Improved nucleation of AlN on in situ nitrogen doped graphene for GaN quasi-van der Waals epitaxy
Improved nucleation of AlN on in situ nitrogen doped graphene for GaN quasi-van der Waals epitaxy
复制标题
改进 AlN 在原位氮掺杂石墨烯上的成核，用于 GaN 准范德华外延
DOI：
10.1063/5.0016054
复制
发表时间：
2020-08-03
影响因子：
4
通讯作者：
Li, Dabing
中科院分区：
文献类型：
--
作者：
Chen, Yang;Zang, Hang;Li, Dabing
在目前的工作中，实现了改善的晶体质量的GaN的石墨烯覆盖的蓝宝石衬底上生长的GaN相比，裸露的蓝宝石衬底上，和GaN的准范德瓦尔斯外延与AlN成核层的生长机制，澄清使用金属有机化学气相沉积。在AlN生长过程中通过NH3源对石墨烯进行原位N掺杂是AlN成核的原因。第一性原理计算表明，N原子首先在石墨烯的台阶边缘掺杂，然后在其中心和AlN核中掺杂，这与实验观察到的成核过程一致。与裸蓝宝石（0.21 eV）相比，石墨烯上Al原子的较低迁移势垒（0.07 eV）产生了更大的AlN核，导致具有较低缺陷密度的上部GaN外延层的质量改善。该工作为精确控制GaN基材料的成核形貌和密度，进而实现高质量的准范德华外延材料及相关高性能器件提供了指导。
In the present work, improved crystal quality of GaN on a graphene-covered sapphire substrate was achieved compared to GaN grown on a bare sapphire substrate, and the growth mechanism of GaN quasi-van der Waals epitaxy with an AlN nucleation layer was clarified using metal-organic chemical vapor deposition. The in situ N-doping of graphene by an NH3 source during AlN growth was responsible for AlN nucleation. The first-principles calculation indicated that N atoms doped initially at the step edges of graphene and subsequently at its center and AlN nuclei followed the same sequence, which is consistent with experimental observations of nucleation. The lower migration barrier of Al atoms (0.07 eV) on graphene created larger AlN nuclei compared to that on bare sapphire (0.21 eV), leading to improved quality of the upper GaN epilayer with lower defect density. This work offers guidance for precisely controlling the nucleation morphology and density of GaN base materials and thus realizing high-quality epitaxial materials and related high-performance devices by quasi-van der Waals epitaxy.