Siti Kudnie Sahari

Performance of CMOS Schmitt Trigger

This paper presents the effect of load capacitance and source voltage on performance of proposed Schmitt trigger circuit. The proposed circuit was designed based on Conventional Schmitt Trigger by manipulating the arrangement of transistors and the width-length ratio. All simulation results have been carried out based on Microwind software on three different designs in term of propagation delay, Energy-delay Product and hystheresis. From the result, the proposed full swing CMOS Schmitt Trigger was able to operate as low voltage (0.8 V-1.5 V).

Sustainable nanopozzolan modified cement: characterizations and morphology of calcium silicate hydrate during hydration

There are environmental and sustainable benefits of partially replacing cement with industrial by-products or synthetic materials in cement based products. Since microstructural behaviours of cement based products are the crucial parameters that govern their sustainability and durability, this study investigates the microstructural comparison between two different types of cement replacements as nanopozzolan modified cement (NPMC) in cement based product by focusing on the evidence of pozzolanic reactivity in corroboration with physical and mechanical properties. Characterization and morphology techniques using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were carried out to assess the pozzolanic reactivity of cement paste modified with the combination of nano- and micro silica as NPMC in comparison to unmodified cement paste (UCP) of 0.5 water to cement ratio (w/c). Results were then substantiated with compressive strength (CS) results as mechanical property. Results of this study showed clear evidence of pozzolanicity for all samples with varying reactivity with NPMC being the most reactive.

Growth kinetic and composition of the interfacial layer for RF sputtering Al2O3 layer on germanium

Purpose The quality of GeOx–Ge interface and the equivalent oxide thickness (EOT) are the main issues in fabricating high-k/Ge gate stack due to the low-k of GeOx interfacial layer (IL). Therefore, a precise study of the formation of GeOx IL and its contribution to EOT is of utmost importance. In this study, the GeOx ILs were formed through post-oxidation annealing of sputtered Al2O3 on the Ge substrate. The purpose of this paper is to report on growth kinetics and composition of IL between Al2O3 and Ge for HCl- and HF-last Ge surface. Design/methodology/approach After wet chemical cleaning with HCl or HF, Al2O3 was grown onto the Ge surface by RF sputtering. Thickness and composition of IL formed after post-anneal deposition at 400°C in dry oxygen ambience were evaluated as a function of deposition time by FESEM and characterized by X-ray photoelectron spectroscopy, respectively. Findings It was observed that the composition and thickness of IL were dependent on the starting surface and an aluminum germinate-like composition was formed during RF sputtering for both HF- and HCl-last starting surface. Originality/value The novelty of this work is to investigate the starting surface of Ge to IL growth between Al2O3/Ge that will lead to the improvement in Ge metal insulator field effect transistors (MISFETs) application.

Wet chemical cleaning effect on the formation of ultrathin interfacial layer between Germanium (Ge) and high-k dielectric

This paper investigates and discusses the effect of wet chemical cleaning; Hydrochloric Acid (HCl) and Hydrofluoric Acid (HF) to the growth of interfacial layer between high-k material (Al2O3) and Ge (100) surface. Characterization and morphology techniques using Field Emission Scanning Electron Microscope (FESEM) was carried out to determine the thickness of interfacial layer between Al2O3 and Ge (100) surface. Results of this study showed that an HF treatment gives a rougher surface of Al2O3 than HCl treatment. Both wet chemical cleaning resulted with step and terrace trend of Al2O3 and interfacial layer. This may be due to initial Ge surface just after HF cleaning is rougher than the initial Ge surface after HCl cleaning.

A Low Power 3.1-10.6 GHz Ultra-wideband CMOS Power Amplifier with Resistive Shunt Feedback Technique

This paper presents the design of power amplifier (PA) 0.18 um CMOS technology for ultra wide band (UWB) application at 3.1-10.6 GHz. This PA design is based on two-stage common source topology with resistive shunt feedback technique and output buffer to achieve flat and higher gain, wider bandwidth and better stability. The simulation results show that the average power gain of 12.4 ± 1.1 dB, input return loss (S11) and output return loss (S22) less than -8.6 dB is achieved. Furthermore, low power consumption is 19 mW from 1.0 V supply voltage.

Study on Morphological, Optical and Electrical Properties of Graphene Oxide (GO) and Reduced Graphene Oxide (rGO)

In this work, graphene oxide (GO) is synthesized via chemical method (improved method) and reduced graphene oxide (rGO) using thermal treatment. The GO and rGO thin films were coated on a glass substrate by using drop casting method. The GO and rGO thin film were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) to make sure the morphological and optical characteristics of the thin film. In addition, the electrical studies were performed by current-voltage (I-V) characteristic. The rGO thin film displays higher conductivity in comparison with GO which is 4.12 x 10-5 S/cm, and also affected the morphological (SEM) and optical properties (FTIR). Morphological and optical data confirms that rGO losses the oxygen groups compare to GO.

A Review on the Extraction of Quantitative Retinal Microvascular Image Feature

Digital image processing is one of the most widely used computer vision technologies in biomedical engineering. In the present modern ophthalmological practice, biomarkers analysis through digital fundus image processing analysis greatly contributes to vision science. This further facilitates developments in medical imaging, enabling this robust technology to attain extensive scopes in biomedical engineering platform. Various diagnostic techniques are used to analyze retinal microvasculature image to enable geometric features measurements such as vessel tortuosity, branching angles, branching coefficient, vessel diameter, and fractal dimension. These extracted markers or characterized fundus digital image features provide insights and relates quantitative retinal vascular topography abnormalities to various pathologies such as diabetic retinopathy, macular degeneration, hypertensive retinopathy, transient ischemic attack, neovascular glaucoma, and cardiovascular diseases. Apart from that, this noninvasive research tool is automated, allowing it to be used in large-scale screening programs, and all are described in this present review paper. This paper will also review recent research on the image processing-based extraction techniques of the quantitative retinal microvascular feature. It mainly focuses on features associated with the early symptom of transient ischemic attack or sharp stroke.

Effect of Substrate Orientation on the Growth of Germanium Oxide in Dry Oxygen Ambience

The present investigation deals with the effect of substrate orientation effect on the growth of thermally oxidized Ge. The thermal oxidation was performed at temperature between 375 and 550°C in dry oxygen ambient under atmospheric pressure. The thickness of thermally oxidized Ge films was measured by spectroscopic ellipsometry and the chemical bonding structures were characterized by using x-ray photoelectron spectroscopy (XPS). No orientation dependence was observed for the oxidation at temperature of 375°C while for oxidation at 490 and 550°C, Ge oxidation and GeO desorption rate of (100) orientation yield higher rate than (111). The larger atomic space of (100) orientation explains the higher oxidation and desorption rate at Ge surface.

Defects Generation in Ge/GeO2 Structure

Thermal oxidation of Ge was performed in dry oxygen ambience at atmospheric pressure at temperature ranging between 375 and 575°C. From SE analysis, the slope of Ge oxide growth and extinction coefficient (k) increases while refractive index (n) does not change with oxidation temperature. The reduction of activation energy for Ge thermal oxidation was explained by the retardation of diffusion oxidant through GeO2 film during Ge oxidation. The generation of an oxygen-defect region in the Ge oxide layer at 490°C oxidation was confirmed by XPS analysis and an O2 anneal at 375°C was effective to reduce this oxygen deficiency.

High-speed domino logic design

Optimized standard CMOS-domino logic to a low cost logic and high speed design is presented. This paper combines a footless dynamic circuit with a robust self-timed inverted clocking scheme, a serial transistor is removed and capacitances at the output node are reduced in the new structures. This can be highly upgrade the operation speed of the circuit with very low power dissipation. Parametric simulation in Microwind 2 shows that over 20% performances enhancement is achieved. However, there are always the tradeoffs in designing high speed CMOS circuit and certain design issues need to be catered. CMOS-domino logic has been believed to gain its popularity in application of desktop computer and mobile devices in near future.