Surasak Niemcharoen

Non-isothermal kinetics of the thermal decomposition of sodium oxalate Na2C2O4

The thermal transformation of Na2C2O4 was studied in N2 atmosphere using thermo gravimetric (TG) analysis and differential thermal analysis (DTA). Na2C2O4 and its decomposed product were characterized using a scanning electron microscope (SEM) and the X-ray diffraction technique (XRD). The non-isothermal kinetic of the decomposition was studied by the mean of Ozawa and Kissinger–Akahira–Sunose (KAS) methods. The activation energies (Eα) of Na2C2O4 decomposition were found to be consistent. Decreasing Eα at increased decomposition temperature indicated the multi-step nature of the process. The possible conversion function estimated through the Liqing–Donghua method was ‘cylindrical symmetry (R2 or F1/2)’ of the phase boundary mechanism. Thermodynamic functions (ΔH*, ΔG* and ΔS*), calculated by the Activated complex theory and kinetic parameters, indicated that the decomposition step is a high energy pathway and revealed a very hard mechanism.

Novel design of solar cell efficiency improvement using an embedded electron accelerator on-chip

In this paper, we propose a novel design of an electron accelerator on-chip by using a small scale device known as a PANDA microring resonator, which can be embedded within the solar cell device, where the trapped electron can be accelerated and moved faster to the final destination. Therefore, the solar cell efficiency can be improved. In principle, a PANDA microring can generate the optical tweezers for hole tapping and transportation. The transported holes can be accelerated and moved via the optical waveguide to the solar cell device contact, where the effect of defects in silicon bulk can be solved. Therefore, this technique can be used to improve the solar cells performance. In practice, the accelerator unit can be embedded within the solar cell device, which allows the trapped holes moving to the required destination. This is claimed to be a novel technique by using a PANDA microring to accelerate the holes for solar cell performance improvement. Finally, this technique is the starting point of using a PANDA microring to enhance the performance of semiconductor device.

Sonochemical Synthesis of Spherical BaTiO3 Nanoparticles

Monosized spherical barium titanate (BaTiO3) nanoparticles have been synthesized successfully via sonochemical reaction. The as-synthesized BaTiO3 nanoparticles were characterized using X-ray diffraction of powder, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The XRD pattern of BaTiO3 particles, which were synthesized under irradiation of ultrasonic sound for 0.5 h, showed sharp diffraction peaks that corresponded to the cubic BaTiO3 phase. Only a small amount of BaCO3 contamination was present in the sample. The Raman active modes of the samples in this study were similar to the cubic phase of BaTiO3. The average diameter of sonochemical synthesized particles was ∼99.54 ± 18.25 nm. The synthesized BaTiO3 nanoparticles were almost spherical.

Particle Accelerator Using Optical Tweezer for Photodetector Performance Improvement

A photodetector performance improvement technique using a particle accelerator in the modified add-drop optical filter is proposed. An optical tweezer is used to control the electron movement within the device, where an electron (particle) can be accelerated and moved faster than the normal condition, where finally the silicon bulk defects and diode performance degradation can be solved. In simulation, a PANDA microring is configured by a modified add-drop filter that can be used to increase the electron speed. In operation, the trapped electrons in a diode can be trapped, controlled, and transported from anode to cathode contacts. In the design system, the trapping probe can be adjusted to fit the atom size from 200 pm (picometer) to 1.4 nm (nanometer) by controlling the ring parameters. The goal of this paper is to present the use of a PANDA microring for photodetector performance improvement, which can be used for many applications.

Extraction of mobility degradation, effective channel length and total series resistance of NMOS at elevated temperature

This article describes the extraction of total series resistance, effective channel length and low field effective channel mobility degradation parameter at temperature in the range of 25°C–125°C of NMOS device. The relation of I<inf>DS</inf> and V<inf>GS</inf> in a linear region was used with a different of channel length. The procedure is based on the measurement of the transconductance characteristics of MOSFET in the linear region. The transconductance characteristics is determine for the several devices of difference drawn channel length. The results shows that, the effective channel length is increased in a range of 5×10⁻¹⁰ m/°C. The low field mobility degradation parameter is decreased by the factor of 0.733. The total series resistance is increased in the range of 1.4 Ω-µm/°C. The errors between the predicted model and measured of I<inf>DS</inf>&V<inf>GS</inf> in linear region is approximately 3 %

Effect of Pb(Y1/2Nb1/2)O3 Additions on Thermal and Electrical Properties of PbZrO3 Ceramics

The solid solution of a (1–x)PbZrO3 – xPb(Y1/2Nb1/2)O3 (PZ – PYN) system, with x = 0.00 – 0.08, was synthesized by the wolframite precursor method. The effects of PYN content on crystal structure, and electrical and thermal properties of PbZrO3 ceramic were investigated. The crystal structure of sintered ceramics was characterized by X-ray diffraction. The pure perovskite phase was obtained for all compositions. The transition temperatures of the AFE to PE phase become lower with PYN increase. The dielectric properties of PZ were improved by the addition of PYN.

Preparation and Properties of Lead Free Bismuth Sodium Titanate−Bismuth Zinc Titanate Ceramics

Lead-free piezoelectric ceramics based on (1–x)Bi 1/2 Na 1/2 TiO 3 – x Bi(Zn 1/2 Ti 1/2 )O 3 (x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30, 0.40, and 0.5) were obtained via solid-state processing techniques. The influence of BZT addition on BNT characteristics, sintering, microstructure and properties was investigated. A single perovskite phase with rhombohedral symmetry was obtained for Bi(Zn 1/2 Ti 1/2 )O 3 substitutions of up to 10 mole%. A small amount of BZT was effective for improving both sintering behavior and dielectric properties of BNT ceramics. Optimized dielectric properties were obtained for samples with a maximum density of ρ = 98.3% for the composition, x = 0.1.

An improvement of electrical characteristics of P-N diode by X-ray irradiation method

This paper presents a new technique of semiconductor fabrication technology, where a soft X-ray annealing method is proposed as a new technique and used in this work. The effect of Pt and Soft X-ray annealing on P-N diodes was investigated. The tested P-N diodes were fabricated at TMEC laboratory using CMOS technology. Results obtained have shown that the platinum doping is affected both reverse and forward current characteristics of P-N diode, the leakage current is increased slightly, while the forward current is also increased 3 to 4 times, which is a result of reduction of carrier recombination lifetime of diode from 72 to 55 µs. The characteristics of P-N diode after X-ray irradiation is improved significantly. There is a slight reduction of leakage current, whereas the forward current is increased about 3 to 4 order of magnitude. Furthermore, the recombination lifetime is decreased from 54 to 48 µs.

Synthesis and Morphology Evolution of Lead-Free Piezoelectric K1/2Na1/2NbO3 Powder at Low Temperature

A synthetic route for modified solid state reaction has been developed for the synthesis of the perovskite phase of potassium sodium niobate, K1/2Na1/2NbO3 (KNN). Potassium oxalate monohydrate (K2C2O4.H2O) and sodium oxalate (Na2C2O4) were employed as a source of potassium and sodium, respectively. The formation of the K1/2Na1/2NbO3 phase was investigated as a function of calcination conditions by TG-DTA and XRD techniques. Morphology and particle size were determined via an SEM technique. It was found that the minor phases of Na2CO3 and K2CO3 tend to form together with K1/2Na1/2NbO3, depending on calcination conditions. The perovskite phase was successfully synthesized at a low temperature of 400°C. As calcination temperatures increased from 600° to 850°C, the KNN solid solution became more homogeneous, XRD peaks became narrower, and a pattern similar to that expected for orthorhombic K1/2Na1/2NbO3 was achieved after 600°C, as indicated by the separate peaks of 0 2 2 and 2 0 0.

White noise due to photocurrents in planar MSM structures on low-resistivity Si

The noise due to photocurrent at low frequencies (3–100 kHz) has been observed of planar aluminum/n-type silicon/ aluminum (Al/n-Si/Al) structures based on low-resistivity silicon. It was found that these structures exposed to illumination showed much lower noise than the full shot noise above 5 kHz under a certain operating condition. If the current noise power spectrum is expressed as Sðx Þ¼ 2eIpC 2 , where e is the electronic charge and Ip is the photocurrent, the noise ratio C 2 lies between 0.2 and 1.0, depending on the bias voltage. These results are attributed to the planar structures of the samples having wide electrode separation. Spatially uniform carrier generation due to illumination at the active surface and the decrease in the cross-correlation between the current components in the structure might be playing the key role to reduce the noise to lower levels than that of full shot noise under a certain operating condition. 2003 Elsevier Ltd. All rights reserved.