Yew Hoong Wong

Band alignment and enhanced breakdown field of simultaneously oxidized and nitrided Zr film on Si

The band alignment of ZrO2/interfacial layer/Si structure fabricated by simultaneous oxidation and nitridation of sputtered Zr on Si in N2O at 700°C for different durations has been established by using X-ray photoelectron spectroscopy. Valence band offset of ZrO2/Si was found to be 4.75 eV, while the highest corresponding conduction offset of ZrO2/interfacial layer was found to be 3.40 eV; owing to the combination of relatively larger bandgaps, it enhanced electrical breakdown field to 13.6 MV/cm at 10-6 A/cm2.

Effects of Oxidation and Nitridation Temperatures on Electrical Properties of Sputtered Zr Thin Film Based on Si in N2O Ambient

The effects of oxidation and nitridation temperatures (500–1100°C) on metal-oxide-semiconductor characteristics of sputtered Zr thin film on Si in N2O ambient have been systematically investigated. The sample being oxidized and nitrided at 700°C has demonstrated the highest effective dielectric constant of 21.82 and electrical breakdown field of 13.6 MV cm−1 at a current density of 10−6 A cm−2. This is attributed to the lowest effective oxide charge, interface-trap density, and total interface-trap density of the oxide and the highest barrier height of conduction band offset between the oxide and semiconductor when compared with others.

Effect of sintering holding time on low-temperature degradation of yttria stabilised zirconia ceramics

Abstract Effect of sintering holding time on low-temperature degradation of 3 mol-% yttria stabilised zirconia was investigated. Yttria stabilised zirconia samples were sintered using a two-step sintering cycle. The samples were initially heated to 1500°C with the heating rate of 10°C min−1, held for 1 minute before cooling down to 1200°C and kept at this temperature for varying holding times from 0 to 10 hours. The phase contents of the zirconia samples were measured using X-ray diffractometer, and the microstructural evaluation was evaluated by field emission scanning electron microscope. All the as-sintered samples exhibited 100% tetragonal phase and bulk density of about 6 g cm−3. The low-temperature degradation study was conducted under autoclave condition containing superheated steam at 180°C and 10 bar vapour pressure for periods up to 24 hours. The results showed that the tetragonal to monoclinic phase transformation decreased with increasing holding time up to 3 hours and thereafter it increased. The sample sintered with 3-hour holding time showed better aging resistance than other samples. It was found that the grain size of this sample was the lowest (0·29 μm) when compared to other samples.

Effects of anodisation parameters on thin film properties: a review

Electrochemical anodisation is a well-received method in the complementary metal-oxide-semiconductor field as it is advantageous; best performed at room temperature which translates into being more affordable and a simple alternative to form nano-structured oxide films for different metals. The quintessential parameters involved allow numerous formations of metal oxide films according to desired morphology and thickness. Therefore, this paper aims to review the effects of anodising parameters such as applied voltage, concentration, temperature, time, current density and post-anodisation annealing among them.

Phase and surface area studies of maghemite nanoparticles dispersed in silica gel

Abstract First, the superparamagnetic maghemite nanoparticles were synthesised using Massarts procedure. Then, the nanocomposites of the synthesised maghemite nanoparticles and silica were produced by dispersing the as-synthesised maghemite nanoparticles into the silica xerogel prepared by sol–gel technique. The system was then heated for 3 days at 140°C. The phase analysis performed using X-ray diffraction confirmed that the as-synthesised nanoparticles and the nanoparticles within the silica gel were maghemite. Surface characteristic of the nanocomposite was evaluated by N2 adsorption. The ‘pure’ silica gel and maghemite nanoparticles showed high values of surface area (150–160 m2 g−1), while the surface area of nanocomposite was less than 40 m2 g−1. This was probably due to the formation of dense structures caused by incorporation of maghemite nanoparticles within the pores of silica gel. The pore width increased with increasing content of maghemite nanoparticles.

Sintering properties of zirconia-based ceramic composite

Abstract This study examines the effects of different ZrB2 content on various mechanical properties and electrical conductivity of ZrB2/Y-TZP composite. Composites with ZrB2 content of up to 20 wt-% were particularly beneficial at the lower sintering temperature range by achieving greater densification and better hardness than Y-TZP monolith. In contrast to the trends estimated from rule of mixture, the increment of ZrB2 content did not result in any significant improvement in the elastic modulus and hardness of the zirconia composites. Nevertheless, all composites showed tremendous improvement in fracture toughness compared with monolithic Y-TZP and thus, suggested that other toughening mechanisms were operative besides transformation toughening of zirconia. Incorporation of ZrB2 up to mass fraction of 20 wt-% into Y-TZP generally did not affect the tetragonal phase stability of zirconia. Significant reduction of electrical resistivity of the composites was achieved with ZrB2 content of 20 wt-% and sintering temperature of 1400°C.

Development of Sn–Cu–Sb alloys for making lead- and bismuth-free pewter

Abstract A systematic study on the development of a set of Sn–Cu–Sb alloys and their characteristics, such as phases evolved, mechanical properties, physical properties, and microstructures, that are commonly sought for making pewter is presented. Alloys with various nominal compositions of Sn–Cu (1–3%)–Sb (3–6%) were prepared and they were die cast for complete characterization. The samples were characterized for hardness, malleability, density, microstructure, and phase identification. The study is expected to help in selecting the right composition of the alloys for making pewter with appropriate combination of properties.

Aloe vera in active and passive regions of electronic devices towards a sustainable development

The increasing awareness towards sustainable development of electronics has driven the search for natural bio-organic materials in place of conventional electronic materials. The concept of using natural bio-organic materials in electronics provides not only an effective solution to address global electronic waste crisis, but also a compelling template for sustainable electronics manufacturing. This paper attempts to provide an overview of using Aloe vera gel as a natural bio-organic material for various electronic applications. Important concepts such as responses of living Aloe vera plant towards electrical stimuli and demonstrations of Aloe vera films as passive and active regions of electronic devices are highlighted in chronological order. The biodegradability and biocompatibility of Aloe vera can bring the world a step closer towards the ultimate goal of sustainable development of electronic devices from “all-natural” materials.The increasing awareness towards sustainable development of electronics has driven the search for natural bio-organic materials in place of conventional electronic materials. The concept of using natural bio-organic materials in electronics provides not only an effective solution to address global electronic waste crisis, but also a compelling template for sustainable electronics manufacturing. This paper attempts to provide an overview of using Aloe vera gel as a natural bio-organic material for various electronic applications. Important concepts such as responses of living Aloe vera plant towards electrical stimuli and demonstrations of Aloe vera films as passive and active regions of electronic devices are highlighted in chronological order. The biodegradability and biocompatibility of Aloe vera can bring the world a step closer towards the ultimate goal of sustainable development of electronic devices from “all-natural” materials.

Characterization of Stoichiometric ZrO2 Thin Film on Si by Angle-Resolved X-Ray Photoelectron Spectroscopy

Simultaneous thermal oxidation and nitridation technique was utilized to transform sputtered Zr to stoichiometric ZrO2 thin films on Si substrate. The stoichiometry of this type of oxide has high dielectric constant value of ~25 may be applied as dielectric in metal-oxide-semiconductor-based power devices. Through nitrous oxide gas environment, the oxidation/nitridation process was performed at 700°C for a set of time of 5–20 min. Chemical properties of the fabricated films have been characterized by angle-resolved x-ray photoelectron spectrometer. From the characterization, it was found that stoichiometric Zr-O (ZrO2) was formed. Nitrogen content in the samples was investigated. It was identified that sample oxidized/nitrided for 15 min gives the highest atomic percentage of nitrogen of 2.64 at% in the interfacial layer. This nitrogen content in the near interface region may help to passivate the Si dangling bonds, which may thus enhance the interface quality of oxide-semiconductor.

Electrical, microstructural, and surface roughness study of thermally oxidized metallic Sm thin film on Si substrate

Electrical, microstructural, and surface roughness of 150 nm sputtered pure samarium metal film on silicon substrates which thermal oxidized in oxygen ambient at various temperatures (600-900 °C) for 15 min have been investigated quantitatively. Effects of oxidation temperatures on the C-V characteristics, surface morphology, and surface roughness of Sm₂O₃ thin films were reported. The smooth and uniform of Sm₂O₃ thin films were revealed by scanning electron microscope and atomic force microscopy analysis. The sample oxidized at 700 °C demonstrated the smallest AV_PB value, lowest STD value (5.56 × 10¹² cm^-2) and D_it values (~10¹⁴ eV^-1 cm^-2).