基于二维材料复合柔性衬底上AlN的生长研究

AlN是发展深紫外光电器件的重要材料，制约其发展和应用的核心问题是异质外延中大失配引起的应力和缺陷问题。本项目拟采取二维材料与常规的蓝宝石或SiC相结合，构建二维材料复合柔性衬底，解决氮化物半导体异质外延过程中因失配而引起的缺陷问题，从而提高材料质量。本项目将从理论和实验两方面开展，在理论上，利用第一性原理计算AlN在二维材料复合柔性衬底上的生长成键机制，获得AlN在柔性衬底上凝聚成核所需能量及迁移势垒，估测其成核能垒。在实验上，利用高温热分解法、化学气相沉积法等构建二维材料复合柔性衬底，阐明二维材料复合柔性衬底的表面和界面控制因素；利用MOCVD生长AlN，获得二维材料复合柔性衬底AlN成核点精准控制方法，揭示AlN在二维材料柔性衬底表面的侧向外延、合并、晶向转变控制因素，建立在二维材料复合柔性衬底上AlN生长模型。

AlN is one of key materials for deep ultraviolet optoelectronic devices. Due to the large mismatch between the substrate and AlN epitaxy, the stress and high density defects usually exist in AlN layer, which has become the key problem for the developing and application of AlN based materials. In the project, two dimensional (2D) materials based hybrid compliant substrates is adopted to solve the stress and defect problems in AlN hetero-epitaxy and thus to improve the AlN quality. This kind of hybrid compliant substrate is composed by 2D materials (Graphene, h-BN, et.al) and general substrates (Sapphire, SiC, et.al). This project will be carried out both in theory and experiment. Theoretically, the first principle will be used to calculate the bonding mechanism of AlN on 2D materials based hybrid compliant substrates, and then to obtain the nucleation energy and migration barrier of AlN on 2D materials based hybrid compliant substrates. Experimentally, methods such as high temperature thermal decomposition and chemical vapor deposition will be implemented to realize the 2D materials based hybrid compliant substrates. The governing factors of surface and interface in 2D compliant substrate should be elucidated. The AlN will be grown by MOCVD. The mechanism of realizing the controllable growth of the AlN nucleation sites on the 2D materials based hybrid compliant substrates and the control factors of AlN epitaxy lateral overgrowth, coalescence and crystal orientation transform will be obtained as well as the model of AlN growth on 2D materials based hybrid compliant substrates will be established.