Enhanced sputter yields of ion irradiated Au nano particles: energy and size dependence

Abstract

Hexagonally arranged Au nanoparticles exhibiting a broad Gaussian-shaped size distribution ranging from 30 nm to 80 nm were deposited on Si substrates and irradiated with Ar(+) and Ga(+) ions with various energies from 20 to 350 keV and 1 to 30 keV, respectively. The size and energy dependence of the sputter yield were measured using high-resolution scanning electron microscopy image analysis. These results were compared to simulation results obtained by iradina, a Monte Carlo code, which takes the specifics of the nano geometry into account. The experimental sputter yields are significantly higher than simulated sputter yields for both bulk and the nano geometry. The difference can be clearly attributed to thermally driven effects, which significantly increase the measured sputter yields.

Sputtering and redeposition of ion irradiated Au nanoparticle arrays: direct comparison of simulations to experiments

“…The blue curve shows the sputter yield calculated by iradina, the red curve shows the results of the model by Järvi et al [18]. The data points plotted in green are the results from the experiment presented in [31]. The dashed orange curve is the sputter yield by Järvi scaled to fit the experimental sputter yield.…”

“…In the y direction, the coordinates from the SEM images were corrected by the viewing angle of 52°in the SEM. The sputtering yields were calculated as described in [14,31]. The results of both experiment and simulation are still comparable for the used energies, since the difference in the sputtering yield for 25 and 30 keV Ga + irradiation is negligible [31].…”

“…The redeposition was simulated for a two-dimensional NP array on a squared 4×4 grid with a side length of 95 nm. This is the average distance of the centers of the Au NPs in the samples investigated experimentally in [31]. The particles were located at the center of these squares.…”

“…The simulation for 16 NPs was performed 120 times with different random seeds to achieve reasonable statistics. The NP sizes were randomly chosen from the size distribution obtained from the samples investigated in experiments [31], shown in figure 2(a) in red. The NP sizes ranged from 20 to 80 nm and were distributed with a Gaussian distribution with a mean value of 51 nm and a standard deviation of 7.6 nm.…”

“…The height of all cells was the same and was defined by the diameter of the largest particle. In most cases, the NP sizes were randomly chosen according to the distribution obtained from experimental data [31]. In the z direction, the particles were positioned at the bottom of the simulation volume, as shown in figure 1(a), side view.…”