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Jesper Wallentin

Position:    Assistant Professor

E-mail:    jesper.wallentin@sljus.lu.se
Phone:   
Cell phone:    +46 70 559 3949
Room:    K542
Address:    Professorsgatan 1
22100 Lund
      Sweden

University:    Lund University
Division:    Synchrotron Radiation Research
Research Area(s):    Materials Science
Nanoelectronics- & photonics
Interests:    X-ray analysis of nanostructures

 
jesper.wallentin

Teaching:

I teach physics 
* FYSA01 General physics at the Faculty of Science:. Responsible for the Quantum physics part of the course.
* Modern X-ray Physics: Diffraction and imaging. Available at the Faculty of Science (FYST51), at LTH, and as a PhD-level course (NFY007F). liveatlund.lu.se/departments/physics-N/FYST51/Pages/default.aspx
 
If you are interested in a MSc project, don't hesitate to contact me.

Group:

  • Zhaojun Zhang, postdoc
  • Lucas Marcal, postdoc
  • Lert Chayanun, PhD student
  • Susanna Hammarberg, PhD student
  • Hanna Dierks, PhD student

Research:

Our research studies single nanostructure devices using coherent X-ray imaging and X-ray diffraction. In particular, we're developing techniques for investigations that combine hard X-ray imaging and X-ray diffraction with electrical measurements [3,5]. Hard X-rays can penetrate through thick samples, allowing measurements of devices in operando. The X-rays can both be used as a pump, to study for instance X-ray induced electrical conductance [5], or as a probe of the structure in nanodevices [3]. Nanowires have demonstrated much stronger response to hard X-rays than expected from bulk data [5]. We have shown that the shape of bent nanowires can be reconstructed in 3D with nanometre precision [2,3].

The image below shows a 3D reconstruction of a nanowire changing shape under the influence of a strong electric field [3].
NW_model_projections_xvid_gif_001.gif

The experiments require intense nanofocused X-ray beams that are only available at synchrotrons such as Petra-III and ESRF, and now also at MAX IV.

The image below shows a recent ptychographic reconstruction from the Nanomax beamline at the new MAX IV synchrotron, depicting a standing GaInP nanowire (courtesy Vilgaile Dagyte and Magnus Borgström).
particle_2_ptycho_object_cropped.jpg

We have simulated the heating from pulsed X-rays using the finite-element software Comsol [1]:
Repeated_pulses_angle_video_gif.gif


For an updated lists of publications, please see ResearcherID or Google Scholar. A selected list of recent work:
  1. L Chayanun, G Otnes, A Troian, et al.: Nanoscale mapping of carrier collection in single nanowire solar cells using X-ray beam induced current J. Synchrotron Radiat. 26 (1) (2018) doi.org/10.1107/S1600577518015229
  2. A. Troian, G. Otnes, X. Zeng, L. Chayanun, V. Dagyte, S. Hammarberg, D. Salomon, R. Timm, A. Mikkelsen, M. T. Borgström, and J. Wallentin, "Nanobeam X-ray fluorescence dopant mapping reveals dynamics of in situ Zn-doping in nanowires" Nano Lett. 18 (10), 6461 (2018) dx.doi.org/10.1021/acs.nanolett.8b02957
  3. L. Chayanun, V. Dagyte, A. Troian, D. Salomon, M. T. Borgström, and J. Wallentin, "Spectrally resolved X-ray beam induced current in a single InGaP nanowire" Nanotechnology 29, 454001 (2018) doi.org/10.1088/1361-6528/aadc76
  4. H Wallander, J Wallentin: Simulated sample heating from a nanofocused X-ray beam J. Synchrotron Radiat. 24 (5) (2017) doi.org/10.1107/S1600577517008712
  5. J Wallentin, D Jacobsson, M Osterhoff, MT Borgström, T Salditt: Bending and twisted lattice tilt in strained core-shell nanowires revealed by nanofocused X-ray diffraction Nano Lett. 17 (7) (2017) (dx.doi.org/10.1021/acs.nanolett.7b00918)
  6. J. Wallentin, M. Osterhoff, and T. Salditt, "In operando X-ray diffraction reveals electrically induced strain and bending in single nanowire device" Adv. Mater. 28 (9), 1788 (2016) http://dx.doi.org/10.1002/adma.201504188
  7. J. Wallentin, M. Osterhoff, R. N. Wilke, K.-M. Persson, L.-E. Wernersson, M. Sprung, and T. Salditt, "Hard X-ray detection using a single 100 nm-diameter nanowire" Nano Lett. 14 (12), 7071 (2014) http://dx.doi.org/10.1021/nl5040545

Jesper Wallentin's pages

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