PhD/Postdoc Positions in Solid State Physics
Stellenangebot vom 16. August 2018
The Department Physics of Correlated Matter (Prof. Dr. L. H. Tjeng) of the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany, is currently seeking to recruit a PhD student or a postdoctoral researcher for the project
All in-situ/ultra-high vacuum ionic liquid gating study on correlated thin films,
lead by Dr. Simone Altendorf. Electrostatic gating is a common approach to alter the properties of thin films. It is utilized in field effect transistors in which controlled and reversible changes in the carrier concentration of the channel material are induced by applied electric fields. The magnitude of the electric fields supported by conventional gate dielectrics, however, is limited by their dielectric properties; and the maximum possible field strength is often not sufficient to tune the charge carrier concentrations over a wide range to, for instance, induce phase transitions. This motivated gating experiments involving ionic liquids (IL). By replacing the insulating solid-state gates with an IL, much higher electric fields can be implemented due to the formation of an electric double layer at the IL–channel interface that supports higher fields. Consequently, field effect transistor devices that are based on ILs can, in principle, electrostatically induce much higher charge carrier densities in the transistor channel. These high carrier densities, in turn, can lead to the formation of novel phases with interesting properties.
It has been long assumed that a purely electrostatic charge accumulation is responsible for the IL gate-induced changes. However, many recent studies show that the observed gating effects in various oxide materials are not in agreement with a purely electrostatic picture, but rather related to electrochemical processes. The exact mechanisms are still being discussed and many contradictory results are being published. One important reason underlying these controversies might be a lack of purity in the experiments. Most ILs are known to be hygroscopic - they easily absorb water from the atmosphere which can considerably change their properties and significantly shrink the electrochemical window of the ILs. Thus, an extremely careful handling of the ILs is required. In most studies, however, at least the critical IL device preparation is done ex-situ.
The Department Physics of Correlated Matter has vast expertise in the growth (molecular beam epitaxy (MBE)) and characterization of high quality thin films all under ultra-high vacuum (UHV) conditions. The goal of this project is to facilitate and perform a true all in-situ/UHV IL gating study on oxide thin films to achieve a better understanding of the mechanisms governing the gate-induced effects.
The project will cover
- Upgrade of the existing UHV thin film system: Design/construction of an all under UHV setup for ionic liquid gating experiments including an in-situ sample and IL device preparation
- In-situ ionic liquid gating experiments
- MBE growth of thin films of strongly correlated materials
- In-situ characterization of thin films by electron diffraction (LEED, RHEED), photoelectron spectroscopy (XPS), electrical transport measurements, atomic force microscopy (AFM)
- Characterization of thin films by hard x-ray photoemission at the synchrotron (e.g. at SPring-8, Japan)
Your profile, skills and experience
- PhD position: Master’s degree in physics, with good knowledge of quantum mechanics
- Postdoc position: PhD in solid state physics
- PhD position: A solid background in thin film deposition methods, previous experience in UHV surface analysis techniques and in gating experiments would be a significant benefit.
- Postdoc position: A strong background in thin film deposition methods and good knowledge of UHV surface analysis techniques are essential. Previous experience in device characterization/gating experiments would be beneficial.
- Interest in planning, designing, and testing new experimental UHV setups.
- Criteria for admission include academic skills, motivation, commitment, creativity, communication skills, and very good knowledge of the English language.
Terms of employment
- The PhD position is on fixed-term contract for three years. The Postdoc position is on fixed-term contract for two years.
- The salary will be according to the conditions of the German federal labor agreement.
- The MPI-CPFS is an equal opportunity employer and encourages diversity.
Please send your complete application documents, including CV, motivation statement, recent transcripts, and two recommendation letters as a single pdf file to:
Dr. Simone Altendorf
Department Physics of Correlated Matter
Max Planck Institute for Chemical Physics of Solids