Richard Ocaya

UFS

a b s t r a c t A novel Schiff base type polyester containing 2,2 -diamino-4,4 -bithiazole (DABT) was pre-pared by low-temperature interface polycondensation of 1,4-benzenedicarbonyl dichloride with 4,4 -(4,4 -bithiazole-2,2 -diylbis(imine-2,1-diyl) diphenol (BDDP), which is derived from a 2,2 -diamino-4,4 -bithiazole (DABT) Schiff base reacted wit...

A complete modular but scalable TCP/IP based scientific instrument control and data distribution system has been designed and realized. The system features an IEEE 802.3 compliant 10 Mbps Medium Access Controller (MAC) and Physical Layer Device that is suitable for the full-duplex monitoring and control of various physically widespread measurement...

This paper describes an experiment that studies the effect of diode temperature and excitation current on forward diode voltage for a common silicon diode, the 1N4148. Experimental data are used to obtain a plausible model relating coefficient of voltage drift with temperature and its validity is then tested. The paper provides a reasonable tempera...

This article describes a simple computer interface that can be used to make reliable time measurements, such as that which may be made when timing the swings of a pendulum. The interface revolves around the IBM computer printer port. It can be constructed cheaply and does not involve the modification of the internal circuits of the computer. In a s...

This paper presents a straightforward but interesting experimental method for p–n diode characterization. The method differs substantially from many approaches in diode characterization by offering much tighter control over the temperature and current variables. The method allows the determination of important diode constants such as temperature co...

In this study, we present the development and characterization of a homegrown magnetron sputtering system (MSS) constructed from repurposed materials. Borosilicate glass slides were used as the substrate material, while Al, Fe, and Cu were employed as target materials. The system was validated, optimized, and successfully utilized for the depositio...

We present evidence for the existence of bias and illumination-driven negative differential conductance (NDC) in Ni-doped aluminium/p-Silicon Schottky diodes. We suggest the Ridley–Watkins–Hilsum (RWH) mechanism as a possible explanation of the origin of this NDC. The NDC is dependent on the bias, doping level, and illumination. The dark currents d...

In this article, a new Schottky diode based on a transparent conducting polymer 2-(4-fluorophenyl)-2-oxoethyl-2-methylprop-2-enoate (PFPAMA) that is doped up to 5% with ZnO is presented. PFPAMA is a promising transparent polymer that is inclined towards n-type behavior with the potential to be used as an electron transport layer. Each device had th...

Zinc oxide (ZnO) has been widely studied over the last decade for its remarkable properties in optoelectronic and photovoltaic devices because of its high electron mobility and excitonic properties. It has probably the broadest range of nanostructured forms that are also easy and cheap to synthesize using a wide variety of methods. The volume of re...

Zinc oxide (ZnO) has been widely studied over the last decade for its remarkable properties in optoelectronic and photovoltaic devices because of its high electron mobility and excitonic properties, probably the broadest range of nanostructured forms, and their ease and low cost of synthesis by a wide variety of methods. The volume of recent work o...

In this article, a new Schottky diode based on a transparent conducting polymer 2-(4-fluorophenyl)-2-oxoethyl-2-methylprop-2-enoate (PFPAMA) that is doped up to 5% with ZnO is presented. PFPAMA 1 L A T E X template 2 A novel conducting polymer-based diode is a promising transparent polymer that is inclined towards n-type behavior with the potential...

A metal-insulator-semiconductor (MIS) diode based on the Bi 2 Se 3 3D topological insulator on p-Si substrate was fabricated for use as a photodiode with the Al/p-Si/Bi 2 Se 3 /Al structure. The current-voltage, series resistance, and impedance characteristics were investigated using standard techniques and a new series resistance compensated metho...

We propose a method of determining the parameters of systems with serialized characteristics, which may suggest the existence of symmetry in the system. The method is demonstrated in extracting the parameters of a metal-semiconductor in the presence of significant series resistance, which is itself important but limits the accuracy of the existing...

Certificate of Attendance

We present a novel resistance-compensated I-V method to extract the series resistance, ideality factor, barrier height and built-in potential of a metal–semiconductor diode. We show that a reduced equation arises from a unique but hitherto unreported symmetry in the Schottky equation when it is written as an ordinary differential equation. In spite...

The series resistance of a metal-semiconductor device remains an important parameter to ascertain for the device. For a long time, there has been the need to find a method that does not make undue assumptions to reach these parameters. In this talk, we propose such a method. We begin by proving that the long-standing Schottky diode equation, wherei...

We present a novel resistance-compensated I-V method to extract the series resistance, ideality factor, barrier height and built-in potential of a metal-semiconductor diode. We show that a reduced equation arises from a unique but hitherto unreported symmetry in the Schottky equation when it is written as an ordinary differential equation. In spite...

The series resistance of a metal-semiconductor device remains an important parameter to ascertain for the device. For a long time, there has been the need to find a method that does not make undue assumptions to reach these parameters. In this talk, we propose such a method. We begin by proving that the long-standing Schottky diode equation, wherei...

This article reports the synthesis and purification of nanosilica (SiO2) derived from the husk of some rice varieties; Faro-44, Faro-46, Faro-52, Nerica-I, and Nerica-II. The husks were pretreated with H2O and HCl. From the measurement results, Nerica-I rice husks produced the highest silica yield and best photophysical properties. Thus, the husks...

Kinetic theory is taught to first-year students of physics as a plausible account of thermal equilibrium on the microscopic scale. However, it does not adequately clarify important properties like elasticity, lattice waves, phonons, optical oscillations, bandgap and so on, that are postulated through atomic vibrations. In this article, we apply sim...

In this chapter, recent developments in solid-state magnetic field sensors are discussed. The discussion encompasses solid-state devices fabricated using Group III-IV compounds and are deployed as thin-films on conductive substrates. The suitability of a measurement sensor is guided by the intended application, which is parametrically defined in te...

We suggest a novel approach to investigate phonon propagation in an FCC lattice through bond-length oscillations in response to a single atom velocity perturbation. The lattice is modelled using the Sutton-Chen embedded atom model (EAM) without any energy loss mechanisms. We begin by showing that the concept of the cutoff distance must be abandoned...

We describe a novel and cost-effective method to enhance the photo-conversion efficiency of blended PbI 2 /TiO 2 perovskite photovoltaic cells by pre-annealing the constituent film components during the fabrication. This approach is also unique because it does not presume a strictly controlled fabrication environment. The average conversion efficie...

In this article, we show that the variation of the wavelength of a non-pumped light-emitting diode (LED) is practically linear with temperature, a novel consequence of Varshni's widely accepted empirical expression. This formula models the bandgap variation for most semiconductors from 0K to their high-temperature limits, subject to fitting paramet...

In this article, we show that the variation of the wavelength of a non-pumped light-emitting diode (LED) is practically linear with temperature, a novel consequence of Varshni's widely accepted empirical expression. This formula models the bandgap variation for most semiconductors from 0K to their high-temperature limits, subject to fitting paramet...

At room temperature, high-responsivity charge-coupled devices (CCD) comprising arrays of several thousand linear photodiodes are readily available. These sensors are capable of ultraviolet to near infrared wavelengths sensing with detecting resolutions of up to 24 dots per millimeter. Their applicability in novel spectrometry applications has been...

The present study evaluates the effects of Ni doping of ZnO nanorods synthesized using the low-temperature chemical bath method. The article is motivated by the apparent variability in the literature which report contrasting results on the effect of Ni doping of the ZnO host matrix. The choice of method was decided by the accepted belief of its hig...

This study investigates the effect of annealing temperature (AT) on structure, morphology and optical properties of hydrothermally synthesized TiO2 nanocrystals. Selected-Area Diffraction (SAED) confirmed high quality monocrystals. XRD and Raman spectroscopy indicate only anatase and rutile phases. At high temperature, the (101) and (001) are prefe...

We compare the structural, morphological and electrical properties of two variants of the ITO/ZnO/(Formula presented.)/PDOT:PSS/Au thin film perovskite device made using two structurally different forms of lead iodide. The first device was based on a commercially sourced, common 12R polytype. The second device uses the rarer 6R polytype, as recentl...

Computational modelling in material science involves mathematical abstractions of force fields between particles with the aim to postulate, develop and understand materials by simulation. The aggregated pairwise interactions of the material’s particles lead to a deduction of its macroscopic behaviours. For practically meaningful macroscopic scales,...

In this study, the electrical and photoresponse properties of a photovoltaic device with Ruthenium(II) complex interfacial thin film were investigated. Heteroleptic Ru(II) complex including bidentate and tridentate ligands thin film was coated on n-Si substrate by the spin coating technique. From current–voltage (I–V) measurements of an Au/Ru(II)/n...

Temperature is a vital thermodynamical function for physical systems. Knowledge of system temperature permits assessment of system ergodicity, entropy, system state and stability. Rapid theoretical and computational developments in the fields of condensed matter physics, chemistry, material science, molecular biology, nanotechnology and others nece...

The laws of Newtonian mechanics allow ab-initio molecular dynamics to model and simulate particle trajectories in material science by defining a differentiable potential function. This paper discusses some considerations for the coding of ab-initio programs for simulation on a standalone computer and illustrates the approach by C language codes in...

Coumarin (CO) doped methylene blue (MB) organic photo-devices were fabricated. The CO-doped MB (0.00, 0.01, 0.03, 0.05, 0.1 wt% CO) were coated onto the surface of a p-type Si substrate by drop casting method. Some electrical parameters of the devices have been examined by current–voltage (I–V), capacitance–voltage (C–V), and conductance–voltage (G...

Computational modelling in material science involves mathematical abstractions of force fields between particles with the aim to postulate, develop and understand materials by simulation. The aggregated pairwise interactions of the material’s particles lead to a deduction of its macroscopic behaviours. For practically meaningful macroscopic scales,...

Computational modelling in material science involves mathematical abstractions of force fields between particles with the aim to postulate, develop and understand materials by simulation. The aggregated pairwise interactions of the material’s particles lead to a deduction of its macroscopic behaviours. For practically meaningful macroscopic scales,...

In this work, it is shown that choosing an organic-on-inorganic Schottky diode for photoconductive sensing by a using a power law exponent (PLE or determined at a single bias point is a limited approach. The standard literature approach does not highlight any bias voltage effects on the distribution of interface state density and other operationall...

Coumarin doped with poly(3-hexylthiophene)/p-Si photodiodes were prepared by the drop-casting technique. The currentevoltage characteristics of the prepared diodes with the structure of Al/ P3HT:Coumarin/p-Si/Al diodes were investigated under dark and various illumination intensities using both IeV and CeV methods. Using both illuminated DC and tra...

Computational modelling in material science involves mathematical abstractions of force fields between particles with the aim to postulate, develop and understand materials by simulation. The aggregated pairwise interactions of the material’s particles lead to a deduction of its macroscopic behaviours. For practically meaningful macroscopic scales,...

The constant pi, or π, is one of the oldest and most recognizable irrational constants. It was known from the earliest days of mathematics and the sciences. Over the ages, many methods of varying complexity have been used to estimate π. This article presents a novel experimental method to estimate π using direct, digital voltmeter measurements on a...

Computational modelling in material science involves mathematical abstractions of force fields between particles with the aim to postulate, develop and understand materials by simulation. The aggregated pairwise interactions of the material’s particles lead to a deduction of its macroscopic behaviours. For practically meaningful macroscopic scales,...

The analysis of robustness of nonlinear systems is at present the subject of intense study. Though largely open at present, questions of system robustness must be addressed as complexity and nonlinearity grow. In attempting to answer some of these questions and suggest new directions, this research focuses on the affine dynamic control system, wher...

A heterojunction diode based on an ambipolar organic semiconductor 2,8-bis(5-(2-octyldodecyl)thien-2-yl)indeno[1,2-b]fluorene-6,12-dione (2OD-TIFDKT) was fabricated on p-Si using a drop-casting technique. The current–voltage and capacitance-voltage characteristics of Al/2OD-TIFDKT/p-Si/Al devices with aluminized contacts were investigated under dar...

The one-parameter point transformation method is applied to clarify the use of symmetries to describe the effects of additive uncertainties on the state-space solutions of an affine control system. The trajectory of the solution in the presence of general, bounded uncertainties gives an idea of system robustness. The boost converter is used for ill...

The one-parameter point transformation method is applied to clarify the use of symmetries for describing the effects of additive uncertainties on the state-space solutions of an affine control system. The trajectory of the solution in the presence of general, bounded uncertainties gives an idea of system robustness. The boost converter is used for...

The design and implementation of a novel room temperature charge-coupled device (CCD) spectrometer is presented. The timing generator and data acquisition circuits driving a 16020 photodiode linear tricolour CCD detector capable of 24 dots per millimetre are described. Linear detection of ultraviolet, infrared and visible (Vis) wavelengths over tot...

Ab-initio molecular dynamics (MD) employs Newtonian mechanics to model and simulate the time evolution of particle trajectories in material science ensembles using a differentiable potential function. Although commercial and free packages exist for MD, their heuristic nature prevents dissection. This open-source C-language package arose out of the...

High-purity hexagonal lead iodide nanoparticles have been synthesized from a depleted lead acid battery. The rare 6R polytype form of PbI$_2$ that is known to have potential in photovoltaic applications was synthesized in high purity. We investigate the effects of annealing time and post-melting temperature on the structure and optical properties u...

High-quality lead iodide (PbI\(_{2}\)) nanoparticles were synthesized from both anode and cathode of a discarded sealed lead-acid accumulator as starting materials. The structure, morphology, chemical composition and optical properties of washed PbI\(_{2}\) were investigated using X-ray diffraction, field emission scanning electron microscope, phot...

The device parameters of Al/p-Si/PCBM:GO/Au diodes were investigated using direct current–voltage (I–V), photocurrent and impedance spectroscopy. The ideality factor of the diode was found to depend significantly on GO content. The calculated barrier heights had low variance over the range of illumination intensities per doping level. Under dark co...

New photodiodes based graphene-organic semiconductor hybrid materials were fabricated for the first time using sol–gel spin coating technique. The current–voltage characteristics of the Au/GO:coumarin/p-Si/Al diodes were investigated under dark and various illumination intensities. The various junction parameters of the diodes were determined using...

The device parameters of Al/p-Si/Zn1-xAlxO-NiO/Al Schottky diode for x=0.005 were investigated over the 50K to 400K temperature range using direct current–voltage (I–V) and impedance spectroscopy. The films were prepared using the sol-gel method followed by spin-coating on p-Si substrate. The ideality factor, barrier height, resistance and capacita...

In this work, we have synthesized modified nickel(II) phthalocyanine containing graphene oxide. Our emphasis is given to understand the effect of doping on the photophysical behavior of semiconducting graphene oxide/nickel(II) phthalocyanine composite films by using I–V and C–V spectroscopy. Al-p-Si/GO:NiPc/Au structures have rectifying behavior wi...

The device parameters of Al/GO:CoPc/p-Si/Au Schottky diodes were investigated using direct current– voltage (I–V), photocurrent and impedance spectroscopy. The ideality factor of the diode was found to depend significantly on GO content. The calculated barrier heights had low variance over the range of illumination intensities per doping level and...

We report on the implementation of a FPGA-based ultra-violet (UV), infra-red (IR) visible (Vis) CCD spectrometer using a linear CCD detector operating at room temperature. The host interface is high-speed USB for data exchange with high-level environments such as Visual Basic, MATLAB and LABVIEW. The high-resolution intensity versus wavelength outp...

Earlier studies of the formation of ZnO nanostructures using the zinc-air cell method have indicated a rich presence of nanostructures such as hierarchical nanowires, nanorods, flower-like and nano-needles with an inherent hexagonal wurtzite structure. Controlling the growth orientation of semiconductor nanostructure arrays, particularly nanowires...

ZnO nano-needles have been synthesized successfully on zinc substrate with the zinc-air cell method at room temperature. The effect of annealing temperature on the structure, morphology and optical properties of ZnO nano-needles were investigated using X-ray diffraction (XRD), Field Emission Scanning electron microscopy (FE-SEM) and ultraviolet-vis...

Earlier studies of the formation of ZnO nanostructures using the zinc-air cell method have indicated a rich presence of nanostructures such as hierarchical nanowires, nanorods, flower-like and nano-needles with an inherent hexagonal wurtzite structure. Controlling the growth orientation of semiconductor nanostructure arrays, particularly nanowires...

We propose a method to synthesize ZnO nanoparticles. A layer of well-aligned zinc oxide (ZnO) nano-needles was synthesized on zinc plate at room temperature using an environmentally friendly zinc-air cell system (ZACs). The zinc plate was the anode, and the air cathode was composed of steel wool. A porous void-paper separated the electrodes and in...

This Design Idea shows a way to drive low-power electronic circuits using a single 1.5V cell. The design is based on a free-running oscillator that drives a flyback transformer to generate a controllable higher voltage. It can be used to power analog circuitry, microcontrollers, and any other light loads.

We propose a simple graphical method to extract the static parameters of an arbitrary schottky diode. The method is an extension of the current-voltage method by the inclusion of a temperature aspect, and hence may be referred to as a current-voltage-temperature (I-V-T) method. The voltage-temperature characteristics are first obtained at two const...

The TL431 exhibits an interesting instability under certain conditions of input supply voltage and capacitive load, causing sustained oscillations that can range from 10kHz up to 1.5MHz, generally depending on the control input voltage. This occurs partly because of a negative resistance region under those conditions. As shown in this Design Idea,...

An integral part of thermoluminescence (TL) measurement system is a temperature controller. Many of the low-cost TL instruments surveyed employ open-loop methods based on external, discrete components to control the temperature of the sample. The repeatability of one such method was found to be low. The motivation for the present implementation was...

An integral part of thermoluminescence (TL) measurement system is a temperature controller. Many of the low-cost TL instruments surveyed employ open-loop methods based on external, discrete components to control the temperature of the sample. The repeatability of one such method was found to be low. The motivation for the present implementation was...

This paper reports on the design, development and application of a solar energy integrator instrument (SI) that is specifically intended to be a low cost solution for solar energy measurements and research. The use of the high-performance PIC18 series embedded controller allows high integration of the data acquisition, supervision and universal ser...

When designing low-power USB circuits that require power supply voltages other than 5 volts, you must decide whether to use a separate battery or a physically small mains based power source. The problem is particularly troublesome if the circuits to be powered require dual rails greater than 5V, such as instrumentation amplifiers based on operation...

We describe a novel application arising from earlier observations that under several different constant currents the p–n diode exhibits different diode voltages at the same temperature. Firstly, we show by theory, simulation and experiment that this voltage difference increases linearly with temperature. Secondly, we show that the approach allows d...

Project INNO/001 is in a state of demonstrated, working prototype. It is based on exhaustive studies and research on current trends and demands of an increasingly connected world.

Data telemetry using latest technologies.

In this design idea the concept of the p-n diode driven at constant current is extrapolated, potentially eliminating voltage references and op amps. The result is a unique implementation of a simple but highly accurate temperature proportional circuit. Interesting applications are also suggested. The operation of the circuit is based on a switched...