蓝宝石图形衬底上利用AlN缓冲层生长高质量GaN

Growth of the High Quality GaN Film on Patterned Sapphire Substrates Using AlN Buffer Layer

在图形化衬底上以AlN作为缓冲层生长高质量的GaN薄膜,国内相关的报道较少。通过引入两步缓冲层生长方法,在蓝宝石图形衬底上生长基于AlN缓冲层的高质量GaN薄膜,利用低温AlN层生长时内部的缺陷,选择性进行腐蚀,形成衬底与外延层界面间的侧向倒斜角,提高光萃取效率;同时在其上继续生长高温AlN,为后续GaN薄膜提供高质量模板。从外延角度出发,以表面形貌及其上生长的GaN薄膜的晶体质量为衡量依据,优化了低温AlN缓冲层以及高温AlN缓冲层的生长参数,优化后LED样品在20 mA测试电流下的光输出功率较参考样品提升了4%。

There are few domestic reports for the high quality GaN film growth using AlN as the buffer layer on the patterned sapphire substrate （PSS） . The high quality GaN thin film using AlN as the buffer layer on PSS was fulfilled by introducing two step growth methods, the internal crystal defects formed among the growth of low temperature AlN, were used for selective corrosion, thus formed undercut sidewall between the substrate and epitaxial layer interface, which can improve the light extraction ef- ficiency; and the following growth of high temperature AIN can provide a high quality template for the growth of subsequent GaN thin films growth. From the epitaxial point of view, and taking the surface morphology and crystal quality of GaN film as the judging basis, the condtitions of low temperature and high temperature AlN buffer layer were systematically studied and optimized. The optimized LED sample show that the light output power is improved by 4% at 20 mA test current compared to reference samples.