Selective area growth of N-polar GaN nanorods by plasma-assisted MBE on micro-cone-patterned c-sapphire substrates

• Published in: Journal of crystal growth 2017-11, Vol.477, p.207-211
• Main Authors: Jmerik, V.N., Kuznetsova, N.V., Nechaev, D.V., Shubina, T.V., Kirilenko, D.A., Troshkov, S.I., Davydov, V.Yu, Smirnov, A.N., Ivanov, S.V.
• Format: Article
• Language: English
• Subjects: A1. Nanostructures; A1. Substrates; A3. Molecular beam epitaxy; A3. Selective epitaxy; Anisotropy; Apexes; B1. Nitrides; B1. Sapphire; Cones; Crystal structure; Epitaxial growth; Gallium nitrides; Nanorods; Nanostructured materials; Nitrogen; Nucleation; Periodic variations; Photoluminescence; Polarity; Quantum wells; Sapphire; Substrates; Surface energy
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2017.05.014

•Site-controlled 100nm-thick GaN(000I¯) NRs are grown by PA MBE on apexes of µ-CPSS.•NRs selectively grow due to anisotropy of GaN surface energy and adatom kinetics.•Disk-like InGaN single QWs embedded in the top parts of the NRs emit at 510nm. The site-controlled selective area growth of N-polar GaN nanorods (NR) was developed by plasma-assisted MBE (PA MBE) on micro-cone-patterned sapphire substrates (µ-CPSS) by using a two-stage growth process. A GaN nucleation layer grown by migration enhanced epitaxy provides the best selectivity for nucleation of NRs on the apexes of 3.5-µm-diameter cones, whereas the subsequent growth of 1-μm-high NRs with a constant diameter of about 100nm proceeds by standard high-temperature PA MBE at nitrogen-rich conditions. These results are explained by anisotropy of the surface energy for GaN of different polarity and crystal orientation. The InGaN single quantum wells inserted in the GaN NRs grown on the µ-CPSS demonstrate photoluminescence at 510nm with a spatially periodic variation of its intensity with a period of ∼6µm equal to that of the substrate patterning profile.