In this thesis, we first searched for high quality graphene samples, including mechanical exfoliation of Kish graphite, AP-CVD method to grow graphene on Pt foil and transfer-free growth of graphene on SiO₂ substrate. Although the synthetic graphene samples are usually large in size, their electronic properties are unfortunately incompatible with that of Kish graphite. The Kish graphite, with the mobility of more than 20,000 cm²V^-1s^-1 on SiO₂ substrate, is an ideal source for graphene studies.

Secondly, we tried several kinds of dielectric materials for the graphene devices, and found the Y₂O₃ and h-BN to be proper for serving as the substrates or insulating layers in graphene devices. Based on the analysis of a self-consistent transport theory within variant screening effect, w...[ Read more ]

In this thesis, we first searched for high quality graphene samples, including mechanical exfoliation of Kish graphite, AP-CVD method to grow graphene on Pt foil and transfer-free growth of graphene on SiO₂ substrate. Although the synthetic graphene samples are usually large in size, their electronic properties are unfortunately incompatible with that of Kish graphite. The Kish graphite, with the mobility of more than 20,000 cm²V^-1s^-1 on SiO₂ substrate, is an ideal source for graphene studies.

Secondly, we tried several kinds of dielectric materials for the graphene devices, and found the Y₂O₃ and h-BN to be proper for serving as the substrates or insulating layers in graphene devices. Based on the analysis of a self-consistent transport theory within variant screening effect, we found that Y₂O₃ introduces few short-range scattering centers. While for h-BN, by comparing the quantum capacitance data of Graphene/Y₂O₃/metal and Graphene/h-BN/metal sandwiched devices, we can see much clear Landau level oscillations in the later one, demonstrating that h-BN is a much better material than Y₂O₃ for capacitance study.

Thirdly, chemical doping is applied for an attempt in graphene applications. Reversible charge transfer between graphene and iodine could transit graphene between semi-metallic and metallic freely. At the same time, the restored graphene possesses higher mobility than its pristine state. Oxygen could assist the charge transfer process between graphene and ZnO quantum dots, rendering the system to be a high performance UV sensors and detectors.

Finally, the Landau level spectrums and band structures of graphene with 1~4 layers were investigated. For monolayer and bilayer, clear Landau level plateaus could be observed. The berry’s phase and unique quantum Hall effect make graphene distinct from traditional 2DEG. In trilayer and tetralayer, things become quite complicated. The first-order approximation model was unable to explain the transport and quantum capacitance data. We introduced a full parameter SWMcC model and did simulations based on these parameters trying to fit the experimental data. We found that for trilayer this model is suitable while for tetralayer the hopping parameters between the inner two layers and the surface two layers is quite different which is a direct evidence for the surface relaxation phenomena.