微纳米GaN六棱锥模板制备及其多波长垂直结构LED器件研究

Because of excellent physical and chemical properties such as long lifetime, low power consumption, non-pollution, etc., light emitting diode (LED) based on gallium nitride (GaN) has numerous applications in display devices and lighting area. Simple device techniques, low-cost and enhanced the luminous efficiency thus are very important to promote popularization and applications of GaN-based LED. The purpose of this project is to fabricate multi-wavelength InGaN/GaN vertical structure LED with semipolar microplanes on the GaN hexagonal pyramids template. We systematically study on the high quality GaN template with hexagonal pyramids fabricated by the electrodeless photo-assisted chemical etching N-faced GaN substrate, master the fabrication technique of high-quality GaN template with hexagonal pyramids, and explore the luminous mechanism and formation mechanism of GaN template with hexagonal pyramids; Multi-wavelength InGaN/GaN multiple quantum wells are homoepitaxially grown on the GaN template with hexagonal pyramids by metal organic vapor phase epitaxy (MOCVD). The influence of the growth conditions of MOCVD on the crystal quality and optical property for the multiple quantum wells is studied. Finally, the multi-wavelength vertical structure LED device with reproducibility are developed, and the deep research on photoelectric property and basic physical problems for devices will be carried out, which would provide theory basis and technical support for GaN-based single chip white LED.

氮化镓（GaN）基发光二极管（LED）具有长寿命、低功耗、无污染等优点，可以应用在显示、照明等领域，简化制备工艺、降低器件成本、提高发光效率对GaN基LED的推广应用具有重要意义。本项目以实现GaN六棱锥模板上制备具有半极性微面InGaN/GaN多波长垂直结构LED器件为目标。系统开展无电光助化学腐蚀N面GaN衬底制备六棱锥模板的研究，掌握高质量GaN六棱锥模板的制备技术，揭示六棱锥模板的发光机制和形成机制；利用MOCVD生长技术在GaN六棱锥模板上同质外延多波长InGaN/GaN多量子阱，研究MOCVD生长条件对多量子阱的晶体质量和发光性能的影响，最终研制出重现性好、多波长垂直结构LED器件；并深入研究器件的光电性能和基本物理问题，为GaN基单芯片白光LED的实现提供理论基础和技术支持。

氮化镓（GaN）基发光二极管（LED）具有长寿命、低功耗、无污染等优点，可以应用在显示、照明等领域，简化制备工艺、降低器件成本、提高发光效率对GaN基LED的推广应用具有重要意义。本项目主要研究微纳米GaN六棱锥模板制备及其多波长垂直结构LED器件。主要的研究成果如下：（1）采用无电光助化学湿法腐蚀法，对GaN 衬底材料的N极性面进行湿法腐蚀，成功制备了高质量微纳米GaN六棱锥衬底模板，系统研究了腐蚀液浓度、腐蚀时间和光照强度对模板形貌和性能的影响，得到了最优化的湿法腐蚀条件，并研究分析了六棱锥的形成机制和发光机制。（2）利用腐蚀得到的微纳米GaN六棱锥结构作为衬底模板，采用MOCVD法在其上外延生长出InGaN/GaN多量子阱结构，开展研究了InGaN/GaN多量子阱生长机制和发光机制，结果表明从晶面的底部到顶部，发光峰逐渐红移，In组分逐渐增加，从而实现多重发光。（3）利用磷酸腐蚀得到高质量GaN十二面锥，系统研究了腐蚀液浓度、腐蚀温度和腐蚀时间对锥体的影响。（4）以十二面锥为模板同质外延半极性微面InGaN/GaN多量子阱结构，从而获得了半极性面量子阱的多重发光，获得了花朵状和星星状的发光图，通过建立物理模型，结合理论计算揭示了生长机制。另外，结合应力分布，Ga极和N极表面上Ga原子和In原子结合速率以及Ga原子和In原子扩散长度，综合分析了此结构多波长发光的机制。由此可见，利用GaN六棱锥和十二面锥作为模板生长的多个半极性面和多In组分的InGaN/GaN 多量子阱实现了多波长发光，有望制备性能稳定的无磷高亮度白光LED。（5）利用镍纳米岛做掩膜和电感耦合等离子刻蚀的方法制备了高密度、尺寸均匀的GaN纳米棒阵列，并采用两种方法对GaN干法刻蚀损伤进行修复处理，进而以修复的GaN纳米棒为核，采用简单的腐蚀再生长方法制备出多波长 InGaN/GaN 多量子阱核壳结构。