和干法刻蝕技術(shù)
薛 松， 孫長征， 郝智彪
(清華大學(xué) 電子工程系 集成光電子學(xué)國家重點實驗室，
北京 100084)
摘 要: 通過對氮化鎵（Gallium nitride， GaN）基藍(lán)色高亮度發(fā)光二極管（High brightness light emitting diode， HB-LED）材料金屬有機(jī)氣相外延（Metal organic vapor phase epitaxy， MOVPE）生長技術(shù)的研究和優(yōu)化以及在有源區(qū)內(nèi)引入新型InxGa1-xN/GaN多量子阱（Multiple quantum wells， MQWs）結(jié)構(gòu)， 獲得了高性能的HB-LED外延片材料。 高分辨率X射線衍射（High resolution X-ray diffraction， HR-XRD）和變溫光致熒光譜（Temperature dependent photoluminescence spectra， TD-PL Spectra）測量表明外延材料的異質(zhì)界面陡峭， 單晶質(zhì)量優(yōu)異， 并由變注入電致熒光譜（Injection dependent electroluminescence spectra， ID-EL spectra）測量獲得： HB-LED芯片的峰值發(fā)光波長在注入電流為2 mA至120 mA變化下藍(lán)移量小于1 nm， 電致熒光譜的半高全寬值（Full width half maximum， FWHM）在注入電流為20 mA時僅為18 nm。 此外， 還介紹了GaN基材料感應(yīng)耦合等離子體（Inductively coupled plasma， ICP）干法刻蝕技術(shù)。考慮實際需要， 本文作者開發(fā)了AlGaN/GaN異質(zhì)材料的非選擇性刻蝕工藝，原子力顯微鏡（Atomic force microscope， AFM）觀察得到AlGaN/GaN刻蝕表面均方根粗糙度RMS僅為0.85 nm， 與外延片的表面平整度相當(dāng)。還獲得了AlGaN/GaN高選擇比的刻蝕技術(shù)， GaN和AlGaN的刻蝕選擇比為60。
關(guān)鍵字: 氮化鎵（GaN）； 發(fā)光二極管（LED）； 材料外延； 干法刻蝕
HU Hui, XUE Song, SUN Chang-zheng, HAO Zhi-biao
（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
