Correlation of the synthesis conditions and microstructure for Bi-based electron shields production

Highlights: • Examined the conditions of electrochemical Bi deposition and the structure of Bi coatings. • Established critical influence of gelatin adding in electrolyte on Bi structure. • Measured the protection efficiency of shields based on Bi under 1,6–1,8 MeV electron irradiation. The various ionizing radiations (electrons, protons, heavy charged particles, X-ray and gamma radiation) are the damaging factors for microelectronic products. The common used material for radiation protection is lead. Recently, Bi deposition has become an interest for the electrochemical community because of bismuth's unique electrical, physical and chemical properties. There is a limited number of authors dealing with Bi films onto metallic substrates by electrochemical deposition. The electrochemical deposition conditions and Bi coatings structure were examined. X-ray diffraction patterns for all samples were indexed to rhombohedral Bi. Coatings with a signified texture (012) are formed in electrolyte without additives. With gelatin adding the growth texture changes and the most intense reflex becomes (110). It was found that gelatin concentration increasing from 0.1 to 0.5 g/L leads Bi microstructural refinement from 4-20 μm to 50 nm-2 μm, respectively. The protection efficiency of shields based on Bi under 1,6–1,8 MeV electron radiation energy was measured. The electron beam attenuation efficiency was estimated by the changing of current-voltage characteristics of semiconductor test structures which were located behind the shields and without them. It has been determined that optimal protection effectiveness and mass-dimensional parameters have Bi shields with 2 g/cm² reduced thickness and 156 attenuation coefficient.