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Effectiveness of Geant4 in Monte Carlo Simulation Studyofphonon Conduction in Sn Host with Si Nanowire Interface

Abstract

We have explored the effectiveness of Geant4 by using it to simulate phonon conduction in Sn Host with Si Nanowire Interface. Our Monte Carlo Simulation shows that the effectiveness of the phonon conduction Geant4 simulation increases when the system attained a steady state of 100 time steps. We have simulated phonon conduction in Sn host with Si nanowire interface using a Geant4Condensed Matter Physics Monte Carlo simulation toolkit in a low cost and less powerful processing computer machine. In the simulation, phonons were displaced inside a computation domain from their initial positions with the velocities and direction vectors assigned to them. A time step was selected so that a phonon can move at most the length of one sub-cell in one time step. Our phonon conduction analysis of SiSn based alloy using Geant4 showed performance enhancement and reasonable predicted thermal values. Numerical predictions of the thermal profile simulations of the values of the temperature in each cell were all within ten percent of the average temperature of Silicon – Tin.

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Electronic and Thermoelectric Properties in Li-Based Half-Heusler Compounds: A First Principle Study

Abstract

In this paper, we performed a first principle study for new half-Heusler LiSrX(X= N, P, and As) working with WIEN2k code in the frame work of the density functional theory, and the Boltzmann theory. We estimated the exchange-correlation potential by the generalized gradient approximation (GGA). Energetically, the three compounds show a high stability in structure type2, we notice that the lattice constant increased while bulk modulus decreased in replacing the ions of size increasing. Based on our calculations, LiSrN, LiSrP, and LiSrAs compounds are mechanically stable, and show semiconductor nature with indirect band gaps of 1.21, 1.75 for LiSrN and LiSrAs, and direct band gap of 1.94 eV for LiSrP. The thermoelectric properties are calculated for LiSrX (X=N, P, and As) and they found a high power factor for the p-type doping concentration.

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Fabrication and Characterisation of ZnO Thin Film by Sol–Gel Technique

Abstract

We investigated the structural and optical properties of zinc oxide (ZnO) thin film as the n-type semiconductor. In this work, the sol–gel method used to fabricate ZnO thin film on glass substrate with 0.5 mol/l of zinc acetate dehydrates. The crystals quality of the thin film analyzed by X-ray diffraction and the optical transmittance was carried out by an ultraviolet-visible spectrophotometer. The DRX analyses indicated that ZnO film have polycrystalline nature and hexagonal wurtzite structure with (002) preferential orientation and the measured average crystallite size of ZnO of 207.9 nm. The thin film exhibit average optical transparency about 90 %, in the visible region, found that optical band gap energy was 3.282 eV, the Urbach energy also was calculated from optical transmittance to optimal value is 196.7 meV.

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Germanium Gradient Optimization for High-Speed Silicon Germanium Hetero-Junction Bipolar Transistors

Abstract

The effect of germanium trapezoidal profile shape on the direct current (DC) current gain (β F), cut-off frequency (f T) and maximum oscillation frequency (f MAX) of silicon-germanium (SiGe) hetero-junction bipolar transistors (HBTs) has been investigated. The energy balance (EB), hydrodynamic (HD) and drift-diffusion (DD) physical transport models in SILVACO technology computer aided design (T-CAD) simulator were used. It was found that the current gain values using energy balance model are higher than hydrodynamic and much higher than those corresponding to drift-diffusion. Moreover, decreasing the germanium gradient slope towards the collector side of the base enhances the maximum oscillation frequencies using HD and EB models whilst, they remain stable for DD model.

Open access
Removal of Methylene Blue by Activated Glass Foams with TiO2 in Dark and Simulated Solar Light

Abstract

The effect of germanium trapezoidal profile shape on the direct current (DC) current gain (βF), cut-off frequency (fT) and maximum oscillation frequency (fMAX) of silicon-germanium (SiGe) hetero-junction bipolar transistors (HBTs) has been investigated. The energy balance (EB), hydrodynamic (HD) and drift-diffusion (DD) physical transport models in SILVACO technology computer aided design (T-CAD) simulator were used. It was found that the current gain values using energy balance model are higher than hydrodynamic and much higher than those corresponding to drift-diffusion. Moreover, decreasing the germanium gradient slope towards the collector side of the base enhances the maximum oscillation frequencies using HD and EB models whilst, they remain stable for DD model.

Open access
Solutions of the Dirac Equation in a Bardeen Black Hole Geometry

Abstract

In this paper we study the Dirac equation in the geometry of a (regular) Bardeen black hole. We will focus on finding new analytical solutions in the vicinity of the black hole horizon. These solutions can be used with the asymptotic solutions (derived in a previous paper) to compute numerical phase shifts that define the scattering amplitudes.

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Spin Coating Method Fabricated of In2O3 Thin Films

Abstract

In this work, the In2O3 thin films have been fabricated using a spin coating technique; this technique was prepared in our laboratory. The effect of the layer times (3, 5, 7 and 9 times) on optical and structural properties was investigated. In2O3 thin films were fabricated by dissolving 0.2 M of the indium chloride dehydrate InCl3.2H2O in the absolute H2O. The In2O3 thin films were crystallized at a temperature of 600 °C with pending time of 1 hour. The optical property shows that the prepared In2O3 thin films for 3 and 5 times have a transmission of about 85 %. The maximum bandgap energy was 3.69 eV for 5 times and the lowest Urbach energy was 0.47 eV for 9 times. From XDR all fabricated In2O3 thin films having one diffraction crystal plan is (222) peak intensity, this attribution have good crystalline structure with minimum crystallite size of the (222) plan is 59.69 nm. The prepared In2O3 thin films can be used in photovoltaic applications due to the existing phase and higher transmission.

Open access
Effect of Cu2O Morphology on Photovoltaic Performance of P-Type Dye-Sensitized Solar Cells

Abstract

Cuprous oxide with different morphologies (3D hierarchical structure consisting of the micrometer dendritic rods and the porous truncated octahedrons) has been successfully synthesized via a facile one-step hydrothermal method using copper (II) acetate and ethyl cellulose as reactants. The p-type dye-sensitized solar cell based on the micrometer porous structure exhibits approximately 15% increase in JSC and VOC than 3D hierarchical structure. This enhancement could be explained by the high dye loading capacity of this porous structure and lowering the recombination process at the oxide/dye/electrolyte interface.

Open access
Estimating Global Solar Radiation from Routine Meteorological Parameters Over a Tropical City (7.23°N; 3.52°E) Using Quadratic Models

Abstract

The need for adequate solar radiation is ever increasing for various applications. However there is an inadequate data of solar radiation in many countries due to the cost of instrument set up. Hence this study investigates two models for estimating solar radiation from routinely measured meteorological parameters. The data were obtained from the International Institute of Tropical Agriculture, Ibadan. The regression coefficients of the quadratic models were determined and used to estimate the global solar radiation for both forward and backward predictions. Their predictive accuracies were compared with four other models and the measured values using standard statistical error indicators. The results showed for forward as compared to backward predictions in bracket root mean square errors 1.2 (1.1); mean bias errors 1.1 (0.8) and mean percentage errors -4.8% (-2.9%) while for backward prediction 1.9 (1.7), 1.7 (1.4) and 7.9% (2.2%) measured in KJm−2day−1 respectively. A positive error value shows an over estimation while a negative value shows an under estimation. The models are versatile for estimating global solar radiation at the horizontal surface, fixing missing data and correcting outliers.

Open access
Experimental Assessment of the Meliss Simulation Model Accuracy of the Direct Solar Irradiance in Brasov, Romania

Abstract

The solar irradiance is the main input parameter when designing solar energy conversion systems. A poor accuracy of the solar irradiance simulation models negatively affect the output energy and the durability of the solar energy conversion system. In the paper, the measured values of the direct solar irradiance in the entire month of July 2016 are analysed and, based on the daily received direct solar energy and the variability of the direct solar irradiance, the days are classified in four categories: clear sky days, partially clear sky days, partially cloudy days and cloudy days. Based on this classification, only four clear sky days were identified in July 2016. The same procedure was applied for the months of July 2013, 2014 and 2015 resulting 13 clear sky days in the entire monitoring period of four years (2013-2016). The measured values of the direct solar irradiance in these 13 selected clear sky days are comparatively analysed against the direct solar irradiance simulated with Meliss clear sky model. Further on, a statistical analysis is performed for the time interval 8:00-16:00 to evaluate absolute, relative and root mean square errors between the measured and simulated values. The results show that the simulation model overestimates, in eleven out of the thirteen clear sky days, the solar direct irradiance in the central part of the day. The measurements were performed in the Renewable Energy Systems and Recycling (RESREC) Research Centre located in the R&D Institute of the Transilvania University of Brasov, Romania.

Open access