Dr. Ali Al Hassan

Dr. Ali Al Hassan

Current position:
  • Scientist, X-ray Characterization and Growth of III-V Semiconductor Nanowires by MBE
Previous position:
  • 2019-2020 Postdoctoral researcher (Uni Siegen)
  • 2015 – 2019 Ph.D., University of Siegen
  • 2012 – 2015 M.Sc., University of Siegen
  • 2006 – 2010 B.Sc., Lebanese University
Field of research:
  • Structural characterization of individual nanowires and ensembles using X-ray techniques
  • Shape study of nano-droplets using grazing incidence small angle X-ray scattering
  • Epitaxial growth of III-V nanowires by MBE


  1. Exploiting flux shadowing for strain and bending engineering in core - shell nanowires
    Al-Humaidi, M.; Jakob, J.; Al Hassan, A.; Davtyan, A.; Schroth, P.; Feigl, L.; Herranz, J.; Novikov, D.; Geelhaar, L.; Pietsch, U.; Baumbach, T.
    2022. Nanoscale. doi:10.1039/D2NR03279A
  2. Transition from elastic to plastic strain release in core−shell nanowires revealed by in-plane x-ray diffraction
    Al Hassan, A.; Salehi, W. A.; Lewis, R. B.; Anjum, T.; Sternemann, C.; Geelhaar, L.; Pietsch, U.
    2021. Nanotechnology, 32 (20), Art.Nr. 205705. doi:10.1088/1361-6528/abe5db
  3. Correlating in situ RHEED and XRD to study growth dynamics of polytypism in nanowires
    Jakob, J.; Schroth, P.; Feigl, L.; Al Humaidi, M.; Al Hassan, A.; Davtyan, A.; Hauck, D.; Pietsch, U.; Baumbach, T.
    2021. Nanoscale. doi:10.1039/d1nr02320a
  4. Spatially-resolved luminescence and crystal structure of single core–shell nanowires measured in the as-grown geometry
    Al Hassan, A.; Lähnemann, J.; Leake, S.; Küpers, H.; Niehle, M.; Bahrami, D.; Bertram, F.; Lewis, R. B.; Davtyan, A.; Schülli, T. U.; Geelhaar, L.; Pietsch, U.
    2020. Nanotechnology, 31 (21), Art.-Nr.: 214002. doi:10.1088/1361-6528/ab7590
  5. High yield of self-catalyzed GaAs nanowire growth on silicon (111) substrate templated by focused ion beam patterning
    Bahrami, D.; Mostafavi Kashani, S. M.; Al Hassan, A.; Davtyan, A.; Pietsch, U.
    2020. Nanotechnology, 31 (18), Art.-Nr.: 185302. doi:10.1088/1361-6528/ab6d99
  6. Correlated Nanoscale Analysis of the Emission from Wurtzite versus Zincblende (In,Ga)As/GaAs Nanowire Core–Shell Quantum Wells
    Lähnemann, J.; Hill, M. O.; Herranz, J.; Marquardt, O.; Gao, G.; Al Hassan, A.; Davtyan, A.; Hruszkewycz, S. O.; Holt, M. V.; Huang, C.; Calvo-Almazán, I.; Jahn, U.; Pietsch, U.; Lauhon, L. J.; Geelhaar, L.
    2019. Nano letters, 19 (7), 4448–4457. doi:10.1021/acs.nanolett.9b01241
  7. Impact of the Shadowing Effect on the Crystal Structure of Patterned Self-Catalyzed GaAs Nanowires
    Schroth, P.; Al Humaidi, M.; Feigl, L.; Jakob, J.; Al Hassan, A.; Davtyan, A.; Küpers, H.; Tahraoui, A.; Geelhaar, L.; Pietsch, U.; Baumbach, T.
    2019. Nano letters, 19 (7), 4263–4271. doi:10.1021/acs.nanolett.9b00380
  8. Complete structural and strain analysis of single GaAs/(In,Ga)As/GaAs core–shell–shell nanowires by means of in-plane and out-of-plane X-ray nanodiffraction
    Al Hassan, A.; Davtyan, A.; Küpers, H.; Lewis, R. B.; Bahrami, D.; Bertram, F.; Bussone, G.; Richter, C.; Geelhaar, L.; Pietsch, U.
    2018. Journal of applied crystallography, 51 (5), 1387–1395. doi:10.1107/S1600576718011287
  9. Determination of indium content of GaAs/(In,Ga)As/(GaAs) core-shell(-shell) nanowires by x-ray diffraction and nano x-ray fluorescence
    Al Hassan, A.; Lewis, R. B.; Küpers, H.; Lin, W.-H.; Bahrami, D.; Krause, T.; Salomon, D.; Tahraoui, A.; Hanke, M.; Geelhaar, L.; Pietsch, U.
    2018. Physical review materials, 2, Art.-Nr.: 014604. doi:10.1103/PhysRevMaterials.2.014604

Further Publications

  1. Davtyan, A., Kriegner, D., Holý, V., AlHassan, A., Lewis, R. B., McDermott, S., Geelhaar, L., Bahrami, D., Anjum, T., Ren, Z., Richter, C., Novikov, D., Müller, J., Butz, B. & Pietsch, U. X-ray diffraction reveals the amount of strain and homogeneity of extremely bent single nanowires. J. Appl. Cryst. (2020). 53, 1310-1320., DOI: /10.1107/S1600576720011516
  2. AlHassan, A., Lähnemann, J., Davtyan, A., Al-Humaidi, M., Herranz, J., Bahrami, D., Anjum, T., Bertram, F., Dey, A. B., Geelhaar, L. & Pietsch, U. Beam damage of single semiconductor nanowires during X-ray nanobeam diffraction experiments. J. Synchrotron Rad. (2020). 27, 1200-1208., DOI: /10.1107/S1600577520009789
  3. Davtyan, A., Favre-Nicolin, V., Lewis, R. B., Küpers, H., Geelhaar, L., Kriegner, D., Bahrami, D., Al-Hassan, A., Chahine, G., Loffeld, O. & Pietsch, U. Coherent X-ray diffraction imaging meets ptychography to study core-shell-shell nanowires. MRS Advances (2018). 3,  2317–2322., DOI: /10.1557/adv.2018.466
  4. Davtyan, A., Lehmann, S., Kriegner, D., Zamani, R. R., Dick, K. A., Bahrami, D., AlHassan, A., Leake, S. J., Pietsch, U. & Holý, V. Characterization of individual stacking faults in a wurtzite GaAs nanowire by nanobeam X-ray diffraction. J. Synchrotron Rad. (2017). 24, 981-990., DOI: /10.1107/S1600577517009584
  5. Davtyan, A., Krause, T., Kriegner, D., AlHassan, A., Bahrami, D., Mostafavi Kashani, S. M., Lewis, R. B., Küpers, H., Tahraoui, A., Geelhaar, L., Hanke, M., Leake, S. J., Loffeld, O. & Pietsch, U. Threefold rotational symmetry in hexagonally shaped core–shell (In,Ga)As/GaAs nanowires revealed by coherent X-ray diffraction imaging. J. Appl. Cryst. (2017). 50, 673-680., DOI: /10.1107/S1600576717004149
  6. Rieger, T., Zellekens, P., Demarina, N., AlHassan, A., Hackemüller, F. J., Lüth, H., Pietsch, U., Schäpers, T., Grützmacher, D. & Lepsaa, M. I. Strain relaxation and ambipolar electrical transport in GaAs/InSb core–shell nanowires. Nanoscale (2017). 9, 18392–18401., DOI: /10.1039/c7nr05201d