van der Waals epitaxial growth of hexagonal boron nitride on graphene for enhanced deep ultraviolet sensing performance†

The integration of hexagonal boron nitride (h-BN) and graphene, known as a van der Waals heterostructure (vdWHT), holds significant potential as a fundamental platform for developing innovative two-dimensional devices such as ultra-thin transistors, capacitors, and photodetectors. However, the currently employed fabrication methods often involve mechanical assembly, which can introduce defects and limit scalability. Herein, we demonstrate a scalable approach to grow lattice-matched h-BN on graphene via metal–organic chemical vapor deposition with a flowrate-modulated epitaxy method. TEM analysis revealed the successful growth of 7 to 8 layers of h-BN on the substrates. Notably, vdWHT h-BN/graphene exhibited superior optical and structural properties compared with h-BN/sapphire. This was evident in the results of UV-Vis and Raman spectroscopies and SEM analysis. Moreover, vdwHT h-BN/graphene demonstrated significantly enhanced DUV sensing performance at 254 nm, with an excellent on/off ratio exceeding 110 compared with the ratio of 3.8 of h-BN/sapphire. These findings underscore the importance of lattice matching in optimizing the properties of h-BN-based heterostructures. The successful fabrication of high-quality vdwHT h-BN/graphene heterostructures opens a new avenue for the development of advanced DUV sensing devices and other 2D applications.