Effect of growth conditions and reactor configuration on the growth uniformity of large-scale graphene by chemical vapor deposition

Abstract

Chemical vapor deposition (CVD) is an affordable method for the preparation of large-scale and high-quality graphene. With the increase in CVD reactor size, gas mass transfer, flow state, and gas phase dynamics become more complicated. In this study, computational fluid dynamics is used to investigate factors affecting the uniformity of large-scale graphene growth under different growth conditions and reactor configurations. The dimensionless number defined in this paper and the Grashof number are utilized to distinguish the species transfer patterns and the flow states, respectively. A gas-surface dynamics model is established to simulate the graphene growth. Results reveal that the graphene growth rate uniformity is the highest at very low pressure and flow rate due to the flow symmetry and diffusion-dominated species transfer. At an increased pressure of 20 Torr, the uniformity of the graphene growth rate becomes higher axially and lower circumferentially with an increasing inlet mass flow rate. When the flow rate is fixed at 1500 SCCM and pressure is reduced from 20 to 2 Torr, graphene growth uniformity first increases and then decreases due to the influence of gas phase dynamics. Graphene growth rates are analyzed across ordinary reactor configurations and four configurations with inner tubes at 20 Torr pressure and 1500 SCCM flow rate. Comprehensive evaluation suggests that the ordinary reactor configuration performs best under these conditions. This research offers insights into the macroscopic growth mechanism of large-scale graphene and provides guidance for designing growth conditions in large-area graphene production.