Thermodynamic Study of Adsorption Capacity between Metal Film and Optical Crystal: Adsorption Energy of Ni Films on LiNbO₃ Substrates

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.

Keywords

• LiNbO₃ substrates
• Ni films
• adsorption energy
• graphene
• direct synthesis