Theses in the RG of Prof. Oestreich

Our research group offers a variety of bachelor and master theses in the fields of spin and charge carrier dynamics in complex semiconductor nanosystems. In the following you can find an overview on recent theses topics as well as on completed theses.

Students are invited to contact us to discuss possible bachelor or master theses. Depending on your field of study we try to find a suitable and interesting topic.

Furthermore we can offer the possibility for a complementary internship. The subject matter of the internship can be closely connected to a thesis.

RECENT THESES TOPICS

  • Transient Absorption Spectroscopy of Transition Metal Dichalcogenides

    TRANSIENT ABSORPTION SPECTROSCOPY OF TRANSITION METAL DICHALCOGENIDES

    Background

    Transition metal dichalcogenide (TMD) monolayers exhibit unique optical properties and are therefore promising candidates for the application in the fields of “spin-“ and “valleytronics”.

    Our research group provides the following comprehensive possibilities for the investigation of such TMD monolayers: fabrication of high-quality TMD monolayers (in collaboration with the LPCNO Toulouse and the research group of Dr. Jannika Lauth), standard measurement techniques like photoluminescence and reflectivity measurements  and complex measurement techniques like the valley noise spectroscopy and the Transient Absorption Spectroscopy.

    The state-of-the-art broadband transient absorption spectrometer is operated in collaboration with the Department for Functional Nanostructures (Lauth/Bigall/Dorfs) and allows for the comprehensive  investigation of the nature, origin and dynamics of photoexcited charge carriers.

    This project will be about the modification of this Transient Absorption Spectrometer and the subsequent investigation of various TMD monolayers. Supervision will be done by a PhD student.

    The results of this experiment are highly required and will influence  any further research of TMD monolayers. So the applicant will be  able to cutting edge research in the field of quantum optics and  semiconductor physics of nanostructures.

    Aim

    The aim of this project is the implementation and examination of an extension of the existing transient absorption spectrometer to create new characterization possibilities for various TMD monolayers.

    Tasks

    The main task of this project is the planning and implementation of a modification of the original transient absorption spectrometer. Subsequent to the modification of the setup manifold characterization measurements on different types of TMD monolayers will be performed.

    In addition the fabrication process (chemical synthesis and exfoliation) and the complete range of characterization measurements (including the valley noise spectroscopy) can be attended.

    Prerequisites1

    - A background in Physics, Nanotechnology or similar

    - A good understanding of geometric, Gaussian and nonlinear optics

    - 3D-thinking, parametric CAD (Inventor/Solidworks) or similar drawing skills

    - A structured way of working and the ability to solve problems independently

    - Adequate English language skills

    What we offer

    - The chance to work in an interdisciplinary and multinational project

    - The opportunity to work in one of the most promising research fields of quantum optics

    - The student will be handed a distinctive experimental setup to work on

    - The chance to gain experience in working with cryogenic gases, a state-of-the-art transient absorption spectrometer, an amplifier laser system  and several other parts of modern semiconductor research

    - A friendly working atmosphere to gain self-employed experimental experience and getting in touch with modern science

    - Personal supervision over the whole project time

    Person of contact: André Frauendorf (frauendorf@nano.uni-hannover.de)

    This thesis topic is suitable for both a bachelor or a master thesis.

    TEM image of Transition Metal Dichalcogenide monolayers (fabricated via chemical synthesis).
    Schematic image of the principle of the Transient Absorption Spectroscopy.
    Typical spectrum of the Transient Absorption Spectroscopy.

    1 Many of these prerequisites are helpful to have, but not strictly necessary. You will receive help and will have the possibility to learn these skills during this project.

  • Spin Manipulation in isotopically enriched silicon

    SPIN MANIPULATION IN ISOTOPICALLY ENRICHED SILICON

    The search for spin based quantum technology has led to the discovery of many material systems such as phosphorus atoms inside an isotopically enriched silicon lattice. Participating in this work gives you the opportunity to dive into the leading edge research on this specific material.
    The ultimate goal of the experiments is implementing a two-qubit device using an ensemble of phosphorus atoms and an electron magnetic resonance technique.

    This thesis is suited for the fields of:
    1. Physics
    2. Nanotechnology

    Person of contact: Eduard Sauter (sauter@nano.uni-hannover.de)

    This thesis topic is recommended for a master thesis.

  • Comparative study of Spin Noise Spectroscopy on single Quantum Dots

    COMPARATIVE STUDY OF SPIN NOISE SPECTROSCOPY ON SINGLE QUANTUM DOTS

    Background

    This project will be about the investigation of single InGaAs or GaAs quantum dots at liquid helium temperatures. This project is directly related to recent publications1,2 about adressing a single hole spin in InAs quantum dots using spin noise spectroscopy.

    The applicant will have his own setup to work on (potentially the same setup as from the publications) which offers a state of the art measurement scheme. Supervision will be done by a PhD student.

    The results of this experiment are highly required and will influence any further research of single quantum dots. So the applicant will be able to cutting edge research in the field of quantum optics and semiconductor physics of nanostructures.

    Aim

    The aim of this project is a comparative study of different measurement schemes for spin noise spectroscopy of individual InGaAs quantum dots.

    Tasks

    The original setup should be modified to enable two different and independent background subtraction schemes. After that the comparative measurements between the two schemes should be performed and the results evaluated.

    Prerequisites3

    - A background in Physics, Nanotechnology or similar

    - A good understanding of geometric and Gaussian optics

    - 3D-thinking, parametric CAD (Inventor/Solidworks) or similar drawing skills

    - A structured way of working and the ability to solve problems independently

    - Adequate English language skills

    What we offer

    - The student will be handed a distinctive experimental setup to work on

    - The chance to gain experience in working with cryogenic gases, a Ti:Sa laser and several other parts of modern semiconductor research

    - A friendly working atmosphere to gain self-employed experimental experience and getting in touch with modern science

    - Personal supervision over the whole project time

    Person of contact: Kai Hühn (huehn@nano.uni-hannover.de)

    This thesis topic is suitable for both a bachelor or a master thesis.

    Fig. 1: Photoluminescence of individual InGaAs quantum dots
    Fig. 2: Photoluminescence spectrum of an individual InGaAs quantum dot

    3 Many of these prerequisites are helpful to have, but not strictly necessary. You will receive help and will have the possibility to learn these skills during this project.

  • Closed Loop Positioning on the Nanoscale

    CLOSED LOOP POSITIONING ON THE NANOSCALE

    Background

    Nanoscale quantum systems are a wide research field with possible future applications in quantum computing and quantum communications. Quantum systems that are accessible using optical means are particularly interesting as a bridge between photon-based and semiconductor-based or solid state-based quantum circuits. To achieve a high degree of reproducibility while investigating such tiny systems an utmost precise position control of the optical setup is necessary. An additional challenge are the ultra low temperatures that are necessary for semiconductor-based quantum dots.

    Aim

    The aim of this project is the implementation of an interferometric readout for the nanoscale and the characterization of positioning reproducibility of a cryogenic confocal microscope.

    Tasks

    To this end, the already existing confocal microscope setup should be augmented by a commercially available two-axis interferometric readout for the integrated nano-positioning stages. The control software has to be changed to utilize the output from the interferometric position readout. Finally repeatability measurements should be taken to ensure proper function of the setup.

    Prerequisites3

    - A background in Physics, Nanotechnology or similar

    - A good understanding of geometric and Gaussian optics

    - 3D-thinking, parametric CAD (Inventor/Solidworks) or similar drawing skills

    - Programming skills in C++, Rust and/ or Python

    - A structured way of working and the ability to solve problems independently

    - Adequate English language skills

    What we offer

    - The student will be handed a distinctive experimental setup to work on

    - A friendly working atmosphere to gain self-employed experimental experience and getting in touch with modern science

    - Personal supervision over the whole project time

    Person of contact:  Pavel Sterin (sterin@nano.uni-hannover.de

    This thesis topic is suitable for both a bachelor or a master thesis.

    Fig. 1: Photoluminescence of individual InGaAs quantum dots
    Fig. 2: Proposed Changes to the Setup
    Fig. 3: Current State of the Setup

    3 Many of these prerequisites are helpful to have, but not strictly necessary. You will receive help and will have the possibility to learn these skills during this project.

PERSON OF CONTACT

Prof. Dr. Michael Oestreich
Professors
Address
Appelstraße 2
30167 Hannover
Building
Room
021
Prof. Dr. Michael Oestreich
Professors
Address
Appelstraße 2
30167 Hannover
Building
Room
021
PD Dr. Jens Hübner
Other Teachers/Employees
Address
Appelstraße 2
30167 Hannover
Building
Room
125
PD Dr. Jens Hübner
Other Teachers/Employees
Address
Appelstraße 2
30167 Hannover
Building
Room
125

RECENT TOPICS FOR INTERNSHIPS

  • Nuclear magnetic resonance

    NUCLEAR MAGNETIC RESONANCE

    You will have the opportunity to learn the principles of a two level quantum system which is at the basis of quantum computation. The experiment consist of manipulating the nuclear spin of hydrogen atoms inside different molecules and measuring the spin dynamics. Applications for nuclear magnetic resonance can be found in Physics, Chemistry, Medicine. This Thesis also provides the basics to understand more advanced spin systems.

    This internship is suited for the fields of
    1. Physics
    2. Nanotechnology

    Person of contact: Eduard Sauter (sauter@nano.uni-hannover.de).

COMPLETED THESES

  • 2020

    Theses:

     

    Master theses:

    • Liza Anika Lengert: Spin Noise Spectroscopy on Single Quantum Dots at Telecom Wavelength

     

    Bachelor theses:

    • Lennard Rötz: Installation eines Tieftemperaturmessplatzes für zeitaufgelöste Photolumineszenz-Spektroskopie an GaAs
    • Maximilian von Baron: Ultrasensitive Spinrauschspektroskopie mittels phasenmodulierter homodyner Detektion
  • 2019

    Theses:

    • Michael Beck: Optical spectroscopy of donor bound excitons and spin relaxation of donor electrons in isotopically enriched silicon
    • Julia Susan Wiegand: Nonequilibrium Spin Noise Spectroscopy on Single Quantum Dots


      Master theses:

      • Kai Jannik Hühn: Spinrauschspektroskopie am einzelnen InGaAs Quantenpunkt
      • André Philipp Frauendorf: Valley- & Spinrauschspektroskopie an Übergangsmetalldichalkogenid- Einzellagen

       

      Bachelor theses:

      • Marco Bonkowski: Optische Messungen der Ladungsträgerlebenszeit in intrinsischem Silizium
    • 2018

      Theses:

       

      Master theses:

      • Eduard Sauter: Spin-Dynamics in Semiconductors
      • Selina Volkert: Konzeption, Aufbau und Evaluierung einer Pound-Drever-Hall basierten Laserfrequenzstabilisierung für hochauflösende Spektroskopie an isotopenreinem Silizium


      Bachelor theses:

      • Nico Meinck: Spektralanalyse eines aktiven Schwingungsisolationssystem für einen optischen Tisch
      • Julia Sziedat: Spectroscopy of two-dimensional materials
      • Liza Lengert: Spindynamik in n-dotierten Halbleitern
    • 2017

      Theses:

      • Jan Gerrit Lonnemann: Einfluss der Ladungsträgerdynamik auf die Spinrelaxation in GaAs


      Master theses:

      • Magnus Neumann: Photolumineszenzspektroskopie von WSe2 Einzellagen mit hoher Ortsauflösung

       

      Bachelor theses:

      • Jakob Moritz Osberghaus: Spinrauschspektroskopie am einzelnen Quantenpunkt
    • 2016

      Theses:

      • Hendrik Arne Kuhn: Optische Untersuchungen an extern verspannten Indiumgalliumnitrid Quantenfilmen und der Spindynamik in hoch n-dotiertem Galliumarsenid
      • Fabian Berski: Elektronen- und Kernspinrauschen in n-Galliumarsenid


      Master theses:

      • Pavel Sterin: Präzise Stokes-Polarimetrie von magnetooptischen Effekten zweiter Ordnung in Galliumarsenid

       

      Bachelor theses:

      • Kai Jannik Hühn: Optische Untersuchung von YAG:Ce3+
      • André Philipp Frauendorf: Spinrauschspektroskopie an kunstlichen Atomen
      • Eduard Sauter: Spin Dynamics in Type-II GaAs/AlAs Quantum Wells
      • Michael Steiniger: Laserfrequenzstabilisierung mittels Pound-Drever-Hall-Verfahren