Gao Yuan, Xu Shengrui, Peng Ruoshi, Tao Hongchang, Zhang Jincheng, Hao Yue
State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071, China.
Materials (Basel). 2020 Sep 5;13(18):3933. doi: 10.3390/ma13183933.
The utilization of sputtered AlN nucleation layers (NLs) and patterned sapphire substrates (PSSs) could greatly improve GaN crystal quality. However, the growth mechanism of GaN on PSSs with sputtered AlN NLs has not been thoroughly understood. In this paper, we deposited AlON by sputtering AlN with O, and we found that the variation of thickness of sputtered AlON NLs greatly influenced GaN growth on PSSs. (1) For 10 nm thin AlON sputtering, no AlON was detected on the cone sidewalls. Still, GaN nucleated preferably in non-(0001) orientation on these sidewalls. (2) If the thickness of the sputtered AlON NL was 25 nm, AlON formed on the cone sidewalls and flat regions, and some small GaN crystals formed near the bottom of the cones. (3) If the sputtered AlON was 40 nm, the migration ability of Ga atoms would be enhanced, and GaN nucleated at the top of the cones, which have more chances to grow and generate more dislocations. Finally, the GaN growth mechanisms on PSSs with sputtered AlON NLs of different thicknesses were proposed.
溅射AlN成核层（NLs）和图案化蓝宝石衬底（PSSs）的应用可以极大地提高GaN晶体质量。然而，在带有溅射AlN NLs的PSSs上生长GaN的机制尚未被完全理解。在本文中，我们通过用O溅射AlN来沉积AlON，并且我们发现溅射的AlON NLs厚度的变化极大地影响了在PSSs上的GaN生长。（1）对于10nm厚的AlON溅射，在锥体侧壁上未检测到AlON。尽管如此，GaN在这些侧壁上优先以非（0001）取向成核。（2）如果溅射的AlON NL厚度为25nm，AlON在锥体侧壁和平坦区域形成，并且在锥体底部附近形成一些小的GaN晶体。（3）如果溅射的AlON为40nm，Ga原子的迁移能力将增强，并且GaN在锥体顶部成核，锥体顶部有更多生长机会并产生更多位错。最后，提出了在具有不同厚度溅射AlON NLs的PSSs上的GaN生长机制。
