Open AccessA patterning-free approach for growth of free-standing graphene nanoribbons using step-bunched facets of off-oriented 4H-SiC(0 0 0 1) epilayers
Author(s) -
Yuchen Shi,
Alexei Zakharov,
Ivan G. Ivanov,
Nikolay A. Vinogradov,
Gholamreza Yazdi,
Mikael Syväjärvi,
Rositsa Yakimova,
Jianwu Sun
Publication year - 2020
Publication title -
journal of physics. d, applied physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.857
H-Index - 198
eISSN - 1361-6463
pISSN - 0022-3727
DOI - 10.1088/1361-6463/ab6149
Subject(s) - materials science , graphene , graphene nanoribbons , scanning tunneling microscope , sublimation (psychology) , nanotechnology , lithography , monolayer , optoelectronics , nanoscopic scale , psychology , psychotherapist
The tunable electronic structure of graphene nanoribbons (GNRs) has attracted much attention due to the great potential in nanoscale electronic applications. Most methods to produce GNRs rely on the lithographic process, which suffers from the process-induced disorder in the graphene and scalability issues. Here, we demonstrate a novel approach to directly grow free-standing GNRs on step-bunched facets of off-oriented 4H-SiC epilayers without any patterning or lithography. First, the 4H-SiC epilayers with well-defined bunched steps were intentionally grown on 4 degree off-axis 4H-SiC substrates by the sublimation epitaxy technique. As a result, periodic step facets in-between SiC terraces were obtained. Then, graphene layers were grown on such step-structured 4H-SiC epilayers by thermal decomposition of SiC. Scanning tunneling microscopy (STM) studies reveal that the inclined step facets are about 13–15 nm high and 30–35 nm wide, which gives an incline angle of 23–25 degrees. LEEM and LEED results showed that the terraces are mainly covered by monolayer graphene and the buffer layer underneath it. STM images and the analysis of their Fourier transform patterns suggest that on the facets, in-between terraces, graphene is strongly buckled and appears to be largely decoupled from the surface.