Quantum transport in two- and one-dimensional graphene

PhD ceremony: Ms. A. Veligura, 14.30 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Quantum transport in two- and one-dimensional graphene

Promotor(s): prof. B.J. van Wees

Faculty: Mathematics and Natural Sciences

In this thesis I present my work on quantum transport in graphene for the last 4 years. All studies were performed on graphene based FETs, where the electronic properties are controlled by tuning the position of the Fermi level in graphene with an applied electrical field.

I start by investigating the sensing capabilities of standard graphene FETs fabricated on a SiO₂ substrate. Because of the influence of the invasive substrate, concealing the intrinsic properties of graphene, such devices show a rather modest mobility of the charge carriers ( m <15,000 cm²V^-1s^-1). To overcome this problem, a new method of obtaining a FET based on free standing graphene membranes was developed. This allowed us to produce ultra-high mobility devices ( m <300,000 cm²V^-1s^-1) and investigate graphene’s electronic properties in the regime of a low concentration and a m m-long mean free path of the charge carriers. Using the developed method, we measured ballistic transport and quantized conductance in suspended graphene for the first time. The thesis is finalized with two chapters devoted to the studies of the magnetoresistance of suspended bilayer graphene and electron-electron interactions that can influence the electronic spectrum of such bilayer system.