We gave theoretical perspective on the graphene-based devices in the next generation. Our theoretical calculations clarified the importance of the hybrid structures comprising graphene and other foreign materials for designing the devices, since the interfaces are essential for the graphene hybrid structures. We also demonstrate the unusual electronic structures of sp² carbon materials by controlling their network topologies.

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  Graphene, a single-layer sheet of carbon atoms, having a unique optoelectronic property different from the conventional two-dimensional electron systems has attracted attention as a promising new optoelectronic material that can overcome the performance limitations of the prior devices. In this paper, we describe the recent advances and trends in the developments of ultra-high frequency optoelectronic and plasmonic devices focusing on the terahertz lasers using graphene-based material systems.

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  High-mobility graphene is fabricated on hexagonal boron nitride (h-BN) using a micromechanical cleavage and dry transfer technique. We demonstrate the photovoltaic effect due to the cyclotron resonance in graphene/h-BN under quantized Hall regime and the electrical spin injection into graphene through a single-layer h-BN tunnel barrier.

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  We give a brief review of thermal transport and thermoelectric properties of graphene and related materials. The thermal conductivity of graphene is extremely high (3,000-5,300 W K⁻¹ m⁻¹) because of strong carbon-carbon bonds and long mean free path of phonons. On the other hand, the thermoelectric coefficients (Seebeck coefficient and Nernst coefficient) are powerful tool for probing the electron scattering mechanism and Dirac fermion features of graphene and related materials.

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