Breaking the Thermodynamic Equilibrium for Monocrystalline Graphene Fabrication by Ambient Pressure Regulation

Abstract

Developing high-quality monocrystalline graphene has been an area of compelling research focus in the field of two-dimensional materials. Overcoming growth cessation presents a significant challenge in advancing the production of monocrystalline graphene. Herein, methods for sustaining a steady and consistent growth driving force are investigated based on the single-crystal growth theory. Comparative analysis revealed that each dynamic regulation method significantly increased the size of graphene compared to samples grown under stable pressure conditions. The grain size of high-quality graphene was significantly increased from ∼400 μm to ∼3 mm. Moreover, experimental measurements and numerical simulations were employed to investigate the impact of ambient pressure on the temperature and flow field. By considering the influence of pressure on the boundary layer and reaction rate constant, the mechanism underlying the dynamic regulation of ambient pressure was elucidated. Ultimately, the crystal growth kinetics theory, initially formulated with considerations of undercooling ΔT and supersaturation S_eff, was developed by inducing the individual parameter of ambient pressure P. Due to diameter expansion and mechanical property promotion, a bilayer graphene Fabry–Perot interference (1100 μm) sensor with a stable signal response (52 dB) and superior minimum detection pressure at 20 kHz (87 μPa/Hz^1/2) was prepared. This innovative approach to regulating ambient pressure during crystal growth enables monocrystalline graphene to possess superior structure and properties for future technologies and provides insights into the production of other two-dimensional materials.