Experimental Nanophysics and Photonics

Final Thesis

The Kneissl research group currently has several bachelor's and master's theses available. Interested students are welcome to contact the scientific staff of the working group, especially Tim Wernicke and Michael Kneissl. On the list of past theses you can additionally find out what our bachelor and master students are currently working on. The AG Kneissl offers Master & Bachelor theses in the following research areas:

  • Epitaxy of nanostructures
  • Nanophotonic devices
  • Semiconductor surfaces and interface physics

Current topics for final thesis

Bachelorarbeiten

Current topics for bachelor thesis

Development of ohmic n-contacts on n-AlGaN layers with Al mole fraction composition higher than 80% (Bachelor)

Efficient deep UV LEDs emitting below 250 nm are essential for gas sensing applications. Ohmic contacts to n-AlxGa1-xN are extremely challenging for very high Al mole fractions mainly due to the low electron affinity and to limitations in the ionized donor concentration. This results in high operating voltages and resistive heating. In this project, we aim to sensibly reduce the contact resistivities as well as the Schottky behavior of our n-contacts on high Al content n-layers by further optimizing the thicknesses in a four-metal electrode V/Al/Ni/Au configuration and the rapid thermal annealing procedure.

Determination of polarization fields in III-nitride heterostructures using capacitance-voltage measurements (Bachelor).

Spontaneous and piezoelectric polarization fields in group III nitride heterostructures lead to lower efficiencies of LEDs and laser diodes in the blue, green and ultraviolet spectral regions. Despite the importance of the subject, both the strength and the orientation of these fields have not yet been determined without gaps, especially for different surface orientations. In this bachelor thesis a new approach to measure the polarization fields by means of capacitance-voltage measurements will be executed and quantified.

Temperature-dependent EL and IV measurements

The internal quantum efficiency and the injection efficiency are strongly temperature dependent. Within the scope of the work, temperature-dependent measurements are to be carried out in order to be able to make statements about quantum efficiency and injection efficiency from the temperature dependence.

Optical polarization of LEDs in the deep UV

By changing the valence bands, the optical polarization of UV LEDs changes from dominant TE to dominant TM emission. In addition, QW thickness, composition and barrier height influence the polarization. Within the scope of the work, a series of LEDs will be measured.

Masterarbeiten

Current topics for master thesis

The AG Kneissl consistently offers master theses. Interested students are welcome to contact the scientific staff of the group, especially Tim Wernicke and Michael Kneissl. Master theses are mainly assigned in the field of metal-organic vapor phase epitaxy (MOVPE). During the master thesis, independent work on the MOVPE equipment should be set up and the growth of AlGaN layers should be optimized by varying different parameters. These layers can then be investigated by standard characterization methods such as X-ray diffraction (XRD), atomic force microscopy (AFM) or even electroluminescence (EL). In the field of LED characterization, temperature-dependent electroluminescence (t-dep. EL), photoluminescence (PL), and Hall measurements can also be performed to gain detailed insight into the properties.

Ansprechpartner für eine Abschlussarbeit

Building EW
Room 640
Address Hardenberg Str. 36
10623 Berlin