【作者】 李俊；

【导师】 陈亚孚； 张国义；

【作者基本信息】 长春理工大学 ， 物理电子学， 2009， 硕士

【摘要】 随着半导体材料的发展,以GaN及其Ⅲ族氮化物为代表的第三代宽禁带半导体由于其优越的特性越来越受到广泛的重视。GaN及其三元化合物在制备高亮度蓝光、绿光和白光LED,短波长激光器,紫外光探测器和高温电子器件等方面有着广泛的应用,但高位错密度GaN对器件的影响是致命的,而高的位错密度又是由于异质外延引起的。为了实现GaN的同质外延生长,进而实现高质量大尺寸的GaN生长,人们正在通过各种方法实现自支撑GaN单晶生长。本论文工作主要以制备自支撑GaN单晶为目标,分别对HVPE的系统设计、GaN的生长原理和生长模式、高质量厚膜GaN生长的优化、及GaN特性的表征、自支撑GaN的获得分别进行了论述与研究。通过计算证实晶格失配和热胀失配是异质外延GaN中位错产生的主要原因,通过腐蚀法用SEM观察GaN中各种位错,并对位错密度进行了估算,对低位错密度高质量GaN材料的HVPE生长、位错性质及遇到的相关物理问题和工艺进行了研究。结合激光剥离技术与生长技术获得了一定面积的厚膜自支撑GaN单晶。更多还原

【Abstract】 With the development of semiconductor materials, the third generation of semiconductors, which are represented by gallium nitride (GaN) and other Ill-nitride wide gap materials, have attracted more and more attention, because of their superior advantages. GaN and its ternary alloys have widespread applications in the fabrication of high bright blue, green, and white light emitting diodes (LEDs), short wavelength laser, ultraviolet (UV) detector and high temperature electronic devices etc. However, the high density dislocations in GaN have fatal effects on devices’ performance. And the high density dislocations results from heteroepitaxy. To achieve homoepitaxy growth of GaN and then obtain high quality and large size GaN films, researchers are trying various methods to realize the growth of free-standing GaN.This paper, with the goal of fabricating free-standing GaN, discussed the system design of Hydride Vapor Phase Epitaxy (HVPE), GaN growth mechanisms and growth modes, optimization of growing thick GaN film with high quality, GaN characterization, and the realization of free standing GaN film, respectively.By calculations it was confirmed that lattice mismatch and thermal coefficient mismatch are major causes for dislocations generating in hetero expitaxy growth of GaN. By etching, all kinds of dislocations in GaN were observed under SEM and the density of dislocations was estimated. In addition, HVPE growth of low dislocation density, high quality GaN, the properties of dislocations and the related physical issues and technique problems met in our research were also discussed. Together with the help of laser lift-off (LLO) process and growth techniques, the thick free-standing GaN films were obtained.更多还原