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Institute of Solid State Physics

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Master Projects

Autonomous Driving for Nanocars

Machine Learning, Exp.-Theory Collaboration, STM, Surface Science

Description: In 2016, the Nobel prize has been awarded for “molecular machines”, tiny molecules which perform various tasks on surface. One interesting application are so-called “nanocars”, for which regular races are held where these nanomachines need to go over the surface to a specific location.

The major challenges for molecular machines in general, and nanocars in particular remains their handling on the surface. Often, this is done by positioning an STM tip close the molecule and then applying a specific electric impulse. However, since the physics are not yet fully understood, the process is mostly based on trial-and-error. Moreover, since there is little human intuition about the interactions of tips, molecules, and surfaces, the handling is often quite inefficient.

The task of this master thesis is to develop and apply a machine learning algorithm (based on supervised learning) that optimizes the manipulation of a nanocar and drives it autonomously across a racetrack. The work will be done in close collaboration with the experimental group of Leonhard Grill at the KFU. Can your code outperform their human driver?

We seek: Highly motivated, self-propelled students with an interest in solid state physics and computational material science. Basic knowledge of Matlab and/or Python is recommended.

Compensation: € 440,-- Forschungsbeihilfe for 6 months.

Contact: Oliver Hofmann o.hofmann@tugraz.at
Or talk to the students in office PH 02 152 (2nd floor, right by the stairs)

Advanced process nodes for analog radiation tolerant ICs

Advanced CMOS process nodes like 28 nm and 40 nm have been introduced in commercial products several years ago. Usage of these processes for high performance digital circuits is being continuously and broadly exploited. But their applicability for analog functions of mixed-signal systems is still to be further explored. In particular this is an interesting research are for particle physics experiments, where scaled down MOS transistor features could offer advantages for radiation tolerance, which is a subject of this project.

We are looking for a candidate interested in device physics and IC design

  • Getting familiar with general radiation effects in MOS transistors
  • Understanding key differences between 28 nm and previous CMOS generations
  • Identifying issues and potentials of 28 nm / 40 nm in analog applications for highly ionizing radiation environments
  • Literature research oriented towards process details and known radiation effects
  • 2D TCAD modeling and analysis of PMOS and NMOS transistor
  • Process studies in Cadence environment based on documentation and simulations, including representative design examples
    Organizational matters
  • Begin: February 2019
  • Working place: IFE/TU Graz, Innfeldgasse 12
  • Employment as Studentische Projektmitarbeiter 20h/week (~1500 Euro/month) for at least 4 months.

Contact: Alicja Michalowska-Forsyth (alicja.michalowska@tugraz.at)

Modeling and Characterization of Semiconductor Devices at Cryogenic Temperatures

The objective of the master thesis is to investigate the behavior of semiconductor devices (resistors, MOS-transistors) in a CMOS-technology at temperatures below 20K. For this, both, simulations on a device-physics level and measurements of test devices should be performed. The simulations will be done in Synopsis TCAD using the latest models. Their results should clearly show the influence of temperature on electrical device properties like resistance, gain and bandwidth. Since semiconductor performance is usually not modeled in these regimes, advanced physical models can be implemented using a C++ API to account for effects not yet implemented in the software.

Initial device measurements and final model verification will be done using a cryostat and measurement equipment located in Villach. These measurements can be used to verify TCAD models and identify effects not yet accounted for in the setup.
Finally, SPICE models should be implemented for an analog simulator. These models will then be used to design circuits that operate at cryogenic temperatures in quantum computing applications.

The main tasks of this thesis work can be summarized as follows:

› Getting familiar with low-temperature effects in semiconductors including literature research
› Initial measurements of existing devices and identification of significant effects
› Getting familiar with TCAD simulations and proper setup
› Developing a TCAD setup that physically models relevant effects
› Verification of TCAD simulation results using measurements of real devices
› Implementation of a SPICE model that represents the device in an analog circuit

Infrastructure: Infineon provides access to the necessary software and technology information. Infineon also provides the possibility to participate on shared reticles in the targeted technologies (if time permits). Measurement costs (test structures, equipment time) are covered by Infineon.

The student is expected to be located in Villach for the duration of the thesis, however, agreements regarding working from home or Graz may be possible. Details upon the monthly salary for the student will be given by HR Infineon after a technical interview.

For further information, please contact Michael.Sieberer@infineon.com or p.hadley@tugraz.at.

Physical Interpretation of Machine Learning Results      >> more >>

The advent of Machine Learning methods has unlocked great potential in computational studies. In particular the exploration of surface structures, that was previously thought to be completely unfeasible, has surged in the recent years. At the same time, machine learning studies are often criticized for their lack of physical insight.

In this master project, we will investigate Bisphenol A aggregates on Ag(111). This system shows an interesting peculiarity: The molecules adsorb in two different ways. The rotational barriers between those two differ, such that one kind of molecules is immobile at room temperature, while the other remains mobile and cannot be sharply imaged in STM studies. The target of this thesis is to investigate the interface using an in-house developed machine learning algorithm and study the relative contribution of covalent, ionic, and van-der-Waals contributions, in order to provide an explanation for the difference between the two adsorption sites.

We seek: Highly motivated, self-propelled students with an interest in solid state physics and computational material science. Basic knowledge of Matlab and/or Python is recommended.

Compensation: € 440,-- Forschungsbeihilfe for 6 months.

Oliver Hofmann email: o.hofmann@tugraz.at
Tel: 0316 873 8964 http://www.if.tugraz.at/hofmann
Or talk to the students in office PH 02 152 (2nd floor, right by the stairs)

Modelling thermal transport in organic semiconductors      >> more >>

Goal: Development of atomistically motivated structure-to-property relationships for heat transport in organic semiconductors – a property, that is crucial for device operation, but is still largely unexplored such that the suggested studies can have a huge impact.

Details: The ability of a material to transport heat is of considerable importance even in cases where its main application is not thermal- related. Some examples where this property plays a central role include thermoelectricity, thermal barrier coatings, phase-change memory, heat-assisted magnetic recording, and extends to the general problem of thermal management of a wide variety of de- vices.

The main objective of the master thesis is to develop structure-to-property relation- ships for thermal transport in organic semiconductors, a cutting-edge research direction with potential applications in fields as varied as microelectronics, optoelectronics, catalysis, and porous materials.

The studies will be addressed by combining molecular dynamics and electronic structure calculations. The applicants should be interested in solid state physics, should have strong motivation for computer simulations, and should be willing to develop codes and scripts.

At the end of the master thesis, the students will have expertise in computa- tional methods for modelling thermal transport, and will have practical knowledge in electronic structure calculations and molecular dynamics. These methodologies constitute a powerful tool to study the electronic, structural and thermodynamic properties of materials.

Aside of the academic profits, we offer a very friendly work environment.

Starting date: any time
Compensation: 440 € per month for 6-8 months
Natalia Bedoya Martinez (bedoyamartinez@tugraz.at, Tel.:873-8465)
Egbert Zojer (egbert.zojer@tugraz.at; Tel.: 873-8475)

      >> more >>

The molecule HATCN is a strong electron acceptor that is commercially used in OLEDs to modify the property of metal substrates. Adsorbed on silver, this molecule shows unusual, fascinating physics. At low coverage, the molecule forms honeycomb patterns, which can be exploited as epitaxial growth template. When the coverage is increased, however, the first monolayer rearranges. This drastically changes the material properties, in particular the system’s work function.

At present only very little is known about the geometric and electronic structure of the rearranged, high- coverage phase. This is now at the focus of a joint efforts including the groups of Prof. Resel (TU Graz), and Prof. Fritz (University Jena), which will perform x-ray and low energy electron diffraction experiments and characterize the system via optical spectroscopy. The aim of this thesis is to provide complimentary computational insight to these experiments. Density-functional theory calculations will be performed in order to predict possible geometric structures, characterize the optical and vibrational properties, and understand the driving force that leads to the observed phase transition.

Oliver Hofmann
Email: o.hofmann@tugraz.at
Tel: 0316 873 8465

Deposition and Characterization of Dielectric Bragg Reflectors       >> more >>

Dielectric Bragg Reflectors (DBR) are commercially manufactured onto rigid substrates, using inorganic materials (e.g. SiO2, TiO2). Recently, organic DBR are under investigation because they allow creation of tunable optical properties. During the wet fabrication processes, the choice of polymers that can be alternated is limited by the condition that the solvents of the alternating materials need to be orthogonal. Our goal is to deposit the organic DBR completely from the vapor phase by an innovative technique called initiated Chemical Vapor Deposition (iCVD). iCVD does not require the use of solvent and allows precise control over layer thickness by coupling with laser interferometry. The polymers that will be alternated will have a large refractive index contrast, as for example Teflon (n≈1.38) and polystyrene (n≈1.59), so to achieve high reflectivity with a limited number of layers. The surface roughness, interfacial roughness, the thickness and the electron densities of each layer will be characterized by X-ray reflectivity (XRR). The results will be compared with ellipsometry and microscopy data.

Compensation: 6 month / 440€ per month

Dr. Anna Maria Coclite, Assistant Professor
Dr. Roland Resel, Associate Professor