Abstract
A reproducible graphene-induced in situ process is demonstrated for the first time for growing large-scale monolayer and bilayer cubic silicon carbide (SiC) crystals on a liquid Cu surface by chemical vapor deposition (CVD) method. Precise control over the morphology of SiC crystals is further realized by modulating growth conditions, thus leading to the formation of several shaped SiC crystals ranging from triangular, rectangular, pentagonal, and even to hexagonal kind. Simulations based on density functional theory are carried out to elucidate the growth mechanism of SiC flakes with various morphologies, which are in striking consistency with experimental observations. In the liquid Cu-assisted CVD system, growth temperature (∼1100 °C) enables sublimation and deposition of silicon oxide (SiO2) derived from quartz tube, while liquid Cu facilitates preformation of graphene originated from methane. The SiO2 and graphene, grown and reacted in situ in the CVD process, are served as the silicon and carbon source for the cubic SiC crystals, respectively. Moreover, the gradual transformation process from SiO2 particles to SiC flakes is directly observed, with several middle stages clearly displayed. The direct in situ growth of SiC crystals offers a novel method for scaled production of SiC crystals and is beneficial to understand its growth mechanism, and thus push forward the way to develop high-temperature and high-frequency electronic devices.