S. Porntheeraphat

Chemical Characterization and Electrical Properties of Indium Oxynitride Grown by Reactive Gas-Timing RF Magnetron Sputtering

This work investigates changes in the chemical composition of InON thin films, grown by reactive gas-timing rf magnetron sputtering with different O2:N2 timing ratio characterized by Auger Electron Microscope (AES), Raman Spectroscopy which are well correlated with the electrical properties of films. The existence of nitrogen and oxygen in the deposited InON thin films was revealed by AES. Two Raman active optical phonons have been clearly observed and assigned to InN E1(TO) at ~470 cm-1 and E1(LO) at ~570 cm-1 and also shifted with different O2:N2 timing ratio. The carrier mobility of InON thin films was decreased when the ratio of O2:N2 timing is increased.

On-Chip Platinum Micro-Heater with Platinum Temperature Sensor for A Fully Integrated Disposable PCR Module

The on-chip platinum micro-heater prototypes for thermal cycling equipped with platinum temperature sensor are fabricated. The device has been designed, fabricated and characterized to explore the feasibility of the micro-heater for a fully integrated disposable lab-on-a-chip with the PCR module. The on-chip micro-heater demonstrates that the temperature transitions are shorter by comparison with the conventional PCR temperature routines.

A Disposable Polydimethylsiloxane Microdevice for DNA Amplification

In this study, we demonstrate the disposable polydimethylsiloxane (PDMS) microchip provided for DNA amplification. The device consists of two main parts. The first part is PDMS/glass stationary chamber, the other part is a temperature-control microdevice on SiO2/Si substrate. This device consists of a thin film Pt-microheater and a Pt-temperature sensor, which were fabricated with CMOS compatible process. The performance of the device in the DNA amplification shows that, with 10 μl of PCR mixture volume, the approximately 700 bp DNA were successfully amplified within 50 minutes by 30 PCR cycles. The amplified products were comparable with those of a conventional method using electrophoresis. The PCR chip is also suitable for mass production.

Effect of Sputtering Power on Physical Properties and Electrochromic Performance of Sputtered-WO3 Thin Films

Tungsten oxide (WO3) electrochromic thin films were deposited onto F-doped tin oxide (FTO) substrates using DC sputtering of tungsten target in presence of oxygen and argon gas. As-deposited films were prepared with different sputtering power at 50 W, 100W and 200W. The effect of power on structural, surface morphology optical and electrochromic properties of the WO3 thin films were characterized by X-ray diffractometer, scanning electron microscope, UV-VIS spectrophotometer and Cyclic voltammetry, respectively. The XRD results show that the crystalline of WO3 can be identified an orientation growth along (222) plane. The average grain size evaluated from SEM image is approximately 200 nm. The films deposited at power of 200 W exhibited better electrochromic properties with greatest optical modulation (∆T) value of ∆T = 31.2 % at l= 550 nm. The cyclic voltammograms (CV) of WO3 thin films evidently exhibited that the WO3 films prepared at power of 200 W displayed the superior electrochromic performance, compared to the others.

Surface Morphology and Structural Investigation of TiN Nanocrystal Thin Films Grown with Different N2 Concentration

In this work, new information on surface morphology, phase and local structure of titanium nitride (TiN) nanocrystal thin films grown with different nitrogen gas concentration by direct current (DC) magnetron sputtering is provided. Surface morphology of the thin films was studied by field emission scanning electron microscope (FE-SEM). Phase and local structure of the TiN nanocrystals were determined by X-ray diffraction spectroscopy (XRD) and X-ray absorption fine structure (XAFS). The TiN nanocrystals were prepared on silicon substrates. N2/Ar gases were used as reactive gases for sputtering Ti target. The amount of these two reactive gases was varied at different ratios (N2/Ar), i.e. 100:0, 75:25, 50:50 and 25:75 respectively. Our results suggested that sputtering Ti target with high N2/Ar gas raSubscript texttio (higher than 75%) provides good TiN layer while sputtering with low N2/Ar gas ratio (lower than 25%) gives Ti layer instead of TiN. In addition, sputtering with 50% N2/Ar gas ratio gives a multiphase system between TiN and Ti. Local structure parameters of these nanocrystal thin films are reported.

Effect of Anodization Process on Morphology of Nickel Coating

In this article we address the process perspective of anodization for fabrication of nickel coating materials. In this work, we also report the mechanical properties and morphology of coating materials with various parameters. We investigated the effect of temperature and plating time with 0.3 (A/cm3) of current density. Light microscopes, Scanning Electron Microscopy and Hardness tester were used to confirm morphology and hardness of target object, respectively. In general it was observed that anodization process also affected on properties of target object. The hardness of target object with anodization process will be increased in first period and slightly decreased with high temperature and longer plating time. The chemical etching treatment had an impact on the morphological features of the AAO templates lead to morphological features of nickel coating materials.

Enhanced Electrochromic Performance of Sol-Gel Derived WO3 Thin Films Assisted by Electrospun PVA Nanofibers

The paper describes the results obtained on the enhanced electrochromic performance of Tungsten oxide (WO3) thin films assisted by electrospun PVA nanofibers. WO3 was fabricated by spin coating technique with tungsten powder as starting precursor. The effect of electrospun-PVA nanofibers layer on structural, chemical composition, surface morphology and electrochromic properties of the films were characterized by X-ray diffractometer (XRD), X-ray photo-emission spectroscopy (XPS), scanning electron microscope (SEM) and UV-VIS spectrophotometer. The XRD analysis suggested that the crystalline of WO3 can be identified as a monoclinic WO3 structure. XPS investigations also confirmed the existence of characteristic peaks of W. The significant enhancement of electrochromic properties of the films is achieved by additive electrospun-PVA nanofiber layer.

A disposable polydimethylsiloxane (PDMS) microdevices for DNA amplification with low power consumption

Polymerase Chain Reaction (PCR) microchip has become an important tool in a molecular biological research. Many researchers have attempt to improve the efficiency of the device in terms of type of materials, fabrication process, temperature control system, design of the device, detection methods, etc. In this study, we demonstrate the disposable polydimethylsiloxane (PDMS) microchip provided for DNA amplification. The devices consists of two mainly parts, first part is PDMS static chamber that casting on Silicon (Si) mold that bonded with thin glass sheet by RF plasma cleaner. The other parts are Pt-microheater and Pt-temperature sensor on SiO2/Si substrate. The thin film Pt-microheater and Pt-temperature sensor (RTD) were fabricated with CMOS compatible process. In the results, with 10 µl of PCR mixture volume, the approximately 700 bp DNA were successfully amplified within 50 minutes by 32 PCR cycles. The amplified products were comparable with conventional method by agarose gel electrophoresis method. With this PCR chip we can save cost by reducing the reagents volume, time consuming and repeatable fabrication. Further information about microchip fabrication and application will be presented.

Local structure investigation of Indium Oxynitride thin films by X-ray absorption fine structure

Indium Oxynitride (InON) thin films prepared by Reactive gas-timing RF magnetron sputtering technique are investigated using X-ray absorption fine structure and first principle calculation. It was found from the former study[2] that optical and electrical properties of these films highly depended on its gas-timing ratio in the sputtering process. Therefore structural investigations of these films are required in order to describe the relation between the gas-timing ratio and their optical properties. The results show that local structure of the InON thin films consist of both indium oxide (In2O3) and indium nitride (InN) phase.

The Optimization of TiN Film Deposited by DC Magnetron Sputtering Provided for Al Diffusion Barrier

Titanium nitride (TiN) film has been widely used as a diffusion barrier layer for VLSI contact metallization because TiN is an excellent barrier against inter-diffusion between Al and Si substrate or silicide. In this work, we studied the properties of TiN films deposited by DC magnetron sputtering with varying N2:Ar flow rate ratio in order to optimize growth conditions and film properties provided for Al diffusion barrier purpose. The TiN films were deposited at the constant pressure level and sputtering time. The crystalline orientation, composition and electrical properties of deposited TiN films were characterized by XRD, AES-depth profile and Four Point Probe measurement, respectively. The XRD results show that the deposited TiN film has two preferred orientations of TiN(111) and TiN(200) planes. The highest intensity of the TiN(111) plane was obtained when the N2:Ar flow rate ratio was 3:1. The electrical resistivity was increased when the N2:Ar flow rate ratio was decreased. The minimum electrical resistivity is 127.8 μΩ-cm when the N2:Ar flow rate ratio is 3:1.