Fabrication of Well-Ordered High-Aspect-Ratio Nanopore Arrays in TiO₂ Single Crystals

Abstract

In this work a successful method for producing high-aspect-ratio nanopatterned single-crystal TiO2 is presented. The method used is based on nanolithography involving swift heavy ion bombardment through a porous anodic alumina mask. Nanopatterning of large areas allows for fabrication of new devices, for example, photonic crystals and electrodes for energy storage and conversion. Crystalline TiO2 also presents optimal characteristics for optical and catalysis applications. Samples were irradiated by MeV Br7+ ions with fluencies ranging from 7.9 × 1013 to 1.2 × 1015 cm-2. The high-energy Br7+ ions induce latent tracks of amorphous material into the TiO2 crystal suitable for selective etching by hydrofluoric acid. High-aspect-ratio (16) nanopatterned areas, up to 4 mm2, were obtained in a single radiation spot onto single-crystalline TiO2.

Universal Block Copolymer Lithography for Metals, Semiconductors, Ceramics, and Polymers

“…[1,2] Because of their novel properties, the nanostructured films are anticipated to be useful for numerous nextgeneration devices such as sensors, [3] electronic or photonic devices, [4,5] catalysts, [6] etc. To date, various film deposition methods such as sol-gel spin-casting, [7] sputtering, chemical vapor deposition (CVD), [8] or atomic layer deposition (ALD) [9,10] have been developed, providing a fine tunability over the film thickness, even on the sub-nanometer scale.…”

Selective binding of oligonucleotide on TiO 2 surfaces modified by swift heavy ion beam lithography

“…1 b) to describe the different zones of the patterned substrate. The depth of the micro-wells (or etching depth) resulting after the localized SHI irradiation and subsequent HF etching, is related to the ion energy and fluence, in addition to the fact that there is a certain chemical etching threshold for rutile TiO 2 [24][25][26][27][28]32]. For the present applied ion energy and fluence a characteristic depth of 2 µm is obtained [28], which is the maximum depth obtainable with the used ion.…”

“…The cumulative effect of ion track formation following high ion fluence irradiation by such ions leads to localized damage and amorphous volumes in rutile single crystals [25][26][27][28][29][30]. Most of the damaged volume can be selectively etched away by an aqueous solution of hydrofluoric acid (HF) [24,26].…”

“…1. A variety of structures in TiO 2 with lateral dimension down to 70 nm and depth of 1 µm have been created by this method over cm 2 areas [25][26][27]29,30]. There are several advantages of using swift heavy-ion beam based lithography compared to other lithography methods.…”

Electrochemical synthesis of core–shell magnetic nanowires

“…Currently, template-assisted electrochemical growth has demonstrated to be a very successful method for the production of nanoscaled systems with nearly ideal cylindrical characteristics [5][6][7] . Most typically, anodic aluminum oxide (AAO) membranes are employed as templates to grow arrays of columnar nano-objects with an adjustable geometry thanks to its versatility and low cost 8 .…”