Graphene on diamond (Bachelor/Master thesis)

The aim of this work is to combine two promising materials in many respects: Graphene and diamond. In order to take advantage of both allotropes of carbon the student will fabricate structured graphene layers on a diamond surface. This can be achieved by different approaches. These include a direct deposition of graphene on the diamond as well as the use of a catalyst. Afterwards, the layer quality will be verified by the measurement with a micro Raman confocal setup. The results will be used to determine the optimal parameter of the fabrication process.

Contact: Dr. Ralf Wunderlich

Nuclear hyperpolarization in diamond (Master thesis)

The nitrogen vacancy (NV) center in diamond is a defect with promising properties for quantum information processing, recently leading to many breakthroughs in this research field.
All applications of the NV center rely on the ease of electronic polarization by illumination at room temperature.
In this thesis, the swap of the NV polarization to nearby nuclear 13-C spin will be investigated in more detail.
To address this issue, diamond samples with different defect densities will be created by irradiation with high energetic electrons. Subsequently, the effect of different defect distances on the polarization transfer shall be studied.

R. Wunderlich et al. J. Phys.: Condens. Matter 30, 305803:1-6 (2018); DOI: 10.1088/1361-648X/aacc32.
R. Wunderlich et al. Phys. Rev. B 96, 220407(R):1-5 (2017); DOI: 10.1103/PhysRevB.96.220407.

Contact: Dr. Ralf Wunderlich

Nuclear hyperpolarization in silicon carbide (Master thesis)

Besides the nitrogen vacancy (NV) centers in diamond, vacancy related defects in silicon carbide (SiC) represent an alternative for a hyperpolarization source in a solid.
Objective of this thesis is the modification of SiC leading to a sufficient defect density for bulk nuclear hyperpolarization, detectable by nuclear magnetic resonance (NMR).

A.L. Falk et al. Phys. Rev. Lett. 114, 247603:1-6 (2015); DOI: 10.1103/PhysRevLett.114.247603.

Contact: Dr. Ralf Wunderlich

Spintronics in diamond (Master thesis)

Spintronics promises a fast switching and low energy consumption compered to today's semiconductor technologies. This is based on the realization of logical states by spin states instead of the electrical charge. This approach is already applied in all modern hard disk application.In this thesis the steps towards the detection of polarized electrons in diamond shall be taken.

Contact: Dr. Ralf Wunderlich

Upgrading a fluorescence setup for magnetic field dependent measurements (Bachelor thesis)

Using the technique of ion implantation, a great variety of elements of the periodic table can be incorporated in a solid state lattice creating certain defects. The magnetic field dependency of the fluorescence of defects in diamond is of particular interest. Such a dependency would give a hint to ODMR-active centers (ODMR = Optically Detected Magnetic Resonance). Task of the student is the planning and the setting up of a magnetic field unit, the calibration as well as first fluorescence measurements.

T. Lühmann et al. J. Phys. D: Appl. Phys. 51, 483002:1-24 (2018); DOI: 10.1088/1361-6463/aadfab.

Contact: Tobias Lühmann, M.Sc.; Dr. Ralf Wunderlich

Production of microwave resonance structures on diamond (Master thesis)

By means of ion beams or vapor deposition, antenna structures can be deposited in or on diamond. The microwaves generated in this way can then be read with NV centers. In this way, novel microwave receivers or radar systems can be built. The student's task is to plan and construct microwave receivers using NV centres in diamond.

M. Chipaux et al. Appl. Phys. Lett. 107, 233502:1-5 (2015); DOI: 10.1063/1.4936758.

Contact: Prof.Dr. Jan Meijer

Production of a current reference by means of colour centres in diamond (Master thesis)

Current standards are indispensable in safety systems such as airbags, measuring units or medical applications. These current standards generate a reference current which is compared with a sensor signal, e.g. to trigger the airbag. The constancy of the current reference is therefore vital in the truest sense of the word. So far, these current standards have been produced using silicon components. In silicon, however, metals can diffuse, making the components unusable. In diamond no substances diffuse, through NV centers it is possible to use quantum mechanical effects, which depend only on natural constants and therefore cannot be changed in time.  The aim is to build a functioning component for a current reference source and to measure its stability (temperature etc.).

Contact: Prof.Dr. Jan Meijer

Temperature measurement using colour centres in nanodiamonds (Master thesis)

The temperature distribution within a cell is still unknown and difficult to measure. To insert a probe into the cell, the sensitive cell membrane has to be disturbed. This leads to undesired side effects. It is also possible to measure only one point at a time and chemical reactions can be disturbed by the probe. Nanodiamonds are biocompatible, membrane-compatible and do not interfere with the cell, as many experiments have shown. The aim of this work is to use the line shift of colour centres to determine the temperature dependence. First, diamond plates with different color centers are investigated. Promising centers are then introduced into nanodiamonds.

Contact: Prof.Dr. Jan Meijer

Stress measurement in diamond based on colour centres

Colour centres in diamond (like the NV and SiV centres) promise new applications and technology for quantum information processing or quantum sensing. Stress-free diamonds and colour centres are necessary for reproducibility and scalability issues. In this work, colour centres will be locally implanted in diamond areas showing stress gradient, as revealed by birefringence measurements. The strain will be determined by optical spectroscopy of the implanted colour centres. Then, its effect on the formation and properties of different colour centres will be studied.

Contact: Tobias Lühmann, M.Sc.; Dr. Sébastien Pezzagna

Photocurrent-based study of defects in diamond

Colour centres in diamond promise new applications and technology for quantum information processing or quantum sensing. Optically detected magnetic resonance (ODMR) is at the heart of high-resolution high-sensitivity magnetic sensing. The implementation of electric readout of spin and charge states of single defects would allow a miniaturisation and large scale use of the devices. In this work, the photocurrents induced by ionisation of different colour centres and dopants in diamond will be studied, with the aim of building efficient Photocurrent-DMR (instead of Optically-DMR) protocols with single centre sensitivity.

Contact: Sascha Becker, M.Sc.; Dr. Sébastien Pezzagna

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