和干法刻蚀技术
(清华大学 电子工程系 集成光电子学国家重点实验室，
北京 100084)
摘 要: 通过对氮化镓（Gallium nitride， GaN）基蓝色高亮度发光二极管（High brightness light emitting diode， HB-LED）材料金属有机气相外延（Metal organic vapor phase epitaxy， MOVPE）生长技术的研究和优化以及在有源区内引入新型InxGa1-xN/GaN多量子阱（Multiple quantum wells， MQWs）结构， 获得了高性能的HB-LED外延片材料。 高分辨率X射线衍射（High resolution X-ray diffraction， HR-XRD）和变温光致荧光谱（Temperature dependent photoluminescence spectra， TD-PL Spectra）测量表明外延材料的异质界面陡峭， 单晶质量优异， 并由变注入电致荧光谱（Injection dependent electroluminescence spectra， ID-EL spectra）测量获得： HB-LED芯片的峰值发光波长在注入电流为2 mA至120 mA变化下蓝移量小于1 nm， 电致荧光谱的半高全宽值（Full width half maximum， FWHM）在注入电流为20 mA时仅为18 nm。 此外， 还介绍了GaN基材料感应耦合等离子体（Inductively coupled plasma， ICP）干法刻蚀技术。考虑实际需要， 本文作者开发了AlGaN/GaN异质材料的非选择性刻蚀工艺，原子力显微镜（Atomic force microscope， AFM）观察得到AlGaN/GaN刻蚀表面均方根粗糙度RMS仅为0.85 nm， 与外延片的表面平整度相当。还获得了AlGaN/GaN高选择比的刻蚀技术， GaN和AlGaN的刻蚀选择比为60。
关键字: 氮化镓（GaN）； 发光二极管（LED）； 材料外延； 干法刻蚀
（State Key Laboratory of Integrated Optoelectronics, Department of Electronic Engineering, Tsinghua University,
Beijing 100084, China）
Abstract:The epitaxy technology of gallium nitride (GaN) based high brightness blue light emitting diode (HB-LED) materials grown by metal organic vapor phase epitaxy (MOVPE) was studied. The InxGa1-xN/GaN multiple-quantum-wells (MQWs) embedded epitaxial materials were characterized by high-resolution X-ray diffraction (HR-XRD), temperature dependent photoluminescence (TD-PL) spectra and injection dependent electroluminescence (ID-EL) spectra, respectively. The HR-XRD and TD-PL results indicate that the HB-LED epitaxial wafers have excellent crystal quality with abrupt heterostructure interfaces. The blue-shift of the emission peak wavelength is less than 1 nm as the injection current varies from 2 mA to 120 mA, and the full width at half maximum (FWHM) of the electroluminescence spectrum at 20 mA is only 18 nm. These data are among the best results reported so far. Secondly, we discussed our work on dry etching of GaN related materials by inductively coupled plasma (ICP). For nonselective etching of AlGaN/GaN heterostructure, the root-mean-square (RMS) surface roughness of the etched sample measured by atomic force microscope (AFM) is only 0.85 nm. On the other hand, we have demonstrated selectivity as high as 60 for AlGaN over GaN.
Key words: GaN; LED; material epitacxy; dry etching; fabrication technology
