Controlled synthesis and decoupling of monolayer graphene on SiC(0001)

Abstract

We describe a process for the growth of a single, electronically decoupled graphene layer on SiC(0001). The method involves annealing in disilane to (1) prepare flat, clean substrates, (2) grow a single graphene layer, and (3) electronically decouple the graphene from the substrate. This approach uses a single process gas, at μTorr pressures, with modest substrate temperatures, thus affecting a drastic simplification over other processes described in the literature.

Equi-biaxial compressive strain in graphene: Grüneisen parameter and buckling ridges

“…It can be seen that the ridges in the synthesized graphene are virtually the same as those induced in graphene by the heating-cooling cycle. Note that during graphene synthesis via either CVD [29,30,52] or SiC sublimation method [31,53], there is a cooling process from high temperature to room temperature, giving rise to compressive strain in the synthesized graphene. As the compressive strain exceeds the graphene buckling strain, buckling ridges are generated.…”

“…Nevertheless, few studies have investigated the morphology of the buckling ridges, especially the ridge network formed under biaxial compression [28]. Interestingly, similar ridge networks are commonly seen in graphene synthesized by chemical vapor deposition (CVD) [29,30] or epitaxial growth method [31].…”

Bifunctional effects of the ordered Si atoms intercalated between quasi-free-standing epitaxial graphene and SiC(0001): graphene doping and substrate band bending

“…However, the ZL plays an important role in passivating the dangling bonds of the SiC(0001) substrate, so that the overlying graphene layer exhibits truly delocalized π orbitals. An elegant way to remove the undesirable influence of the ZL on the overlying graphene is to prepare so-called quasi-free-standing epitaxial graphene (EG) through decoupling the ZL from the substrate [2] by the intercalation of various elements such as H [5,[10][11][12][13][14][15][16][17], Li [18], Na [19], O [20][21][22], F [2,23], Au [9,24], Cu [25], Fe [26,27], Yb [28], Al [29], Pt [30], Ge [7,31,32] and Si [33][34][35]. Among them, semiconducting elements in group IV, like Si and Ge, turn out to be easily intercalated by deposition at room temperature (RT) and…”

Structural and electronic properties of Li-intercalated graphene on SiC(0001)

“…When grown on the Si terminated SiC(0001) surface, the first carbon buffer layer has a detrimental effect on the graphene charge carrier mobility and needs to be eliminated [3]. Intercalation of elements such as hydrogen [4,5], gold [6], germanium [7], silicon [8,9], nitrogen [10], fluorine [11], oxygen [12], lithium [13][14][15], and sodium [16][17][18] have all been shown to decouple the buffer layer and transform it into a quasi-free-standing graphene layer with varying degrees of doping depending on the intercalant. The alkali metals induce a strong n-type doping when deposited on graphene samples.…”