Synthesis, Characterisation and Optimisation of ZnO Thin film & Nanowire array for Dynamic Pressure Sensing Application

Abstract

Piezoelectric technology based dynamic pressure sensors are widely used for the measurement of rapid pressure variations with respect to time. Quartz is the piezoelectric material ruling the dynamic pressure sensor industry even now. Though researches are happening in the area of piezoelectric materials, they are not further taken up to device level. A complete understanding of these new materials and features of the devices developed by utilising them will be a supporting factor to take up their commercial application. In this work, an earnest attempt is made to bridge the gap between the laboratory and commercialisation.

ZnO is one of the piezoelectric materials with promising features to meet future world’s requirement. In the last few years, extensive investigations had been performed regarding the synthesis of thin film and nanostructures of ZnO. However, a comprehensive study on their device application is not available in the literature. The present research work focuses on the optimisation of the fabrication processes and experimental evaluation of the packaged dynamic sensors realised using ZnO thin film and nanowire array.

An exhaustive literature survey has been conducted to study the properties of various piezoelectric materials, substrate materials, different thin film deposition methods, Nanowire synthesis methods and characterisation methods used for evaluation of dynamic pressure sensors. ZnO thin films were fabricated using RF reactive magnetron sputtering for four different thicknesses by varying deposition duration and characterisation of these films were conducted to study their crystal structure, morphology & chemical composition. These films were packaged as dynamic pressure sensors and were experimentally evaluated for their suitability for dynamic pressure sensing applications. Based on the test results, most optimised sensor was determined from these four versions.

A similar approach was followed to study the suitability of ZnO nanowire array for dynamic pressure sensing application. ZnO nanowire array was synthesised using hydrothermal method, characterised for its material properties and the as-synthesised nanowire array was evaluated for dynamic pressure sensing application after packaging.

Both thin film and nanowire array of ZnO exhibited encouraging results when packaged and tested as dynamic pressure sensor. Dynamic pressure sensors realised using ZnO thin film are on par with the commercially available dynamic pressure sensors. ZnO nanowire array based sensor also showed promising results.

This research work concludes that ZnO, in its thin film and nanowire form, is highly suitable for the development of dynamic pressure sensors and recommends its commercial deployment.