Step-edge instability during epitaxial growth of graphene from SiC(0001)

Abstract

The unique electronic properties of graphene offer the possibility that it could replace silicon when microelectronics evolves to nanoelectronics. Graphene grown epitaxially on silicon carbide is particularly attractive in this regard because SiC is itself a useful semiconductor and, by suitable manipulation of the growth conditions, epitaxial films can be produced that exhibit all the transport properties of ideal, two-dimensional graphene desired for device applications. Nevertheless, there is little or no understanding of the actual kinetics of growth, which is likely to be required for future process control. As a step in this direction, we propose a local heat release mechanism to explain finger-like structures observed when graphene is grown by step flow decomposition of SiC(0001). Using a continuum equation of motion for the shape evolution of a moving step, a linear stability analysis predicts whether a shape perturbation of a straight moving step grows or decays as a function of growth temperature, the background pressure of Si maintained during growth, and the effectiveness of an inert buffer gas to retard the escape of Si atoms from the crystal surface. The theory gives semi-quantitative agreement with experiment for the characteristic separation between fingers observed when graphene is grown in a low-pressure induction furnace or under ultrahigh vacuum conditions.Comment: 4 pages, 5 figure

Large homogeneous mono-/bi-layer graphene on 6H–SiC(0 0 0 1) and buffer layer elimination

“…The ex situ samples were heat treated in a designed arrangement to minimize the temperature gradient while the in situ sample was heated by running current through it, which creates a thermal gradient in the surface region. Although homogenous sample heating may be of importance for obtaining graphene layers of the highest quality, the results of ours [18,21] and other groups [19,20,23] have proved that the use of a considerably higher growth temperature in combination with a background ambient gas pressure are the key factors for obtaining large homogenous layers of graphene. More information on the operational conditions elaborated in our growth experiments can be found in [25].…”

“…On the C-terminated SiC(000-1) surface larger grains but multilayer films with an azimuthal disorder between the different layers are typically obtained [14,17]. Since SiC is an excellent substrate for graphene based electronic devices further efforts [18][19][20][21][22][23] with the aim to achieve large area graphene with a uniform thickness were recently carried out. These efforts involved growth of the graphene in an ambient gas and were quite successful, since they proved it possible to prepare large and homogenous areas of single layer graphene on the SiC(0001) surface.…”

Growth of large domain epitaxial graphene on the C-face of SiC

“…9,12 In the stepdown growth, it is not clear why decomposition takes place in the middle of the terrace. One possibility is that the heat released by crystallization of carbon atoms into graphene produces an increase in local temperature, 25 which facilitates decomposition. One may think that there is a significant higher energy barrier for the stepdown process than for the propagation on a terrace.…”

Structural and Electronic Properties of Graphene on 4H- and 3C-SiC

“…2.6(d)). It was found that Si-face EG nucleates and exhibits much higher growth rate at the macro-steps compared to the terraces [86][87][88]. Si-face EG grown by low-temperature sublimation in argon forms on top of the buffer layer and exhibits high electron doping, similarly to the case of Si-face EG grown by UHV-sublimation [51].…”