Ageing dynamics of ion bombardment induced self-organization processes

Abstract

Instabilities caused during the erosion of a surface by an ion beam can lead to the formation of self-organized patterns of nanostructures. Understanding the self-organization process requires not only the in-situ characterization of ensemble averaged properties but also probing the dynamics. This can be done with the use of coherent X-rays and analyzing the temporal correlations of the scattered intensity. Here, we show that the dynamics of a semiconductor surface nanopatterned by normal incidence ion beam sputtering are age-dependent and slow down with sputtering time. This work provides a novel insight into the erosion dynamics and opens new perspectives for the understanding of self-organization mechanisms.

Self-organized nanopatterning of silicon surfaces by ion beam sputtering

“…This slowing down is known as ageing, a phenomenon which occurs in many processes far from equilibrium. For IBS systems, it has been experimentally demonstrated in the case of GaSb targets [240].…”

On the use of two-time correlation functions for X-ray photon correlation spectroscopy data analysis

“…Unfortunately, this point is not always clear in the literature. Instances can be found in which the width of the diagonal contour is taken as being proportional to the relaxation time (Ruta et al, 2013;Bikondoa et al, 2013) -i.e. the ACS-1-TCF convention is used -and where quantitative values of the relaxation time and the stretching parameter at different sample ages are reported.…”

“…However, it would have been more natural to report quantitative values obtained following the CCS-1-TCF convention, as this is the one habitually used in glassy systems theory (Wolynes & Lubchenko, 2012). But because the ageing is so slow in the systems studied by Ruta et al (2013) and Bikondoa et al (2013), the ACS-and CCS-1-TCFs are essentially equivalent. In other work (Mü ller et al, 2011), it is unclear if the 1-TCFs extracted from a 2-TCF that has sharp-cut division due to avalanche dynamics follow the CCS or the ACS convention.…”

“…Ion beam sputtered surfaces are non-equilibrium systems that show ageing (Bikondoa et al, 2013). One theoretical approach to describe the temporal evolution and dynamics of such systems is the continuum theory, which uses partial differential equations to describe the evolution of the surface height (Muñ oz-García et al, 2009).…”

Advanced techniques for characterization of ion beam modified materials

“…Ion beam modification of materials is well established as a unique tool to shape and design materials at different length scales with controlled modification of electrical, optical, structural, mechanical and chemical properties for a wide range of research and applications, including advanced electro-optical devices, engineered nanostructures, nuclear materials, and space exploration [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Recent examples include swift heavy ion irradiation at oblique incidence to produce graphitic nanostripes on the surface of silicon carbides (SiC) as a result of silicon sublimation induced by intensive electronic energy deposition along the ions path [1].…”