ELECTRONIC MATERIALS Influence of fast neutron irradiation on the phase composition and optical properties of homogeneous SiO x and composite Si–SiO x thin films Diana Nesheva 1 , Zsolt Fogarassy 2 , Margit Fabian 2 , Temenuga Hristova-Vasileva 1 , Attila Sulyok 2 , Irina Bineva 1 , Evgenia Valcheva 3 , Krassimira Antonova 1 , and Peter Petrik 2, * 1 Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria 2 Centre for Energy Research, Konkoly Thege Miklos ut 29-33, 1121 Budapest, Hungary 3 Faculty of Physics, Sofia University ‘St. Kliment Ohridski’, 5 James Bourchier, Blvd., 1164 Sofia, Bulgaria Received: 25 June 2020 Accepted: 12 September 2020 Ó Springer Science+Business Media, LLC, part of Springer Nature 2020 ABSTRACT Layers and devices utilizing semiconductor nanocrystals have been the subjects of intensive research due to applications in opto- and microelectronic devices, solar cells, detectors, memories and in many more fields. We have shown pre- viously that those nanocrystals in dielectric matrices undergo a substantial reformation during electron irradiation. The research of the interaction between semiconductor nanoclusters and irradiation is important for both the intentional modification of the structures and for understanding the stability of those devices under harsh, radiative conditions (e.g. space, nuclear, medical diagno- sis, or similar applications). In the present research, we investigated the influ- ence of neutron irradiation on substoichiometric silicon oxide. We investigated both homogeneous case and inhomogeneous case of matrices with silicon nanoclusters. We found that a fast neutron flux of 5.5 9 10 13 neutrons/cm 2 s and a fluence of 3.96 9 10 17 neutrons/cm 2 induce phase separation in the homogeneous films, whereas it decreases the volume fraction of the amorphous silicon phase caused by the reducing size of amorphous nanoclusters in the inhomogeneous films. Handling Editor: Kevin Jones. Address correspondence to E-mail: petrik@mfa.kfki.hu https://doi.org/10.1007/s10853-020-05338-3 J Mater Sci Electronic materials