Effect of Growth Pressure on Graphene Direct Growth on an A-Plane Sapphire Substrate: Implications for Graphene-Based Electronic Devices

Abstract

Graphene direct growth was performed on an a-plane (1–120) sapphire substrate using low-pressure chemical vapor deposition (LPCVD) without a metal catalyst. The direct graphene growth on a-plane sapphire is very attractive not only for the preparation of a template substrate of remote epitaxy but also for the fabrication of low-cost graphene-based electronic devices. The growth pressure dependence was systematically studied to reveal the growth mechanism of graphene. It was found that the graphene island density decreased with growth pressure, while the growth rate increased. In addition, single-layer graphene with high uniformity was successfully obtained because the graphene growth was driven by the catalytic effect of the a-plane sapphire surface. Finally, high-quality and highly uniform single-layer graphene with a Raman D/G ratio of 0.2 was demonstrated on the whole surface of a 2 in. a-plane sapphire substrate at a growth pressure of 5 kPa.

Influence of substrate sapphire orientation on direct CVD growth of graphene

“…Furthermore, the Hall effect mobility values of 424 and 870 cm 2 V −1 s −1 were reported for the graphene grown on the r-plane and a-plane, respectively. 30,51) As for the a-plane, the mobility and the I D /I G ratio are similar between the previous and present studies. 51) The reported mobility for the r-plane appears smaller than our values, but this could be due to the higher I D /I G ratio and the higher carrier density.…”

“…30,51) As for the a-plane, the mobility and the I D /I G ratio are similar between the previous and present studies. 51) The reported mobility for the r-plane appears smaller than our values, but this could be due to the higher I D /I G ratio and the higher carrier density. 30) Figure 6 also shows that the carrier density is largely varied from sample to sample, which could be originated from changes in the substrate sapphire structures due to subtle differences in the CVD conditions and/or the adsorption/intercalation of gaseous species from the atmosphere.…”

Remote epitaxial interaction through graphene

“…The effect of growth methods and the range of temperature on graphene damage should be systematically studied to understand the limits and to seek improvements that can be made for performing better remote epitaxy ( 16 , 42 ). Recently, direct growth of graphene on several oxide substrates of interest ( 43 ) have been demonstrated, allowing consecutive remote epitaxial growth of films in the growth chamber under high vacuum. In addition, remote epitaxy has been performed on transition metal dichalcogenides, which demonstrates all aspects of remote epitaxy that we have discussed so far ( 14 , 44 ).…”

A review on transfer methods of two-dimensional materials

“…By enabling the controlled production of highquality layered materials independently of the growth conditions of the devices. This approach not only offers greater flexibility in selecting target substrates, but also mitigates limitations and dependencies on the growth conditions of the 2D materials [36][37][38][39][40][41][42]. Nevertheless, ongoing research endeavors are focused on refining and optimizing the transfer techniques employed for these materials, since certain stages of the process have the potential to introduce defects into the target wafer, thereby significantly altering its inherent properties [43,44].…”