Evolution of ion track morphology in a-SiNx:H by dynamic electronic energy loss

Abstract

Amorphous hydrogenated silicon nitride ($\text{a}$-SiN${}_{\text{x}}$:H) thin films irradiated with 100 MeV Ni${}^{7+}$ results in the formation of continuous ion track structures at the lower fluence of $5\times 10^{12}$ ions/cm${}^2$ whereas at higher fluence of $1\times 10^{14}$ ions/cm${}^2$ the track structures fragment into discontinuous ion track like structures . The observation of the discontinuous ion track like structures at the high fluence of $1\times 10^{14}$ ions/cm${}^2$ shows clearly that higher fluence irradiation may not always lead to dissolution of the microstructure formed at lower fluence. The results are understood on the basis of a dynamic electronic energy loss (S${}_e$) in the course of irradiation resulting from the out-diffusion of hydrogen from the films and a continuous increase in density of $\text{a}$-SiN${}_{\text{x}}$:H films.

10 pages, 5 figures