Abstract
In-plane and vertically stacked heterostructures of graphene and hexagonal boron nitride (h-BN-G and G/h-BN, respectively) are both recent focuses of graphene research. However, targeted synthesis of either heterostructure remains a challenge. Here, via chemical vapour deposition and using benzoic acid precursor, we have achieved the selective growth of h-BN-G and G/h-BN through a temperature-triggered switching reaction. The perfect in-plane h-BN-G is characterized by scanning tunnelling microscopy (STM), showing atomically patched graphene and h-BN with typical zigzag edges. In contrast, the vertical alignment of G/h-BN is confirmed by unique lattice-mismatch-induced moiré patterns in high-resolution STM images, and two sets of aligned selected area electron diffraction spots, both suggesting a van der Waals epitaxial mechanism. The present work demonstrates the chemical designability of growth process for controlled synthesis of graphene and h-BN heterostructures. With practical scalability, high uniformity and quality, our approach will promote the development of graphene-based electronics and optoelectronics.
Highlights
In-plane and vertically stacked heterostructures of graphene and hexagonal boron nitride (h-BN-G and G/Hexagonal boron nitride (h-BN), respectively) are both recent focuses of graphene research
Of particular importance is those by Ajayan and coworkers, who demonstrated the synthesis of randomly distributed h-BN-G heterostructures on copper foils by simultaneously introducing carbon and ammonia borane precursors in the growth process[8]
We develop a novel temperature-triggered reaction route in chemical vapour deposition (CVD) process to achieve the selective growth of h-BN-G and G/h-BN heterostructures on Cu foils, relying on a high carbon/hydrogen ratio molecule of benzoic acid as carbon source
Summary
The corresponding height histogram over the whole layer presents a single-peak distribution (Fig. 1f), indicating the formation of in-plane patching structure of graphene and h-BN in the second growth step, owing to the concomitant BN etching reaction. The graphene in h-BN-G may have been slightly doped by boron or nitrogen during the etching growth process, no more than 10 cm À 1 blue or red shift of G peak in Raman spectra can be induced as previously reported[26,27] This significant blue shift could be attributed to the p-doping effect of SiO2 or the adsorbed water layer between graphene and the hydrophilic substrate[28,29,30]. The B 1s map in Fig. 2f shows homogeneous contrast distribution throughout the detection area, suggesting that the pre-grown h-BN layer remains intact
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