TY - JOUR
T1 - Microscopic Mechanisms of Initial Formation Process of Graphene on SiC(0001) Surfaces
T2 - Selective Si Desorption from Step Edges
AU - Imoto, Fumihiro
AU - Iwata, Jun Ichi
AU - Boero, Mauro
AU - Oshiyama, Atsushi
PY - 2017/3/9
Y1 - 2017/3/9
N2 - Simulations within the density functional theory framework clarify the microscopic mechanism responsible for the initial stage of graphene formation on the SiC(0001) surface. Favorable reaction pathways for the desorption of either Si or C atoms from the stepped surface have been found by determining the desorption and the subsequent migration pathways, quantified in terms of the corresponding energy barriers for the first time. We find that the energy barrier for the desorption of an Si atom at the step edge and the subsequent migration toward stable terrace sites is lower than that of a C atom by 0.75 eV, indicative of the selective desorption of Si from the SiC surface. We also find that the subsequent Si desorption is an exothermic reaction. This exothermicity comes from the energy gain due to the bond formation of C atoms being left near the step edges. This is likely to be a seed of graphene flakes.
AB - Simulations within the density functional theory framework clarify the microscopic mechanism responsible for the initial stage of graphene formation on the SiC(0001) surface. Favorable reaction pathways for the desorption of either Si or C atoms from the stepped surface have been found by determining the desorption and the subsequent migration pathways, quantified in terms of the corresponding energy barriers for the first time. We find that the energy barrier for the desorption of an Si atom at the step edge and the subsequent migration toward stable terrace sites is lower than that of a C atom by 0.75 eV, indicative of the selective desorption of Si from the SiC surface. We also find that the subsequent Si desorption is an exothermic reaction. This exothermicity comes from the energy gain due to the bond formation of C atoms being left near the step edges. This is likely to be a seed of graphene flakes.
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U2 - 10.1021/acs.jpcc.6b11985
DO - 10.1021/acs.jpcc.6b11985
M3 - Article
AN - SCOPUS:85015611233
VL - 121
SP - 5041
EP - 5049
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 9
ER -