具有石墨烯/铟锑氧化物复合透明电极的GaN发光二极管  

GaN-based light emitting diode with graphene/indium antimony oxide composite transparent electrode

作　　者：郭伟玲[1] 邓杰[1] 王嘉露 王乐[1] 邰建鹏 Guo Wei-Ling;Deng Jie Wang;Jia-Lu Wang;Le Tai;Jian-Peng(Optoelectronics Technology Lab.Ministry of Education,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学光电子技术教育部重点实验室

出　　处：《物理学报》2019年第24期301-305,共5页Acta Physica Sinica

基　　金：国家重点研究发展计划(批准号:2017YFB0403100,2017YFB0403102)资助的课题~~

摘　　要：近年来,石墨烯材料由于优异的光电性能获得了广泛关注,并应用于发光二极管的透明电极以取代昂贵的铟锑氧化物(indium tin oxide,ITO)透明电极,但由于石墨烯与p-GaN功函数不匹配,二者很难形成好的欧姆接触,因而造成器件电流扩展差和电压高等问题.本文将ITO薄层作为石墨烯透明电极与p-Ga N间的插入层,以改善石墨烯与p-Ga N层的欧姆接触.所制备的石墨烯透明电极的方块电阻为252.6Ω/□,石墨烯/ITO复合透明电极的方块电阻为70.1Ω/□;石墨烯透明电极与p-Ga N层的比接触电阻率为1.92×10^–2Ω·cm^2,ITO插入之后,其比接触电阻率降低为1.01×10^–4Ω·cm^2;基于石墨烯透明电极的发光二极管(light emitting diode,LED),在20 m A注入电流下,正向电压为4.84 V,而石墨烯/ITO复合透明电极LED正向电压降低至2.80 V,且光输出功率得到提高.这归因于石墨烯/ITO复合透明电极与p-Ga N界面处势垒高度的降低,进而改善了欧姆接触;另外,方块电阻的降低,使得电流扩展均匀性也得到了提高.所采用的复合透明电极减少了ITO的用量,得到了良好的欧姆接触,为LED透明电极提供了一种可行方案.In recent years,graphene has received wide attention due to its excellent optoelectronic properties and has been applied to transparent electrodes of light-emitting diodes to replace the scarce and expensive indium antimony oxide(ITO),which is a typical current spreading layer in lateral GaN LED.However,there are some problems in graphene transparent electrode,such as the mismatch between graphene work function and p-GaN work function,and difficult-to-form good Ohmic contact with p-GaN,resulting in poor current expansion and high voltage of devices.In this paper,a thin ITO layer is used as an insertion layer between a three-layer graphene transparent electrode and and p-GaN,thereby improving the Ohmic contact between them.And a three-layer graphene/ITO composite transparent electrode LED is prepared and also compared with the pristine three-layer graphene LED.The thickness of ITO is only 50 nm,which is much thinner than the thickness of ITO in conventional LED.The sheet resistance of the prepared three-layer pristine graphene transparent electrode is 252.6Ω/□,and the sheet resistance of the three-layer graphene/ITO composite transparent electrode is reduced to 70.1Ω/□.The specific contact resistance between the three-layer pristine graphene transparent electrode and the p-GaN layer is 1.92×10^–2Ω·cm^2,after the ITO being inserted,the specific resistance is reduced to 1.01×10^–4Ω·cm^2.Based on the three-layer graphene transparent electrode LED,the forward voltage is 4.84 V at an injection current of 20 mA,while the forward voltage of the three-layer graphene/ITO composite transparent electrode LED is reduced to 2.80 V;under small currents,the ideal factor of the three-layer graphene/ITO composite transparent electrode LED is less than that of the three-layer graphene transparent electrode LED.In addition,with the current increasing,the luminous intensity of the three-layer graphene/ITO composite transparent electrode LED increases,so does the radiant flux,which is because the addition of the ITO th

关 键 词：透明电极 石墨烯 铟锑氧化物 比接触电阻率 

分 类 号：TN3[电子电信—物理电子学]