Physics Department Seminar: “Electron Scattering and Transport in Graphene Devices”

Posted on 4/8/2019 9:29:14 AM

Join us on Friday, April 12, at 2:30 p.m. in Weyandt Hall, Room 331 for “Electron Scattering and Transport in Graphene Devices,” presented by Dr. Ray Sachs.

Abstract

Graphene has become a widely researched material since its discovery in 2004. It has interested scientists due to the exceptional electronic properties of the relativistic Dirac fermions. I will present the research I have done to study the charged impurity scattering mechanism in graphene by placing a device on high-κ material. An entire device with metal electrodes can be fabricated on SiO 2 substrates and transferred to any arbitrary substrate using a specially developed transfer method. This method eliminates the need to locate single layer graphene with optical microscopy for alignment and patterning on substrates other than 300 nm thick SiO2 which may be difficult. The target substrate used is 200 μm thick SrTiO3 (STO). With the dielectric constant two orders of magnitude higher than SiO2 at room temperature, we expected to observe an associated increase in the carrier mobility with the increased dielectric screening of charged impurities. The mobility is found to only be affected around the charge neutral 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.

Department of Physics