Etched ion tracks in amorphous SiO₂ characterized by small angle x-ray scattering: influence of ion energy and etching conditions

Abstract

Small angle X-ray scattering was used to study the morphology of conical structures formed in thin films of amorphous SiO 2. Samples were irradiated with 1.1 GeV Au ions at the GSI UNILAC in Darmstadt, Germany, and with 185, 89 and 54 MeV Au ions at the Heavy Ion Accelerator Facility at ANU in Canberra, Australia. The irradiated material was subsequently etched in HF using two different etchant concentrations over a series of etch times to reveal conically shaped etched channels of various sizes. Synchrotron based SAXS measurements were used to characterise both the radial and axial ion track etch rates with unprecedented precision. The results show that the ion energy has a significant effect on the morphology of the etched channels, and that at short etch times resulting in very small cones, the increased etching rate of the damaged region in the radial direction with respect to the ion trajectory is significant.

Dependence of track etching kinetics on chemical reactivity around the ion path

“…On the other hand, recent experiments measuring the track etching parameters with nanometric resolution contradicted with these models. In particular, nonlinear dependence of lengthwise track etching rates on the ion energy losses was observed 25 .…”

Raman characterization of phonon confinement and strain effects from latent ion tracks in α‐quartz

“…[22,25,26] Through chemical etching, it is possible to preferentially remove the disordered volume of the ion track and produce open features in the crystal structure (nanowells). [27][28][29][30][31] It is believed that phonons can be scattered or confined by the presence of various defects and nanostructures, including ion tracks and nanopores. [32][33][34] Studying the ion trackinduced alteration of the phonon spectrum helps one understand how energy and heat transfer may be tailored by irradiating materials with ion beams.…”

Analysis of nanometre sized aligned conical pores using SAXS

“…The capability to artificially mimic this behaviour is highly desirable since it forms the basis for chemical-and bio-sensing at the molecular level. The ion track etching method can be used to create artificial uniform and parallel narrow channels with controlled openings as small as just a few nanometres [1,2] in a variety of materials including polymers and ionic crystals [3][4][5][6], various glasses, minerals and inorganic insulators [2,[7][8][9][10][11][12]. Ion track etched pores in polymers are extensively used in commercial applications such as filtration and laboratory cell culture (for example, see [13]) and as sensors [14][15][16] and templates for nanowire growth [17].…”

“…Our study addresses these issues by using small-angle X-ray scattering (SAXS) as the main method for characterising the etched ion track channels. SAXS has previously been used to characterise unetched cylindrical ion tracks [24][25][26][27][28] and to a lesser extent etched ion tracks in SiO 2 and the mineral apatite [11,29,30], but an appropriate model for SAXS of conical etched ion tracks has not been realised. In this paper we present the analytical techniques we developed for accurately reconstructing the size and shapes of conical etched pores and apply them to two different material systems.…”

“…In previously published work [11] a systematic study of the dependence upon irradiation and etching conditions of ion track etching in a-SiO 2 was conducted. In [11] the SAXS technique combined with chemical etching allowed us to determine ion track etch rates in both the axial and radial directions, as well as the cone opening angles, for a range of ion energies and etchant concentrations. Data was analyzed using an average of the results obtained for a tilt sequence of measurements for each sample from an ion energy/etchant concentration series.…”