The project focuses on ultrathin 2D semiconductors that are of interest for application in field-effect transistors, light-emitting diodes, solar cells, photodetectors, lasers and sensors.
You will carry out spectroscopy on excitons and charge carriers in 2D nanosheets and superlattices of e.g. lead chalcogenides (PbX with X=S, Se or Te) and cadmium chalcogenides (CdX). These materials cover a wide range of dielectric constants, band gaps, and effective masses of electrons and holes. Variation of material composition and nanogeometry allows one to exploit effects of quantum confinement and to realize unusual optoelectronic properties. For instance, the electronic band structure for a honeycomb geometry exhibits a linear increase of the kinetic energy with wave vector instead of the classic quadratic increase, giving rise to highly mobile, massless Dirac carriers as in graphene.
You will study the formation, mobility and decay kinetics of excitons and charge carriers with femtosecond and nanosecond pump-probe laser techniques with optical and terahertz/microwave conductivity detection. You investigate interactions between excitons at higher density and possible formation of an electron-hole plasma.
At low temperature excitons may form a Bose-Einstein condensate and at higher density a crossover to electron-hole Cooper pairs can occur. You will study the formation and properties of these many-body phases in relation to the composition and nanogeometry of the materials.
You carry out experiments in the laboratory of prof. Laurens Siebbeles
www.cheme.tudelft.nl/om at Delft University of Technology in The Netherlands. The project is sponsored via a TOP grant from The Netherlands Organisation for Scientific Research (NWO) and will be conducted in collaboration with a PhD student performing synthesis with prof. Daniel Vanmaekelbergh (http://www.staff.science.uu.nl/~vanma101/) and a PhD student on theory with prof. Henk Stoof (http://www.staff.science.uu.nl/~stoof101/) at Utrecht University.
TU Delft offers an attractive benefits package and offers a Doctoral Education Programme aimed at developing your skills. Please visit www.phd.tudelft.nl for more information. As PhD student you will be given a contract for four years with a monthly salary in the range
€2191 to €2801 (excluding holiday allowance ~8%), while as a postdoc the contract is for three years with a salary depending on experience. Please e-mail your letter of application, CV and recommendation letters to L.D.A.Siebbeles@tudelft.nl.