High-purity germanium (Ge) crystals with well-defined dislocation density are the central component of the LEGEND experiment for the detection of neutrinoless double-beta decay. The Leibniz-Institut für Kristallzüchtung (IKZ) is part of the LEGEND collaboration and conducts research on improved further processing of enriched germanium.
Kevin-Peter Gradwohl is working on this project and supported the team as part of his PhD thesis on the purification, growth and defect investigation of high-purity germanium crystals. He has studied the dislocations in the Ge crystals in detail both experimentally, in particular by white-beam X-ray imaging, and by extending the open-source code "ParaDiS" to crystals with diamond structure to calculate the dislocation multiplication numerically. In addition, his work included the hydrogen reduction and purification of isotopically enriched Ge, crystal growth of Ge by Czochralski method, and the investigation of their electrical properties.
Mr. Gradwohl studied materials science and has been working on a doctoral thesis on "Growth and defect investigation of high-purity germanium crystals for radiation detector applications" at the IKZ since 2018. The native Austrian completed both his Master's and Bachelor's degree with honours after his professional training in mechanical engineering. Already during his studies, Kevin-Peter Gradwohl specialized in crystal growth and characterization during an academic exchange program with Northwestern Polytechnical University (Xi'an, China) and numerous internships.
With the DGKK Young Scientists Award, the association honours outstanding scientific achievements of young scientists in the field of crystal growth. The prize is endowed with 2.500 €. The award ceremony took place on October 7, 2021 at the Deutsche Kristallzüchtertagung (DKT) in Berlin.
Further information:
Kevin-Peter Gradwohl
Dr. habil. R. Radhakrishnan Sumathi
Section Semiconductors
