Fabrication and opto-electrical characterization of honeycomb semiconductors

Sponsor:       NOW Toppunt, since April 2016

Supervisors:  prof. dr. Daniël Vanmaekelbergh

Graphene is a two-dimensional (2D) flat material which exhibits fascinating physical properties due to its honeycomb lattice structure. Calculations [1] and experiments [2] have shown that charge carriers have a linear energy dispersion (Dirac cones) near the corners of the Brillouin zone, indicating that they behave like massless particles. These fundamental properties result in interesting optical and electrical features.

My research will focus on the fabrication and characterization of artificial graphene by nano pattering inside a high mobility 2D electron gas (2DEG) confined in an InGaAs/InAlAs quantum well (QW). Electron beam (e-beam) lithography is used to create a mask with a honeycomb structure, which will be used to etch inside the surface of the sample. Main goal of this project aims at revealing Dirac cones in the band structure of the electrons by performing low-temperature transport measurements and local-probe spectroscopy in scanning tunneling microscopy measurements. When Dirac cones are obtained, other interesting electrical and optical properties can be investigated.

In parallel, block copolymer (BCP) lithography will be further developed on this material to reach lattice dimensions which are not accessible with e-beam lithography. Using this technique, other lattices types (kagome, Lieb) could be fabricated and investigated.

This research is performed in collaboration with the institute d’electronique, de microelectronique et de nanotechnologie (IEMN) at Lille, France.

[1] A. Castro Neto et al., Reviews of Modern Physics 81, 109-162 (2009)

[2] K. Novoselov et al., Nature 438, 197-200 (2005)