Humboldt-Universität zu Berlin - Faculty of Mathematics and Natural Sciences - Strukturforschung / Elektronenmikroskopie

Prof. Christoph T. Koch, PhD

 

Prof. Christoph T. Koch AG Strukturforschung / Elektronenmikroskopie
Institut für Physik
Humboldt-Universität zu Berlin
Newtonstraße 15
12489 Berlin, Germany
Room: 3’210
Tel:  +49 (0)30 / 2093-82460
Email: Christoph.Koch@hu-berlin.de
Website:
https://www.physik.hu-berlin.de/sem

 

Secretary: Marion Götsch
Tel: +49 (0)30 / 2093-7652
Fax: +49 (0)30 / 2093-7643

Research Interests:

The research of the structure research and electron microscopy group focuses on the development of new methods in quantitative (scanning) transmission electron microscopy and -spectroscopy and their application to relevant materials science problems.

Short Biography:

  • 1996 - 1997: Undergraduate studies at Heidelberg University (physics)
  • 1997 - 1998: Exchange student at Arizona State University
  • 1998 - 2002: PhD in physics at Arizona State University (Adv.: Prof. John C.H. Spence)
  • 2002 - 2011: Postdoc at MPI for Metals Research, Stuttgart
  • 2011 - 2015: Professorship (W3) at Ulm University, Dept. of Physics  (endowed by Carl Zeiss Foundation)
  • since 2015: Professorship (W3) at Humboldt-Universität zu Berlin, Dept. of Physics
  • since 2020: Managing director of the Dept. of Physics at Humboldt-Universität zu Berlin

Recent Publications:

(Complete list of publications until 2015)

Researcher ID: E-9689-2011, Google Scholar Research profile, ORCID: 0000-0002-3984-1523 

Inline Holography with Electrons and Photons

  • [76] A. Parvizi, J. Mller, S.A. Funken, C.T. Koch, "A practical way to resolve ambiguities in wavefront reconstructions by the transport of intensity equation", Ultramicroscopy 154 (2015) 16
  • [70] C.T. Koch, “Towards full-resolution inline electron holography”, Micron 63 (2014) 69-75
  • [62] C. Ozsoy Keskinbora, C. Boothroyd, R. Dunin-Borkowski, P.A. van Aken, C. Koch, “Hybridization approach to in-line and off-axis (electron) holography for superior resolution and phase sensitivity”, Scientific Reports 4 (2014) 7020
  • [36] C.T. Koch and A. Lubk, “Off-axis and inline electron holography: A quantitative comparison”, Ultramicroscopy 110 (2010) 460-471
  • [37] T. Latychevskaia, P. Formanek, C.T. Koch and A. Lubk, “Off-axis and inline electron holography: experimental comparison”, Ultramicroscopy 110 (2010) 472-482
  • [24] C.T. Koch, “A flux-preserving inline electron holography reconstruction
    algorithm for illumination of partial spatial coherence”, Ultramicroscopy 108, 141-150 (2008)
  • [3] J. Spence, C. Koch, “Atomic String Holography”, Physical Review Letters 86 (24), 5510 (2001)

Strain Mapping

  • [77] D. Tyutyunnikov, M. Mitsuhara, C.T. Koch, "Two-dimensional misorientation mapping by rocking dark-eld transmission electron microscopy", Ultramicroscopy
    159 (2015) 2633
  • [69] K. Song, C.T. Koch, J.K. Lee, D.Y. Kim, J.K. Kim, A. Parvizi, W.Y. Jung, C.G. Park, H.J. Jeong, H.S. Kim, Y. Cao, T. Yang. L.-Q. Chen, S.H. Oh, "Correlative High-Resolutin Mapping of Strain and Charge Density in a Strained Piezoelectric Multilayer", Advanced Materials Interfaces 2014 (2014) 1400281
  • [63] V. B. Ozdol, D. Tyutyunnikov, P. A. van Aken and C. T. Koch "Strain Mapping for Advanced CMOS Technologies", Cryst. Res. Technol. 49 (2014) 38-42
  • [35] C.T. Koch, V.B. Özdöl and P.A. van Aken, “An efficient, simple, and precise
    way to map strain with nanometer resolution in semiconductor devices”, Applied
    Physics Letters 96 (2010) 091901
  • [32] B. Özdöl, C.T. Koch, and P.A. van Aken, “A non-damaging electron microscopy approach to map In distribution in InGaN light-emitting diodes” , Journal of Applied Physics 108 (2010) 056103
  • [40] H. Rösner, C.T. Koch, and G. Wilde, “Strain Mapping along Al-Pb interfaces”,
    Acta Materialia 58 (2010) 162-172

Electron Diffraction / Dynamic Inversion Problem / Phase Retrieval from Diffraction Patterns

  • [55] W. Van den Broek, C. T. Koch, "Method for retrieval of the three-dimensional
    object potential by inversion of dynamical electron scattering", Physical Review
    Letters 109 (2012) 245502
  • [64] C.T. Koch and W. Van den Broek, "Measuring three-dimensional positions of atoms to the highest accuracy with electrons", Comptes Rendus Physique 15 (2014) 119-125
  • [67] R.S. Pennington, W. Van den Broek and C.T. Koch, "Third-dimension information retrieval from a single convergent-beam transmission electron diraction pattern using an articial neural network", Phys. Rev. B 89 (2014) 205409
  • [73] R.S. Pennington, C.T. Koch, "A three-dimensional polarization domain retrieval method from electron diraction data", Ultramicroscopy 155 (2015) 4248
  • [41] C.T. Koch, “Aberration-Compensated Large-Angle Rocking-Beam Electron
    Diffraction”, Ultramicroscopy 111, 828-840 (2011) (LARBED)
  • C.T. Koch, “Many-Beam Solution to the Phase Problem in Crystallography”,
    arXiv:0810.3806
  • [27] C.T. Koch, “Using dynamically scattered electrons for 3-dimensional potential reconstruction”, Acta Cryst. A 65 (2009) 364-370
  • [10] C.T. Koch, “Solving non-centrosymmetric two-dimensional crystal structures by dynamic electron diffraction”, Acta Cryst. A61, 231-236 (2005)
  • [9] J.S. Wu, U. Weierstall, J.C.H. Spence, C.T. Koch, “Iterative phase retrieval without support”, Optics Letters 29 (23), 2737-2739 (2004)
  • [8] C. Koch and J. Spence, “A useful disentanglement of the exponential of the sum of two non-commuting matrices one of which is diagonal”, J. Phys. A: Meth. Gen. 36, 803-816 (2003)

Electron Tomographic Techniques

  • [55] W. Van den Broek and C.T. Koch, “Method for Retrieval of the Three-Dimensional Object Potential by Inversion of Dynamical Electron Scattering”, Phys. Rev. Lett. 109 (2012) 245502
  • [60] W. Van den Broek and C. T. Koch, “A General Framework for Quantitative Three-Dimensional Reconstruction from Arbitrary Detection Geometries in TEM”, Phys. Rev. B 87 (2013)  184108
  • [43] N.Y. Jin-Phillipp , C.T. Koch, and P.A. van Aken, “3D elemental mapping on
    nanomaterials using core-loss EFTEM tomography” Ultramicroscopy 111, 1255-1261 (2011)

Grain Boundaries in Ceramics and Semiconductors

  • [44] Y. Kauffmann, S.H. Oh, C.T. Koch, A. Hashibon, C. Scheu, M.
    Rühle, and W.D. Kaplan, “Quantitative Analysis of Layering and In-Plane Structural Ordering at an Alumina-Aluminum Solid-Liquid Interface”, Acta Mat. 59 (2011) 4378-4386
  • [38] C.T. Koch, “Determination of grain boundary potentials in ceramics by impedance spectroscopy and inline electron holography”, International Journal of Materials Research 2010/01 (2010) 43-49
  • [34] S. von Alfthan, N.A. Benedek, L. Chen, A. Chua, D. Cockayne, K.J. Dudeck,
    C. Elsässer, M.W. Finnis, C.T. Koch, B. Rahmati, M. R¨hle, S.-J. Shih, A.P.
    Sutton, ”The structure of grain boundaries in strontium titanate: theory, simulation,
    and electron microscopy”, Annual Reviews in Materials Science 40 (2010)
    557-599
  • [15] C.T. Koch, “Examination of Structural Properties of Interfaces by Electron
    Diffraction”, Mat. Sci. Eng. A 422, 41-50 (2006)
  • [16] A. Subramaniam, C.T. Koch, R.M. Cannon, and M. Rühle, “Intergranular
    Glassy Films: an Overview”, Mat. Sci. Eng. A 422, 3-18 (2006)
  • [18] S. Bhattacharyya, C.T. Koch, M. Rühle “Potential Profiles across Interfaces obtained by Exit Face Wave Function Reconstruction of Fresnel Through Focal Series”, Ultramicroscopy 106525-538 (2006)
  • [20] C.T. Koch, S.H. Garofalini, “Determining the radial pair-distribution
    function within intergranular amorphous films by numerical nanodiffraction”, Ultramicroscopy 106, 383-388 (2006)
  • [31] D. Abou-Ras, C.T. Koch, V. Küstner, P.A. van Aken, U. Jahn, M.A. Contreras,
    R. Caballero, C.A. Kaufmann, R. Scheer, T. Unold, H.-W. Schock “Grainboundary
    types in chalcopyrite-type thin films and their correlations with film
    texture and electrical properties”, Thin Solid Films 517 (2009) 2545-2549
  • [42] D. Abou-Ras, R. Caballero, J. Dietrich, J. Kavalakkatt, J. Klaer, C.T. Koch, M.
    Nichterwitz, T. Rissom, and S.S. Schmidt, “Analysis of Cu(In,Ga)(S,Se)2 thinfilm
    solar cells by means of electron microscopy”, Sol. En. Mat. Sol. Cells (2011)
    in press
  • [48] Z. Zhang, W. Sigle, C.T. Koch, M. Rühle, “Dynamic behavior of nanometer-scale amorphous intergranular film in silicon nitride by in situ high-resolution transmission electron microscopy”, Journal of the European Ceramic Society 31 (2011) 1835-1840

Dislocations

  • [14] J.C.H. Spence, H. Kolar, G. Hembree, C.J. Humphreys, J. Barnard, R. Datta,
    C.T. Koch, F. Ross, J.F. Justo, “Imaging dislocation cores – the way forward”, Philosophical Magazine 86, 4781-4796 (2006)
  • [2] C.Koch, J. Spence, C. Zorman, M. Mehregany
    and J. Chung, “Modelling of HREM and nanodiffraction for dislocation kinks
    and core reconstruction”, Journal of Physics: Condensed Matter 12, 10175 (2000)
  • [4] J. Spence, C. Koch, “Experimental evidence for dislocation core structures in silicon”, Scripta Materialia, 45(11), 1273-1278 (2001)
  • [5] J. Spence, C. Koch, “On the measurement of dislocation core periods by nanodiffraction”, Philosophical Magazine B 81(11), 1701-1711 (2001)

EELS – Bandgap Mapping

  • [39] L. Gu, V.B. Özdöl, W. Sigle, C.T. Koch, V. Srot, and P.A. van Aken,
    “Correlating the structural, chemical and optical properties of semiconductors with nanometer resolution”, Journal of Applied Physics 107 (2010) 013501
  • [25] L. Gu, V. Srot, W. Sigle, C.T. Koch, P.A. van Aken, “VEELS band gap measurements using monochromated electrons”, Journal of Physics: Conference Series 126 (2008) 012005 (4 pages)
  • [22] L. Gu, V. Srot, W. Sigle, C.T. Koch, P.A. van Aken, F. Scholz, S.B. Thapa, C.
    Kirchner, M. Jetter and M. R¨uhle, “Bandgap measurements of direct and indirect
    semiconductors using monochromated electrons”, Phys. Rev. B 75 (2007) 195214
  • [28] L. Gu, W. Sigle, C.T. Koch, J. Nelayah, V. Srot and P. A. van Aken, “Mapping
    of valence energy losses via energy-filtered scanning transmission electron
    microscopy”, Ultramicroscopy 109 (2009) 1164-1170

EELS – Plasmonics

  • [49] V. J. Keast, K. Birt, C.T. Koch, S. Supansomboon and M. B. Cortie, “The role of plasmons and interband transitions in the color of AuAl2, AuIn2 and AuGa2″, Appl. Phys. Lett. 99 (2011) 111908
  • [47] B. Ögüt, W. Sigle, N. Talebi, R. Vogelgesang, C.T. Koch,
    P.A. van Aken, “Magnetic Coupling of Plasmonic Eigenmodes of Rectangular
    Slits in Thin Silver Films”, ACS Nano 5 (2011) 6701-6706
  • [45] L. Gu, W. Sigle, C.T. Koch, B. Ögüt, P. A. van Aken, N. Talebi R. Vogelgesang, J. Mu, X. Wen, J. Mao, “Wedge-plasmon modes in single-crystalline gold nanoplatelets”, Phys. Rev. B 83 (2011) 195433
  • [33] W. Sigle, J. Nelayah, C.T. Koch, B. Ögüt, L. Gu, and P.A. van Aken, “EFTEM
    study of surface plasmon resonances in silver nanoholes”, Ultramicroscopy 110
    (2010) 1094-1100
  • [29] W. Sigle, J. Nelayah, C.T. Koch, P.A. van Aken, “Electron energy losses in Ag
    nanoholes: from localized surface plasmon resonances to rings of fire”, Optics
    Letters 34 (2009) 2150-2152
  • [30] J. Nelayah, L. Gu, W. Sigle, C.T. Koch, L. Pastoriza-Santos, L.M Liz-Marzan,
    and P.A. van Aken, “Direct imaging of surface plasmon resonances on single triangular silver nanoprisms at optical wavelength using low-loss EFTEM imaging”, Optics Letters 34 (2009) 1003-1005

Other

  • [12] C.T. Koch, W. Sigle, R. Höschen, M. Rühle, E. Essers, G. Benner and M. Matijevic, “SESAM: exploring the frontiers of electron microscopy”, Micoscopy and
    Microanalysis 12 (2006) 506-514

Dissertations