Author(s): Chen, L (Chen, Li); Lin, W (Lin, Wei); Chen, HY (Chen, Hangyang); Xu, HQ (Xu, Houqiang); Guo, CY (Guo, Chenyu); Liu, ZB (Liu, Zhibin); Yan, JC (Yan, Jianchang); Sun, J (Sun, Jie); Liu, H (Liu, Huan); Wu, JS (Wu, Jason); Guo, W (Guo, Wei); Kang, JY (Kang, Junyong); Ye, JC (Ye, Jichun)

Source: CRYSTAL GROWTH & DESIGN Volume: 21 Issue: 5 Pages: 2911-2919 DOI: 10.1021/acs.cgd.1c00086 Published: MAY 5 2021

Abstract: Semipolar III-nitrides have attracted great attention due to their weak polarization field for optoelectronic devices. High-quality AlN is a perfect template in the epitaxial growth of AlGaN-based ultraviolet optical devices. In this work, (11 (2) over bar2) semipolar AlN was grown on m-plane sapphire by the hierarchical growth mode. A high density of extended defects due to the lattice mismatch and anisotropic growth rate is identified in the as-grown AlN thin film. The influence of thermal annealing and AlN regrowth on the evolution of stacking faults and dislocations in AlN was thoroughly investigated by high-resolution transmission electron microscopy. Extending defects turned into partial dislocations after high-temperature treatment, by which the stacking faults were buried inside the AlN template, incapable of propagating into the AlN regrowth layer. As a result, the AlN regrowth layer exhibits superior crystalline quality. However, compressive strain is found after high-temperature annealing (HTA), which introduces new defects in the AlN regrowth layer. Strain management is demonstrated to be crucial for the quality control of the AlN layer. Overall, high-temperature annealing and regrowth processes proved to be stable and repeatable techniques in the realization of high-efficiency semipolar UV semiconductor devices.

Accession Number: WOS:000648580100036

ISSN: 1528-7483

eISSN: 1528-7505

Full Text: https://pubs.acs.org/doi/10.1021/acs.cgd.1c00086