Improvement in electrical properties of CVD graphene on low temperature pulsed laser deposited boron nitride on SiO2/Si substrate

Graphene has been extensively researched over the past decade due to its outstanding electrical, optical and mechanical properties. Since charge carriers in graphene are confined within one atomic layer thickness, their transport properties are easily influenced by the surrounding medium. Recently, significant enhancement in the transport properties of graphene has been observed as it forms layered heterostructure with hexagonal Boron Nitride (hBN), which offers an inert surface, high surface optical phonon modes for heat dissipation and a nearly lattice matched structure [1]. In general, the methods for synthesizing hBN require either high growth or high annealing temperature (~1000 °C) [2-3]. Pulsed laser deposition (PLD) offers an attractive alternative to overcome the high temperature requirement by increasing the excitations of deposited atoms and extending resonance time of the energetic species presence at the condensation surface. This facilitates low temperature growth of amorphous BN (a-BN) [4] which can then be phase transformed to polycrystalline hBN by low temperature annealing [5]. Here, we are reporting the electrical characterization of chemical vapor deposition (CVD) graphene on 5 and 30 nm BN grown on SiO₂/Si substrate initially by PLD at 200 °C, and annealing at 400 °C for transformation to polycrystalline hBN. As synthesized BN was found to improve the electrical properties of graphene by significantly enhancing mobility, reducing carrier inhomogeneity and lowering extrinsic doping compared to graphene transferred on SiO₂/Si substrate.