Staff profile
Mr Leon Bowen, BSc (Hons), MBA
(email at leon.bowen@durham.ac.uk)
Background
Leon Bowen studied for a BSc (Hons) in Forensic / Materials Engineering at Sheffield Hallam University. During his studies he had completed a 12 month industrial placement at the Materials and Engineering Research Institute (MERI) also at Sheffield Hallam University. After a successful spell his placement was extended to 16 months and provided an excellent grounding for Leon to begin his career. Leon was eventually employed by MERI after completing his final year exams. During his employment Leon progressed and developed further while also studying for MBA part-time in industrial management. Leon later moved to Oxford Instruments Micro-Analysis Ltd, where he had developed his understanding in high technological products (Hardware and Applications). Leon has a deep understanding of micro-analysis techniques for both online and offline processing operations. He is able to apply the technology to the science and research in an interdisciplinary environment. Leon later joined Durham University where he is part of a team (Dr Mendis, Prof Karl Coleman, Prof Robert Holdsworth and previously Prof Ken Durose) in creating a solid user base both internally and externally as well as many SME’s for the facility. Leon is trained in INCA feature, and GSR (Gun Shot Residue) applications, INCA Wavelength, INCA Energy, Detector technology (INCAx-Sight LN2, Si Drift detectors, INCAx-Stream and INCAmics Hardware, EDAX Genesis applications, vacuum technology and maintenance.
Member / Supporting of (links) –
Department of Physics, Department of Chemistry, Department of Earth Sciences, Department of Engineering and Computing Sciences, Department of Biological and Biomedical Sciences, Institute of Hazard, Risk and Resilience, Microsystems Technology Group, Geospatial Research Ltd, Structural Research Geology Group, Centre for Materials Physics
GASH Project, Unconventional Hydrocarbons, PV21, Stephenson Institute for Renewable Energy, Supergen 'SuperSolar' Project
Current Academic Collaborators Include:
Newcastle University, University Of Leeds, London South Bank University, Liverpool University, St.-Petersburg Academic University — Nanotechnology Research and Education Centre, Northumbria University, University of Mugla, TR.
Biography
i) Responsibility within facility
Oversee the smooth technical operation of the facility
Technical responsibility and management for the Hitachi SU70 and analytical attachments. Technical responsibility for the management of the FEI Dual Beam Helios Nano Lab MK 2.
Responsibility for the development of EM preparation techniques. Responsibility for high end coating requirements and techniques (high resolution Carbon, Au/Pd target, Cr target and Pt target). Responsibility for overseeing secure server access, data transfer and data management operations alongside Mark Short.
ii) Teaching Activities
Responsibility for passing on high end microscopy skill sets through coaching and training in the area of SEM, EDX, WDX, EBIC, FIB, CL EBID and IBID, offline processing and 3D reconstruction.
iii) Research Activities
To be involved as required in all areas of research in providing logical approaches to individual problems or requirements of EM techniques.
See Links
iv) Collaborations
Shared responsibility for developing and maintaining cross departmental, cross university and industry collaborations.
Application Interest
i) Micro-Analysis
Interests include high level X-Ray Micro-Analysis, complex spectra analysis and spectrum manipulation. Quantification analysis, Phase analysis techniques, Multichannel and simultaneous analysis techniques, image quantification techniques and signal mixing operations.
ii) EBIC (Electron Beam Induced Current)
Applying EBIC techniques for profiling P/N junctions in semiconductors and voltage bias experiments
iii) WAVELENGTH Analysis
iv) Combined EBIC and CL investigations
v) Low KV BSE imaging
vi) FIB - Circuit Editing
Focused Ion Beam (FIB) circuit edit allows the customer to cut tracks or add metal connections within a device. Services include sample preparation; repair mistakes in circuit designs, repairs include isolating lines and connecting lines, modify circuits for performance optimization, modifications on singulated die or on decapsulated parts. Such circuit edits can support basic electrical design characterisation or verification of redesign parameters.
FIB circuit editing employs a finely focused Ga+ ion beam to image, etch and deposit materials on an integrated circuit.
FIB edits can be done quickly and easily, at a small fraction of the cost of a new lot of wafers in a fab. Circuit edits are often performed once a design flaw has been identified, to ensure that the proposed fix will solve the complete problem. With state of the art equipment, it is possible to edit circuits with 65 nm technology and multiple layer metal stacks. Bearing in mind that this approach is a challenging one and working with the customer is essential. Ideally gas inject would be Tungsten although Pt is commonly used. Pt is a reliable short term repair to validate redesign. Reality is that Pt electrical properties will degrade over time. This is because the deposits consist of Pt crystals embedded in a carbon matrix. The conduction occurs via hopping between crystals which will be very sensitive to changes in the matrix and the distance between the crystals.
Ideal use of FIB for circuits designs are to the strengths of FIB technology for circuit designs as they are significantly faster and less expensive than running a new lot of designs through a fabrication process. Being able to make multiple modifications to a single circuit can only be positive to quickly determining route cause poor performance.
vii) BIB – Broad Ion beam techniques – See related links
viii) High Resolution Imaging
Research Interest
Minerals / Rock / Clays / Crystals / Fault zones / Nano wire developments / CNT’s, Shale gas / Semiconducting materials / MEMS devises / Thin Films / Renewable technologies / Photovoltaics / Contaminated land and water treatment technologies / Nano Structuring and Patterning techniques / Sample Interaction simulations / developments of preparation techniques / Experimental approaches / Anything difficult and challenging / Combining technologies / Image quantification and Phase analysis/ Collaborations welcome /
Selected publications
1) Bernard S., Mathia, E.J., Wirth R., Schreiber A., Bowen L., Aplin A.C., Schulz H-M., Horsfield B. “FIB-SEM and TEM investigations of an organic-rich shale maturation series (Lower Toarcian Posidonia Shale): Nanoscale pore system and fluid-rock interactions” (Accepted) AAPG Bulletin
2) R.E. Holdsworth, E.W.E. van Diggelen, C.J. Spiers , H. de Bresser, R.J. Walker & L. Bowen “Fault rock from the SAFOD core samples: Implications for weakening at shallow depths along the San Andreas Fault, California” Journal of Structural Geology 33 (2011) 132
3) JD Major, L Bowen, K Durose, “Focused Ion Beam and Field emission gun- scanning electron microscopy for the investigation of voiding and interface phenomena in thin film solar cells” Prog Photovolt: Res Appl 10.1002 (2011) 1164
4) B. L. Williams, B. Mendis, L. Bowen, D. P. Halliday and K. Durose (2011). “Vapor-Liquid-Solid Growth of Cadmium Telluride Nanowires by Close-Space-Sublimation for Photovoltaic Applications” MRS Proceedings, 1350, mrss11-1350-ee06-25 doi:10.1557/opl.2011.872
5) Binh T.T. Nguyen, Stuart J. Jones, Neil R. Goulty, Alexander J. Middleton, Neil Grant , Alison Ferguson, Leon Bowen “The role of fluid pressure and diagenetic cements in porosity preservation in Triassic fluvial reservoirs of the Central Graben, North Sea” (Accepted) AAPG Bulletin
6) Nor F. Za'bah, Kelvin S. K. Kwa, Leon Bowen, Budhika Mendis, and Anthony O'Neill. “A method for fabricating single crystal silicon nanowires is presented using top-down optical lithography”. [J. Appl. Phys. 112, 024309 (2012)]
8) GE Cirlin, VG Dubrovskii, YB Samsonenko, AD. Bouravleuv, K Durose, YY. Proskuryakov, BG Mendis, L. Bowen, MA Kaliteevski, RA. Abram, DA. Zeze, "Self-catalyzed, pure zincblende GaAs nanowires grown on Si(111) by molecular beam epitaxy", Phys Rev B82 (2010) 035302
9) Jonathan D. Major, Leon Bowen, Robert E. Treharne and Ken Durose (2012). “Assessment of Photovoltaic Junction Position in CdTe Solar Cells Using a Combined FIB-EBIC Technique”. MRS Proceedings, 1432 , mrss12-1432-g11-06 doi:10.1557/opl.2012.1031
10) R. E. Treharne, B. L. Williams, L. Bowen, B. G. Mendis, K. Durose (2012) “Investigation of Post-Deposition and In Situ Cl Treatments for Fully-Sputtered CdTe/CdS Thin - Film Solar Cells” (conference paper IEEE PVSC)
11) BG Mendis, L Bowen, QZ Jiang, "A contactless method for measuring the recombination velocity of an individual grain boundary in thin-film photovoltaics", Appl Phys Lett 97 (2010) 092112
12) Claire J Horwell, Ben J Williamson, Ken Donaldson, Jennifer S Le Blond , David E Damby, Leon Bowen (2012) “Inherent characteristics and external factors influencing the respiratory toxicity of volcanic crystalline silica; relevance for the variable silica hazard” (Accepted)
13) Mendis, BG, Bowen, L. “Cathodoluminescence measurement of grain boundary recombination velocity in vapour grown p-CdTe”. 17th International Conference Microscopy of semiconducting Materials [Journal of Physics Conference Series, 326, 012017 (2011)]
Acknowledge work
1) N De Paola, T Hirose, T Mitchell, D Di Toro, C Viti, T Shimamoto, "Fault lubrication and earthquake propagation in thermally unstable rocks", Geology 39 (2011) 35
2) Linzi E. Dodd, Andrew J. Gallant and David Wood (2012). “Ti-TiOx-Pt Metal-Oxide-Metal Diodes Fabricated via a Simple Oxidation Technique”. MRS Proceedings, 1415 , mrsf11-1415-tt04-06 doi:10.1557/opl.2012.72
3) Wellings, J.S., Samantilleke, A.P., Heavens, S.N., Warren, P., Dharmadasa, I.M. “Electrodeposition of CuInSe2 from ethylene glycol at 150°C” Solar Energy Materials and Solar Cells Vol 93, 9 (2009) 1518-1523
4) J S Wellings, A P Samantilleke, PWarren, S N Heavens and I M Dharmadasa “Comparison of electrodeposited and sputtered intrinsic and aluminium-doped zinc oxide thin films” Semicond. Sci. Technol. 23 (2008) 125003 (7pp)
5) J.S. Wellings, N.B. Chaure a, S.N. Heavens b, I.M. Dharmadasa. “Growth and characterisation of electrodeposited ZnO thin films Thin Solid Films” 516 (2007) 3893–3898
6) A.B.M.O. Islam, N.B. Chaure, J. Wellings, G. Tolan, I.M. Dharmadasa. “Development of electrodeposited ZnTe layers as window materials in ZnTe/CdTe/CdHgTe multi-layer solar cells” Materials Chararterisation 60 (2 0 0 8) 1 6 0 – 1 6 3
7) A.P. Samantilleke, M.F.Cerqueira, B.Mari. “Segregation of Te at the back contact in electrochemically deposited CdTe thin film solar cells” Journal of Crystal Growth 320 (2011) 13–17