PVT法AlN晶体生长模式调控研究  

Regulation of AlN Crystal Growth Mode by PVT Method

作　　者：覃佐燕 金雷[2] 李文良 谭俊 何广泽 武红磊[3] QIN Zuoyan;JIN Lei;LI Wenliang;TAN Jun;HE Guangze;WU Honglei(College of Electronics and Information Engineering,Shenzhen University,Shenzhen 518060,China;The 46th Research Institute,China Electronics Technology Group Corporation,Tianjin 300220,China;College of Physics and Optoelectronic Engineering,Shenzhen University,Shenzhen 518060,China)

机构地区：[1]深圳大学电子与信息工程学院,深圳518060 [2]中国电子科技集团有限公司第四十六研究所,天津300220 [3]深圳大学物理与光电工程学院,深圳518060

出　　处：《人工晶体学报》2024年第9期1542-1549,共8页Journal of Synthetic Crystals

基　　金：国家重点研发计划(2022YFB3605303);深圳市计划项目(JCYJ20210324093007020);国家自然科学基金(62474113);广东省重点领域研发计划项目(2020B010169003)。

摘　　要：物理气相传输(PVT)法制备AlN晶体时,亚晶的产生会降低晶体质量,甚至多晶化。本文通过调节热/动力学生长条件,研究AlN晶体中亚晶产生及变化规律,提出抑制方法调控生长模式。实验结果表明,大的温度波动导致晶体表面气相物质过饱和度波动变大,增加高指数晶面的形成概率,这些晶面因非一致性难以实现完美聚并。本文还研究了稳定温场条件下,气相物质输运对生长模式的影响。实验及模拟结果显示,传统坩埚内气相物质由晶体边缘向中心迁移,与台阶方向相反,晶体表面易演变成混合生长模式。通过设计的新型坩埚,实现气相物质顺台阶流方向迁移,满足层状可控生长的基本条件。在2 200~2 300℃下,随温度降低,晶体呈c轴优势生长,侧向扩展能力降低;随温度升高,侧向扩展能力变强,但晶体表面高指数晶面形成概率增加;温度约2 250℃时,两者达到平衡,适合亚晶的抑制和消除。结合BCF理论分析,降低过饱和度可增强螺旋位错驱动生长的二维平铺能力,并增大台阶宽度,有利于将亚晶界分散融入台阶流中。优化后的实验,促进了生长模式向螺旋位错驱动生长模式的转变,亚晶逐渐被湮灭,获得高质量AlN晶体,其(0002)面的X射线单晶摇摆曲线半峰全宽为58″,拉曼谱的E_2(High)半峰全宽为3.3 cm^(-1),位错密度为2.87×10^(3) cm^(-2)。The generation of sub-grains during the preparation of AlN crystals by physical vapor transport(PVT)method can reduce crystal quality,and even lead to the development of polycrystallization.In this paper,the generation and evolution of sub-grains were studied by adjusting the thermodynamic and kinetic growth conditions,and effective suppression methods were proposed to regulate crystal growth mode.The experimental results show that the large temperature fluctuation leads to the large fluctuation of the gaseous substances supersaturation on the crystal surface.It promotes the formation probability of highindex facets,which are difficult to achieve perfect coalescence due to non-uniformity.The influence of the transport path of gaseous substances on the crystal growth mode under the condition of a stable temperature field was also studied.The experimental and simulation results show that during the crystal growth under the traditional crucible structure,the transmission path of gaseous substances migrates from the edge to the center on the crystal surface,which is opposite to the direction of the growth step.The crystal surface is prone to forming step clusters and evolving into Stranski-Krastanov growth mode.A novel crucible was designed to enable the migration of gaseous substances along the crystal growth step direction,which met the basic conditions of layer-by-layer growth.The experimental results of growth temperature from 2200℃to 2300℃show that as the decrease of temperature,crystal growth exhibits c-axis dominant growth,and lateral expansion capability decreases. As the temperature increases, the lateral expansion capability increases, but the probability of the formation ofhigh-index crystal facets increases continuously. When the temperature is about 2 250 ℃, the two reach a balance, which issuitable for the suppression and elimination of sub-grains. Combined with BCF theory analysis, reducing the supersaturationenhances the two-dimensional tiling ability of screw dislocation-driven growth, and incr

关 键 词：AlN晶体 PVT法 亚晶 混合生长模式 螺旋位错驱动生长 

分 类 号：O782[理学—晶体学]