown that,compared with the traditional ITO+DBR structure devices,the average reflectivity is increased from 86.25%to 96.71% under full angle incidence in the wavelength range of 400～550 nm.High pressure inversion gallium nitride LED devices were prepared with series-wound traditional ITO+DBR structure and the three core grains of the ODR structure.The device size is0.2 mm×0.66 mm,the effective reflection area is increased by 4.8%,and saturation current is increased by 12 mA.After being encapsulated with 3030 stents,and under the test current of30 mA,the voltage is decreased by 0.163 V,radiation power is increased by 3.78%,and the luminous efficiency is increased by 5.42% when the color rendering index is 71.The NP-METAL which connected cells of LED was put on the DBR layer and make up the ODR structure,the average reflectance Rave over the wavelength from 400 nm to 550 nm and the incident angle from0°to 90°would increase from 86.25%to 96.71%,compared with the traditional structure.The 3 cells connected in series were formed in the 0.2 mm×0.66 mm HVFC LED chip.Compared to the chip with traditional structure,the chip with ODR structure which had double ISO layers would increase 4.8%effective reflection area,when test current was 30 mA bonded in emc3030,could decrease 0.163 V Voltage,increase 3.78% radiant powerand increase 5.42%luminous efficiency at Ra 71.
引文
[1] Marko I P,Sweeney S J.Optical and Electronic Processes in Semiconductor Materials for Device Applications[M]//Singapore:Springer Singapore,2015:253-297.
[2]陈泉润,张涛,郑伟波,等.基于白光LED可见光通信的研究现状及应用前景[J].半导体光电,2016,37(4):455-460.Chen Quanrun,Zhang Tao,Zheng Weibo,et al.Present research situation and application prospects of VLC based on white LED[J].Semiconductor Optoelectronics,2016,37(4):455-460.
[3]钱可元,胡飞,吴慧颖,等.大功率白光LED封装技术的研究[J].半导体光电,2005,26(2):118-120.Qian Keyuan,Hu Fei,Wu Huiying,et al.Packaging technique of high-power white LED[J].Semiconductor Optoelectronics,2005,26(2):118-120.
[4] Baur J,Baumann F,Peter M,et al.Status of high efficiency and high power thin GaN-LED development[J].Physica Status Solidi C,2009,6(S2):S905-S908.
[5] Horng R H,Shen K C,Kuo Y W,et al.Effects of cell distance on the performance of GaN high-voltage light emitting diodes[J].ECS Solid State Lett.,2012,1(5):R21-R23.
[6] Lin Y S,Hsiao S Y,Tseng C L,et al.Effect of a cooling step treatment on a high-voltage GaN LED during ICP dry etching[J].J.of Electronic Materials,2017,46(2):941-946.
[7] Egawa T,Oda O.LEDs Based on Heteroepitaxial GaN on Si Substrates[M].Singapore:Springer Singapore,2017.
[8] Zhou S,Zheng C,Lv J,et al.GaN-based flip-chip LEDs with highly reflective ITO/DBR p-type and via hole-based n-type contacts for enhanced current spreading and light extraction[J].Optics&Laser Technol.,2017,92:95-100.
[9]唐晋发,郑权.应用薄膜光学[M].上海:上海科学技术出版社,1984.Tang Jinfa,Zheng Quan.Application of Thin Film Optics[M].Shanghai:Shanghai Science and Technology Press,1984.
[10] Malitson I H.Interspecimen comparison of the refractive index of fused silica[J].J.Opt.Soc.Am,1965,55:1205-1208.
[11] Devore J R.Refractive indices of rutile and sphalerite[J].J.of The Opt.Society of America,1951,41(6):266-266.
[12] Adachi S.Optical Constants of Crystalline and Amorphous Semiconductors[M].NewYork:Springer US,1999.
[13] Hoogenboom J P, Moerland R J.Subnanometer-accuracy optical distance ruler based on fluorescence quenching by transparent conductors[J].Optica,2016,3(2):112-117.
[14] Aleksandar D.Algorithm for the determination of intrinsic optical constants of metal films:application to aluminum[J].Appl.Opt.,1995,34(22):4755-4767.
[15] Poxson D J,Schubert M F,Mont F W,et al.Broadband omnidirectional antireflection coatings optimized by genetic algorithm[J].Opt.Lett.,2009,34(6):728-730.
