A high quality reflective vertical surface is required for various optical micro electro mechanical system (MEMS) devices. In this paper, we discuss an extensive investigation of Ti∕Au sputtering, with respect to temperature, pressure, and electric power input, followed by rapid thermal annealing (RTA) to improve the adhesion and reflection characteristics of a vertical micromirror. The vertical surface was fabricated by means of the deep reactive ion etching (DRIE) process of a silicon-on-insulator (SOI) wafer, with an 80-μm-thick layer of Si. Then, 20-nm-thick Ti and 200-nm-thick Au films were deposited on the vertical surface as adhesion and reflective layers, respectively, using rf/dc magnetron sputtering. The Au films were deposited at room temperature (20°C) and annealed at 380°C for 30s in a RTA chamber. While taking into consideration the conformability and the reflectance of the Au vertical mirror, the process conditions were optimized at an argon pressure of 10mTorr and an electric power input of 300W. The best surface roughness obtained was 7nm (rms) for a useful upper sidewall with a reflectance of 97.5% in the IR (Infrared) range (1500nm–1600nm).
ABO3 perovskite-type multifunctional BiFeO3 material is a good candidate for a variety of device applications such as photocatalyst, gas sensor, biosensor, thermoelectric material, and so on due to its remarkable magnetoelectric coupling property. The future scope of this perovskite material can be broadened by its cost-effective, highly efficient, and easily available nature. Herein, we discuss recent developments in multifunctional BiFeO3 based on two crucial applications such as sensors and photocatalyst from the recent research literature. We have also addressed the effects of doping which includes the bandgap reduction, finer pore size, and crystallite size leading to higher efficiency. Additionally, the BiFeO3 composites due to their larger surface area involve more active molecules on the surface thereby increasing the efficiency even more. Finally, some of the future scopes of the research are also addressed in this article.
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