Josef Humlíček

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Group subject:

Nanostructures in III-V semiconductors and in cuprates/manganites


Name and Curriculum vitae of contact person:

Josef Humlíček (Prof., RNDr. , CSc. )

Affiliation:

Institute of Condensed Matter Physics, Masaryk University Brno

Position - Head of the ICMP

Fields of scientific activity:

Research in bulk and layered materials, predominantly semiconductors and high-temperature superconductors, with emphasis on optical spectroscopy:

• Elemental and III-V semiconductors, Si-Ge alloys.

• Optical spectra of high-temperature superconductors and cuprate/manganate superlattices.

• Infrared spectroscopy and ellipsometry.

• Temperature dependence of optical response.

• The supervisor of 11 successful diploma theses and 4 PhD theses.

Publications:

Author or co-author of more than 100 scientific publications (mostly published in international journals) to which more than 1300 references appeared in the literature. Monographs on Analysis of Spectrum Line Profiles and Sensitivity of Optical Measurements on Planar Stratified Structures. Six invited contributions to five books.

Selected study stays abroad:

• In 1987/88 and 90/91 invited by Prof. M. Cardona to 10 and 6 month stays at MPI Stuttgart.

• Since 1992 almost regular stays at MPI Stuttgart for 1-2 months per year, the last in 2003.

• In 1997 one month stay at Iowa State University.

Selected solved projects:

• EU: CIPA-CT93-0032 "TOPHIGHTS" (Technology and optical properties of high-temperature superconductors).

• EU: CIPA-CT94-0224 Development of In-Situ Monitoring Technologies for the control of advanced surface and materials Processing Systems.

• EU: CIPA-CT94-0131 "RESPECT" (Real-Time Spectroscopic Analysis: In-Situ Analysis of Spectroscopic Measurements for Process Monitoring and Control by High-Performance Parallel Computation).

Selected related publications from last 5 years:

• J. Šik, M. Schubert, G. Leibiger, V. Gottschalch, G. Kirpal, J. Humlíček, Near-band-gap optical functions spectra and band-gap energies of GaNAs/GaAs superlattice heterostructures measured by spectroscopic ellipsometry, Appl. Phys. Lett. 76, 2859-2861 (2000).

• D. Munzar, C. Bernhard, T. Holden, A. Golnik, J. Humlíček, and M. Cardona, „Correlation between the Josephson coupling energy and the condensation energy in bilayer cuprate superconductors“, Phys. Rev. B 64, 024523 (2001).

• J. Humlíček, D. Munzar, K. Navrátil, M. Lorenc, J. Oswald, J. Pangrác, E. Hulicius, Polarization anisotropy of photoluminescence from multilayer InAs/GaAs quantum dots, Physica E 13, 229-232 (2002).

• A. Dubroka, G. Cristiani, H.-U. Habermeier, and J. Humlíček, Infrared study of YBa2Cu3O7/La0.67Ca0.33MnO3 superlattices, Thin Solid Films, accepted (2003).

Group members:

Josef Humlíček, Dominik Munzar, Václav Holý, Karel Navrátil, Jan Fikar, Adam Dubroka

Main Research Subjects:

• Development of the theory of nucleation of semiconductor nanostructures during epitaxial growth.

• Theory of x-ray scattering from self-organized nanostructures.

• Studies of local chemical composition in quantum wells, wires and dots in IV-IV and III-V heterostructures.

• Strain in nanostructures, electron states in strained heterostructures.

• Connection of absorption and luminescence in quantum wells and superlattices.

• Polarization dependence of the optical and photoluminescence spectra.

• Intrinsic superlattices in layered HTSC cuprates.

• Optical response of cuprate/manganite heterostructures, where superconductivity and magnetism coexist/compete at the nanometer scale.

Selected Specific Equipment:

The group is equipped with a variety of optical spectrometers covering a wide spectral range from far-infrared to ultraviolet. Several home-built ellipsometers operate from mid-infrared to ultraviolet; two of them use multichannel detectors and optical fibres, allowing fast in-situ measurements. Optical spectroscopy can be performed in the temperature range from Liquid He to about 1100 K. A hot/wall epitaxial reactor can be used to grow simple layered structures.

Research-grade AFM is used to monitor the surface morphology. The X-ray labs are equipped with high-precision diffractometers, partly capable of measurements at elevated temperatures. X-ray reflectometers working at grazing incidence are used to study very thin layers in the heterostructures and the quality of their interfaces.

Additional recent selected publications by group members:

• G. Springholz , V. Holý, M. Pinczolits, and G. Bauer: Self-organized growth of 3D quantum dot crystals with fcc-like vertical stacking and tunable lattice constant, Science 282, 734 (1998).

• V. Holý, U. Pietsch. and T. Baumbach: High-Resolution X-Ray Scattering From Thin Films and Multilayers, (Springer-Verlag,Berlin, Heidelberg, New York, 1999).

• V. Holý, G. Springholz, M. Pinczolits, G. Bauer: Strain induced vertical and lateral correlations in quantum dot superlattices, Phys.Rev. Lett. 83, 356 (1999)

• M. Meduňa, V. Holý, Roch T., Bauer G., Schmidt O.G., Eberl K., Diffuse x-ray reflectivity from self-assembled ripples with superimposed roughness in Si/Ge superlattices, Semicond. Sci. Technol., 17, 480-486 (2002)

• Munzar D., Bernhard C., Holden T., Golnik A., Humlíček J., Cardona M., Correlation between the Josephson coupling energy and the condensation energy in bilayer cuprate superconductors, Physical Review B 64, 024523 (2001).

• Bernhard C., Holden T., Humlíček J., Munzar D., Golnik A., Klaeser M., Wolf Th., Carr L., Homes C., Keimer B., Cardona M., In-plane polarized collective modes in detwinned YBa2Cu3O6.95 observed by spectral ellipsometry, Solid State Communications 121, 93 (2002).

• Boris A. V., Munzar D., Kovaleva N. N., Liang B., Lin C. T., Dubroka A., Pimenov A. V., Holden T., Keimer B., Mathis Y-L., Bernhard C., Josephson Plasma Resonance and Phonon Anomalies in Trilayer Bi2Sr2Ca2Cu3O10, Physical Review Letters 89, 277001 (2002) .

• Munzar D., Holden T., Bernhard C., Approximate tight-binding sum rule for the superconductivity-related change of c-axis kinetic energy in multilayer cuprate superconductors, Physical Review B 67, 020501 (2003).
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