Dr Thomas Walther

CPhys, PhD, Dipl-Phys

School of Electrical and Electronic Engineering

Reader in Advanced Electron Microscopy

Semiconductor Materials and Devices Research Group

Headshot of Thomas Walther
Profile picture of Headshot of Thomas Walther
t.walther@sheffield.ac.uk
+44 114 222 5891

Full contact details

Dr Thomas Walther
School of Electrical and Electronic Engineering
Profile

I received my undergraduate degree in physics from RWTH Aachen in 1993 and my PhD in materials science from the University of Cambridge in 1996/97.

I was a postdoc at CEA Grenoble, Université d’Aix-Marseille (both in France) and University of Bonn (in Germany) where I later became assistant professor in the chemistry department.

After a short spell at a new research centre where I sat up an electron microscopy lab in the same city, I joined the University of Sheffield as Senior Lecturer in 2006 and was promoted to a readership in 2010.

My research focuses on electron microscopy as a fundamental tool to measure chemical changes at the interfaces between different materials with atomic resolution. This can produce fantastic images that directly show where the atoms are located!

My research is relevant for understanding epitaxial growth processes as well as degradation and failure of semiconductor devices, such as transistors, light-emitting diodes, lasers and solar cells: atoms can sometimes move to lattice positions where they should not be, their agglomeration producing extended lattice defects called dislocations that can multiply and finally lead to device failure.

These studies bridge the gap from fundamental science to applied engineering.

My research involves aspects of electron optics, solid state physics and inorganic chemistry as it combines different experimental methods of high-resolution analytical electron microscopy, based on inelastic electron scattering and X-ray photon generation, with detailed modelling of atomic movements in solids.

Presently, this methodology is expanded into materials for energy conversion and storage, such as electrodes in batteries.

Qualifications
  • CPhys, Fellow of the Institute of Physics, Fellow of the Royal Microscopical Society
  • PhD (Materials Science & Metallurgy), University of Cambridge, 1997
  • Dipl.-Phys. (Physics), RWTH Aachen, Germany, 1993
Research interests
  • Method development for analytical transmission electron microscopy, including energy-dispersive X-ray and electron energy-loss spectroscopy
  • Diffusion and segregation measurements in semiconductor nano-structures
  • Lattice defects in quantum dots, nano-wires and quantum wells
  • Characterization of doping, surface treatments, metal layers for plasmonics and oxides for energy storage applications
  • Microstructural characterization of prototype electronic devices, such as photodiodes, field-effect transistors, quantum well, quantum dot or quantum cascade lasers, photovoltaic cells
  • Engagement in electron microscopy societies and international conference organisation
Publications

Books

Edited books

  • Walther T & Hutchison JL (Ed.) (2013) 18th International Conference on Microscopy of Semiconducting Materials. Bristol: Institute of Physics Publishing. RIS download Bibtex download
  • Walther T & Midgley PA (Ed.) (2011) 17th International Conference on Microscopy of Semiconducting Materials. Bristol: IOP Publishing. RIS download Bibtex download
  • Walther T, Nellist PD, Hutchinson JL & Cullis AG (Eds.) (2010) 16th International Conference on Microscopy of Semiconducting Materials. Bristol: IOP Publishing. RIS download Bibtex download

Journal articles

Chapters

Conference proceedings papers

  • Walther T (2019) Measuring grain boundary segregation: tomographic atom probe field ion microscopy (APFIM) vs. analytical scanning transmission electron microscopy (STEM). Journal of Physics: Conference Series, Vol. 1190(1). Thessaloniki, Greece, 24 June 2018 - 29 June 2018. View this article in WRRO RIS download Bibtex download
  • Angadi VC & Walther T (2016) Influence of background subtraction and deconvolution on calculation of EELS core‐loss intensities (pp 891-892) RIS download Bibtex download
  • Walther T & Wang X (2015) Self-consistent absorption correction for quantitative energy- dispersive X-ray spectroscopy of InGaN layers in analytical transmission electron microscopy. Journal of Physics: Conference Series, Vol. 644 (pp 012006-012006) View this article in WRRO RIS download Bibtex download
  • Angadi VC, Abhayaratne & Walther T (2015) Development of automated background subtraction technique for electron energy-loss spectroscopy. http://www.mmc2015.org.uk/ (pp P.4027-P.4027). Manchester, 29 June 2015 - 2 July 2015. RIS download Bibtex download
  • Wang X, Chauvat MP, Ruterana P & Walther T (2015) Determination of indium concentration of InGaN alloys from plasmon spectroscopy. MMC2015, Manchester, UK RIS download Bibtex download
  • Angadi VC & Walther T (2014) Core-loss edge detection and background subtraction techniques for EELS. abstract booklet online(poster #3) (pp 13-13). Coventry, 15 October 2014 - 16 October 2014. RIS download Bibtex download
  • Dimitrakopulos GP, Kioseoglou J, Florini N, Komninou P, Walther T, Morakis K, Hatzopoulos Z, Pelekanos NT & Kehagias T (2014) Nanostructure properties of GaAs/AlGaAs core-shell nanowires. abstract booklet(B-B-II-28). Warsaw, 15 September 2014 - 18 September 2014. RIS download Bibtex download
  • Dimitrakopulos GP, Florini N, Kioseoglou J, Walther T, Germanis S, Hatzopoulos Z, Pelekanos NT & Kehagias T (2014) Morphology and misfit accommodation of InAs quantum dots on non-singular (211)B GaAs surfaces. abstract booklet(B-B-I-15). Warsaw, 15 September 2014 - 18 September 2014. RIS download Bibtex download
  • Bazioti C, Dimitrakopulos GP, Kehagias T, Walther T, Papadomanolaki E & Iliopoulos E (2014) Quantitative transmission electron microscopy of high alloy content InGaN deposited by PAMBE: from epilayers to quantum wells. H-2-4(abstract booklet). Warsaw, 15 September 2014 - 18 September 2014. RIS download Bibtex download
  • Walther T (2014) Comparison of the silicon/phosphorus ratio in natural and synthetic nagelschmidtite for possible use as standard for microanalysis based on X-ray lines of Si and P. 18th Int. Microscopy Congress (IMC2014), Vol. Instrumentation & Techniques (IT-5-P-3376) (pp 616-617). Prague, 7 September 2014 - 12 September 2014. RIS download Bibtex download
  • Walther T (2014) Investigation of the optical properties of silica nano-particles with low refractive index by electron energy-loss spectroscopy. Microscience Microscopy Congress MMC 2014 (pp P1059-P1059). Manchester, 30 June 2014 - 3 July 2014. RIS download Bibtex download
  • Zhang H, Ross IM, Zhang S & Walther T (2014) Production of regular quantum dot arrays by focused ion beams. 8th Int. Conf. Quantum Dots (pp 135-135). Pisa, 11 May 2014 - 16 May 2014. RIS download Bibtex download
  • Florini N, Kioseoglou J, Dimitrakopulos GP, Walther T, Hatzopoulos Z, Pelekanos NT & Kehagias T (2014) qHRTEM analysis of the (211)B In(Ga)As QDs/GaAs heterostucture. 18th Int. Microscopy Congress (IMC2014), Vol. Materials Science MS-1-P-2977 (pp 2340-2341). Prague, 7 September 2014 - 12 September 2014. RIS download Bibtex download
  • Bazioti C, Kehagias T, Walther T, Papadomanolaki E, Iliopoulos E & Dimitrakopulos GP (2014) Strain relaxation of high-In content InGaN epilayers grown by PAMBE. 18th Int. Microscopy Congress (IMC2014), Vol. MS-14-O-2233 (pp 3714-3715). Prague, 7 September 2014 - 12 September 2014. RIS download Bibtex download
  • Walther T (2014) Approaches for quantifying hyperspectral images of interfaces in analytical scanning transmission electron microscopy. Int. Conf. on Electron Microscopy & 35th Annual Meeting of EMSI (pp 63-64). Delhi, 9 July 2014 - 11 July 2014. RIS download Bibtex download
  • Kehagias T, Florini N, Walther T, Moratis K, Hatzopoulos Z & Pelekanos NT (2014) Core-shell GaAs/AlGaAs nanowires grown on Si(111). 18th Int. Microscopy Congress (IMC2014), Vol. Materials Science MS-1-O-2638 (pp 2185-2186). Prague, 7 September 2014 - 12 September 2014. RIS download Bibtex download
  • Ross IM, Li W & Walther T (2014) The influence of emitter conditioning on the performance of a tungsten <111> cold field emission gun operating at 300 kV. Journal of Physics: Conference Series, Vol. 522(1) RIS download Bibtex download
  • Walther T (2013) Nanoparticle characterisation by advanced transmission electron microscopy: chemical identification, local spectroscopy, mapping and detection limits. 1st International Symposium on Profiling 2013(Book of Abstracts) (pp 103-103). Portugal, 2 September 2013 - 4 September 2013. RIS download Bibtex download
  • Benz F, Walther T & Strunk HP (2013) Towards the structure of rare earth luminescence centres - terbium doped aluminium nitride as an example system. Journal of Physics: Conference Series, Vol. 471 (pp 012032-1-012032-4). Bristol, 7 April 2013 - 11 April 2013. RIS download Bibtex download
  • Zhang H, Ross IM & Walther T (2013) Study of site controlled quantum dot formation on focused ion beam patterned GaAs substrates. Journal of Physics: Conference Series, Vol. 471 (pp 012047-1-012047-4). Bristol, 7 April 2013 - 11 April 2013. RIS download Bibtex download
  • Taghi Khani A & Walther T (2013) Investigation of growth of thin layers of perovskite on native silicon dioxide by a combination of atomic force microscopy and transmission electron microscopy. Journal of Physics: Conference Series, Vol. 471 (pp 012037-1-012037-4). Bristol, 7 April 2013 - 11 April 2013. RIS download Bibtex download
  • Qiu Y, Nguyen VH, Dobbie A, Myronov M & Walther T (2013) Calibration of thickness-dependent k-factors for germanium X-ray lines to improve energy-dispersive X-ray spectroscopy of SiGe layers in analytical transmission electron microscopy. Journal of Physics: Conference Series, Vol. 471 (pp 012031-1-012031-6). Bristol, 7 April 2013 - 11 April 2013. RIS download Bibtex download
  • Lari L, Ross IM, Walther T, Black K, Cheze C, Geelhaar L, Riechert H & Chalker PR (2013) GaN-based radial heterostructure nanowires by MBE and ALD. Journal of Physics: Conference Series, Vol. 471 (pp 012039-1-012039-4). Bristol, 7 April 2013 - 11 April 2013. RIS download Bibtex download
  • Qiu Y, Norris DJ & Walther T (2012) Calibration of thickness-dependent k-factors of Germanium X-ray lines for improved analytical transmission electron microscopy of SiGe layers. 15th European Microscopy Congress, Vol. 2(Physical Sciences: Tools and Techniques) (pp 643-644). Oxford, 16 September 2012 - 21 September 2012. RIS download Bibtex download
  • Walther T (2012) Simultaneous imaging of single gold atoms and lattice fringes of nano-particles in annular dark-field scanning transmission electron microscopy. 15th European Microscopy Congress, Vol. 2(Physical Sciences: Tools and Techniques) (pp 397-398). Oxford, 16 September 2012 - 21 September 2012. RIS download Bibtex download
  • Parri MC, Qiu Y & Walther T (2012) Comparing experiment with theory of X-ray absorption in thin SiGe films. 15th European Microscopy Congress, Vol. 2(Physical Sciences: Tools and Techniques) (pp 693-694). Oxford, 16 September 2012 - 21 September 2012. RIS download Bibtex download
  • Parri MC & Walther T (2012) Determining sample thickness in transmission electron microscopy using X-ray line intensity ratios. 15th European Microscopy Congress, Vol. 2(Physical Sciences: Tools and Techniques) (pp 645-646). Oxford, 16 September 2012 - 21 September 2012. RIS download Bibtex download
  • Norris DJ, Dobbie A, Myronov M, Leadley DR, Parker EHC & Walther T (2012) Surface roughening of chemical vapour deposited SiGe layers. 15th European Microscopy Congress, Vol. 1(Physical Sciences: Applications) (pp 933-934). Oxford, 16 September 2012 - 21 September 2012. RIS download Bibtex download
  • Zhang H, Ross IM, Hopkinson M, Zhang S & Walther T (2012) Quantum dot nucleation on focused ion beam patterned GaAs substrates. 15th European Microscopy Congress, Vol. 1(Physical Sciences: Applications) (pp 927-928). Oxford, 16 September 2012 - 21 September 2012. RIS download Bibtex download
  • Zhang, H , Ross, IM , Hopkinson, M , Zhang, S & Walther, T (2012) Study of controlled quantum dot formation on focused ion beam patterned GaAs substrates. IEEE-Nano2012, Vol. digital abstract booklet (pp 716-718). London, 20 August 2012 - 23 August 2012. RIS download Bibtex download
  • Ross IM, Kawazu M, Sawada H, Papworth A & Walther T (2012) Performance of a cold field-emission gun double aberration corrected TEM/STEM at 80kV. Journal of Physics: Conference Series, Vol. 371 (pp 012013) RIS download Bibtex download
  • Ross IM & Walther T (2012) Configuring a 300kV cold field-emission gun for optimum analytical performance. Journal of Physics: Conference Series, Vol. 371 (pp 012012) RIS download Bibtex download
  • Amari H, Ross IM, Wang T & Walther T (2012) Characterization of thickness, elemental distribution and band-gap properties in AlGaN/GaN quantum wells by aberration-corrected TEM/STEM. Journal of Physics: Conference Series, Vol. 371 (pp 012014) RIS download Bibtex download
  • Parri MC & Walther T (2012) Self-consistent absorption corrections for low-energy X-ray lines in energy-dispersive X-ray spectroscopy. Journal of Physics: Conference Series, Vol. 371 (pp 012063-1-012063-4). Birmingham, UK, 6 September 2011 - 9 September 2011. RIS download Bibtex download
  • Norris DJ, Ross IM, Dobbie A, Myronov M, Whall TE, Parker EHC, Leadley DR, Walther T & IOP (2011) A TEM study of Ge-on-(111)Si structures for potential use in high performance PMOS device technology. 17TH INTERNATIONAL CONFERENCE ON MICROSCOPY OF SEMICONDUCTING MATERIALS 2011, Vol. 326 RIS download Bibtex download
  • Qiu Y, Lari L, Ross IM, Walther T & IOP (2011) Comparison of the contrast in conventional and lattice resolved ADF STEM images of InGaAs/GaAs structures using different camera lengths. 17TH INTERNATIONAL CONFERENCE ON MICROSCOPY OF SEMICONDUCTING MATERIALS 2011, Vol. 326 RIS download Bibtex download
  • Ross IM, Norris DJ, De Jaeger B, Lee W, Meuris M, Walther T & IOP (2011) Analysis of partially oxidised epitaxial silicon mono-layers on germanium virtual substrates using aberration corrected scanning transmission electron microscopy. 17TH INTERNATIONAL CONFERENCE ON MICROSCOPY OF SEMICONDUCTING MATERIALS 2011, Vol. 326 RIS download Bibtex download
  • Revin DG, Atkins CN, Commin JP, Cockburn JW, Qiu Y, Walther T, Kennedy K & Krysa AB (2011) Room temperature GaAs/AlGaAs quantum cascade lasers with InGaP and InAlP waveguides. Optics InfoBase Conference Papers RIS download Bibtex download
  • Schmid HK, Irsen S & Walther T (2010) ELNES fine structure of transition metal oxides recorded by HR-EELS. Past, Present and Future of (S)TEM and its Applications (pp 51-51). Paris, 9 June 2010 - 11 June 2010. RIS download Bibtex download
  • Qiu Y, Krysa AB & Walther T (2010) STEM imaging of InP/AlGaInP quantum dots. Journal of Physics: Conference Series, Vol. 245 (pp 012087). Nottingham RIS download Bibtex download
  • Norris DJ, Ross IM, Cullis AG, Walther T, Myronov M, Dobbie A, Whall T, Parker EHC, Leadley DR, De Jaeger B , Lee W et al (2010) TEM analysis of Si-passivated Ge-on-Si MOSFET structures for high performance PMOS device technology. Journal of Physics: Conference Series, Vol. 241 RIS download Bibtex download
  • Walther T (2008) Simple method to improve quantification accuracy of energy-dispersive X-ray spectroscopy in an analytical transmission electron microscope by specimen tilting. EMC2008- 14th European Microscopy Congress, Vol. 2 (Materials Science) (pp 375-376). Berlin, 1 September 2008 - 5 September 2008. RIS download Bibtex download
  • Walther T (2008) Comparison of transmission electron microscopy mehods to measure layer thicknesses to sub-monolyer precision. EMC2008- 14th European Microscopy Congress, Vol. 2 (Materials Science) (pp 377-378). Berlin, 1 September 2008 - 5 September 2008. RIS download Bibtex download
  • Walther T & Stegmann H (2008) Comparison of monochromated electron energy-loss with X-ray absorption near-edge spectra: ELNES vs. XANES. EMC2008- 14th European Microscopy Congress, Vol. 1 (Instrumentation and Methods) (pp 65-66). Berlin, 1 September 2008 - 5 September 2008. RIS download Bibtex download
  • Walther T, Atkinson K, Sweeney F & Rodenburg JM (2008) Measuring coherence in an electron beam for imaging. EMC2008- 14th European Microscopy Congress, Vol. 1 (Instrumentation and Methods) (pp 165-166). Berlin, 1 September 2008 - 5 September 2008. RIS download Bibtex download
  • Liu C, Walther T & Rodenburg JM (2008) Investigating the influence of dynamic scattering on ptychographical iterative techniques. EMC2008- 14th European Microscopy Congress, Vol. 1 (Instrumentation and Methods) (pp 723-724). Berlin, 1 September 2008 - 5 September 2008. RIS download Bibtex download
  • Walther T (2008) A comparison of transmission electron microscopy methods to measure wetting layer thicknesses to sub-monolayer precision - art. no. 012091. EMAG: ELECTRON MICROSCOPY AND ANALYSIS GROUP CONFERENCE 2007, Vol. 126 (pp 12091-12091) RIS download Bibtex download
  • Walther T (2008) A simple method to improve the quantification accuracy of energy-dispersive X-ray microanalysis - art. no. 012090. EMAG: ELECTRON MICROSCOPY AND ANALYSIS GROUP CONFERENCE 2007, Vol. 126 (pp 12090-12090) RIS download Bibtex download
  • Liew SL, Walther T, Irsen S, Hopkinson M, Skolnick MS & Collis AG (2008) Investigating the Capping of InAs Quantum Dots by InGaAs. MICROSCOPY OF SEMICONDUCTING MATERIALS 2007, Vol. 120 (pp 259-262) RIS download Bibtex download
  • Qiu Y, Walther T, Liu HY, Jin CY, Hopkinson M & Cullis AG (2008) Comparing InGaAs and GaAsSb Metamorphic Buffer Layers on GaAs Substrates for InAs Quantum Dots Emitting at 1.55 mu m. MICROSCOPY OF SEMICONDUCTING MATERIALS 2007, Vol. 120 (pp 263-268) RIS download Bibtex download
  • Ross IM, Gass M, Walther T, Bleloch A, Cullis AG, Lever L, Ikonic Z, Califano M, Kelsall RW, Zhang J & Paul DJ (2008) Structural and Compositional Properties of Strain-Symmetrized SiGe/Si Heterostructures. MICROSCOPY OF SEMICONDUCTING MATERIALS 2007, Vol. 120 (pp 269-272) RIS download Bibtex download
  • Walther T (2008) Quantifying the Top-Bottom Effect in Energy-Dispersive X-Ray Spectroscopy of Nanostructures Embedded in Thin Films. MICROSCOPY OF SEMICONDUCTING MATERIALS 2007, Vol. 120 (pp 185-188) RIS download Bibtex download
  • Walther T (2008) Determining Buried Wetting Layer Thicknesses to Sub-Monolayer Precision by Linear Regression Analysis of Series of Spectra. MICROSCOPY OF SEMICONDUCTING MATERIALS 2007, Vol. 120 (pp 247-250) RIS download Bibtex download
  • Schmid H, Walther T & Stegmann H (2006) Mn-L ELNES fine structure recorded by high energy-resolution EELS. 16th International Microscopy Congress, Vol. 2 (Instrumentation) (pp 846-846). Sapporo, 3 September 2006 - 8 September 2006. RIS download Bibtex download
  • Walther T, Quandt E, Greve H & Faupel F (2006) Energy-dispersive x-ray mapping with a new monochromatic and aberration-corrected 200kV field-emission scanning transmission electron microscope. 16th International Microscopy Congress, Vol. 2 (Instrumentation) (pp 873-873). Sapporo, 3 September 2006 - 8 September 2006. RIS download Bibtex download
  • Walther T, Sehrbrock A & Quandt E (2006) Analysis of focused ion beam cut profiles by transmission electron microscopy. 16th International Microscopy Congress, Vol. 2 (Instrumentation) (pp 1112-1112). Sapporo, 3 September 2006 - 8 September 2006. RIS download Bibtex download
  • Walther T & Stegmann H (2006) Performance evaluation of a new monochromatic and aberration-corrected 200kV field-emission scanning transmission electron microscope. 16th International Microscopy Congress, Vol. 2 (Instrumentation) (pp 607-607). Sapporo, 3 September 2006 - 8 September 2006. RIS download Bibtex download
  • Walther T, Schmid H & Stegmann H (2006) Electron energy-loss spectroscopy at 0.1-0.2eV resolution in a new monochromatic and aberration-corrected 200kV field-emission scanning transmisssion electron microscope. 16th International Microscopy Congress, Vol. 2 (Instrumentation) (pp 833-833). Sapporo, 3 September 2006 - 8 September 2006. RIS download Bibtex download
  • Walther T, Daneu N & Recnik A (2005) New methods for the quantitative chemical study of planar defects and interfaces by transmission electron microscopy. 7th Multinational Congress on Microscopy (MCM2005) (pp 75-78). Ljubljana, 26 June 2005 - 30 June 2005. RIS download Bibtex download
  • Stegmann H, Walther T, Quandt E, Zschech E & Schmeisser D (2005) High resolution ELNES characterization of chemical bonding in low-dielectric constant materials for interconncet isolation. Microscopy Congress 2005 (pp 238-238). Davos RIS download Bibtex download
  • Walther T, Recnik A & Daneu N (2005) ConceptEM: a new method to quantify solute segregation to interfaces or planar defect structures by analytical TEM and applications to inversion domain boundaries in doped zinc oxide. Microscopy of Semiconducting Materials, Vol. 107 (pp 199-202) RIS download Bibtex download
  • Cullis AG, Norris DJ, Walther T, Migliorato MA & Hopkinson M (2005) The mechanism of the Stranski-Krastanov transition. Quantum Dots: Fundamentals, Applications, and Frontiers, Vol. 190 (pp 71-88) RIS download Bibtex download
  • Daneu N, Walther T & Recnik A (2004) Application of a new method for measuring small amounts of dopants at planar faults: tin-rich inversion boundaries in zinc oxide. 13th European Microscopy Congress (EMC 2004), Vol. 3 (pp 63-64). Herentals, 22 August 2004 - 27 August 2004. RIS download Bibtex download
  • Simon J, Walther T & Mader W (2004) Diffusion and segregation effects in doped manganite/titanate thin film structures. 13th European Microscopy Congress (EMC 2004), Vol. 2 (Materials Sciences) (pp 243-244). Herentals, 22 August 2004 - 27 August 2004. RIS download Bibtex download
  • Cullis AG, Norris DJ, O'Neill JP, Ross IM, Migliorato MA, Hopkinson M, Parbrook PJ, Wang T & Walther T (2004) Segregation in compound semiconductors: the Stranski-Krastanow epitaxial transition and electron beam damage processes. 13th European Microscopy Congress (EMC 2004), Vol. 2 (Materials Sciences) (pp 417-418). Herentals, 22 August 2004 - 27 August 2004. RIS download Bibtex download
  • Walther T (2004) A new way to process and analyse quantitatively series of energy-filtered images of planar structures such as thin films or interfaces. 13th European Microscopy Congress (EMC 2004), Vol. 1 (Instrumentation and Methodology) (pp 251-252). Herentals, 22 August 2004 - 27 August 2004. RIS download Bibtex download
  • Walther T (2004) The limits of lattice imaging compared to annular dark-field imaging for determining size distributions of nano-particles. 13th European Microscopy Congress (EMC 2004), Vol. 2 (Materials Sciences) (pp 119-120). Herentals, 22 August 2004 - 27 August 2004. RIS download Bibtex download
  • Walther T (2004) A simple method to determine the chromatic aberration of a transmission electron microscope with imaging energy filter. 13th European Microscopy Congress (EMC 2004), Vol. 1 (Instrumentation and Methodology) (pp 33-34). Herentals, 22 August 2004 - 27 August 2004. RIS download Bibtex download
  • Jungk T, Walther T & Mader W (2003) Flutuation electron microscopy on a-Ge and polycrystalline gold. Microscopy and Microanalysis, Vol. 9(Suppl. 3) (pp 152-153). Cambridge, 7 September 2003 - 12 September 2003. RIS download Bibtex download
  • Walther T (2003) Electron energy loss spectroscopic profiling of semiconductor hetero- and nano-structures: theory, implementation, applications. MICROSCOPY OF SEMICONDUCTING MATERIALS 2003(180) (pp 27-32) View this article in WRRO RIS download Bibtex download
  • Mayer J, Pidun M & Walther T (2002) Spectrum imaging studies of ohmic contacts on GaN thin films. 15th International Congress on Electron Microscopy, Vol. 3 (Interdisciplinary) (pp 263-264). Onderstepoort, 1 September 2002 - 6 September 2002. RIS download Bibtex download
  • Walther T, Sobal N, Hilgendorff M & Giersig M (2002) Energy filtered TEM study of silver-cobalt nano-particles. 15th International Congress on Electron Microscopy, Vol. 3 (Interdisciplinary) (pp 261-262). Onderstepoort, 1 September 2002 - 6 September 2002. RIS download Bibtex download
  • Walther T (2002) Spectrum imaging of thin films of oxides and perovskites. 15, Vol. 3 (Interdisciplinary) (pp 123-124). Onderstepoort, 1 September 2002 - 6 September 2002. RIS download Bibtex download
  • Walther T (2002) Energy filtered TEM study of gold nano-particles on nano-crystalline anatase support. 15th International Congress on Electron Microscopy, Vol. 3 (Interdisciplinary) (pp 259-260). Onderstepoort, 1 September 2002 - 6 September 2002. RIS download Bibtex download
  • Recnik A, Daneu N, Walther T, Kawasaki M & Mader W (2002) Solving the atomic structure of inversion boundaries in Sb2O3-doped zinc oxide. 15th International Congress on Electron Microscopy, Vol. 1 (Physics and Materials) (pp 531-532). Onderstepoort, 1 September 2002 - 6 September 2002. RIS download Bibtex download
  • Walther T, Recnik A & Daneu N (2002) Test of a new analytical method to measure the composition of a planar fault. 15th International Congress on Electron Microscopy, Vol. 1 (Physics and Materials) (pp 535-536). Onderstepoort, 1 September 2002 - 6 September 2002. RIS download Bibtex download
  • Cullis AG, Norris DJ, Walther T, Migliorato MA & Hopkinson M (2002) Epitaxial island growth and the Stranski-Krastanow transition. CURRENT ISSUES IN HETEROEPITAXIAL GROWTH-STRESS RELAXATION AND SELF ASSEMBLY, Vol. 696 (pp 3-10) RIS download Bibtex download
  • Barf J, Walther T, Steinecker A & Mader W (2001) Exit wave reconstruction and elemental mapping of twin boundaries in the system ZnO-Ga2O3. Microscopy and Microanalysis, Vol. 7(Suppl. 2) (pp 290-291). New York, 2001 - 2001. RIS download Bibtex download
  • Albrecht M, Grillo V, Borysiuk J, Remmele T, Strunk HP, Walther T, Mader W, Prystawko P, Leszczynski M, Grzegory I & Porowski S (2001) Correlating compositional, structural and optical properties of InGaN quantum wells by transmission electron microscopy. MICROSCOPY OF SEMICONDUCTING MATERIALS 2001(169) (pp 267-272) View this article in WRRO RIS download Bibtex download
  • Walther T, Cullis AG, Norris DJ & Hopkinson M (2001) How InGaAs islands form on GaAs substrates: the missing link in the explanation of the Stranski-Krastanow transition. MICROSCOPY OF SEMICONDUCTING MATERIALS 2001(169) (pp 85-88) View this article in WRRO RIS download Bibtex download
  • Barf J, Walther T & Mader W (2000) Structure and chemistry of domains and interfaces in Ga2O3-doped ZnO. 4th German-Slovenian Seminar on Joint Projects in Materials Science and Technology (pp 2-3). Stuttgart RIS download Bibtex download
  • Daneu N, Walther T, Recnik A, Bernik S & Mader W (2000) Quantitative EDS analysis of inversion boundaries in Sn-doped ZnO. 4th German-Slovenian Seminar on Joint Projects in Materials Science and Technology (pp 14-15). Stuttgart RIS download Bibtex download
  • Pidun M, Karduck P, Mayer J, Heime K, Schineller B & Walther T (2000) Auger depth profile analysis and EFTEM analysis of annealed Ti/Al-contacts on Si-doped GaN. Joint Meeting of the Belgian and Dutch Societies for Microscopy (pp 172-173). Rijnsburg, 2000 - 2000. RIS download Bibtex download
  • Marko IP, Yablonskii GP, Gurskii AL, Lutsenko EV, Kalisch H, Heuken M, Walther T, Mader W & Heime K (2000) Thermal stability of ZnMgSSe / ZnSe laser heterostructures. ISCS-27. Piscataway, 2000 - 2000. RIS download Bibtex download
  • Schulmeister K, Walther T & Mader W (2000) Structural and spectroscopic characterisation of amorphous silicon sub-oxides. 12th European Congress on Electron Microscopy, Vol. 2 (Physical Sciences) (pp 465-466). Brno, 9 July 2000 - 14 July 2000. RIS download Bibtex download
  • Daneu N, Walther T, Recnik A, Bernik S & Mader W (2000) Structure and composition of inversion boundaries in Sn-doped ZnO. 12th European Congress on Electron Microscopy, Vol. 2 (Physical Sciences) (pp 435-436). Brno, 9 July 2000 - 14 July 2000. RIS download Bibtex download
  • Recnik A, Ceh M, Daneu N, Walther T & Mader W (2000) Charge balance models for inversion boudnaries in ZnO. 12th European Congress on Electron Microscopy, Vol. 2 (Physical Sciences) (pp 437-438). Brno, 9 July 2000 - 14 July 2000. RIS download Bibtex download
  • Walther T, Barf J & Mader W (2000) Quantification of segregation to grain boundaries and diffusion at interfaces by energy-filtered transmission electron microscopy. 12th European Congress on Electron Microscopy, Vol. 2 (Physical Sciences) (pp 409-412). Brno, 9 July 2000 - 14 July 2000. RIS download Bibtex download
  • Pack A, Hoernes S & Walther T (2000) The behaviour of olivine in refractories used in steel making processes - Thermodynamic considerations. APPLIED MINERALOGY, VOLS 1 AND 2 (pp 875-878) RIS download Bibtex download
  • Yan Y, Walther T & Kirk MA (1999) Measurement of oxygen disorder and nano-twin microstructure associated with columnar defects in YBa2Cu3O7-x. Materials Research Society Fall Meeting, Vol. 540 (pp 267-272). Boston (book), cambridge (on-line), 1998 - 1998. RIS download Bibtex download
  • Walther T & Mader W (1999) Application of spatially resolved electron energy-loss spectroscopy to the quantitative study of thin layer systems. Optik, Vol. 110(Suppl. 8) (pp 58-58). Dortmund RIS download Bibtex download
  • Walther T & Mader W (1999) Investigation of gold nano-particles by energy-filtered imaging. ELECTRON MICROSCOPY AND ANALYSIS 1999(161) (pp 243-248) RIS download Bibtex download
  • Walther T & Mader W (1999) Application of spatially resolved electron energy-loss spectroscopy to the quantitative analysis of semiconducting layer structures. MICROSCOPY OF SEMICONDUCTING MATERIALS 1999, PROCEEDINGS(164) (pp 121-128) RIS download Bibtex download
  • Walther T & Humphreys CJ (1997) Quantification of the composition of silicon germanium/silicon structures by high-angle annular dark field imaging. ELECTRON MICROSCOPY AND ANALYSIS 1997(153) (pp 303-306) RIS download Bibtex download
  • Boothroyd CB, Dunin-Borkowski RE & Walther T (1997) Scattering distribution from semiconductors as a function of angle and energy loss in the electron microscope. Materials Research Society Symposium - Proceedings, Vol. 466 (pp 113-118) RIS download Bibtex download
  • Walther T, Humphreys CJ, Cullis AG & Robbins DJ (1997) A study of interdiffusion and germanium segregation in low-pressure chemical vapour deposition of SiGe/Si quantum wells. MICROSCOPY OF SEMICONDUCTING MATERIALS 1997(157) (pp 47-54) RIS download Bibtex download
  • DuninBorkowski RE, Schaublin RE, Walther T, Boothroyd CB, Preston AR & Stobbs WM (1995) The determination of absorption parameters in Si and GaAs using energy filtered imaging. ELECTRON MICROSCOPY AND ANALYSIS 1995, Vol. 147 (pp 179-182) RIS download Bibtex download
  • Walther T, Schaublin RE, DuninBorkowski RE, Boothroyd CB, Humphreys CJ & Stobbs WM (1995) The role of plasmon scattering in the quantitative contrast analysis of high-resolution lattice images of GaAs. ELECTRON MICROSCOPY AND ANALYSIS 1995, Vol. 147 (pp 195-198) RIS download Bibtex download
  • Walther T, Hetherington CJD & Humphreys CJ (1995) A contribution to the quantitative comparison of experimental high-resolution electron micrographs and image simulations. MICROSCOPY OF SEMICONDUCTING MATERIALS 1995, Vol. 146 (pp 53-56) RIS download Bibtex download
  • Walther T & Humphreys CJ (1995) The limitations of pattern recognition and displacement measurement techniques for evaluating HREM images of strained semiconductor interfaces. ELECTRON MICROSCOPY AND ANALYSIS 1995, Vol. 147 (pp 103-106) RIS download Bibtex download
  • Walther T, Boothroyd CB & Humphreys CJ (1995) Strain relaxation induced local crystal tilts at Si/SiGe interfaces in cross-sectional transmission electron microscope specimens. MICROSCOPY OF SEMICONDUCTING MATERIALS 1995, Vol. 146 (pp 11-16) RIS download Bibtex download
  • Walther T, Gerthsen D, Carius R, Förster A & Urban K (1994) AlAs/GaAs quantum well structures: interface properties investigated by high-resolution transmission electron microscopy and photoluminescence spectroscopy. 4th International Conference on Formation of Semiconductor Interfaces (ICFSI-4) (pp 562-565). Singapore RIS download Bibtex download
  • WALTHER T, BOOTHROYD CB, HUMPHREYS CJ & CULLIS AG (1994) The effect of thin crystal strain relaxation on high-resolution images of Si/Si0.8Ge0.2 quantum wells. ELECTRON MICROSCOPY 1994, VOL 1 (pp 365-366) RIS download Bibtex download
  • WALTHER T, GERTHSEN D, CARIUS R, FORSTER A & URBAN K (1993) CORRELATION BETWEEN THE STRUCTURAL AND OPTICAL-PROPERTIES OF ALAS/GAAS QUANTUM-WELL STRUCTURES. MICROSCOPY OF SEMICONDUCTING MATERIALS 1993(134) (pp 449-454) RIS download Bibtex download
  • Wang X & Walther T () Joint plasmon and core-loss fitting for electron energy loss spectroscopy of InGaN (pp 893-894) RIS download Bibtex download
  • Walther CG & Walther T () Sub-diffraction limited imaging of nano-rulers using Structured Illumination Microscopy. Frontiers in BioImaging, 14 July 2016 - 15 July 2016. RIS download Bibtex download
  • Angadi V & Walther T () Systematic Study of Background Subtraction Techniques for EELS. http://emag2016.iopconfs.org/, 6 April 2016 - 8 April 2016. RIS download Bibtex download
  • Qiu Y, Krysa AB, Cullis AG & Walther T () Scanning transmission electron microscopy study of InP quantum dots. Photon '10, Vol. abstract booklet (pp P1-55). Southampton, 23 August 2010 - 26 August 2010. RIS download Bibtex download
  • Nguyen VH, Dobbie A, Myronov M, Norris DJ, Walther T & Leadley DR () Epitaxial growth by RP-CVD of relaxed germanium layers on (110) and (111) silicon substrates. 7th Int. Conf. Silicon Epitaxy and Heterostructures (ICSI-7), Vol. abstract booklet. Leuven, 29 August 2011 - 2 September 2011. RIS download Bibtex download
  • Walther T, Simon J & Stegmann H () Combining imaging with local spectroscopy in an energy-filtered TEM/STEM. Microscopy Congress 2005 (pp 240-240). Davos RIS download Bibtex download
  • Daneu N, Recnik A, Walther T & Mader W () A new method of analytical TEM for the determination of very small amounts of dopants at interfaces. 8th Asian-Pacific Conf. on Electron Microscopy (pp 438-439). Tokyo, 2004 - 2004. RIS download Bibtex download
  • Walther T, Boothroyd CB & Humphreys CJ () The dependence of the growth rate of LPCVD grown SiGe quantum wells on the Ge composition and the layer thickness. EUREM-11 (Europ. Conf. Electron Microscopy), Vol. 1 (pp 317-318). Brussels, 1996 - 1996. RIS download Bibtex download
  • Walther T & Mader W () Methods for reliable elemental mapping despite low signal-to-noise ratios and overlapping ionisation edges. Dreiländertagung für Elektronenmikroskopie(abstract booklet) (pp 29-29). Innsbruck, 9 September 2001 - 14 September 2001. RIS download Bibtex download
  • Walther T, Benner G, Stegmann H, Thesen A & Quandt E () First results from a monochromated and Cs-corrected 200kV STEM. EDGE 2005: Endhanced Data Generated with Electrons(abstract booklet) (pp 55-55). Grundlsee, 1 May 2005 - 5 May 2005. RIS download Bibtex download
  • Chong RKK, Dunin-Borkowski RE, Walls MG, Tence M, Walther T, Gemming T, Bayle-Guillemaud P, Champion Y, Hytch MJ & Snoeck E () Round-robin results of the quantitative analysis of FeNi nanoparticle compositions. EDGE 2005: Endhanced Data Generated with Electrons(abstract booklet) (pp 50-50). Grundlsee, 1 May 2005 - 5 May 2005. RIS download Bibtex download
  • Lutsenko EV, Zubialevich VZ, Pavlovskii VN, Marko IP, Gurskii AL, Yablonskii GP, Kalisch H, Walther T, Schoen O, Protzmann H , Luenenbuerger M et al () Optically pumped transverse lasers based on ZnMgSSe/ZnSe and InGaN/GaN heterostructures. Proceedings SPIE, Vol. 4751 (pp 542-548). Minsk RIS download Bibtex download
  • Gerthsen D, Walther T & Rosenauer A () Quantitative high-resolution electron microscopy of semiconductor heterostructures. Japanese-German Forum on Information Technology (pp 6-10). Oita RIS download Bibtex download

Patents

  • Walther T (2011) Collection of electromagnetic Radiation emitted from Particle-irradiated Samples. WO 2011030156 (A2) Appl. 17 Mar 2011. RIS download Bibtex download

Reports

  • Walther CG & Walther T (2014) Book review of ‘Fundamentals of Fluorescence Microscopy’ by Partha Pratim Mondal and Alberto Diaspro, Springer, Dordrecht, 2014, ISBN: 978-94-007-7544-2 RIS download Bibtex download
  • Walther T (2014) Leserbrief zum Beitrag ‘Auswendig lernen und wieder vergessen’ by J. Loviscach (abbreviated commentary on teaching mathematics to engineering students; in German) RIS download Bibtex download
  • Walther T (2011) Book review of 'Sample Preparation Handbook for Transmission Electron Microscopy' by J. Ayache, L. Beaunier, J. Boumendil, G Ehret, D. Laub (Springer, New York, 2010, ISBN 978-1-4419-5974-4), published in infocus magazine RIS download Bibtex download
  • Quandt E, Walther T, Sehrbrock A & Wehner B (2005) Electron microscopy RIS download Bibtex download
  • Quandt E, Walther T, Sehrbrock A & Wehner B (2005) Electron microscopy of TMR structures RIS download Bibtex download
  • Ludwig A, Feydt J, Walther T & Zotov N (2005) Structural studies of Fe-Pt multilayers RIS download Bibtex download
  • Ludwig A, Groudeva-Zotova S, Ehmann M, Feydt J, Savan A, Sehrbrock A, Walther T & Wehner B (2005) Structural and magnetic properties of FeCo films modified by combinatorial ion implantation RIS download Bibtex download
  • Quandt E & Walther T (2004) Transmission electron microscopy RIS download Bibtex download
  • Quandt E, Sehrbrock A, Walther T & Wehner B (2004) Electron microscopy at the Center for Advanced European Studies and Research RIS download Bibtex download
  • Cullis AG, Norris DJ, Migliorato MA, Hopkinson M & Walther T (2003) Modelling of the Stranski-Krastanow transition and epitaxial island growth RIS download Bibtex download
  • Walther T, Gerthsen D, Stenkamp D, Carius R & Förster A (1993) Korrelation optischer und struktureller Eigenschaften von AlAs/GaAs- Quantentopfstrukturen RIS download Bibtex download

Theses / Dissertations

  • Walther T (1997) A study of compositional variations in semiconductor heterostructures by transmission electron microscopy. University of Cambridge. RIS download Bibtex download
  • Walther T (1993) Untersuchung struktureller Eigenschaften von AlAs/GaAs- Quantentopfstrukturen mittels hochaufloesender Transmissions-Elektronenmikroskopie. RWTH Aachen. RIS download Bibtex download
Teaching activities
  • EEE345 'Engineering Electromagnetics'
  • EEE6233 'Physical Principles of Imaging: Radiation-Matter Interaction'
Professional activities and memberships
  • Reader in Advanced Electron Microscopy
  • Departmental Tutor for Postgraduate Research Students
Research students
Student Degree Status Primary/Secondary
Guo R PhD Current Primary
Luo P PhD Current Secondary
Yan H PhD Current Secondary
Wang X PhD Graduated Primary
Amari H  PhD Graduated Primary
Angadi V  PhD Graduated Primary
Parri M C PhD Graduated Primary
Qiu Y PhD Graduated Primary
Taghi Khani A PhD Graduated Primary
Zhang H PhD Graduated Primary