蓝宝石外延生长GaN厚膜的自分离及断裂机理研究

项目名称： 蓝宝石外延生长GaN厚膜的自分离及断裂机理研究

项目编号： No.61204013

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 信息四处

项目作者： 李佳

作者单位： 河北工业大学

项目金额： 25万元

中文摘要： III族氮化物半导体及其组分可调的三四元合金是迄今禁带宽度调制范围最宽的半导体体系，在军用和民用领域均有重大应用价值。制备高质量的III族氮化物首先需要制备出高质量的同质衬底如GaN和AlN。制备GaN衬底时由于应力的积聚经常出现翘曲甚至断裂，难以实现GaN厚膜与衬底的完整分离。以往应力模型对应力按标量处理，没有体现应力的各向异性特征，并且均依赖于曲率测量，不能从根本上解释自分离、翘曲以及断裂现象。本项目拟深入研究蓝宝石-GaN厚膜体系的应力特性，探索剪切形变、晶格失配、热失配以及形核合并对GaN厚膜应变的影响，通过应力与应变的基本关系，建立张量形式的三维应力模型；通过研究应力的各向异性机理、GaN厚膜倾向于岛状生长的原因以及临界厚度的微观原子机制、裂纹源从弹性向塑性形变的转化、岛状形核对应力的影响以及张应力的产生机制，揭示GaN厚膜与蓝宝石衬底的自分离以及GaN厚膜产生翘曲和断裂的机理。

中文关键词： GaN厚膜；蓝宝石；应力；曲率；翘曲

英文摘要： Group III-nitride semiconductors and their ternary and quaternary alloys with variable concentration have great application value for military and civil use because they have the widest adjustable forbidden gap. Fabricating high quality III-nitride materials needs to fabricate high quality native subatrate such as GaN and AlN. Bending and cracking often occur in fabricating GaN substrate because of the stress concentration. Therefore, it is difficult that the GaN thick-films fully separate from the substrate. The previous stress models deal with the stress in terms of a scalar quantity and can not exhibit the character of stress anistropy, and all depend on the curvature measurement. As a result， those models can not essentially interpret the phenomenon of self-separation, bending and cracking. The present project will thoroughly investigate the stress properties of the sapphire-GaN system, and explore the effect of shear deformation, lattice mismatch, thermal mismatch and nucleation coalescence on the strain of GaN thick-films, and estabish the three-dimentions stress model with tensor form by the relation of stress-strain. We will reveal the mechanism of bending, cracking, and self-separation from the sapphire substrate for GaN thick-films by investigating the mechanism of stress anistropy, the reason of their

英文关键词： GaN thick film；sapphire；stress；curvature；bending