Formation of voids and their role in the recovery of sputtered AlN during high-temperature annealing
Formation of voids and their role in the recovery of sputtered AlN during high-temperature annealing
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DOI：
10.1063/5.0088948
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发表时间：
2022-06
影响因子：
3.2
通讯作者：
L. Cancellara;S. Hagedorn;S. Walde;D. Jaeger;M. Albrecht
中科院分区：
文献类型：
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作者：
L. Cancellara;S. Hagedorn;S. Walde;D. Jaeger;M. Albrecht
用透射电子显微镜和二次离子质谱仪研究了在蓝宝石衬底上反应溅射生长的氮化铝在高温退火过程中的结构恢复。由于吸附原子扩散长度的限制，生长的薄膜显示出高密度的平面缺陷，如基面和棱柱状的层错，从而呈现出柱状结构。高密度纳米管的存在与非故意氧杂质的存在有关。基于原子分辨电子显微镜分析，我们发现薄膜中的基面层错和棱柱状层错是通过爬升机制消失的，并将这一过程描述为空位扩散促进的JOG形核过程。在生长的薄膜中存在的纳米管转变为刻面空洞，并作为促进位错通过攀升湮灭的多余空位的有益来源。纳米管到刻面孔洞的转变类似于从开放沟道气孔到闭合刻面气孔的转变，这在多孔硅中已经观察到，可以用经典的烧结理论来描述。
The structural recovery of AlN grown by reactive sputtering on a sapphire substrate during high-temperature annealing is studied by means of transmission electron microscopy and secondary ion mass spectrometry. The as-grown film shows high-density planar defects, such as basal and prismatic stacking faults, caused by the limited diffusion length of the adatoms and, thus, presents a columnar structure. The presence of high-density nanopipes is associated with the presence of unintentional oxygen impurities. Based on the atomic resolution transmission electron microscopy analysis, we show that basal and prismatic stacking faults vanish in the films via a climb mechanism and describe this process as the nucleation of jogs promoted by the diffusion of vacancies. The nanopipes present in the as-grown film transform into faceted voids and act as a beneficial source of excess vacancies that promote dislocation annihilation by climb. The transformation of nanopipes to faceted voids resembles the transition from open channel pores to close faceted pores, which has been observed in porous silicon and can be described in terms of a classical sintering theory.