ABSTRACT
Applications of graphene in electronics demand high-mobility, high-unifor mity and wafer-size materials. Epitaxial graphene (EG) grown on SiC provides a viable way to meet this requirement. Consequently, it has attracted great interest. After extensive studies, its structural and electronic properties are basically known. However, the growth mecha nism, in particular, the growth kinetics, is less understood. Such understanding is crucial for improving the growth and technologically important. We review recent progresses made in the past few years for epitaxial graphene growth on silicon carbide, with emphasis on the growth mechanism and kinetics. By analysing common surface morphological features, the basic growth mechanism is inferred. Growth under different local pressure conditions indicates that silicon desorption is an essential process and it can be used to control the growth. The effect of the initial surface condition is discussed. Furthermore, it is shown that other processes, such as carbon diffusion and SiC recombination have important influences
on the growth and thus deserve more studies. Macroscopic island growth found on the C-face of SiC manifests another growth mode and its implication is discussed. 3.1 Introduction
3.1.1 GrapheneOwing to its exceptional properties, graphene have drawn enormous attention from researchers in various fields, shortly after its freestanding form was made avail able [62] and its potential electronic application was realized [5]. Among these properties many are the extreme. Graphene is a two-dimensional network of car-bon atoms arranging in a honeycomb lattice. Each carbon atom covalently con nects with three nearest neighbours by sp2 bonding, one of the strongest chemical bonds in nature. The strong bonding makes graphene the strongest material ever measured, yet flexible because of its two-dimensionality. The measured Young’s modulus of graphene is as high as 1 TPa [46]. The strong covalent bond, combined with the low atomic mass of carbon, gives rise to a very high speed of sound, which suggests a good ability to conduct heat. In addition, the two-dimensionality of graphene further enhances its thermal conductivity. A recently experiment show that its thermal conductivity is ~5000 W/mK [4], well surpassing the best bulk thermal conductor, diamond, whose thermal conductivity is about 2000 W/mK. Graphene is one atom thick, which gives it a large aspect ratio. Because it is thin, it is fairly transparent and absorbs only 2.3% of light [58]. Moreover, graphene is an extraordinary electrical conductor. It has the highest mobility at room temper-ature [9,57]. It is an ideal material for spintronics owing to its small spinorbit interaction. It is the first material having demonstrated room temperature spin transport in a scale of micrometres [90]. Furthermore, because of its very peculiar band structure, electrons in graphene behave like Dirac fermions and obey chiral symmetry, which leads to many exotic effects, such as half integer quantum Hall effect [61,100], Klein tunnelling [43,99], weak antilocalization [97], Veselago lens for electrons [15] and fractional quantum Hall effect [8,23], etc. Thus, it provides an excellent playground for condensed matter physicists.
