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We have developed a dry transfer method that allows graphene to be transferred from polymerthyl-methacrylate (PMMA)/Si (silicon) substrates on commercially available hexagonal boron nitride (hBN) crystals. With this method we are able to fabricate graphene devices with little wrinkles and bubbles in graphene sheets, but that do not degrade the electronic quality more than the SiO2 substrate does. For hBN to perform the function described above substrate cleanliness is critical to get high quality graphene devices. Using hBN as a substrate, graphene exhibits enhanced mobility, reduced carrier inhomogeneity, and reduced intrinsic doping compared to graphene on SiO2 substrate.

We report the observation and systematic investigation of a local and nonlocal transport in HgTe quantum wells with inverted band structure corresponding to the two-dimensional topological insulator phase. We examine the probe spacing and probe configuration dependencies of the resistance near the charge neutrality point, where the transport is dominated by edge states. We provide details on the model, which takes into account the edge and bulk contribution to the total current and reproduces our experimental results.

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Stacking of two-dimensional materials, in the form of heterostructures, is recently considered as a promising candidate for thermoelectric devices application because it can combine the advantages of the individual 2D materials. The structural, electronic, and thermoelectric properties of group IV–VI [AB/XY (A = Ge, B = O, S, Se, Te, X = C, Sn, Si, Sn, and Y = Se, S)] van der Waals heterostructures are investigated by using first principles calculations. Binding energies and thermal stability showed that all heterobilayers are energetically and thermally stable. Calculated electronic band structure confirmed that IV–VI [AB/XY (A = Ge, B = O, S, Se, Te, X = C, Sn, Si, Sn, and Y = Se, S)] van der Waals heterostructures have indirect with type-II band alignment, which is crucial for separation of photogenerated carriers in solar cell device applications. Transport coefficients including Seebeck coefficient, electrical conductivity and power factor versus chemical potential are calculated by using Boltzmann transport theory which is implemented in BoltzTrap code. Among these heterobilayers, GeO/CSe has considerably large power factor at 800 K, making it more promising for good thermoelectric purposes. These findings pave the way for designing future electronic and thermoelectric devices.