Abstract
For atomically thin two-dimensional materials, interfacial effects may dominate the entire response of devices, because most of the atoms are in the interface/surface. Graphene/sapphire has great application in electronic devices and semiconductor thin-film growth, but the nature of this interface is largely unknown. Here we find that the sapphire surface has a strong interaction with some of the carbon atoms in graphene to form a C-O-Al configuration, indicating that the interface interaction is no longer a simple van der Waals interaction. In addition, the structural relaxation of sapphire near the interface is significantly suppressed and very different from that of a bare sapphire surface. Such an interfacial C-O-Al bond is formed during graphene growth at high temperature. Our study provides valuable insights into understanding the electronic structures of graphene on sapphire and remote control of epitaxy growth of thin films by using a graphene–sapphire substrate.
Highlights
For atomically thin two-dimensional materials, interfacial effects may dominate the entire response of devices, because most of the atoms are in the interface/surface
In a field-effect transistor system, strong hybridization between 2D materials and contact metals can eliminate the van der Waals gap, which results in a reduction of the tunnel barrier for carriers[7]
We observe that the atomic configuration at the interface is C-O-Al, which is further confirmed by density functional theory (DFT) calculations
Summary
For atomically thin two-dimensional materials, interfacial effects may dominate the entire response of devices, because most of the atoms are in the interface/surface. The pristine surface of αAl2O3 is further identified to be Al-terminated and the interfacial C-O-Al bond is likely formed during high-temperature growth of Gr. All these findings provide valuable insights into the binding nature between 2D materials on a substrate and would be beneficial to the strategy of remote epitaxial growth by using a Gr buffer layer.
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