Abstract
The adhesion of a graphene monolayer onto terminated or 2x1-reconstructed diamond (111) surfaces has in the present study been theoretically investigated by using a Density Functional Theory (DFT) method. H, F, O, and OH species were used for the surface termination. The generalized gradient spin density approximation (GG(S)A) with the semiempirical dispersion corrections were used in the study of the Van der Waals interactions. There is a weaker interfacial bond (only of type Wan-der-Waals interaction) at a distance around 3 Å (from 2.68 to 3.36 Å ) for the interfacial graphene//diamond systems in the present study. The strongest binding of graphene was obtained for the H-terminated surface, with an adhesion energy of -10.6 eV. In contrast, the weakest binding of graphene was obtained for F-termination (with an adhesion energy of -2.9 eV). For all situations in the present study, the graphene layer was found to retain its aromatic character. In spite of this, a certain degree of electron transfer was observed to take place from graphene toOontop-,Obridge-, and OH-terminated diamond surface. In addition, graphene attached toOontop-terminated surface showed a finite band gap.
Highlights
For the growth of epitaxial graphene onto a Si/SiC/SiO2 substrate, the Si/SiC/SiO2 was observed to limit the carrier mobility by causing additional scattering from charged surface states and impurities, low surface phonon energy, and large trap density
In the search for the optimal graphene// diamond (GD) interfacial distance, the separation between the attached graphene ad-layer and the diamond surface was varied from 2 Ato 5A, at step sizes of 0.2A
It has been shown that the adsorbates can affect the adsorption energy of an attached graphene sheet on top of terminated diamond surfaces
Summary
For the growth of epitaxial graphene onto a Si/SiC/SiO2 substrate, the Si/SiC/SiO2 was observed to limit the carrier mobility by causing additional scattering from charged surface states and impurities, low surface phonon energy, and large trap density. SiO2 is highly thermally resistive, which will limit the intrinsic properties of graphene and thereby reduce the current capacity of graphene [6, 7]. Experimental work has suggested that, by replacing SiO2 with diamond, it will be possible to achieve a high current-carrying capacitance of intrinsic graphene and to increase the breakdown current density of grapheme [6]. Diamond consists of only sp3-hybridized carbon atoms. It has a large band gap and possesses excellent properties such as high thermal stability, radiation hardness, chemical resistance, and heat dissipation [7]. The graphene-on-diamond system has been explored in many applications such as high-frequency graphene transistors [13] and spin-polarized conducting wires [14]
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