A New Approach for Radiation Damage Studies by Incorporation of Dilute Self-Irradiating Defects in Thin Films

  Tzvi Tempelman [1]  ,  Michael Shandalov [2]  ,  Eyal Yahel [2]  ,  Itzhak Kelson [3]  ,  Michael Schmidt [3]  ,  Yuval Golan [1]  
[1] Department of Material Engineering, Ben-Gurion University, Beer Sheva 84105, Israel
[2] Department of Physics, NRCN, P.O. Box 9001, Beer-Sheva 84190, Israel
[3] School of Physics and Astronomy, Tel Aviv University, Tel Aviv 84105, Israel

We present a new method to produce a model system for the study of radiation damage in non-radioactive materials. The method is based on homogeneous incorporation 228Th ions in PbS thin films using a small volume chemical bath deposition (CBD) technique. Controlled doping of the thin films with minute amounts of radioactive elements such as thorium is expected to provide a unique path for studying radiation damage in materials without the need of sealed enclosure.

We developed CBD process for controlled doping of PbS thin films with active 228Th isotope, which was achieved by altering different deposition parameters and metal ion complexation agents, due to 228Th daughters presence in solution.

The 228Th-doped films were characterized using x-ray diffraction, which indicated a single phase material. Film morphology and thickness were determined using scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) mapping in the analytical transmission electron microscope (A-TEM), x-ray photoelectron spectroscopy (XPS) depth profiles and a-autoradiography indicated that the Th ions were homogeneously distributed throughout the films, suggesting Pb substitution by Th ions in the crystal lattice. The properties of the PbS(228Th) film activity and isotopes distribution were investigated by using a-spectroscopy and g-spectroscopy. In this work, we show our preliminary results on radiation damage accumulation in these films. The measurements were performed using photo luminescence (PL) spectroscopy technique, where band-to-band and defect states emissions were monitored. Isochronal annealing will be performed to determine damage mechanisms by monitoring changes in electrical resistivity of the samples. The resulting films showed promise as a model system for the analysis of dilute defect systems in thin films.