Figure 5
From: The influence of AlN buffer layer on the growth of self-assembled GaN nanocolumns on graphene
TEM image of GaN nanocolumn sample synthesized with nominally the same growth conditions as sample G1. (a) Overview cross-sectional HAADF STEM image, showing vertical GaN nanocolumns (star-marked and purple arrows), inclined GaN nanocolumns (red arrows) and GaN crystallites (brown arrows). (b) HAADF STEM image of two GaN nanocolumns within yellow frame in a. (c) Combined color map of the Ga (green), Al (blue) and O (red) elemental distributions (EDS/EELS) on the corresponding region in b. (d) Magnified image of the lower part of the GaN nanocolumn near the interface of the left GaN nanocolumn in b (green frame), with the elemental mapping near the interfaces between the GaN nanocolumn, AlN island, graphene and silica glass (blue frame) by EDS (Ga, Al, Si) and EELS (N, O, C). The red scale bars are 5 nm. (e) HAADF STEM image of the GaN nanocolumns that is light-blue framed in a. The inclined GaN nanocolumn (yellow-dashed line) is possibly directly nucleated on graphene (indicated by the absence of any AlN layer [cyan frames] at the base). There are two broken GaN nanocolumns (red framed area) sharing the same AlN island and another inclined GaN nanocolumn (dark-yellow dashed line) in the background. An irregular GaN crystallite (brown outline) likely grown directly on graphene is also observed.
