Low T direct plasma assisted growth of graphene on sapphire and its integration in graphene/MoS2 heterostructure-based photodetectors

We report on outstanding photo-responsivity, R > 103 A/W, fast response (~0.1 s), and broadband sensitivity ranging from the UV to the NIR in two terminal graphene/MoS2 photodetectors. Our devices are based on the deterministic transfer of MoS2 on top of directly grown graphene on sapphire, and their performance outperforms previous similar photodetectors using large-scale grown graphene. Here we devise a protocol for the direct growth of transparent (transmittance, Tr > 90%), highly conductive (sheet resistance, R□ < 1 kΩ) uniform and continuous graphene films on sapphire at 700 °C by using plasma-assisted chemical vapor deposition (CVD) with C2H2/H2 gas mixtures. Our study demonstrates the successful use of plasma-assisted low-temperature CVD techniques to directly grow graphene on insulators for optoelectronic applications.