Annealing Effect of High Dielectric Material for Low Voltage Electrowetting on Dielectric (EWOD)

Hsiu-Hsiang Chen,Chien-Chung Fu

doi:10.5539/mas.v8n3p10

Abstract

In this paper, the high dielectric constants for Ta2O5 (~18.8) and Nb2O5 (~25.5) were deposited by a RF reactive magnetron sputtering and respectively annealed at 700 °C and 400 °C O2 ambiance for 30 min in a conventional furnace. The purpose of this study is to optimize the annealing condition (various temperatures at N2 or O2 ambiance) of the high-dielectric-constant Ta2O5 and Nb2O5 films deposited by RF reactive magnetron sputtering to enhance the dielectric constant of those films to further lower the operating voltage. Based on the results, an electrowetting optical deflector (EOD) filled with the water (1% sodium dodecyl sulfate (SDS)) and dodecane was fabricated and tested, and the contact angle of the inclined liquid surface on the left and right sidewall can be varied about 70° at 9 V operating voltage. This study provides a practical way to fabricate a high dielectric constant layer for low voltage electrowetting on dielectric (EWOD) application.

Highlights

Electrowetting phenomenon was first exploited by Lippmann (1875)
The purpose of this study is to optimize the annealing condition of the high-dielectric-constant Ta2O5 and Nb2O5 films deposited by RF reactive magnetron sputtering (Lin et al, 2011; Zhou, Luo, Li, & Liu, 2009; Coskun & Demirel, 2013; Lai, Lin, Huang, Gai, & Qu, 2006) to enhance the dielectric constant of those films to further lower the operating voltage
The results show that the surface roughness rose as the annealing temperature increased

Summary

Introduction

Electrowetting phenomenon was first exploited by Lippmann (1875). By varying the voltage between the electrolyte droplet and the substrate, the contact angle of droplet can be modulated. Till Berge (1993) inserted a thin insulating layer between the electrolyte droplet and the electrode to eliminate the electrolysis problem, the contact angle change can be dramatically increased at a large voltage. This improved technology was so called EWOD. Since it initiated an explosive growth in electrowetting research, especially in the field of optics (Mugele & Baret, 2005; Kuiper, Hendriks, Hayes, Feenstra, & Baken, 2005; Hou, Zhang, Smith, Yang, & Heikenfeld, 2010; Ceyssensa et al, 2013)

Objectives

Results

Conclusion