The influence of AlN buffer layer on the growth of self-assembled GaN nanocolumns on graphene
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The influence of AlN buffer layer on the growth of self-assembled GaN nanocolumns on graphene. / Liudi Mulyo, Andreas; Rajpalke, Mohana K.; Vullum, Per Erik; Weman, Helge; Kishino, Katsumi; Fimland, Bjorn-Ove.
I: Scientific Reports, Bind 10, Nr. 1, 853, 21.01.2020.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - The influence of AlN buffer layer on the growth of self-assembled GaN nanocolumns on graphene
AU - Liudi Mulyo, Andreas
AU - Rajpalke, Mohana K.
AU - Vullum, Per Erik
AU - Weman, Helge
AU - Kishino, Katsumi
AU - Fimland, Bjorn-Ove
PY - 2020/1/21
Y1 - 2020/1/21
N2 - GaN nanocolumns were synthesized on single-layer graphene via radio-frequency plasma-assisted molecular beam epitaxy, using a thin migration-enhanced epitaxy (MEE) AlN buffer layer as nucleation sites. Due to the weak nucleation on graphene, instead of an AlN thin-film we observe two distinguished AlN formations which affect the subsequent GaN nanocolumn growth: (i) AlN islands and (ii) AlN nanostructures grown along line defects (grain boundaries or wrinkles) of graphene. Structure (i) leads to the formation of vertical GaN nanocolumns regardless of the number of AlN MEE cycles, whereas (ii) can result in random orientation of the nanocolumns depending on the AlN morphology. Additionally, there is a limited amount of direct GaN nucleation on graphene, which induces non-vertical GaN nanocolumn growth. The GaN nanocolumn samples were characterized by means of scanning electron microscopy, transmission electron microscopy, high-resolution X-ray diffraction, room temperature micro-photoluminescence, and micro-Raman measurements. Surprisingly, the graphene with AlN buffer layer formed using less MEE cycles, thus resulting in lower AlN coverage, has a lower level of nitrogen plasma damage. The AlN buffer layer with lowest AlN coverage also provides the best result with respect to high-quality and vertically-aligned GaN nanocolumns.
AB - GaN nanocolumns were synthesized on single-layer graphene via radio-frequency plasma-assisted molecular beam epitaxy, using a thin migration-enhanced epitaxy (MEE) AlN buffer layer as nucleation sites. Due to the weak nucleation on graphene, instead of an AlN thin-film we observe two distinguished AlN formations which affect the subsequent GaN nanocolumn growth: (i) AlN islands and (ii) AlN nanostructures grown along line defects (grain boundaries or wrinkles) of graphene. Structure (i) leads to the formation of vertical GaN nanocolumns regardless of the number of AlN MEE cycles, whereas (ii) can result in random orientation of the nanocolumns depending on the AlN morphology. Additionally, there is a limited amount of direct GaN nucleation on graphene, which induces non-vertical GaN nanocolumn growth. The GaN nanocolumn samples were characterized by means of scanning electron microscopy, transmission electron microscopy, high-resolution X-ray diffraction, room temperature micro-photoluminescence, and micro-Raman measurements. Surprisingly, the graphene with AlN buffer layer formed using less MEE cycles, thus resulting in lower AlN coverage, has a lower level of nitrogen plasma damage. The AlN buffer layer with lowest AlN coverage also provides the best result with respect to high-quality and vertically-aligned GaN nanocolumns.
KW - CHEMICAL-VAPOR-DEPOSITION
KW - RAMAN-SCATTERING
KW - FREESTANDING GAN
KW - NANOWIRES
KW - LUMINESCENCE
KW - GRAPHITE
KW - NANORODS
KW - EPITAXY
KW - SURFACE
KW - YELLOW
U2 - 10.1038/s41598-019-55424-z
DO - 10.1038/s41598-019-55424-z
M3 - Journal article
C2 - 31964934
VL - 10
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 853
ER -
ID: 248235035