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Institut für Festkörperphysik

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Bachelorprojekte

A bachelor project serves as an introduction to scientific research. During this project, 4 weeks are spent in a research laboratory (150 hours, 6 ECTS). At the conclusion of the research, a report about the results is written and a 20 minute public presentation is given. The time necessary to write the report and prepare the presentation are included in the 150 hours.

A true scientific publication must be original work; it should describe scientific results that have never been reported before. Ideally, a bachelor report should have the character of a scientific publication. A bachelor report is not intended to be a review of work done by others.

A scientific publication should begin with a short and clear description of what was done, why it was done, and what the main results are. It is not a novel where the reader should be kept in suspense until the last page. Tell the ending on the first page and then use the rest of the report to fill in the details.

After the initial statement of your own results, give the reader some background information. All scientific projects build on the work of others. You should make it clear what the state-of-the-art was at the start of your project. This section should be brief, no more than about 3 pages. Provide the reader with references to books or articles that describe your research topic in more detail.

The bulk of a bachelor report should contain a discussion of the scientific issue you attempted to resolve, the methodology you used, a presentation of the data, and a discussion of the results. The recommended length of the report is 15-25 pages.

The TU will scan all master and PhD theses electronically for plagiarism. While there is currently no plan to systematically scan the bachelor theses, everything in electronic form might be scanned at some time. It should be clear from the way the references are placed which ideas you claim as your own and which you have taken from others.

To protect the privacy of students, the university does not publish a list of student names or email addresses. However, when a bachelor student works in our institute, we typically list their names and email addresses on our institute website. This makes it easier for members of the institute to contact each other. If you do not want to be listed on the website, please inform the secretary when your project starts.

A list of possible bachelor projects is given below. There is a certain flexibility in defining bachelor projects. You may propose the topic of a bachelor project to a member of the scientific staff. If you have questions about bachelor projects at the Institute of Solid State Physics, please contact Peter Hadley.

Some bachelor reports that have been completed in our institute can be found here.

Richtlinien zur Erstellung einer Bachelorarbeit im Bachelorstudium Technische Physik

Structure Search At Interfaces / Machine Learning      >> mehr >>

Description: We are currently developing our own algorithm to determine the geometric structure at inorganic/organic interfaces. This program employs machine learning techniques to establish the potential energy surface of organic/inorganic interfaces based on only a small number of density functional theory calculations. We are looking for highly motivated Bachelor students that are interested in computational physics, programming or method development and that would like to tackle projects that are directly relevant for our current research efforts. No specific skills or knowledge is required, but familiarity with Linux and basic programming experience (ideally Python) is recommended. Available topics include:

Explore, Expand, Exploit, Exterminate (Optimize Search Strategy)
Our algorithm explores the potential energy surface as evenly as possible. The data generated is then exploited (via machine learning) to sample and refine the predicted low-energy configurations. Both parts (exploration and exploitation) are computationally very expensive. The performance of the algorithm thus critically depends on finding a good ratio between those two, as well as using a good exploration strategy. Within this topic, we will critically assess exploration vs. exploitation for a variety of test systems, and determine a strategy to choose an optimal training set for a given budget of CPU time.

High-performance polymorphs (Machine Learning for various properties)
The same material can exhibit huge differences in its properties depending on the polymorph it assumes. To gauge the potential of a material for practical applications, it is often important to find what the “best” polymorph for a given property would be, even if it is not the energetically most favorable structure. The task in this project is to modify our algorithm such that it optimizes properties other than the energy and predicts, e.g., polymorphs with high interface dipoles or large charge-transport mobilities.

Molecular Lego
Finding out how molecules adsorb on a surface is a challenging task on its own. Research groups all around the world are developing methods to exploit the potential energy surface with advanced methods such as genetic algorithms, basin hopping and Gaussian process regression. We take this task a step further and project the energies onto meaningful building blocks of the molecule. This allows us to identify the main interacting parts of the molecules and in the future exchange building blocks to favorize specific adsorption positions. We search for bachelor students who want to improve the algorithm or apply it to a new set of molecules. 

Transition Rates and Barriers (Metastable Phases)
Some of the most interesting materials are not thermodynamically stable, but only kinetically trapped by (more or less) large reaction barriers. Developing new materials therefore requires not only finding structures with outstanding properties, but also knowledge about their expected lifetime. A rough estimate of the barrier height can be obtained by calculating the vibrational properties of different structures and determining their intersection. The task of this bachelor thesis is to assess the quality of this approximation for a selected example

Hessian Learning and Geometry Optimization
One of the key factors determining the efficiency of geometry optimization at the quantum-mechanical level is the initial guess of the Hesse matrix, i.e. the second derivative of energy with respect to atomic displacements. Most contemporary algorithms are designed for molecules or solid crystals in mind, but yield poor results for interfaces. The task of the present topic is to use machine-learning approaches to create an improved Hesse-Matrix guess for specific polymorphs based on pre-calculated Hesse-Matrices of other structures.

Teaching Atom Species to Machine Learning
Let us assume we have two molecules, i.e. a dimer, and wish to know their interaction energy: Of course this energy depends on their relative positions and orientations. We can calculate the energy for a limited number of positions and orientations, but attaining the full picture requires the use of machine leaning. Machine learning of molecular interactions relies on descriptors that depend on the relative positions and orientations and allow us to compare different dimers. We have developed such a descriptor based on radial distance functions. However, as of yet it does not account for different atoms species. This is where you come in! Help us to improve our machine learning model by implementing atom species dependence.

Contact:
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)

Performancevergleich zweier Moleküle bei der Messung eines FRET Signals      >> mehr >>

Bei Förster Resonanz Energie Transfer (FRET) interagieren zwei unterschiedlich fluoreszente Moleküle, ein Donor und ein Akzeptor, über Dipol Wechselwirkung und übertragen Energie. Kurz gesagt regt man den Donor an und misst ein Akzeptorsignal das nur von FRET stammen kann. Ohne zu tief in die Theorie zu gehen hängt FRET vom Überlapp der Fluoreszenzspektren der beiden Moleküle ab wie es in Abbildung 1 zu sehen ist. Durch die Wahl zweier verschiedener Moleküle wird erreicht, dass die Signale weiter voneinander getrennt werden und es so später, im angewendeten Algorithmus zur Auswertung, zu einer einfacheren Interpretation der Ergebnisse führt.
In dieser Arbeit wird ein System untersucht wie es in Abbildung 2 zu sehen ist. Zwei Papierfasern werden mit verschiedenen Molekülen (Donor und Akzeptor) gefärbt und physikalisch gebunden. Anschließend wird das System über ein Mikroskop mit verschiedenen Filtersätzen untersucht und die resultierenden Bilder werden mit einem bestehenden Algorithmus bearbeitet und analysiert.
Ziel der Arbeit ist es zu sehen ob durch die geschickte Wahl zweier Moleküle eine einfachere Interpretation der Ergebnisse möglich gemacht werden kann.

Untersuchung der Verbesserung eines Signales durch die Anwendung von Korrekturfaktoren      >> mehr >>

Bei dieser Arbeit geht es darum zu untersuchen ob sich die Qualität des Signals einer Messmethode durch die Anwendung von Korrekturfaktoren verbessern lässt. Das gemessene Signal kommt von Förster Resonanz Energie Transfer (FRET). Bei diesem Effekt können zwei unterschiedlich fluoreszente Moleküle, ein Donor und ein Akzeptor, über Dipol Wechselwirkung Energie übertragen. Das resultierende Signal wird nach der Messung mit einem Algorithmus (Matlab) getrennt um herauszurechnen wie viel des Signales tatsächlich von FRET kommt. In dieser Arbeit wird ein System untersucht wie es in Abbildung 1 zu sehen ist. Zwei Papierfasern werden mit verschiedenen Molekülen (Donor und Akzeptor) gefärbt und physikalisch gebunden. Anschließend wird das System über ein Mikroskop mit verschiedenen Filtersätzen untersucht und die resultierenden Bilder werden mit dem oben genannten Algorithmus bearbeitet und analysiert. Ziel der Arbeit ist es zu sehen ob der Algorithmus mit Korrekturfaktoren zu einer signifikanten Verbesserung des Signals führt gegenüber dem Algorithmus ohne Korrekturfaktoren.

Molecular Packing Determination on Basis of Molecular Dynamics Simulations       >> mehr >>


The prediction of crystal structures of molecular material is an important topic in modern pharmaceutical research. Here we test a software package which uses the geometry of the crystallographic unit cell as well as the molecular geometry as input parameter to determine the molecular packing. A couple of examples will be taken from known crystal structures to test the algorithm of molecular packing determination by Molecular Dynamics simulations.


CONTACT: Roland Resel (roland.resel@tugraz.at)

Messungen von Nanopartikeltransport durch Sackpapier

Im Rahmen dieser Arbeit soll eine Messmethode zum Tranport von Nanopartikeln durch Filterpapiere, die von Prof. Bergmann vom Institut für Elektronische Sensorsysteme entwickelt wurde, auf Sackpapiere angewendet werden. Dabei sollen verschiedene Arten von Nanopartikeln in Bezug auf den Transport durch Sackpapier untersucht werden.

Kontakt: Robert Schennach

Computational project: Surface Polymorph Formation      >> mehr >>

Thin film and monolayers of organic molecules assume morphologies that do not occur in the bulk material, but exhibit properties that are superior for certain applications. Whether such surface-induced phases form depends strongly on the substrate used as well as the deposition conditions. In this computational project, we will study how different external factors, such as the dielectric constant of a solvent or the electron chemical potential (i.e., the Fermi-level) provided by the substrate, affects the relative stability of experimentally known bulk- and surface-induced phases. The target of this work is to identify systems that are particularly sensitive and will be used for further research in the group.

Measuring the doping concentration in semiconductor devices      >> mehr >>

Most semiconducting transistors contain regions that have been doped n-type and regions that have been doped p-type. In this project, capacitance-voltage measurements will be used to determine the doping concentrations od diodes, MOSFETs and JFETs. To quantify the measurement errors that are made, the frequency dependent noise behavior of the current preamp will be measured and a Fourier analysis of the noise will be performed. The instruments will be controlled with a Python script. Contact p.hadley@tugraz.at

Elektrostatisches Deseign neuartiger Materialien      >> mehr >>

Organische Halbleitermaterialien sind eine viel versprechende Materialklasse für Anwendungen im Bereich von Bildschirmen, Raumbeleuchtung, Solarzellen, elektronischen Bauelementen, Sensoren, aber auch molekularer Elektronik. Eine große Stärke der organischen Halbleitermaterialien ist dabei, dass sich ihre Eigenschaften effizient durch chemische Variation der Struktur der verwendeten Moleküle verändern lassen. Im Rahmen der hier vorgestellten Bachelorarbeit(en) [zum beschriebenen Themenkomplex lassen sich mehrere, voneinander unabhängige Projekte definieren] soll mit Hilfe quantenmechanischer Simulationen (unter Verwendung existierender Codes) untersucht werden, inwiewit auch "physikalische Effekte" zu einer gezielten Steuerung der Materialeigenschaften eingesetzt werden können. Dazu soll durch den Einbau wohl definierter dipolarer Gruppen in verschiedene Moleküle die Potentiallandschaft, die die Elektronen in den Materialien "spüren", gezielt manipuliert werden. Kontakt: Egbert Zojer

Herstellung und Charakterisierung von organischen photovoltaischen Bauelementen      >> mehr >>

The reliable and cost-efficient manufacturing of organic photovolatic cells is the prerequisite for their potential application in industrial photovoltaics. Highly efficient double-layer cells can be fabricated by sequential dip-coating of differently solvable conjgated polymers. The power efficiency of such cells can be optimized by an electronic tuning of the polymer thin films either by doping with fullerene type dopants or by the coplymer blend technique. This new organic photovoltaic cells are characterized concerning their essential parameters. Contact: g.leising@tugraz.at

Wachstum und Charakterisierung von dünnen organischen Filmen mit dip-coating       >> mehr >>

Dip-coating is an overlooked high-tech approach to manufacture highly controlled and defined thin films of conjugated polymers. The precondition for a successful application of this technique is the basic understanding and control oft he deposition process and a deeper understanding of the nature of the film forming parameters. Prestudies support the high potential of this thin film technique with the perspective of application for large area manufacturing for organic electronics and organic optoelectronics. Contact: g.leising@tugraz.at

Wachstum und Charakterisierung von neuartigen einkristallinen organischen Halbleitern      >> mehr >>

g.leising@tugraz.at

Quantum-Kaskaden Laser für moderne Specktroskopie      >> mehr >>

Quantum-Cascade Lasers (QSL) are a new and high-tech approach in the area of mobile spectroscopy. The strongly icreasing demand in the segments like enviromement (water and air quality), health (near patient testing) and food control, to name a few, is met by the availablity of new spectroanalytic strategies. Du to their wavelength tunability, QSL offer the opportunity to collect spectra of gases, liquids and solids without the need of dispersive element (grating, prism). A series of bachelor projects is offered in this area.
Contact: g.leising@tugraz.at