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Universität Leipzig

Faculty of Physics and Earth Sciences

Felix Bloch Institute for Solid State Physics

Semiconductor Physics Group

Topics for Bachelor and Master Theses



Please inquire more details about these topics from Prof. Grundmann or other members of the Semiconductor Physics Group. Depending on your interests, your thesis will have a focus on thin film fabrication, the investigation of structural, electrical or optical properties or device work. Also, the topics range from fundamental aspects of quantum structures and light-matter coupling all the way to practical work in electronics. Consult our research profile for an overview.

 
 

Master thesis

 

Sputter deposition of amorphous oxynitride semiconductors

More information The disorder on the anion lattice of amorphous metal-oxynitride semiconductors (such as ZnON) is more favorable for high electron mobility than the more common disorder on the cation lattice (such as in zinc-tin-oxide). Using sputtering, (Zn,Mg)(O,N) compound thin films shall be fabricated. The goal is the simultaneous optimization of high optical transparency and large electron mobility.

Further information about our previous work in this field:

A. Reinhardt, H. Frenzel, H. von Wenckstern, D. Spemann, M. Grundmann
Electron transport mechanism in rf-sputtered amorphous zinc oxynitride thin films
phys. stat. sol. (a) 213, 1767 (2016) | doi

S. Bitter, P. Schlupp, H. von Wenckstern, M. Grundmann
The Vital Role of Oxygen for the Formation of Highly Rectifying Schottky Barrier Diodes on Amorphous Zinc-Tin-Oxide with Various Cation Composition
ACS Appl. Mater. Interfaces 9, 26574 (2017) | doi

 

Carrier modulation and structure distortion of CuI by anion doping

More information Copper iodide (CuI) has been regarded as one of the best transparent p-conductive and thermoelectric materials. The substitution of the monovalent I atoms, e. g. by divalent O, S, Se or Te ions, will allow band structure engineering for control of electrical and thermal transport properties. The structure distortion of zinc-blende CuI will be investigated considering the octahedral configuration of divalent anions, which may induce novel physical phenomena in CuI-based material system.

Further information about our previous work in this field:

C. Yang, D. Souchay, M. Kneiß, M. Bogner, H. M. Wei, M. Lorenz, O. Oeckler, G. Benstetter, Y.Q. Fu, M. Grundmann
Transparent Flexible Thermoelectric Material Based on Non-toxic Earth-Abundant p-Type Copper Iodide Thin Film
Nature Commun. 8, 16076 (2017) | doi

C. Yang, M. Kneiß, M. Lorenz, M. Grundmann
Room-temperature Synthesized Copper Iodide Thin Film as Degenerate p-Type Transparent Conducting Material with a Boosted Figure of Merit
PNAS 113, 12929-12933 (2016) | doi

 

Electrical and optical properties of (Cu,Ag)I solid solution thin films

More information Halide compounds such as CuI and AgI are promising semiconductor materials as a result of their superior optoelectrical properties. We have already demonstrated the superior performances of CuI as a p-type transparent conductor and a transparent thermoelectric material. However, semiconducting AgI is scarcely investigated because of its poor air-stability under light. The photodecomposition of AgI could be inhibited in the form of solid solutions. Hence, we will investigate the solid solution of CuI and AgI by co-sputtering technique for improvement of electrical, thermal and also ionic conductivities. Also the band structures of the solid solutions will be investigated for optoelectronic applications.

Further information about our previous work in this field:

C. Yang, D. Souchay, M. Kneiß, M. Bogner, H. M. Wei, M. Lorenz, O. Oeckler, G. Benstetter, Y.Q. Fu, M. Grundmann
Transparent Flexible Thermoelectric Material Based on Non-toxic Earth-Abundant p-Type Copper Iodide Thin Film
Nature Commun. 8, 16076 (2017) | doi

M. Grundmann, F.-L. Schein, M. Lorenz, T. Böntgen, J. Lenzner, H. von Wenckstern
Cuprous Iodide - a p-type transparent semiconductor: history and novel applications
phys. stat. sol. (a) 210, 1671 (2013) | doi

 

Epitaxy and bandgap engineering of (Ga,In)N solid solutions using PLD

More information GaN and InN have rather different optimal growth parameters. Using our combinatorial PLD approach, material gradients of GaN-(Ga,In)N shall be fabricated and investigated.

H. von Wenckstern, M. Kneiß, P. Storm, M. Grundmann
A review of the segmented-target approach to combinatorial material synthesis by pulsed-laser deposition
Phys. Status Solidi B XXX, 1900626 (2019) | doi

H. von Wenckstern, Z. Zhang, F. Schmidt, J. Lenzner, H. Hochmuth, M. Grundmann
Continuous composition spread using pulsed-laser deposition with a single, segmented target
CrystEngComm 15, 10020 (2013) | doi

 

Epitaxy of Al2O3 and (Al,Ga)2O3 solid solutions

More information We want to grow epitaxial Al2O3 on native substrate in various orientations (c-plane and r-plane). Also we want to grow on top (Al,Ga)2O3 alloy films and investigate lattice mismatch and optical properties of this alloy in corundum structure (Al-rich).

 

Characterization of electronic defects in Ga2O3 single crystals

More information The ultra-wide bandgap semiconductor Ga2O3 is a promising candidate for next generation power electronics. Defect states within the active region of such devices may have detrimental influence on their performance. Within this thesis, defect states in single crystalline Ga2O3 shall be investigated by deep-level transient spectroscopy (DLTS), optical DLTS and in cooperation with Prof. A. Pöppl (Abteilung MQF) by electron spin resonance measurements.

 

Characterization of bendable amorphous semiconductors

More information Amorphous oxide semiconductors are a material class combining good electrical properties and room temperature fabrication even on flexible substrates. Within the thesis, basic electronic devices shall be investigated in dependence on the bending radius and the number of bending events. For that a tool shall be designed and used to investigate zinc tin oxide based devices.

 

Raman tensor of optically anisotropic materials

More information The Raman tensor is an important material property which allows to determine the crystal orientation, the selection rules for the phonon modes as well as the scattered intensity in Raman spectroscopy. However, for optically anisotropic samples the standard Raman formalism does not hold in general and thus we have recently extended this formalism by taking into account birefringence effects which appear in the transparent spectral region. This formalism shall be extended to the absorption spectral range, where additional effects like the presence of singular axes have to be considered.

Further information about our previous work in this field:

C. Kranert, C. Sturm, R. Schmidt-Grund, M. Grundmann
Raman Tensor Formalism for Optically Anisotropic Crystals
Phys. Rev. Lett. 116, 127401 (2016) | doi

C. Kranert, C. Sturm, R. Schmidt-Grund, M. Grundmann
Raman tensor elements of β-Ga2O3
Sci. Rep. 6, 35964 (2016) | doi

 

Photonic topologic cavities - growth and optical properties

More information Topological protected chiral edge mode states are promising for directed photon transport without backscattering. We found in anisotropic microcavities pairs of circularly polarized exceptional points, which are promising starting points for reaching non-trivial topology. Those microcavities shall be further developed by further reducing symmetry and investigated by optical methods in close cooperation with external partners in sample growth and theory.

Further information about our previous work in this field:

S. Richter, T. Michalsky, C. Sturm, B. Rosenow, M. Grundmann, R. Schmidt-Grund
Exceptional points in anisotropic planar microcavities
Phys. Rev. A 95, 023836 (2017) | doi

 
 
 
 

Bachelor thesis

 

Sputter deposition of amorphous CuI-based thin films

More information Transparent amorphous semiconductors (TAS) are key materials in the practical applications of transparent flexible electronics. However, high performance p-type TAS is still an open issue. We will sputter CuI thin films with suitable dopants such as In, Sn, Sb, Pb or Bi. The local coordinations of these dopants are different from the tetrahedral configuration of Cu+ in CuI, possibly leading to suppressed crystallization of zincblende CuI. The transport and mechanic properties of amorphous CuI thin films will be investigated.

Further information about our previous work in this field:

C. Yang, D. Souchay, M. Kneiß, M. Bogner, H. M. Wei, M. Lorenz, O. Oeckler, G. Benstetter, Y.Q. Fu, M. Grundmann
Transparent Flexible Thermoelectric Material Based on Non-toxic Earth-Abundant p-Type Copper Iodide Thin Film
Nature Commun. 8, 16076 (2017) | doi

C. Yang, M. Kneiß, M. Lorenz, M. Grundmann
Room-temperature Synthesized Copper Iodide Thin Film as Degenerate p-Type Transparent Conducting Material with a Boosted Figure of Merit
PNAS 113, 12929-12933 (2016) | doi

 

Implantation of germanium into Ga2O3 and (Al,Ga)2O3 thin films

More information Doping of semiconductors is a prerequisite for their application on real world devices. For (Al,Ga)2O3 it was found that doping during thin film deposition is ineffective. Within this work the influence of germanium ion implantation on the electrical properties of (Al,Ga)2O3 thin films will be investigated and compared to Ga2O3 control samples.
(This topic can be combined to a master thesis together with: Implantation of halides into Ga2O3 and (Al,Ga)2O3 thin films)

 

Implantation of Halides into Ga2O3 and (Al,Ga)2O3 thin films

More information Doping of semiconductors is a prerequisite for their application on real world devices. For (Al,Ga)2O3 it was found that doping during thin film deposition is ineffective. Within this work the influence of ion implantation of halides on the electrical properties of (Al,Ga)2O3 thin films will be investigated and compared to Ga2O3 control samples.
(This topic can be combined to a master thesis together with: Implantation of germanium into Ga2O3 and (Al,Ga)2O3 thin films)

 

HfO2/Al2O3 insulators for MIM structures

More information Metal-insulator-metal structures are used within electronic circuits requiring more than one metallization layer. Within the thesis stacked HfO2/Al2O3 layers will be deposited by magnetron sputtering and investigated regarding their insulating properties as well as bias and temporal stability. Finally, the crossing shall be tested within ring oscillators.

 

Raman and IR Spectrocopy of anisotropic materials

More information The knowledge of the phonon frequencies is important to understand their coupling with excitons and electrons as well as to deduce the optical response in the infrared spectral, crystal orientation and to judge the crystal quality of a sample. Whereas for isotropic samples, e.g. Si, the behavior of the phonons with respect their vibration and propagation direction is well understood, for anisotropic materials birefringence effects have to be considered. By means of Raman spectroscopy and IR Spectroscopy the properties of the phonon modes of anisotropic crystals, e.g. KTP and K2Cr2O7, shall be determined.


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