Universität Leipzig

Faculty of Physics and Earth Sciences

Felix Bloch Institute for Solid State Physics

Semiconductor Physics Group

Research Methods

For execution of our research agenda we employ various experimental methods and theoretical routines, ranging from thin film deposition, the characterization of structural, electrical and optical properties to device fabrication and characterization.

Our vision: From deposition to device

 Thin Film Epitaxy and Deposition

In pulsed laser deposition (PLD), a ceramic target is ablated by pulses from a high power laser. From the developing plasma, particles are deposited onto the heated and rotating substrate. Using PLD we perform epitaxy of oxide and nitride thin films and heterostructures (quantum wells, superlattices, ...) in material systems such as (Mg,Zn)O, (In,Ga,Al)2O3, ZnFe2O3, La(Ni,Mn)O3, BiFeO3, BaTiO3 and TiN. Using sputter methods (Kathodenzerstäubung) we deposit amorphous semiconductor thin films and thin films of copper iodide. Also we use reactive sputtering for the creation of Schottky contacts on various oxide semiconductors. With plasma-enhanced chemical vapor deposition (PECVD) we deposit insulators and dielectric layers in the Si/SiOxNy system. Using thermal evaporation we deposit metals (Au, Al, Ti, ...) for Ohmic and Schottky contacts. Also oxide nanostructures are fabricated using carbo-thermal evaporation schemes.

More on pulsed laser deposition
System 1: Excimerlaser (Coherent LPX Pro 305, wavelength 248 nm, pulse energy 1100 mJ, pulse repetition 50 Hz),
large-area PLD chambers for 3-inch diameter wafers, max. growth temperature 750°C, multi-target manipulator (E-, F-, W-chamber).

System 2: Excimerlaser (Coherent LPX Pro 305, wavelength 248 nm, pulse energy 1100 mJ, pulse repetition 50 Hz),
large-area PLD chamber for 4-inch diameter wafers, max. growth temperature 750°C, selectable multi-target manipulators for planar or cylindrical targets, heater with tilt option for radial coating of free-standing nano- and microwires (S-chamber),
laser-MBE chamber für 10x10 mm2 substrates with in-situ RHEED (double-differentially pumped up to 0.1 mbar chamber pressure), CO2-laser heater up to 1.400°C growth temperature (SURFACE systems), suitable for growth of nitride and oxide heterostructures (B-chamber),
high-pressure PLD chamber for nano- and microstructures, for cylindrical targets, up to 200 mbar partial pressure, heater up to 920°C (Q-chamber).

System 3: Excimerlaser (Coherent LPX Pro 305, wavelength 248 nm, pulse energy 1100 mJ, pulse repetition 50 Hz),
large-area PLD chamber for 4-inch diameter wafers, extendable up to 8-inch diameter, max. growth temperature 750°C, multi-target manipulator (G-chamber) for combinatorial PLD (continuous composition spread PLD, CCS-PLD).

Selection of ceramic PLD targets

Key publications

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. Lorenz, H. Hochmuth, M. Kneiß, M. Bonholzer, M. Jenderka, M. Grundmann
From high-TC superconductors to highly correlated Mott insulators - 25 years of pulsed laser deposition of functional oxides in Leipzig
Semic. Sci. Technol. 30, 024003 (2015) | 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

More on sputter deposition
Sputter system from MANTIS for deposition of amorphous metal oxides and oxynitrides and reactively sputtered Schottky contacts (PtOx, PdOx, ...).
Key publications

S. Müller, H. von Wenckstern, F. Schmidt, D. Splith, H. Frenzel, M. Grundmann
Method of choice for fabrication of high-quality β-gallium oxide-based Schottky diodes
Semic. Sci. Technol. 32, 065013 (2017) | doi

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

H. Frenzel, T. Dörfler, P. Schlupp, H. von Wenckstern, M. Grundmann
Long-throw magnetron sputtering of amorphous Zn-Sn-O-thin films at room temperature
phys. stat. sol. (a) 212, 1482 (2015) | doi

Home-built sputter system for deposition of metal halogen semiconductors, such as copper iodide and related materials.
Key publications

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, F.-L. Schein, M. Lorenz, M. Grundmann
Room-temperature domain-epitaxy of copper iodide thin films for transparent CuI/ZnO heterojunctions with high rectification ratios larger than 109
Sci. Rep. 6, 21937 (8 pages) (2016) | doi

More on plasma-enhanced chemical vapor deposition
Key publication

R. Schmidt-Grund, T. Nobis, V. Gottschalch, B. Rheinländer, H. Herrnberger, M. Grundmann
a-Si/SiOx Bragg-reflectors on micro-structured InP
Thin Solid Films 483, 257 (2005) | doi

More on thermal evaporation
More on carbo-thermal evaporation
GERO tube furnace F 70-500, up to 1350°C
More on thermal annealing

 Structural Characterization

Structural characterization...

More on scanning electron microscopy
Field emission gun scanning electron microscope (FEI Nanolab 200) with focussed ion beam for high resolution SEM imaging, preparation of cross-sections and TEM lamellae.
Key publications

S. Müller, H. von Wenckstern, O. Breitenstein, J. Lenzner, M. Grundmann
Microscopic identification of hot spots in multi-barrier Schottky contacts on pulsed laser deposition grown zinc oxide thin films IEEE Transact. Electr. Dev. 59, 536 (2012) | doi

C. Sturm, H. Hilmer, R. Schmidt-Grund, M. Grundmann
Observation of strong exciton-photon coupling at temperatures up to 410 K
New J. Phys. 11, 073044 (2009) | doi

More on laser scanning microscopy
Confocal laser scanning microscope (KEYENCE VK-X 210) with 16 bit photomultiplier, laser differential-interference contrast, with automatic XY-image composition (stitching).
More on atomic force microscopy
Scanning probe microscope (Park XE-150) for atomic force microscopy (AFM), scanning tunneling microscopy (STM), piezo force microscopy (PFM), magnetic force microscopy (MFM), scanning capacitance microscopy (SCM), variable enhanced conductive AFM, scanning spread resistance (SSRM), Kelvin probe force microscopy (KPFM), nanoindentation.
Key publications

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

More on profilometer
Stylus profiler (Bruker Dektak XT) for 2D roughness surface characterization, and step height measurements, and advanced 3D mapping and film stress analyses.
More on X-ray diffraction
PANalytical X'pert PRO materials research diffractometer for XRD, high-resolution XRD, X-ray reflectivity; with PIXcel3D array detector, four-circle high precision goniometer, modular optics.
Key publications

H. Wei, M. Grundmann, M. Lorenz
Confinement-driven metal-insulator transition and polarity-controlled conductivity of epitaxial LaNiO3/LaAlO3 (111) superlattices
Appl. Phys. Lett. 109, 082108 (2016) | doi

M. Grundmann, M. Scheibe, M. Lorenz, J. Bläsing, A. Krost
X-ray multiple diffraction of ZnO substrates and heteroepitaxial thin films
phys. stat. sol. (b) 251, 850 (2014) | doi

X-ray diffractometer Philips X'pert with wide-angle Bragg-Brentano goniometer with secondary graphite monochromator, and with high-resolution (triple-axis) goniometer with 4 x Ge(220) monochromator.

 Electrical Characterization

Electrical characterization...

More on IV and CV characterization
More on Hall effect
More on thermal admittance spectroscopy (TAS)
More on deep level transient spectroscopy (DLTS/ODLTS)
More on Seebeck effect
More on magneto-transport
More on wafer probing

 Optical Characterization

The characterization of optical properties of bulk material, thin films and nanostructures concerns the determination of the complex dielectric function tensor with spectroscopic ellipsometry, the phonon modes with Raman spectroscopy, and recombination properties using photoluminescence with spectral, spatial, angular, polarization and time resolution. Also cathodoluminescence is used for hyper-spectral imaging of thin films, nano- and microstructures. All methods can be recorded as a function of temperature.

More on spectroscopic ellipsometry
Generalized, spectroscopic ellipsometry from MIR to VUV spectral ranges (0.04-9 eV), in particular for optically anisotropic materials, Bragg mirrors, oxide heterostructures and combinatorial gradient samples.

VUV ellipsometer (Woollam VUV-VASE Gen II, 0.14-2.4 μm)
Key publications

C. Sturm, R. Schmidt-Grund, V. Zviagin, M. Grundmann
Temperature dependence of the dielectric tensor of monoclinic dielectric Ga2O3 single crystals in the spectral range 0.5-8.5 eV
Appl. Phys. Lett. 111, 082102 (2017) | doi

C. Sturm, J. Furthmüller, F. Bechstedt, R. Schmidt-Grund, M. Grundmann
Dielectric tensor of monoclinic Ga2O3 single crystals in the spectral range 0.5-8.5 eV
APL Mater. 3, 106106 (2015) | doi

Full Müller matrix ellipsometer (Woollam RC2-D+NIR, 0.19-1.69 μm, 1088 wavelenghts)

UV-VIS-NIR ellipsometer (Woollam VASE, 0.24-1.70 μm)
Key publication

J. Sellmann, C. Sturm, R. Schmidt-Grund, C. Czekalla, J. Lenzner, H. Hochmuth, B. Rheinländer, M. Lorenz, M. Grundmann
Structural and optical properties of ZrO2 and Al2O3 thin films and Bragg reflectors grown by pulsed laser deposition
phys. stat. sol. (c) 5, 1240-1243 (2008) | doi

FTIR ellipsometer (Woollam IR-VASE, 2-30 μm)
Key publication

C. Bundesmann, A. Rahm, M. Lorenz, M. Grundmann, M. Schubert
Infrared optical properties of MgxZn1-xO thin films (0≤x≤1): Long-wavelength optical phonons and dielectric constants
J. Appl. Phys. 99, 113504 (2006) | doi

UV-VIS-NIR multi-channel ellipsometer (Woollam M2000, 0.36-1.70 μm, 512 wavelengths)
More on Raman scattering
(Micro-) Raman spectroscopy with 532, 355, 325 and 266 nm excitation, U1000 double monochromator and LN2-cooled CCD detector, UV microscopy and polarization optics. In particular determination of the Raman tensor of optically uniaxial and biaxial crystals considering birefringent effects.
Key publications

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

C. Kranert, M. Jenderka, J. Lenzner, M. Lorenz, H. von Wenckstern, R. Schmidt-Grund, M. Grundmann
Lattice parameters and Raman-active phonon modes of β-(AlxGa1-x)2O3
J. Appl. Phys. 117, 125703 (2015)| doi

More on photoluminescence (PL)
Photoluminescence is used to investigate radiative recombination channels in various materials and structures.

cw-photoluminescence using various lasers, e.g. HeCd (325 nm), for excitation without particular spatial resolution. Spectra are detected using various photomultipliers (GaAs, MCP) and CCDs and are recorded as a function of excitation density and temperature.
Key publications

C.P. Dietrich, M. Lange, G. Benndorf, J. Lenzner, M. Lorenz, M. Grundmann
Competing exciton localization effects due to disorder and shallow defects in semiconductor alloys
New J. Phys. 12, 033030 (2010) | doi

M. Lange, C.P. Dietrich, K. Brachwitz, T. Böntgen, M. Lorenz, M. Grundmann
(Zn,Cd)O thin films for the application in heterostructures: structural and optical properties
J. Appl. Phys. 112, 103517 (2012) | doi

Time-resolved photoluminescence using a fs Ti:Sa laser (Coherent VERDI-10, Coherent MIRA-F, APE Pulse Select, U-Oplaz TP-2000B SHG/THG) for excitation and single photon counting (Hamamatsu MCP-PM) for detection.
Key publications

A. Müller, M. Grundmann
Tunneling dynamics of excitons in random semiconductor alloys
Phys. Rev. B 87, 035134 (2013) | doi

M. Stölzel, A. Müller, G. Benndorf, M. Brandt, M. Lorenz, M. Grundmann
Determination of unscreened exciton states in polar ZnO/(Mg,Zn)O quantum wells with strong quantum-confined Stark effect
Phys. Rev. B 88, 045315 (2013) | doi

Micro-photoluminescence using various cw- and fs-lasers for excitation with high, diffraction-limited spatial resolution. Spectra can be recorded angularly resolved (Fourier imaging) and time-resolved with a streak camera (Hamamatsu C5680/Jobin-Yvon iHR320).
Key publications

C.P. Dietrich, M. Lange, C. Sturm, R. Schmidt-Grund, M. Grundmann
One- and two-dimensional cavity modes in ZnO microwires
New J. Phys. 13, 103021 (2011) | 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

Optical pumping using fs- (Ti:Sa, Coherent VERDI-18, Coherent MIRA-HP, APE Pulse Select, U-Oplaz TP-2000B SHG/THG) and ns- (SpitLight Compact DPSS, Innolas, >2 mJ/100Hz, 266/355 nm) lasers for the investigation of lasing phenomena.
Key publications

M. Wille, E. Krüger, S. Blaurock, V. Zviagin, R. Deichsel, G. Benndorf, L. Trefflich, V. Gottschalch, H. Krautscheid, R. Schmidt-Grund, M. Grundmann
Lasing in cuprous iodide microwires
Appl. Phys. Lett. 111, 031105 (2017) | doi

M. Wille, C. Sturm, T. Michalsky, R. Röder, C. Ronning, R. Schmidt-Grund, M. Grundmann
Carrier density driven material dynamics of lasing ZnO Nanowires
Nanotechnology 27, 225702 (2016) | doi

More on cathodoluminescence (CL)
Cathodoluminescence is used to image lateral variations of the emission spectrum in thin films, micro- and nanostructures. The sample temperature can be varied from liquid helium up to room temperature.
Key publications

C.P. Dietrich, M. Lange, F.J. Klüpfel, H. von Wenckstern, R. Schmidt-Grund, M. Grundmann
Strain distribution in bent ZnO microwires
Appl. Phys. Lett. 98, 031105 (2011) | doi

T. Nobis, E.M. Kaidashev, A. Rahm, M. Lorenz, J. Lenzner, M. Grundmann
Spatially inhomogeneous impurity distribution in ZnO micropillars
Nano Lett. 4, 797-800 (2004) | doi

T. Nobis, E.M. Kaidashev, A. Rahm, M. Lorenz, M. Grundmann
Whispering gallery modes in nano-sized dielectric resonators with hexagonal cross section
Phys. Rev. Lett. 93, 103903 (2004) | doi


 Further Characterization Methods

Various other characterization methods of our lab

More on magnetization measurement/VSM
Physical property measurement system (PPMS-9, Quantum Design) with up to 9 T magnetic field, liquid helium cooling, sample temperature range 1.9-400 K, vibrating sample magnetometer (VSM), and for magnetotransport measurements including Hall effect, with sample rotator.
More on thermal conductivity measurement

 Device Processing

We fabricate various devices such as diodes, transistors, photodetectors and solar cells as well as integrated circuits (inverters, ring oscillators, ...) using (multiple) lithographic steps.

More on photolithography
More on reactive ion etching
Reactive ion etching (PlasmaPro NGP80 ICP, Oxford) with inductively coupled plasma and fluor-based chemistry .


We develop theories for optical modes in nano- and microstructures, anisotropic optics, pseudomorphic strain in heterostructures and X-ray scattering among others.

More on theory
Key publications

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

S. Richter, T. Michalsky, L. Fricke, C. Sturm, H. Franke, M. Grundmann, R. Schmidt-Grund
Maxwell consideration of polaritonic quasi-particle Hamiltonians in multi-level systems
Appl. Phys. Lett. 107, 231104 (2015) | doi

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

M. Grundmann
Theory of Semiconductor Solid and Hollow Nano- and Microwires With Hexagonal Cross-Section Under Torsion
phys. stat. sol. (b) 252, 773-785 (2015) | doi

M. Grundmann
Strain in Pseudomorphic Monoclinic Ga2O3-based Heterostructures
phys. stat. sol. (b) 254, 1700134 (2017) | doi

M. Grundmann, J. Zúñiga-Pérez
Pseudomorphic ZnO-based heterostructures: from polar through all semipolar to nonpolar orientations
phys. stat. sol. (b) 253, 351-360 (2016) | doi

M. Grundmann, M. Scheibe, M. Lorenz, J. Bläsing, A. Krost
X-ray multiple diffraction of ZnO substrates and heteroepitaxial thin films
phys. stat. sol. (b) 251, 850-863 (2016) | doi

T. Nobis, M. Grundmann
Low order whispering gallery modes in hexagonal nanocavities
Phys. Rev. A 72, 063806 (2005) | doi

Funding is provided through the FUGG/HbfG and EFRE schemes as well as several cooperative projects and individual grants. Most of our research is within the university's research profile area "Complex Matter".

Image credits: Ch. Yang, Zh. Zhang, J. Lenzner, S. Richter, M. Lorenz, C. Kranert, T. Nobis, M. Grundmann, all Universität Leipzig.
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