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

 

Magneto-electric properties of doped BiFeO3/BaTiO3 superlattices

More information The combination of the multiferroic and ferroelectric materials BiFeO3 and BaTiO3 in thin layer heterostructures and superlattices leads to new and - compared to the bulk materials - enhanced magnetoelectric properties. These are important for novel magnetic field sensors and depend on details of the interface formation. Such structures shall be fabricated with pulsed laser deposition (PLD) and the structural and magnetoelectric properties investigated.

Further information about our previous work in this field:

V. Lazenka, M. Lorenz, H. Modarresi, J.K. Jochum, H.P. Gunnlaugsson, M. Grundmann, M.J. Van Bael, K. Temst, A. Vantomme
Interface induced out-of-plane magnetic anisotropy in magnetoelectric BiFeO3/BaTiO3 superlattices
Appl. Phys. Lett. 110, 092902 (2017) | doi

M. Lorenz, V. Lazenka, P. Schwinkendorf, M.J. Van Bael, A. Vantomme, K. Temst, M. Grundmann, T. Höche
Epitaxial coherence at interfaces as origin of high magnetoelectric coupling in multiferroic BaTiO3-BiFeO3 superlattices
Adv. Mater. Interf. 3, 1500822 (2016) | doi

 

Optical and magneto-optical properties of BiFeO3/BaTiO3 composites and superlattices

More information The combination of the multiferroic and ferroelectric materials BiFeO3 and BaTiO3 in thin layer heterostructures and superlattices gain magneto-electric properties. The influence of the magneto-electrical properties and its switching on the (effective) dielectric function shall be investigated for the aim of optical detection of magnetic or electric fields as well as for application as remanent magneto-electro-optical switches. The main technique will be Mueller-matrix ellipsometry.

Further information about our previous work in this field:

V. Lazenka, M. Lorenz, H. Modarresi, J.K. Jochum, H.P. Gunnlaugsson, M. Grundmann, M.J. Van Bael, K. Temst, A. Vantomme
Interface induced out-of-plane magnetic anisotropy in magnetoelectric BiFeO3/BaTiO3 superlattices
Appl. Phys. Lett. 110, 092902 (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 ZnO-GaN solid solutions

More information The alloying of wide-bandgap semiconductors ZnO and GaN causes significant bandgap bowing, enabling strong visible absorption for effective solar-light harvesting. However, the development of ZnO-GaN solid solutions has been limited by the synthesis method. Using pulsed laser deposition (PLD) technique, epitaxial superlattices as well as continuous composition spread (CCS) thin films of ZnO-GaN solid solution shall be fabricated. The goal is tackling the critical problems of ZnO-GaN solid solution in epitaxial growth and band-structure engineering for photovoltaic application.

Further information about our previous work in this field:

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

 

Properties of cubic (In,Ga)2O3 thin films

More information Binary In2O3 is an oxide semiconductor with high electron mobility. However, basic devices like field-effect transistors are challenging to fabricate because Schottky barrier diodes to In2O3 are of inferior quality so far. Band gap engineering of In2O3 by alloying with Ga2O3 has lead to significant improvements of Schottky diode performance. Within this thesis systematic studies on the structural, optical and electrical properties of cubic (In,Ga)2O3 are conducted and simple devices such as Schottky barrier diodes and field-effect transistors will be fabricated and characterized.

 

Growth and characterization of ε-(In,Ga)2O3 thin films

More information For the ultra wide bandgap semiconductor Ga2O3 five different polymorphs exits with the monoclinic β-gallia structure is the equilibrium structure. Another polymorph with interesting properties is the so-called ε-Ga2O3 phase having a spontaneous piezoelectric polarization. Within this thesis structural, electrical and optical properties of ε-(In,Ga)2O3 thin films will be investigated. Further, lateral transport measurements at ε-(In,Ga)2O3/Ga2O3 heterostructures will be conducted.

 

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

 

Propagation of coherent states in microwires

More information Transport of coherent photon states in micro and nanostructures is a key for future information and quantum technology. ZnO based microcavities are model systems for investigating related basic physical properties. We have already observed in real time propagation over more than 10µm distance as well as spatial coherence. Using spatially, temporally, momentum and polarization resolved photoluminescence techniques as well as interferometry and single photon counting; propagation, photon statistics and coherence properties of exciton-polariton Bose Einstein condensates in such structures shall be investigated in detail.

Further information about our previous work in this field:

M. Wille, T. Michalsky, E. Krüger, M. Grundmann, R. Schmidt-Grund
Absorptive lasing mode suppression in ZnO nano- and microcavities
Appl. Phys. Lett. 109, 061102 (2016) | doi

H. Franke, C. Sturm, R. Schmidt-Grund, G. Wagner, M. Grundmann
Ballistic propagation of exciton-polariton condensates in a ZnO-based microcavity
New J. Phys. 14, 013037 (2012) | doi

 

Electro-optical mode switching in ZnO microwire waveguides using ferroelectric materials

More information Transport and manipulating of photon modes in nano- and microscale waveguides is a key requirement for future optical data processing. The mode properties shall be switched by means of ferroelectric polarization fields. For this purpose, ferroelectric materials (BiFeO3) shall be deposited on microwire cavities, which allow for remanent switching of ferroelectric polarization fields, and the effect on the optical modes shall be investigated using spatially, temporally, momentum and polarization resolved photoluminescence techniques as well as interferometry.

 
 
 
 

Bachelor thesis

 

Optical properties of oxygen-doped titanium nitride (TiN) thin films

More information We investigate MgO/TiN superlattices which represent a hyperbolic optical metamaterial (in certain wavelength ranges) when TiN exhibits a negative index of refraction. Such medium is suitable for the construction of superlenses and interesting due to its modified optical density of states and can lead to faster optical emission from molecules or quantum dots. The incorporation of oxygen into the TiN during growth or annealing procedures as well as its impact on optical properties shall be investigated using mainly X-ray diffraction and spectroscopic ellipsometry.

Further information about our previous work in this field:

M. Lorenz, H. Wei, F. Jung, S. Hohenberger, H. Hochmuth, M. Grundmann
Two-dimensional Frank - van der Merwe growth of functional oxide and nitride thin film superlattices by pulsed laser deposition
J. Mat. Res. 32, 3936 (2017) | doi

M. Bonholzer, M. Lorenz, M. Grundmann
Layer-by-layer growth of TiN by pulsed laser deposition on in-situ annealed (100) MgO substrates
phys. stat. sol. (a) 211, 2621 (2014) | doi

 

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)

 

Stabilization of hexagonal InGaO3

More information Hexagonal InGaO3 is made up of alternating layers of GaO5 and In6 polyhedra and results in differences of electric transport properties for transport parallel and perpendicular to these layers. Within this work, InGaO3 thin films on ZnO buffer layers or substrates will be investigated with respect to structural and electrical properties.

 

Optimizing the conductivity of p-type zinc cobalt oxide

More information Nickel-doped zinc cobalt oxide is a p-type semiconductor with good electrical conductivity even in the amorphous state. By investigating thin films with a lateral variation of the cation composition, optimal growth conditions for obtaining highly p-conducting samples.

 

Band gap engineering of (Mg,Ni)O:Li

More information NiO is a transparent p-type semiconductor that was used within transparent UV photovoltaic cells. By alloying NiO with Mg allows to tune the conduction band energy for optimal charge carrier collection and doping with Li shall enhance the electrical conductivity. Within the thesis thin films with lateral variation of the cation composition shall be investigated with respect to their optical and electrical properties.

 

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.

 

Manipulation of wave-guiding in microwires

More information Transport and manipulating of photon modes in nano- and microscale waveguides is a key requirement for future optical data processing. Wave-guiding in ZnO microwires shall be investigated by means of spatially, temporally, momentum and polarization resolved photoluminescence techniques as well as interferometry. It shall further be investigated how the properties of the guided modes can be manipulated by illumination with additional laser spots.

 

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.

 

This page is always under construction...
  top of this page contact webmaster - last updated: 5 December 2017