Defect reduction of super widegap semiconductor AlN by high temperature metalorganic vapor phase epitaxy and device applications

基于我们开发的低温缓冲层技术，蓝宝石衬底上的蓝、绿、白发光二极管和紫色激光二极管已经实现了商业化。氮化物半导体的应用不仅限于可见光范围，而且可以应用于紫外线范围。固态UV/DUV光发射器/探测器的预期应用包括灭菌器、DNA分析仪、激光刀、火焰传感器、皮肤病学、分子镊子、天气观测、气体分解、光刻等。以前，AlN在蓝宝石或碳化硅等其他材料上生长在或低于1200□。我们之前的质量输运研究表明，为了实现Al前驱体的充分迁移，AlN的生长必须高于1200□。本研究的目的如下：(1)利用升华法生长AlN衬底(2)利用金属有机气相外延（MOVPE）在蓝宝石上高温生长AlN(3)制备高质量的algan基量子结构和紫外发射器件2003年，与Ibiden公司合作，定制设计的可升温高达1800℃的MOVPE反应器安装并运行。在SiC上进行了AlN的升华生长和自发成核。2004年，在外延横向生长（ELO）低位错密度AlGaN上成功制备了世界上波长最短的蓝宝石激光二极管。采用高温MOVPE法在蓝宝石表面生长出了高质量、厚的AlN。2005年，我们利用ELO技术成功地在蓝宝石上生长出低位错密度AlN，位错密度低至10^7cm^<-2>或更低。

Blue, green and white light emitting diodes and violet laser diodes on sapphire substrates have been already commercialized which are based on the low temperature buffer layer technology developed by us. Applications of nitride semiconductors are not limited to visible range, but can be applied to ultraviolet range. Expected applications of solid state UV/DUV light emitters/detectors include sterilizer, DNA analyzer, laser knife, flame sensor, dermatology, molecular tweezers, weather observation, gas decomposition, photolithography, etc. Formerly, AlN was grown at or lower than 1,200□ on other materials such as sapphire or SiC. Our previous mass transport study showed that in order to achieve sufficient migration of Al precursor, AlN should be grown higher than 1,200□.The objective of this study is as follows ;(1)Growth of AlN substrate by sublimation(2)Growth of AlN on sapphire by metalorganic vapor phase epitaxy (MOVPE) at high temperature, and(3)Fabrication of high quality AlGaN-based quantum structure and UV emitting deviceIn 2003, custom designed MOVPE reactor which is capable of raising temperature as high as 1,800□ was installed and operated with the cooperation of Ibiden Co.,Ltd. Sublimation growth of AlN on SiC and spontaneous nucleation was performed. In 2004, world's shortest wavelength laser diode on sapphire was successfully fabricated on epitaxially lateral overgrown (ELO) low dislocation density AlGaN. High quality and thick AlN was grown on sapphire by high temperature MOVPE. In 2005, we successfully grow low dislocation density AlN on sapphire using ELO technique with a dislocation density as low as 10^7cm^<-2> or less.