Chiu-Hsien Wu

Analysis of the Sensing Properties of a Highly Stable and Reproducible Ozone Gas Sensor Based on Amorphous In-Ga-Zn-O Thin Film

In this study, the sensing properties of an amorphous indium gallium zinc oxide (a-IGZO) thin film at ozone concentrations from 500 to 5 ppm were investigated. The a-IGZO thin film showed very good reproducibility and stability over three test cycles. The ozone concentration of 60–70 ppb also showed a good response. The resistance change (ΔR) and sensitivity (S) were linearly dependent on the ozone concentration. The response time (T90-res), recovery time (T90-rec), and time constant (τ) showed first-order exponential decay with increasing ozone concentration. The resistance–time curve shows that the maximum resistance change rate (dRg/dt) is proportional to the ozone concentration during the adsorption. The results also show that it is better to sense rapidly and stably at a low ozone concentration using a high light intensity. The ozone concentration can be derived from the resistance change, sensitivity, response time, time constant (τ), and first derivative function of resistance. However, the time of the first derivative function of resistance is shorter than other parameters. The results show that a-IGZO thin films and the first-order differentiation method are promising candidates for use as ozone sensors for practical applications.

Amorphous indium gallium zinc oxide thin film-based ozone sensors

Gas sensors with good performance should exhibit characteristics such as high sensitivity, low energy consumption, and low fabrication costs. A metal-oxide semiconductor material, amorphous indium-gallium-zinc-oxide (InGaZnO4, has a good stability-IGZO), is with potential for use in gas sensor. It can be used for continuously measurement of the gas content. To obtain more sensitivity, parameters of UV light is measured. The sensitivity is significantly improved at low light intensity. And stability was also determined, that reduce the light intensity does not reduce the stability of sensors.

Monitoring and dynamic control of distance and tilt angle measurements in micro-alignment instrument using an imaging approach

An accurate and simple optical triangulation method is proposed for determining the distance and the tilt angle between the window and the SQUID sensor in a scanning SQUID microscope (SSM) system. The surface of window near the sensor plane is roughened with Alumina powder so that the incident and reflected traces of the laser beam passing the window surface become visible and can be measured precisely with a normal optical microscope. Using the proposed approach, the distance between the sensor and the sample can be reproducibly adjusted to 30 microm or less. This method can also be applied to photolithography apparatus to detect the relative positions of the mask and the wafer.

The properties of metamaterials based on gold thin film and nanoparticles

THz metamaterials are designed and fabricated. The resonance frequency of the SRRs (split ring resonators) based on thin film and nanoparticles is studied. Nanoparticle constituted metamaterial has a good absorb of THz spectrum. We compare the properties between thin film metamaterials and nanoparticles metamaterials. The transmission spectra of Au metamaterial was measured. The redshift was obtained when the metamaterials covered semiconductor The redshift phenomenon of absorbed wavelength of nanoparticle will be studied.

Influence of magnetoplasmonic γ-Fe2O3/Au core/shell nanoparticles on low-field nuclear magnetic resonance

Magnetoplasmonic nanoparticles, composed of a plasmonic layer and a magnetic core, have been widely shown as promising contrast agents for magnetic resonance imaging (MRI) applications. However, their application in low-field nuclear magnetic resonance (LFNMR) research remains scarce. Here we synthesised γ-Fe2O3/Au core/shell (γ-Fe2O3@Au) nanoparticles and subsequently used them in a homemade, high-Tc, superconducting quantum interference device (SQUID) LFNMR system. Remarkably, we found that both the proton spin–lattice relaxation time (T1) and proton spin–spin relaxation time (T2) were influenced by the presence of γ-Fe2O3@Au nanoparticles. Unlike the spin–spin relaxation rate (1/T2), the spin–lattice relaxation rate (1/T1) was found to be further enhanced upon exposing the γ-Fe2O3@Au nanoparticles to 532u2009nm light during NMR measurements. We showed that the photothermal effect of the plasmonic gold layer after absorbing light energy was responsible for the observed change in T1. This result reveals a promising method to actively control the contrast of T1 and T2 in low-field (LF) MRI applications.