石墨烯晶体管优化制备工艺在单片集成驱动氮化镓微型发光二极管中的应用  

Applications of graphene transistor optimized fabrication process in monolithic integrated driving gallium nitride micro-light-emitting diode

作　　者：苑营阔 郭伟玲[1] 杜在发 钱峰松 柳鸣 王乐[1] 徐晨[1] 严群[2] 孙捷 Yuan Ying-Kuo;Guo Wei-Ling;Du Zai-Fa;Qian Feng-Song;Liu Ming;Wang Le;Xu Chen;Yan Qun;Sun Jie(Key Laboratory of Optoelectronics Technology,Ministry of Education,College of Microelectronics,Beijing University of Technology,Beijing 100124,China;National and Local United Engineering Laboratory of Flat Panel Display Technology,Fuzhou University,and Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China,Fuzhou 350100,China;Quantum Device Physics Laboratory,Chalmers University of Technology,Göteborg 41296,Sweden)

机构地区：[1]北京工业大学微电子学院,光电子技术教育部重点实验室,北京100124 [2]福州大学平板显示技术国家地方联合工程实验室,中国福建光电信息科学与技术创新实验室,福州350100 [3]瑞典查尔摩斯理工大学,量子器件物理实验室,哥德堡41296

出　　处：《物理学报》2021年第19期199-207,共9页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2018YFA0209000);中国福建光电信息科学与技术创新实验室项目(批准号:2021ZZ122)资助的课题。

摘　　要：在显示领域,微型发光二极管(micro-LED)潜力巨大,有望引领下一代新型显示技术的发展方向,其显示性能在很多方面优于现有的液晶、有机发光二极管(OLED),但巨量的micro-LED像素点与驱动电路不在同一晶圆上制备,面临巨量转移的技术瓶颈.本文将新兴的石墨烯场效应晶体管作为驱动元件与氮化镓(GaN)micro-LED进行单片集成,因为二者直接制备于同一衬底上,所以从根源上规避了巨量转移的技术难题.此外,传统光刻工艺中紫外光刻胶直接接触石墨烯,会引入严重掺杂导致场效应晶体管性能较差,进而影响集成器件性能.本文提出了一种利用聚甲基丙烯酸甲酯(PMMA)薄膜作为保护层,直接旋涂紫外光刻胶进行垫层光刻的全新工艺方法,优化了石墨烯场效应晶体管制备工艺.首先在分立的石墨烯场效应晶体管中进行验证,相比于没有进行PMMA薄膜保护的器件,采用新工艺制备的石墨烯器件狄拉克点的栅极电压(V_(g))距零点的偏差降低了22 V,载流子迁移率提升了32%.此外,将新工艺应用到集成器件制备后,发现集成器件性能得到了大幅提升.利用此新技术,由于有PMMA的保护,紫外光刻胶不再与敏感的石墨烯沟道直接接触.掺杂效应和随之而来的器件性能下降被有效扼制.因为此技术简便而廉价,所以也可应用到石墨烯之外的其他二维材料中,例如MoS2和h-BN,有望对本领域的器件工程师产生一定的参考价值.In the information display field,micro-light-emitting diodes(micro-LEDs)possess high potentials and they are expected to lead the direction of developing the next-generation new display technologies.Their display performances are superior to those produced by the currently prevailing liquid crystal and organic light-emitting diode based technologies.However,the micro-LED pixels and their driving circuits are often fabricated on different wafers,which implies that the so-called mass transfer seems to be inevitable,thus facing an obvious bottleneck.In this paper,the emerging graphene field effect transistors are used as the driving elements and integrated onto the GaN micro-LEDs,which is because the pixels and drivers are prepared directly on the same wafer,the technical problem of mass transfer is fundamentally bypassed.Furthermore,in traditional lithographic process,the ultraviolet photoresist directly contacts the graphene,which introduces severe carrier doping,thereby leading to deteriorated graphene transistor properties.This,not surprisingly,further translates into lower performances of the integrated devices.In the present work,proposed is a technique in which the polymethyl methacrylate(PMMA)thin films act as both the protection layers and the interlayers when optimizing the graphene field effect transistor processing.The PMMA layers are sandwiched between the graphene and the ultraviolet photoresist,which is a brand new device fabrication process.First,the new process is tested in discrete graphene field effect transistors.Compared with those devices that are processed without the PMMA protection thin films,the graphene devices fabricated with the new technology typically show their Dirac point at a gate voltage(V_(g))deviation from V_(g)=0,that is,22 V lower than their counterparts.In addition,an increase in the carrier mobility of 32%is also observed.Finally,after applying the newly developed fabrication process to the pixel-and-driver integrated devices,it is found that their performances are improved s

关 键 词：石墨烯 氮化镓 微型发光二极管 聚甲基丙烯酸甲酯 

分 类 号：TN312.8[电子电信—物理电子学] TQ127.11[化学工程—无机化工]