SAMCO Collaborates on Development of Ferroelectric Nanotubes with Cambridge University

Key Technology Development Department

SAMCO, Inc.

Introduction

SAMCO and Cambridge University began collaboration in the field of thin film deposition systems for ferroelectric films (Liquid Source Misted Chemical Deposition / LSMCD) in 1999. This report provides an overview of research regarding technology for "high aspect-ratio ferroelectric nanotubes"(patent-pending), which was published at the 10th European Meeting on Ferroelectricity (EMF 2003, Cambridge, UK).

Overview of SBT Nanotubes

The primary objectives of the SAMCO-Cambridge collaboration were to study potential applications of various ceramic films deposited using LSMCD systems, and to optimize the deposition system design. The basic LSMCD technique was originally developed by Symetrix Corporation (Colorado, USA) [3, 4, 5], and is based on mixing sol-gel or MOD (metal organic deposition) source materials into a solution of appropriate viscosity, creating a mist out of the solution, and then applying the mist to the substrate surface at ambient temperature and in a reduced pressure environment. After deposition, heat treatment is performed to create the desired film properties.

• Sample bulleted list that may appear in an article, with sentence-length bullet items.
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• Photonic Crystal Lasers on InP Substrates, Photonic Crystal Waveguides on SOI Substrates
• In this project, nanotubes were fabricated with a diameter of 800 nm, a thickness of less than 100 nm, and a length of 80µm. The nanotubes were formed in an array across the silicon wafer with a gap of approximately 1.5µm between adjacent tubes.

The dimensions and distance between the nanotubes can be adjusted at will. SEM photos of the nanotubes are shown in Fig. 1. A more recently developed deposition system [6, 7] is expected to yield the capability to fabricate even smaller structures. The deposition parameters are shown in Table 1.
Flat films were deposited separately to evaluate the crystal structure and electrical properties of the films of which the nanotubes were composed. The evaluation results are shown in Fig. 2 and Fig. 3. At present, we are working on evaluation of the crystal structure and electrical properties of the actual nanotubes. For more details regarding this technology, please refer to the abstract of the paper presented by F.D. Morrison, M. Alexe, T. Tatsuta, O. Tsuji, and J.F. Scott at the 10th European Meeting on Ferroelectricity (Aug. 3-8, 2003, Cambridge, UK).

Potential for Utilization in Functional Devices

It is possible that either individual high aspect ratio SBT nanotubes, or an entire array of nanotubes, could be used to fabricate functional devices. More specifically, there exists the potential for utilization in fields such as photonics devices, MEMS devices, and data storage devices. For example, it may be possible to create a voltage variable photonic crystal device by adding upper and lower electrodes to an array of SBT nanotubes. In addition, there are other potential applications, such as use in inkjet printer heads, micro pump implants for drug delivery, creation of new compound materials, and the development of 3D-FRAM and trenches for next-generation DRAM memory devices.