Researchers from KIT, PDI in Berlin and the University of Siegen succeeded in monitoring the temporal evolution of polytypism in GaAs nanowires during growth . For this, the group of researchers performed time-resolved in situ x-ray diffraction experiments at the NANO beamline at ANKA (KIT) with a dedicated MBE growth chamber.
From their measurements, the researchers were able to conclude on information about the temporal evolution of the mean thickness of a faultless segment of both polytypes in a large ensemble of growing nanowires. Their investigations and results --- already rewarded with a YIN Poster Award  in late 2013 --- are now being published in the Journal "Physical Review Letter" . Supplementary information were obtained by post-growth ex-situ X-ray diffraction experiments at the European Synchrotron Facility (ESRF) with a highly focused X-Ray beam . The time-resolved in-situ observation of such key parameters as the mean thickness of the polytypic segments during growth is an important step towards future technological applications of nanowires including, for example, more efficient LEDs, sensors, and transistors.
 Philipp Schroth, Martin Köhl, Jean-Wolfgang Hornung, Emmanouil Dimakis, Claudio Somaschini, Lutz Geelhaar, Andreas Biermanns, Ullrich Pietsch, Sondes Bauer, Sergey Lazarev, and Tilo Baumbach, Evolution of polytypism in GaAs nanowires during growth revealed by time-resolved in situ x-ray diffraction, Phys. Rev. Lett. 114, 055504 (2015)