Designing self-organized nanopatterns on Si by ion irradiation and metal co-deposition

Abstract

Dot and ripple nanopatterns on Si surfaces with defined symmetry and characteristic dot spacings of 50-70 nm were created by 1 keV Ar ion irradiation at normal incidence and simultaneous co-deposition of Fe atoms at grazing incidence. Fe was continuously supplied from different sputter targets surrounding the Si substrate, leading to a steady-state Fe content in the near-surface region of the substrates. The pattern formation is self-organized, most probably caused by ion-induced phase separation. Patterns were analyzed with atomic force microscopy and the Fe content in the irradiated layer was measured with Rutherford backscattering. The symmetries of the produced patterns are isotropic, four-fold symmetric, three-fold symmetric and various types of two-fold symmetric patterns, depending on the geometrical arrangement of the sputter targets. Pattern formation was studied for a steady-state coverage of Fe between 0.5 and 3.3 × 10 15 Fe cm −2 . The threshold coverage for the onset of pattern formation is about 0.5-1 × 10 15 Fe cm −2 . The coherence length of the patterns is comparable to the average dot spacing. Nevertheless, the autocorrelation analysis reveals a residual long-range periodicity of some patterns. The dot spacing can be adjusted between about 20 nm and several hundred nm depending on the ion species and ion energy.

Self-organized nanopatterning of silicon surfaces by ion beam sputtering

“…Specifically, Fig. 16 Interestingly, in a recent work [102] the symmetry of nanodot patterns has been controlled by means of an experimental configuration which differs from the one depicted in Fig. 15.…”

Nanostructures on fused silica surfaces produced by ion beam sputtering with Al co-deposition

“…Ion beam parameters (species, incidence angle, energy, flux, etc) and substrate parameters (material, temperature, initial surface topography, etc) interact to generate the features of such nanopatterns. Recently, numerous experiments on sputtering with simultaneous co-deposition [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] and theoretical studies [40][41][42][43][44][45][46][47] on simultaneous metal co-deposition during IBS or surfactant sputtering [32-38, 46, 47] have been performed to elucidate the formation mechanism of self-organized nanostructures and to generate various nanopatterns. In principle, the simultaneous use of metal atoms modulates the sputtering yield of the substrate during IBS, which results in diverse physical and chemical phenomena (e.g., island formation or phase separation).…”

Metal impurity-assisted formation of nanocone arrays on Si by low energy ion-beam irradiation

“…Recently, interest in surface chemistry has been renewed through the revelation that metal impurities might play a major role in the nanoripple pattern formation [35]. This interest has further grown with the development of so-called surfactant sputtering as evidenced by recent studies of the role of metal impurities in nanopatterns formation [7,26,[36][37][38]. Surfactant sputtering, based on the co-deposition of surfactant atoms from a nearby metal target during ion irradiation, can form a variety of the aforementioned patterns on Si surfaces [2,3,5,27,36,37,39].…”