Growth of Large-Area Graphene Single Crystals in Confined Reaction Space with Diffusion-Driven Chemical Vapor Deposition

Abstract

To synthesize large-area graphene single crystals, we specifically designed a low-pressure chemical vapor deposition (LPCVD) reactor with confined reaction space (L 22 mm × W 13 mm × H 50 μm). Within the confined reaction space, a uniform distribution of reactant concentrations, reduced substrate roughness, and the shift of growth kinetics toward a diffusion-limited regime can be achieved, favoring the preparation of large-area, high-quality graphene single crystals. The gas flow field and mass transport pattern of reactants in the LPCVD system simulated with a finite element method support the advantages of using this confined reaction room for graphene growth. Using this spaceconfined reactor together with the optimized synthesis parameters, we obtained monolayer, highly uniform, and defect-free graphene single crystals of up to ∼0.8 mm in diameter with the field-effect mobility of μ EF ∼ 4800 cm 2 V −1 s −1 at room temperature. In addition, structural design of the confined reaction space by adjusting the reactor's dimensions is of facile controllability and scalability, which demonstrates the superiority and preference of this method for industrial applications.

P‐GaSe/N‐MoS2 Vertical Heterostructures Synthesized by van der Waals Epitaxy for Photoresponse Modulation

“…Considering the importance of sample uniformity to practical applications, we have made more attempts for improving the growth, for example, suppression of the amount of source (Figure S2, Supporting Information) and introduction of inner tube (Figure S3c, Supporting Information), which give a limited improvement on result. To further improve the uniformity, we will try to employ space‐confined strategy for growth, which benefit to produce large‐area and high quality thin flakes with the unprecedented uniformity and controllability . It is easy to find that GaSe flakes are inclined to deposit on the surface of MoS 2 and only a few small irregular microstructures can be found on the bare SiO 2 /Si substrate, which suggests the precursor has a lower nucleation and migration energy barrier on MoS 2 than on SiO 2 /Si substrate (Figures S3 and S4, Supporting Information) .…”

Space‐Confined Chemical Vapor Deposition Synthesis of Ultrathin HfS2 Flakes for Optoelectronic Application

“…The mass‐transport process plays an important role in the growth of HfS 2 . On the basis of Blasius model, the thickness of the laminar boundary layer δ is inversely proportional to the square root of the reactant's flow velocity, which is also inversely proportional to the mass‐transport efficiency. The gas flow through the rear mica surface with confined space is much slower than that on the front mica surface without confined space, which is attributed to the reduced interface between the mica surface and the inner tube.…”

Achieving highly uniform two-dimensional PbI 2 flakes for photodetectors via space confined physical vapor deposition

“…Space confined chemical vapor deposition (CVD) has been used for the synthesis of large-sized graphene [36][37][38][39], BN [40], and other low-dimensional materials [41][42][43], where the confined space was employed to decrease the flow velocity and the vapor pressure. To confine the space, either the vapor trapping tube with only one side opened or Cu enclosure was used, which is suitable for the CVD growth of 2D materials but cannot be applied for PVD growth of 2D materials.…”