Highly ordered freestanding TiO(2) nanotube arrays with atomic layer control of wall thickness were fabricated using an organic-inorganic hybrid nanoporous template and atomic layer deposition (ALD). The hybrid nanoporous template with a high-aspect-ratio cylindrical nanopore array can be readily fabricated by pattern transfer from a thin silicon-containing block copolymer film into a thick cross-linked organic polymer layer. The template exhibited excellent thermal stability and thus allowed the high-temperature ALD process to conformally deposit TiO(2) thin films on the inner surface of cylindrical nanopores. The ultrafine thickness tunability of the ALD process made it possible to develop TiO(2) nanotubes with various wall thicknesses. After the template was removed using a dry etch followed by calcination, vertically aligned and highly crystalline anatase TiO(2) nanotube arrays were produced without collapse or bundling. We also fabricated the highly uniform freestanding arrays of multi-component nanotubes composed of TiO(2)/Al(2)O(3)/TiO(2) nanolaminate and Ti-Al-O mixed-phase films with precisely controlled thickness and composition.

A novel and feasible methodology is developed to fabricate well‐ordered, freestanding 1D n‐ZnO/p‐Si nanotube (NT) and nanorod (NR) arrays via double‐patterning technology with block copolymer (BCP) self‐assembly, atomic layer deposition (ALD), and inductively coupled plasma (ICP) dry etching. To obtain the well‐ordered NT pattern, a self‐assembled, Si‐containing poly(styrene‐block‐4‐(tert‐butyldimethylsilyl)oxystyrene) BCP on an SU‐8/p‐Si wafer is employed as a template. After n‐ZnO deposition on the self‐assembled BCP template by ALD, an ICP etching process is performed to produce well‐defined, independent n‐ZnO/p‐Si NT arrays. The insights into the nanoarrays presented here are directly applicable to the fabrication of n‐ZnO/p‐Si NT/NR patterns and Si NT/NR patterns by precisely controlling the ALD cycles and ICP etching time. The electrical properties of a single n‐ZnO/p‐Si NT are measured by conductive atomic force microscopy, and the results show the typical rectifying behavior of a nanodiode with superior electrical properties. This simple and useful approach provides a very convenient route for fabricating high‐density nanodiode patterns. Additionally, the possibility of various applications is confirmed by simple analyses, including examinations of contact angle and reflectance. Furthermore, the wettability and antireflection properties can be controlled by changing the nanoarray morphology.

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