Ion impact energy distribution and sputtering of Si and Ge

Abstract

Structural characterization of CdSe/ZnS quantum dots using medium energy ion scattering Appl. Phys. Lett. 101, 023110 (2012) Design and capabilities of an experimental setup based on magnetron sputtering for formation and deposition of size-selected metal clusters on ultra-clean surfaces Rev. Sci. Instrum. 83, 073304 (2012) Influence of ion source configuration and its operation parameters on the target sputtering and implantation process Rev. Sci. Instrum. 83, 063304 (2012) Note: Measuring effects of Ar-ion cleaning on the secondary electron yield of copper due to electron impact Rev. Sci. Instrum. 83, 066105 (2012) Surface instability of binary compounds caused by sputter yield amplification J. Appl. Phys. 111, 114305 (2012) Additional information on J. Appl. Phys. The spatial distribution of ion deposited energy is often assumed to linearly relate to the local ion-induced sputtering of atoms from a solid surface. This-along with the assumption of an ellipsoidal region of energy deposition-is the central mechanism used in the Bradley and Harper [J. Vac. Sci. Technol. A 6, 2390(1988] explanation of ion-induced surface instabilities, but it has never been assessed directly. To do this, we use molecular dynamics to compute the actual distribution of deposited energy and relate this to the source of sputtered atoms for a range of ion energies (250 eV and 1500 eV), ion species (Ar, Kr, Xe, and Rn), targets (Si and Ge), and incidence angles (0 , 10 , 20 , 30 , 40 , 50 , 60 , 70 , and 80 ). It is found that the energy deposition profile is remarkably ellipsoidal but that the relation between local deposited energy and local sputtering is not simple. It depends significantly upon the incidence angle, and the relation between energy and local sputter yield is nonlinear, though with a nearly uniform power-law relation. These results will affect, in particular, surface instability models based upon simpler approximations. V C 2012 American Institute of Physics. [http://dx

Surface instability and pattern formation by ion-induced erosion and mass redistribution

“…The simulations I presented here are very similar to the crater function analyses discussed in several previous publications [22,[25][26][27][28][29]. However, up to now the crater function analysis relies on MD simulations of ion impact, which are feasible only for very low ion energies and a very limited number of projectiles.…”

“…In this way it is possible to account for preferential sputtering in the case of compound materials such as SiO 2 and also the incorporation of ions into the materials as it is the case for Ga ion irradiation. I introduce the variation of the thickness of the irradiated layer with ion incidence angle as an extension to the existing linear theories of pattern formation (BH model [1], CV model [18] and crater function models [22,[25][26][27][28][29]). This dependence D(h) has a significant effect on the curvature coefficient not only for mass redistribution but also for the coefficient for ion-induced viscous flow.…”

“…In the CV model [18] and also in crater function (cf) models [22,[25][26][27][28][29] the last two terms in the inner bracket of Eq. 27 and the last term in Eq.…”

“…The equations for the height evolution dhðx; y; tÞ=dt of a surface, originating from atomic mass redistribution caused by ballistic displacements as well as ion beam erosion, are revisited. The calculations follow the description of Bradley and Harper [1], Carter and Vishnyakov [18] and Davidovitch et al [20] and descriptions found in papers on crater function analyses [22,[25][26][27][28][29]. However, I take into account additional contributions to the height evolution in the linear expansions, which were not considered so far.…”

“…Several theoretical approaches describe erosion as well as mass transport on the basis of crater functions (cf models) [22,[25][26][27][28][29] derived from molecular dynamics simulations. The crater function is the average height distribution h(x, y) following ion impact for a significant number of ions incident on an identical and initially flat surface with h 0 (x, y) = 0.…”