High-quality bilayer graphene grown on softened copper foils by atmospheric pressure chemical vapor deposition
- PDF / 7,279,539 Bytes
- 10 Pages / 595.276 x 793.701 pts Page_size
- 88 Downloads / 220 Views
Published online 14 July 2020 | https://doi.org/10.1007/s40843-020-1394-3
High-quality bilayer graphene grown on softened copper foils by atmospheric pressure chemical vapor deposition 1,2
1
1
1
1
2
1
Qiao Chen , Qiyang Song , Xin Yi , Qiao Chen , Wenjia Wu , Meirong Huang , Chuanwen Zhao , 1,3* 2* Shun Wang and Hongwei Zhu ABSTRACT Bilayer graphene (BLG) shows great application prospect and potential in next-generation electronics because of its unique electrical and mechanical properties. However, the scalable synthesis of large-area high-quality BLG films is still a great challenge, despite the maturity of chemical vapor deposition (CVD) technique. In this study, we report a robust method to grow BLGs on flat, softened Cu foils by atmospheric pressure CVD. A moderate amount of residual oxygen accelerates the growth of BLG domains while suppressing the formation of multilayers. Raising the nucleation density at low hydrogen pressure efficiently increases the film continuity. Based on the optimized CVD process, the growth of graphene 2 films on 4×4 cm Cu foils with an average BLG coverage of 76% is achieved. The morphology and structure characterizations demonstrate a high quality of the BLG. Dual gate field-effect transistors are investigated based on AB-stacked BLG, with a tunable bandgap and high carrier mobility of up 2 −1 −1 to 6790 cm V s at room temperature. Keywords: graphene, bilayer, chemical vapor deposition, Cu foil
INTRODUCTION The realizations of tunable bandgap, unconventional superconductivity and ultrahigh hardness in bilayer graphene (BLG) make it fascinating for fundamental research as well as emerging electronic applications [1–3]. A scalable approach to synthesizing high-quality BLG is of great importance. Large-area single-layer graphene (SLG) can be achieved by chemical vapor deposition (CVD) on copper [4–6], thanks to the negligible solubility of carbon atoms in Cu and the self-limited growth me-
chanism [6,7]. However, it becomes a great challenge for BLG, owing to the complex manufacturing processes brought by the additional layers of graphene. Strategies such as using hazard gas (e.g., H2) with high partial pressure [8–10], edge etching of the top graphene layer [11], and using alloy or multicomponent catalyst substrates [12–15] have been explored to synthesize BLG. Nevertheless, it is still imperative to develop a practical and industrially viable method for BLG preparation. BLG can be prepared based on small ad-layered graphene (ALG), which is often formed beneath SLG synthesized on Cu [8–11,15–17]. Efforts have been made to investigate the nucleation and growth kinetics of ALG [18–21]. The understanding of the growth mechanism of ALG facilitates the layer uniformity of desired large-area products. For example, continuous SLG films have been achieved by simultaneous growth of SLG on both sides of the suspended Cu foil, which suppresses the ALG growth in a normal CVD process [22]. Different from SLG growth, BLG growth requires two unequal sides of Cu. It is essential to ensure
Data Loading...
