Surface morphology control of nonpolar m-plane AlN homoepitaxial layers by flow-rate modulation epitaxy (Phys. Status Solidi B 2/2017)

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• 作者：Junichi Nishinaka ; Yoshitaka Taniyasu ; Tetsuya Akasaka and Kazuhide Kumakura
• 刊名：physica status solidi (b)
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：254
• 期：2
• 全文大小：1043K
• ISSN：1521-3951

文摘

Nonpolar AlGaN-based heterostructures play a critical role in realizing high-performance light emitting devices in the deep ultraviolet spectral region. A prerequisite for obtaining high-quality AlGaN-based heterostructures is an AlN buffer layer with a flat surface. However, even the homoepitaxy of nonpolar m-plane AlN layers cannot yet provide the desired flatness. In their study presented here (article no. 1600545), Nishinaka et al. investigated the surface morphologies of m-plane AlN homoepitaxial layers grown by the flow-rate modulation epitaxy (FME) method. The authors employed a continuous supply and three types of FME: group-III-source FME, group-V-source FME, and FME with groups III and V alternated. Nishinaka et al. found that the average V/III ratio affected the anisotropic step-flow velocity in the +cand a-directions. This is probably because of the difference of dangling bonds at each step edge. The cover image shows the crystal structure of wurtzite AlN and an atomic force microscopy image of the m-plane AlN surface with bunched steps toward +c-direction grown under a N-poor condition. The bunched steps and wide terraces indicate the enhancement of adatom migration. Thus, the surface morphologies of m-plane AlN homoepitaxial layers can be controlled.