Electron Transport and Scattering in Graphene Devices Transferred to SrTiO3 Substrates

Graphene has become one of the most widely researched materials lately since its discovery in 2004. It has interested scientists due to the exceptional electronic properties of the relativistic Dirac fermions. In this thesis I will present the research I have done to study the charged impurity scattering mechanism in graphene by placing a device on a high dielectric material. An entire device with metal electrodes can be fabricated on SiO2 substrates and transferred to any arbitrary substrate using the device transfer method that I have developed. This method eliminates the need to locate single layer graphene with optical microscopy for alignment and patterning on substrates other than 300nm thick SiO2 which may be very difficult. The target substrate I used is 200 micron thick SrTiO3 (STO). The dielectric constant is two orders of magnitude higher than SiO2 at room temperature and increases to 5,000 to 10,000 at cryogenic temperatures. We expected to observe an associated increase in the mobility with the increased dielectric screening of charged impurities. The mobility is only affected around the Dirac point which is in agreement with theory. An unusual gate dependent hysteretic effect and time dependence is also observed and explained using a surface dipole model of STO. It is graphene that is sensitive to the surface states of the STO