Effect of irradiation with continuous 28 MeV He2+ion beam and short-pulsed 200 keV C+ion beam on optical properties of multilayer Al-Si-N coatings

The article reports on radiation defect formation parameters and radiation resistance of multilayer coatings from thin layers of aluminum and silicon nitrides deposited on sodium-calcium-silicate glass and monocrystalline silicon substrates by reactive magnetron sputtering. The samples were irradiated with helium ions of 28 MeV on a cyclotron and carbon ions 200 keV on an accelerator in the mode of short-pulse implantation. The characteristics of local absorption and luminescence centers before and after irradiation and their probable nature were determined. The optical centers had been identified as point intrinsic defects of a growth and radiation nature. The accumulation of radiation defects in layers of amorphous silicon nitride a-Si3N4 prevailed over the accumulation in crystalline c-AlN layers due to the diffusion of defects in amorphous layers and the formation of secondary defects in them. Changes in optical properties led to the conclusion about the high radiation resistance of the coatings. The main reasons for the resistance of coatings to ion irradiation were the high concentration of growth defects, their strong interaction and the wide band gap of the nitrides. Coatings deposited on silicon substrates had a higher radiation resistance compared to the same coatings deposited on glass substrates.