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

TL;DR

This study investigates how ion irradiation affects the morphology of amorphous hydrogenated silicon nitride films, revealing that higher fluences cause fragmentation of ion tracks due to dynamic electronic energy loss and hydrogen out-diffusion.

Contribution

It provides new insights into the evolution of ion track structures in a-SiNx:H films under different irradiation fluences, emphasizing the role of dynamic electronic energy loss.

Findings

Low fluence creates continuous ion tracks.

High fluence causes fragmentation of tracks.

Hydrogen out-diffusion influences track morphology.

Abstract

Amorphous hydrogenated silicon nitride ($\textit{a}$-SiN$_\mathrm{\textit{x}}$: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 $\textit{a}$-SiN$_\mathrm{\textit{x}}$:H films.