利用单层六方BN材料(hexagonal BN:hBN)作为成核层, 用金属有机物化学气相沉积法生长AlN薄膜, 得到应力小裂纹少的外延材料。实验中, 对hBN材料进行人为表面化学修饰, 以增加hBN的缺陷和后续AlN生长的成核中心。对比分析了有无hBN成核层时生长的AlN薄膜质量, 证实了hBN有助于减少AlN外延层中的裂纹, 空气孔隙及应力。研究了V/III生长参数对AlN薄膜表面形貌、晶体质量和应力的影响, 得到合适的生长窗口, 获得完全无应力的氮化铝外延层, 且其位错密度与蓝宝石上生长的氮化铝相当.

Monolayer hexagonal BN (hBN) material served as the nucleation layer in AlN epilayer by metal-organic chemical vapor deposition. Through this method both the stress and the cracks in AlN films were greatly suppressed. The monolayer hBN material was treated with artificial surface chemical modification to increase the defects in hBN and the nucleation sites for the subsequent AlN growth. We analyzed the quality of AlN materials with/without the hBN nucleation layer. The results show the hBN layer can help decrease the cracks, air voids and stress in AlN films. Meanwhile, the impacts of different V/III ratios on the surface morphology, the crystal quality and the stress in AlN films were studied. An optimized V/III-ratio range was obtained. Under the optimized growth condition, the stress in the AlN layer with the hBN nucleation layer can be eliminated completely, and the crystal quality of the AlN films with a hBN nucleation layer was comparable with that of AlN directly grown on sapphire.