中国物理B ›› 2024, Vol. 33 ›› Issue (10): 106801-106801.doi: 10.1088/1674-1056/ad7671

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Pit density reduction for AlN epilayers grown by molecular beam epitaxy using Al modulation method

Huan Liu(刘欢)1, Peng-Fei Shao(邵鹏飞)1,2, Song-Lin Chen(陈松林)1, Tao Tao(陶涛)1, Yu Yan(严羽)1, Zi-Li Xie(谢自力)1, Bin Liu(刘斌)1, Dun-Jun Chen(陈敦军)1, Hai Lu(陆海)1,2, Rong Zhang(张荣)1,2,3, and Ke Wang(王科)1,2,†   

  1. 1 Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China;
    2 Hefei National Laboratory, Hefei 230088, China;
    3 Xiamen University, Xiamen 361005, China
  • 收稿日期:2024-07-05 修回日期:2024-08-24 接受日期:2024-09-03 发布日期:2024-09-29
  • 通讯作者: Ke Wang E-mail:kewang@nju.edu.cn
  • 基金资助:
    Project supported by the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0303400), the National Key R&D Program of China (Grant No. 2022YFB3605602), the Key R&D Program of Jiangsu Province (Grant Nos. BE2020004-3 and BE2021026), the National Naturaal Science Foundation of China (Grant No. 61974065), and Jiangsu Special Professorship, Collaborative Innovation Center of Solid-State Lighting and Energysaving Electronics.

Pit density reduction for AlN epilayers grown by molecular beam epitaxy using Al modulation method

Huan Liu(刘欢)1, Peng-Fei Shao(邵鹏飞)1,2, Song-Lin Chen(陈松林)1, Tao Tao(陶涛)1, Yu Yan(严羽)1, Zi-Li Xie(谢自力)1, Bin Liu(刘斌)1, Dun-Jun Chen(陈敦军)1, Hai Lu(陆海)1,2, Rong Zhang(张荣)1,2,3, and Ke Wang(王科)1,2,†   

  1. 1 Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China;
    2 Hefei National Laboratory, Hefei 230088, China;
    3 Xiamen University, Xiamen 361005, China
  • Received:2024-07-05 Revised:2024-08-24 Accepted:2024-09-03 Published:2024-09-29
  • Contact: Ke Wang E-mail:kewang@nju.edu.cn
  • Supported by:
    Project supported by the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0303400), the National Key R&D Program of China (Grant No. 2022YFB3605602), the Key R&D Program of Jiangsu Province (Grant Nos. BE2020004-3 and BE2021026), the National Naturaal Science Foundation of China (Grant No. 61974065), and Jiangsu Special Professorship, Collaborative Innovation Center of Solid-State Lighting and Energysaving Electronics.

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摘要： We have investigated homoepitaxy of AlN films grown by molecular beam epitaxy on AlN/sapphire templates by adopting both the continuous growth method and the Al modulation epitaxy (AME) growth method. The continuous growth method encounters significant challenges in controlling the growth mode. As the precise $\rm Al/N=1.0$ ratio is difficult to achieve, either the excessive Al-rich or N-rich growth mode occurs. In contrast, by adopting the AME growth method, such a difficulty has been effectively overcome. By manipulating the supply time of the Al and nitrogen sources, we were able to produce AlN films with much improved surface morphology. The first step of the AME method, only supplying Al atoms, is important to wet the surface and the Al adatoms can act as a surfactant. Optimization of the initial Al supply time can effectively reduce the pit density on the grown AlN surface. The pits density dropped from 12 pits/μm$^2$ to 1 pit/μm$^2$ and the surface roughness reduced from 0.72 nm to 0.3 nm in a $2\times 2 $ μm$^2$ area for the AME AlN film homoepitaxially grown on an AlN template.

关键词: Al modulation epitaxy, molecular beam epitaxy, AlN, pits

Abstract: We have investigated homoepitaxy of AlN films grown by molecular beam epitaxy on AlN/sapphire templates by adopting both the continuous growth method and the Al modulation epitaxy (AME) growth method. The continuous growth method encounters significant challenges in controlling the growth mode. As the precise $\rm Al/N=1.0$ ratio is difficult to achieve, either the excessive Al-rich or N-rich growth mode occurs. In contrast, by adopting the AME growth method, such a difficulty has been effectively overcome. By manipulating the supply time of the Al and nitrogen sources, we were able to produce AlN films with much improved surface morphology. The first step of the AME method, only supplying Al atoms, is important to wet the surface and the Al adatoms can act as a surfactant. Optimization of the initial Al supply time can effectively reduce the pit density on the grown AlN surface. The pits density dropped from 12 pits/μm$^2$ to 1 pit/μm$^2$ and the surface roughness reduced from 0.72 nm to 0.3 nm in a $2\times 2 $ μm$^2$ area for the AME AlN film homoepitaxially grown on an AlN template.

Key words: Al modulation epitaxy, molecular beam epitaxy, AlN, pits

中图分类号:  (Thin film structure and morphology)

  • 68.55.-a
81.15.-z (Methods of deposition of films and coatings; film growth and epitaxy) 77.55.hd (AlN) 61.72.Ff (Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.))