Abstract
The growth of large areas of two-dimensional homogeneous graphene depends on the bond between the metal film, which acts as a catalyst, and the substrate material. The structural differences between the metal and the various anisotropic crystals make this growth method a challenge for the feasibility of growing graphene on optical crystals. In this paper, the evolution of the adsorption energy between nickel (Ni) films and Lithium Niobate (LiNbO3, LN) crystals is modelled under different thermal treatment environments by constructing a physical model of the temperature dependence of the adsorption energy between the two materials. With the aid of a series of simulated full annealing processes, the changes in adsorption energy at different temperatures were calculated. The results show that there are two “temperature windows” with target annealing temperatures of 700–800 K and 950–1050 K that prove to have high adsorption energies. This is of great guiding and practical significance for the direct transfer-free synthesis of graphene on LiNbO3 substrates.
Highlights
Since graphene was first prepared by mechanical exfoliation in 2004 [1], research reports on graphene have sprung up due to its fascinating physical and electrical properties, such as excellent mechanical strength [2], ultrafast carrier mobility [3], near transparency in a wide spectral range from visible to infrared [4], and high thermal conductivity [5]
We built a model of LiNbO3 substrate covered with Ni film and systematically simulated the changes in adsorption energy between them at different temperatures
The results of the simulated cooling process show that the adsorption energy rises with a decreasing temperature for annealing processes when the target temperature is exactly in the “temperature window”, which indicates a better adsorption between the Ni film and the surface of LiNbO3 substrate
Summary
Since graphene was first prepared by mechanical exfoliation in 2004 [1], research reports on graphene have sprung up due to its fascinating physical and electrical properties, such as excellent mechanical strength [2], ultrafast carrier mobility [3], near transparency in a wide spectral range from visible to infrared [4], and high thermal conductivity [5]. The macroscopic result of this detachment is that the Ni film wrinkles after suffering annealing treatment The occurrence of this phenomenon seems to be related only to the nature of the two materials (the Ni film and the LiNbO3 substrate) themselves, and not to the process of carbon doping, because two kinds of samples (one without carbon ion implantation and the other with carbon ion implantation) with the same coating treatment were found to have similar wrinkles after the same annealing process.
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