等离子体表面处理对硅衬底GaN基蓝光发光二极管内置n型欧姆接触的影响

发布时间：2018-07-18 13:45

【摘要】：硅衬底GaN基发光二极管(LED)的内置n型欧姆接触在晶圆键合时的高温过程中常常退化,严重影响LED的工作电压等器件性能.本文深入研究了内置n电极蒸镀前对n-GaN表面的等离子体处理工艺对硅衬底GaN基发光二极管n型欧姆接触特性的影响.实验结果表明,1.1 mm×1.1 mm的LED芯片在350 m A电流下,n-GaN表面未做等离子体处理时,n电极为高反射率Cr/Al的芯片正向电压为3.43 V,比n电极为Cr的芯片正向电压高0.28 V.n-GaN表面经O2等离子体表面处理后,Cr/Al和Cr电极芯片的正向电压均有所降低,但Cr/Al电极芯片的正向电压仍比Cr电极芯片高0.14 V.n-GaN表面经Ar等离子体处理后,Cr/Al电极芯片正向电压降至Cr电极芯片的正向电压,均为2.92 V.利用X射线光电子能谱对Ar等离子体处理前后的n-GaN表面进行分析发现,Ar等离子体处理增加了n-GaN表面的N空位(施主)浓度,更多的N空位可以提高n型欧姆接触的热稳定性,缓解晶圆键合的高温过程对n型欧姆接触特性的破坏.同时还发现,经过Ar等离子体处理并用HCl清洗后,n-GaN表面的O原子含量略有增加,但其存在形式由以介电材料GaO_x为主转变为导电材料GaO_xN_(1-x)和介电材料GaO_x含量相当的状态,这会使得接触电阻进一步降低.上述两方面的变化均有利于降低LED芯片的正向电压.
[Abstract]:The built-in n-type ohmic contact of Si substrate GaN-based light-emitting diodes (LED) often degenerates during the high temperature process of wafer bonding, which seriously affects the performance of LED devices such as operating voltage. In this paper, the effect of plasma treatment process on n-GaN surface on n-ohmic contact characteristics of GaN-based light-emitting diodes on Si substrate has been studied. The experimental results show that when the surface of n-GaN is not treated by plasma at 350 Ma current, the forward voltage of the chip with high reflectivity Cr-Al is 3.43 V, which is 0.28 V. n-GaN surface voltage higher than that of Cr with n electrode Cr. The positive voltage of Cr / Al and Cr electrode chips decreased after O _ 2 plasma surface treatment. However, the forward voltage of Cr / Al electrode chip is still 0.14 V. n-GaN higher than that of Cr electrode chip, and the forward voltage of Cr / Al electrode chip decreases to 2.92 V after treatment by ar plasma. X-ray photoelectron spectroscopy (XPS) was used to analyze n-GaN surface before and after ar plasma treatment. It was found that ar plasma treatment increased the N vacancy (donor) concentration on n-GaN surface, and increased the thermal stability of n-type ohmic contact. The damage of n-type ohmic contact was alleviated by the high temperature process of wafer bonding. It was also found that the O atom content of n-GaN surface increased slightly after ar plasma treatment and HCl cleaning, but its existing form changed from the dielectric GaOx to the conductive GaOxN1-x and the dielectric GaOx. This will further reduce the contact resistance. The above two changes are helpful to reduce the forward voltage of LED chip.
【作者单位】：南昌大学国家硅基LED工程技术研究中心;晶能光电(江西)有限公司;中国科学院苏州纳米技术与纳米仿生研究所
【基金】：国家高技术研究发展计划(批准号:2015AA03A102) 国家重点研发计划(批准号:2016YFB0400104) 国家自然科学基金(批准号:61534007,61404156,61522407,61604168) 中国科学院前沿科学重点研究项目(批准号:QYZDB-SSW-JSC014);中国科学院苏州纳米技术与纳米仿生研究所自有资金(批准号:Y5AAQ51001)资助的课题江苏省自然科学基金(批准号:BK20160401) 中国博士后基金(批准号:2016M591944) 发光学及应用国家重点实验室开放课题(批准号:SKLA-2016-01) 集成光电子学国家重点联合实验室开放课题(批准号:IOSKL2016KF04,IOSKL2016KF07)~~
【分类号】：TN312.8

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