| CZECH NANO TEAM | Physics of Nanostructures and Nanotechnologies

• Very low energy electron microscopy in various instrumental modes, electron optical problems, new principles of generation of very low energy beams, detection issues, data processing, image interpretation

• Application of very low energy electron beams to examination of solid surfaces, methodology of experiment
• Examination of semiconductor structures, metal alloys and metal-matrix composites with low energy electrons

• Auger electron spectro-microscopy, methodology, instrumentation, data processing.

Supervisor of 5 successful diploma theses and 3 PhD dissertations.

Publications:

Author or co-author of 165 scientific publications (50 were published in impacted international journals), to which more than 85 references (excluding self-citations of any kind) appeared in the literature, editor of three books, author of invited contributions to three books, 21 Czech and one UK patent.

Societies and congresses:

Member of the Executive Board of the European Microscopy Society, member of the European Microbeam Analysis Society, president of the Czechoslovak Microscopy Society (1995-2002), president of the 12th European Congress on Electron Microscopy, Brno 2000, member of the Advisory Board of the International Centre of Advanced Materials Science and Electron Microscopy in Berlin.

Selected study stays abroad:

• Between 1989 and 1996 12 stays at the Technical University Clausthal, Germany (11 months in total),

• between 1992 and 2001 9 stays at the University of York, UK (9 months in total),

• in 2002 and 2003 visiting professorship at the University of Toyama, Japan (4+1 months)

Selected solved projects:

• EC-PECO-12283 (1994-7) "Novel heterostructure devices and materials assessment for communication and information technologies"

• PST.CLG.97082 (2000-01) "Scanning low energy electron microscopy" (NATO)

Selected related publications from last 5 years:

• L. Frank, I. Müllerová, K. Faulian, E. Bauer: The scanning low-energy electron microscope: first attainment of diffraction contrast in the scanning electron microscope. Scanning 21 (1999), 1-13.

• L. Frank, I. Müllerová, M.M. El Gomati: A novel in-lens detector for electrostatic scanning LEEM mini-column, Ultramicroscopy 81 (2000), 99-110.

• I. Müllerová, L. Frank: Multidimensionality of the scanned imaging with very low energy electrons, G.I.T. Imaging and Microscopy 2 No. 2 (2000), 20-23.

• L. Frank, M. Zadražil, I. Müllerová: Scanning electron microscopy of nonconductive specimens at critical energies in a cathode lens system, Scanning 23 (2001), 36-50.

• L. Frank: Advances in scanning electron microscopy, in: Advances in Imaging and Electron Physics, ed. P.W.Hawkes, Vol. 123, Elsevier 2002, pp. 327-373.

• L. Frank, K. Matsuda, P. Hrnčiřík, I. Müllerová: Low energy contrast of metal matrix composite in SEM. Microscopy and Microanalysis 9 [Sup. 3] (2003), 328-329.

Group members:

Luděk Frank, Ilona Müllerová, Jitka Zobačová, Petr Hrnčiřík, Pavel Klein

Main Research Subjects:

The first subject is methodology and instrumental research regarding exploitation of low energy electrons to examination of solid surfaces. While in a standard electron microscope column the aberrations and hence the primary spot size in a scanning system or point resolution in a directly imaging device deteriorate steeply when decreasing the electron energy, the principle of electron energy being variable along the optical path enables one to get over these limitations. Various electron optical configurations, causing electrons retarded close to the specimen, can be proposed now and examined in detail by computer aided design tools. They might provide with high resolution low energy imaging but require reconsidering the principles of signal detection and specimen manipulation and treatment. The low energy systems are also completed with attachments providing complementary signals in order to facilitate the image interpretation.

The second subject is application of the very low energy scanned electron beams to acquisition of novel types of image contrasts that visualize in a nontraditional way the chemical, crystallinic and electronic structure of the target. Experiments demonstrating for the first time specific kinds of very low energy contrasts are performed upon solving selected tasks from various branches of materials science. Examples might be the wave optical, i.e. diffraction and interference, contrasts in backscattered signal as well as the contrast of the local density of states. Important directions include quantitative imaging of the dopant distribution in semiconductor, precipitation in metal alloys, particle-matrix interfaces in metal-matrix composites, etc.

Selected Specific Equipment:

The crucial experimental equipment include scanning electron microscopes containing tailored adaptations enabling one to lower the beam energy down to arbitrarily low energy of impact. The uppermost instrumental class is represented by the cold field emission gun equipped scanning electron microscope JEOL 6700F with resolution of 1 nm at 15 keV beam energy and 9 nm at 10 eV as the best result achieved so far. The ultrahigh vacuum microscope of own construction provides 10-10 mbar oil-free pressure and standard equipments adequate to surface analysis equipments (specimen insertion via air-lock, in-situ specimen cleaning, in-situ thin film coaters under construction). This device achieves the image resolution 26 nm at 10 eV. Small routine low energy microscope serves to less demanding experiments.

The microscopes are equipped with original detector assemblies of own design, and efforts are being exerted toward novel principles of multichannel position sensitive detector structures capable of multiplying the information yield.

Additional recent selected publications by group members:

• L. Frank, I. Müllerová: Strategies for low- and very-low-energy SEM. J. El. Microsc. 48 (1999), 205-219.

• I. Müllerová: Imaging of specimens at optimized low and very low energies in scanning electron microscopes. Scanning 23 (2001), 379-394.

• I. Müllerová, M.M. El Gomati, L. Frank: Imaging of the boron doping in silicon using low energy SEM, Ultramicroscopy 93 (2002), 223-243.

• I. Müllerová, L. Frank: Scanning low energy electron microscopy, in: Advances in Imaging and Electron Physics, ed. P.W.Hawkes, Vol. 128, Elsevier 2003, pp. 309-443.

• F. Mika, J. Ryšávka, F. Lopour, M. Zadražil, I. Müllerová, L. Frank: Computer controlled low energy SEM. Microscopy and Microanalysis 9 [Sup. 3] (2003), 116-117.

• I. Müllerová, L. Frank: Contrast mechanisms in the scanning low energy electron microscopy. Microscopy and Microanalysis 9 [Sup. 3] (2003), 120-121.

• J. Zobačová, L. Frank: Specimen charging and detection of signal from non-conductors in a cathode lens-equipped scanning electron microscope. Scanning 25 (2003), 150-156.

• I. Müllerová, L. Frank: Contrast at very low energies of the gold/carbon specimen for resolution testing. Scanning 26 (2004), 18-24.