Vertical GaN nanocolumns grown on graphene intermediated with a thin AlN buffer layer. (30th October 2018)

• Record Type: Journal Article
• Authors: Liudi Mulyo, Andreas; Rajpalke, Mohana Krishnappa; Kuroe, Haruhiko; Vullum, Per-Erik; Weman, Helge; Fimland, Bjørn-Ove; Kishino, Katsumi
• Is Part Of: Nanotechnology. Volume 30:Number 1(2019)
• Publication Date: 2018-10-30
• Subjects: III-N semiconductors -- nanocolumn -- nanowire -- nanorod -- graphene -- GaN -- molecular beam epitaxy; Nanotechnology -- Periodicals; Nanotechnology -- Periodicals; Nanotechnology; Publications périodiques; Nanotechnologies; Periodicals; 620.5
• DOI: 10.1088/1361-6528/aae76b
• Languages: English
• ISSNs: 0957-4484

Abstract

Abstract: We report on the self-assembled growth of high-density and vertically-oriented n -doped GaN nanocolumns on graphene by radio-frequency plasma-assisted molecular beam epitaxy. Graphene was transferred to silica glass, which was used as the substrate carrier. Using a migration enhanced epitaxy grown AlN buffer layer for the nucleation is found to enable a high density of vertical GaN nanocolumns with c -axis growth orientation on graphene. Furthermore, micro-Raman spectroscopy indicates that the AlN buffer reduces damage on the graphene caused by impinging active N species generated by the radio-frequency plasma source during the initial growth stage and nucleation of GaN. In addition, the grown GaN nanocolumns on graphene are found to be virtually stress-free. Micro-photoluminescence measurements show near band-edge emission from wurtzite GaN, exhibiting higher GaN bandgap related photoluminescence intensity relative to a reference GaN bulk substrate and the absence of both yellow luminescence and excitonic defect emission. Transmission electron microscopy reveals the interface of GaN nanocolumns on graphene via a thin AlN buffer layer. Even though the first few monolayers of AlN on top of graphene are strained due to in-plane lattice mismatch between AlN and graphene, the grown GaN nanocolumns have a wurtzite crystal structure without observable defects. The results of this initial work pave the way towards realizing low-cost and high-performance electronic and optoelectronic devices based on III-N semiconductors grown on graphene.