Designer materials on demand: honeycomb semiconductors by lithographic design

Abstract

Graphene is a one-atom thick layer of carbon which are arranged in a two-dimensional honeycomb symmetry. Although this material holds tremendous electrical properties due to its high charge carrier mobility and electrical conductivity, it cannot be applied directly into classical transistors since it cannot be ‘switched off’. Since the electronic structure of graphene only depends on the nanosymmetry inside the material, it can be ‘inserted’ into other materials, such as classical semiconductor materials used in electronic devices. This research investigates the possibility to fabricate honeycomb semiconductors: semiconductor materials with a honeycomb nano geometry, implementing the graphene-like electrical properties into the electronic structure of a two-dimensional semiconductor material. The honeycomb semiconductors are fabricated using lithography, creating a hexagonal array of pores into the two-dimensional semiconductor. Since this technique is widely used in the semiconductor industry, direct application into electrical devices is a possibility. This thesis describes the design, fabrication, and the electronical characterization of a honeycomb semiconductor, and discusses the obtained results using a theoretical ‘muffin-tin’ model. This research shows a prospect to creating designer materials: materials in which scientist have full control over it’s (electrical) properties by using different materials, different symmetries and/or different dimensions.