Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Sakakibara, Ryotaro*; Bao, J.*; Yuhara, Keisuke*; Matsuda, Keita*; Terasawa, Tomoo; Kusunoki, Michiko*; Norimatsu, Wataru*
Applied Physics Letters, 123(3), p.031603_1 - 031603_4, 2023/07
Times Cited Count：1 Percentile：54.89(Physics, Applied)We here report a step unbunching phenomenon, which is the inverse of the phenomenon of step bunching. When a 4H-SiC (0001) surface is annealed at a high temperature, step bunching arises due to the different velocities of the step motion in adjacent steps, resulting in steps with a height of more than several nanometers. We found that the bunched steps, thus, obtained by hydrogen etching in an Ar/H
atmosphere were "unbunched" into lower height steps when annealed subsequently at lower temperatures. This unbunching phenomenon can be well explained by the consequence of the competition between energetics and kinetics. Our findings provide another approach for the surface smoothing of SiC by hydrogen etching and may give significant insight into the application of SiC power devices and two-dimensional materials growth techniques in general.
Sumi, Tatsuya*; Nagai, Kazuki*; Bao, J.*; Terasawa, Tomoo; Norimatsu, Wataru*; Kusunoki, Michiko*; Wakabayashi, Yusuke*
Applied Physics Letters, 117(14), p.143102_1 - 143102_5, 2020/10
Times Cited Count：4 Percentile：26.53(Physics, Applied)A systematic structural study of epitaxial graphene samples on the SiC (0001) surface has been performed by the surface X-ray diffraction method, which is a non-contact technique. For samples with only a buffer layer, one layer graphene, and multilayer graphene, the distances between the buffer layer and the surface Si atoms were found to be 0.23 nm. This value is the same as reported values. For quasi-free-standing graphene samples prepared by the rapid cooling method, there was no buffer layer and the distance between the quasi-free-standing graphene and the surface Si atoms was 0.35 nm, which is significantly shorter than the value in hydrogen-intercalated graphene and slightly longer than the interplane distance in graphite. The Si occupancy deviated from unity within 1 nm of the SiC surface. The depth profile of the Si occupancy showed little sample dependence, and it was reproduced by a simple atomistic model based on random hopping of Si atoms.
C thin filmNorimatsu, Wataru*; Matsuda, Keita*; Terasawa, Tomoo; Takata, Nao*; Masumori, Atsushi*; Ito, Keita*; Oda, Koji*; Ito, Takahiro*; Endo, Akira*; Funahashi, Ryoji*; et al.
Nanotechnology, 31(14), p.145711_1 - 145711_7, 2020/04
Times Cited Count：6 Percentile：38.95(Nanoscience & Nanotechnology)We show that boron-doped epitaxial graphene can be successfully grown by thermal decomposition of a boron carbide thin film, which can also be epitaxially grown on a silicon carbide substrate. The interfaces of BC on SiC and graphene on BC had a fixed orientation relation, having a local stable structure with no dangling bonds. The first carbon layer on BC acts as a buffer layer, and the overlaying carbon layers are graphene. Graphene on BC was highly boron doped, and the hole concentration could be controlled over a wide range of 2
10
to 210
cm
. Highly boron-doped graphene exhibited a spin-glass behavior, which suggests the presence of local antiferromagnetic ordering in the spin-frustration system. Thermal decomposition of carbides holds the promise of being a technique to obtain a new class of wafer-scale functional epitaxial graphene for various applications.
-polarization Raman microscopySaito, Yuika*; Tokiwa, Kenshiro*; Kondo, Takahiro*; Bao, J.*; Terasawa, Tomoo; Norimatsu, Wataru*; Kusunoki, Michiko*
AIP Advances (Internet), 9(6), p.065314_1 - 065314_6, 2019/06
Times Cited Count：4 Percentile：16.07(Nanoscience & Nanotechnology)