Investigation of the Thermal and Electrical Properties of Graphene

Abstract

In this thesis, we developed a process to transfer and pattern graphene flakes on a pre-fabricated MEMS device that incorporates thermal-bridge structures, and performed thermal measurements on both suspended and supported graphene samples. The thermal conductivity of graphene shows strong dependence on the sample size, and can be significantly reduced by phonon coupling with the substrate or by thermal boundary scattering at the contacts. When exposed to an N2 gas ambient, graphene exhibits an n-type behavior, and the charge transfer is attributed to N2-graphene interactions at both single-vacancy defects and edges of the graphene. By introducing a small proportion of p-type O2/H2O molecules into N2 as the gas environment, we have demonstrated a graphene field-effect transistor whose doping type can be reversibly controlled by the gate-voltage as a result of selective charge transfer from the two dopant species.