Silvaco ATLAS Software Research Articles

Enhanced CZTSSe Thin‐Film Solar Cell Efficiency: Key Parameter Analysis

This work presents a numerical simulation study on CZTSSe‐based thin‐film solar cells using Silvaco Atlas software, focusing on optimization and loss analysis. Starting from an initial power conversion efficiency of 12.73%, the ZnO/CdS/CZTSSe cell structure is systematically optimized. Through precise adjustment of layer thickness and doping density, the efficiency is improved to 18.75%. The optimal parameters are 2.5 μm (1017 cm−3) for CZTSSe, 0.01 μm (1018 cm−3) for CdS, and 0.02 μm (1019 cm−3) for ZnO. Loss analysis reveals that increasing CZTSSe thickness beyond 2.5 μm leads to higher bulk series resistance, while thicker CdS and ZnO layers reduce photocurrent generation. Doping density significantly impacts open‐circuit voltage, while layer thickness primarily affects short‐circuit current and fill factor. Performance improves at lower temperatures, achieving 22.2% efficiency at 250 K. These findings provide valuable insights for developing high‐efficiency CZTSSe solar cells.

Theoretical simulation of time-related electrical performance of 63NiO/ZnO integrated betavoltaic battery

The temporal electrical performance of a 63NiO/ZnO integrated betavoltaic battery is examined. Utilizing first-principles calculations combined with Monte Carlo simulations, we study the energy band structure and density of states of 63NiO, particularly when 63Ni undergoes a 12.5% decay. Our findings reveal that, when the 63NiO layer is 4 μm thick, the decay's impact is akin to substitution doping. Leveraging this insight, we employed Silvaco ATLAS software to simulate the time-dependent short-circuit current, open-circuit voltage, maximum output power, and energy conversion efficiency of the 63NiO/ZnO integrated betavoltaic battery. These results were compared with those of a NiO/ZnO separate betavoltaic battery. At 6.93 years, the maximum output power of the integrated and separate devices was found to be 10.19 and 9.77 nW/cm2, respectively, corresponding to 8.67% and 88.79% of their initial values. Notably, prior to this point, the integrated device exhibited significantly superior performance; at 4.58 years, it demonstrated 2.28 times higher maximum output power compared to the separate device, followed by only a slight difference in performance thereafter.

Optimized Design of Carbon Nanotube Field-Effect Transistor Using Taguchi Method for Enhanced Current Ratio Performance

Abstract Presently, the integrated circuit (IC) industry grapples with obstacles in downsizing MOSFET technology further, hindered by its inherent physical constraints. Therefore, the substitution of silicon with carbon nanotubes (CNTs) holds promise for paving a novel path in semiconductor industries, driven by their diminutive dimensions and superior electrical properties. Hence, this project employed SILVACO ATLAS software in conjunction with the Taguchi method to refine a CNTFET design for optimal performance. In this work, response variables consists of on-current (Ion), current ratio (Ion/Ioff) and threshold voltage (Vth) are extracted. In this particular design, the Taguchi method was employed to ascertain the most effective combination of design parameters and materials to achieve optimal CNTFET performance, as assessed by the three key response variables. The design parameter and material that had been chosen were the diameter of carbon nanotube (Dcnt), dielectric material (K) and oxide thickness (tox). Each of the design parameters and material had three different values. For K, the values are 3.9 (SiO2), 25 (ZrO2) and 80 (TiO2). While for Dcnt and tox, the values are 4.0 nm, 6.0 nm, 8.0 nm and 2.0 nm, 4.0 nm, 6.0 nm respectively. According to the Taguchi optimization findings, the ideal combination of parameters comprises a CNT diameter of 4.0 nm, an oxide thickness of 2.0 nm, and the use of TiO2 (80) as the dielectric material. The ANOVA analysis underscores the significance of prioritizing optimization efforts towards the CNT diameter parameter. This is attributed to its substantial contribution, accounting for 93.55% of the variation in the Ion/Ioff value, surpassing the influence of dielectric materials and oxide thickness.

Dual‐Stepped Gate Vertical Double‐Diffused Metal‐Oxide‐Semiconductor Field‐Effect Transistor with Enhanced Device Performance

Herein, vertical double‐diffused metal‐oxide‐semiconductor field‐effect transistor(VDMOS) with improved device structure is proposed. Gate engineering is applied in the proposed device and two devices namely dual‐stepped gate technology (DSGT) and modified dual‐stepped gate technology (m‐DSGT) are proposed here. Due to the effect of gate engineering, switching ability is improved and area specific on‐resistance is reduced. Devices are simulated using Silvaco Atlas software. Breakdown voltages for conventional and m‐DSGT are 278.63 and 280.02 V, respectively, for = 0 V. The current density of conventional and m‐DSGT devices is and under the conditions on gate‐driven voltage of 1 V for = 10 V. Using 2D numerical simulations, the electrical performance of both DSGT and m‐DSGT devices is examined. The results demonstrate 76.6% decrease in specific on‐resistance, 4.22 times increase in current density, and 26.67% faster switching speed compared to conventional VDMOS, thus, improving the device performance.

Improving FTO/ZnO/In2S3/CuInS2/Mo solar cell efficiency by optimizing thickness and carrier concentrations of ZnO, In2S3 and CuInS2 thin films using Silvaco-Atlas Software

Optimization of optical and electrical properties of active semiconducting layers is required to enhance thin film solar cells' efficiency and consequently became the cornerstone for sustainable energy production. Computational studies are one of the ways forward to optimize solar cells’ characteristics. In this study, Silvaco-Atlas, a powerful software that excels in both 2D and 3D electrical simulations of semiconductors has been used for the simulation in order to investigate the solar cell properties. The architecture of the solar cell simulated was FTO/ZnO/In2S3/CuInS2/Mo. This study aims to optimize solar cell efficiency by optimizing film thicknesses and carrier concentrations via simulation. The designed solar cell was exposed to the presence of a sun spectrum of AM1.5 from a 1kW/m2 incident power density at 300K. The thickness values of the window (ZnO), absorber (CuInS2) and buffer (In2S3) layers were varied to record a solar cell's optimum thickness. The resulting FTO/ZnO/In2S3/CuInS2/Mo solar cell formed by simulation is presented. The best efficiency and fill factor of the solar cell simulated were found to be 41.67% and 89.19%, respectively. The recorded values of current density and the open circuit voltage of the cell were 40.33mA/cm2 and 1.15 V, respectively. Additionally, the maximum power of the simulated solar cell device was 41.68 mW. Optimization results revealed that the most efficient cell found was made up of a window layer with a thickness of 0.03μm, an absorber layer with a thickness of 6.0μm and a buffer layer with a thickness of 0.2μm. The optimized carrier concentration of ZnO, In2S3 and CuInS2 was respectively 1e21 cm-3, 1e20 cm-3, 3e18 cm-3 and the optimized Al-doped ZnO value was 1e25 cm-3. The Absorption spectra indicated that the solar cell's peak absorption occurs between 350 nm and 1250 nm and presented a good external quantum efficiency (EQE) of around 84.52% to 92.83% which indicates good efficiency in the visible domain. This performance is attributed to the transparency of FTO, ZnO and good absorption of In2S3 and CuInS2 thin films.

Triple junction solar cell with Cu In1-x Gex Se as absorbents layers

The design of multi-junction solar cells is guided by both the theoretical optimum bandgap combinations as well as the realistic limitations to materials with these bandgaps. Nowadays, triple-junction III-V multi-junction solar cells are commonly used as GaAs, InGaAs; InGaP ... In this work, we are interested in studying triple junctions based on thin-film solar cells Cu(In1-xGax) Se2, CuInSe2, and CuGaSe2 quaternaries using Silvaco ATLAS software. Incorporating Cu(In0.34Ga0.66) Se2 as an absorber in the middle sub-cell increased the open-circuit voltage by 0.72 V. The highest cell efficiency is 20.89 % (Voc = 2.33 V, Jsc = 9.97 mA/cm2, FF = 89.62%). This triple-junction solar cell demonstrates the potential and limitations of future improvements when voltage and current are considered.

Electrical behavior of n-GaAs Schottky nanowire in wide temperature range for different contacts

This research aims to study the impact of metal work function ?m on the I–V characteristics of a n-GaAs Schottky nanowire structure, using 3D Silvaco-Atlas software. The electrical characteristics have been performed in a wide temperature range of 300-550K. This allows us to study and discuss the influence of temperature and the metal work function ?m on the performance of our proposed device. The results show a great dependence between ?m and the electrical parameters. A decrease in current is observed with increasing ?m, as well as an increase in barrier height with increasing ?m and a decrease with increasing temperature.

Simulation aided design of a high efficient GaSb based single-junction solar cell

AbstractOwing to their elevated absorption coefficient, superior resistance to radiation and reduced effective electron mass, gallium antimonide (GaSb) semiconductors were documented to be suitable for photovoltaic systems applications. However, they were found to suffer from low efficiency. This work has been dedicated to enhance the design of GaSb based single-junction solar cells having window and back surface field made from AlGaAsSb material. The purpose is to maximize their electrical performance by considering doping and thickness of layers as design variables. A methodology of optimization was proposed. It is based on computer aided design through simulations performed under SILVACO-ATLAS software and a numerical procedure that was developed to achieve optimal design of this particular solar cell. The approach encompasses analysis of variance and derivation of response surface models to get explicit expression of the objective function corresponding to efficiency. The obtained results have shown an efficiency which is higher than all the previous known values established in literature.

Ni/Ga2O3 based Schottky diode temperature sensor

Temperature sensors are the integrated part of electronics used in most of the applications. Present work demonstrates the temperature sensor based on ultra-wide bandgap semiconducting material, i.e.,Ga2O3. The material is known for its wider bandgap and radiation hardness properties. Ni/Ga2O3 based Schottky barrier device is simulated for sensing the temperature in the current range of 100 µA to 0.1 µA and in temperature range from 200 K to 600 K using SILVACO Atlas software. Relevant models such as bandgap narrowing, Schokely-Read-Hall, etc. were employed to ensure accuracy in the results. The simulated current–voltage (I-V) plots showed exponential variation and followed ideal thermionic emission model. The I-V plots were used to find the thermal sensitivity of device under considerations, which showed linearity in the measured current range. The maximum sensitivity is estimated as 3.22 mV/K at measuring current level of 0.1 µA.

A miniaturized advanced rectenna integrated circuit for implantable applications

This paper presents analysis and design of a new miniaturized advanced rectenna integrated circuit for RF energy harvesting applications. The rectenna circuits consist of (antenna, rectifying circuit) and matching network connected together. The 1 × 4.5 mm2 planar L-shaped dipole antenna implanted inside human ‘s body arm for operation in ISM dual-bands like 1.5GHz and 5.8GHz. The new device quantum well asymmetric spacer tunnel layer (QW-ASPAT) rectifier diodes based on GaAs and InGaAs platforms have been used for the mesa size area of 10 × 10 μm2. The DC, RF, and C-V characteristics of the new rectifier diodes were performed and modelled by using SILVACO ATLAS software. The highest extracted curvature coefficient, kv value of the both QW-ASPAT devices at zero bias was about 33 V−1 compared with the standard structures was 13 V−1. The cut off frequency of the proposed QW-GaAs and QW-InGaAs devices are 26GHz and 46GHz respectively. The fully integrated rectenna circuit was performed by Advanced Design System (ADS) software. The maximum DC output voltage and power of the proposed rectenna system were 0.7 V,1.5 V and 167 μw, 325 μw when used single, and double stage voltage doubler rectifiers respectively at the input RF power of 0 dBm.

A-ITZO based thin film transistor for ammonia gas sensing: a simulation study

This work is an optimization study by numerical simulation of the performance of amorphous indium tin zinc oxide thin film transistor (a-ITZO TFT) based gas sensor using SILVACO-ATLAS software. The optimization process is focused on the catalytic source/drain electrode, dielectric material and work-function difference. Based on simulation results, when the electrode material is switched from cobalt to molybdenum, the value of drain current was found to be increased from 39 μA to 231 μA. For molybdenum, ruthenium and cobalt with a work function difference of 200 meV, the OFF state current sensitivity (SIOFF) and ON State current sensitivity (SION) values were found to be 607.27 and 213.2, 102.81 and 0.35 and 0.015 and 0.90 respectively. An increase in the sensitivity of simulated structure was observed with the value of work function difference that indicates an increase in the concentration of gas. The impact of the dielectric material also reveals that high-k dielectric materials boost the sensitivity of the proposed device. The simulation results confirm the a-ITZO TFTs potential in gas sensing applications.

Optimizing efficiency of InGaP/GaAs dual-junction solar cells with double tunnel junction and bottom back surface field layers

Dual-junction solar cells have permitted to augment markedly efficiency of solar energy harvesting. This is because they involve a combination of III-V semiconductor materials with different band gaps which enables for better absorbance of the solar spectrum and consequently higher efficiency. In these last years, intensive research has been dedicated to develop reliable methods for performing structural optimization of these devices. This work proposes a new numerical procedure in order to achieve optimal design of a dual junction solar cell made of InGaP/GaAs tandem combination. This particular structure relies on the InGaP single junction solar cell, which is used as a front stack, and a back surface field. Optimization was conducted sequentially through post processing data results generated from large parametric simulations performed by using the 2D SILVACO-ATLAS software. The procedure encompasses using either a quadratic response surface model or an artificial neural network model at each stage of the optimization process to determine the actual optimal design of the solar cell. The obtained final optimal design has been shown to yield, under the AM1.5 spectrum, an efficiency of 35.15% at temperature 20°C which is higher than that of previous known results from literature.

Design and numerical investigation of Perovskite/Silicon tandem solar cell

This paper reports the simulation of a Perovskite/Silicon tandem solar cell, based on methylammonium mixed bromide-iodide lead perovskite, CH3NH3PbI3−xBrx and Silicon-hetero-junction (SHJ) structures as top and bottom cells, respectively, using Silvaco-atlas software. In this work we have simulated the single perovskite and the single silicon solar cells, where the power conversion efficiency (PCE) of the perovskite and the silicon are 24.38% and 21.43% respectively. A good agreement with other simulation and experimental results found in literature is achieved. We have also modeled the Perovskite/Silicon tandem structure with perovskite and silicon as top and bottom cells, respectively. The results show a PCE of 27.02% for the tandem solar cell. To enhance the efficiency and to achieve the current matching between the sub-cells, adjusting the perovskite top cell thickness of our structure can efficiently improve the PCE of the tandem solar cell reaching 31.67%.

Simulation and performance optimization of GaAs/GaSb tandem solar cell

Multi-junction solar cells provide the highest efficiencies. Intense research activity is being held with the aim to increase the actual performance reached by these cells. Harvesting most of the solar spectrum and finding the optimum design variables in terms of structural parameters and carrier concentrations are the main topics being investigated by solar developers. The GaAs/GaSb based dualjunction solar cell was found suitable for the best absorption of solar spectrum. In this work, an optimization approach was applied to fix the optimal parameters of the top base layer of this structure that provide the maximum efficiency. To achieve this, a series of numerical simulations were carried out by means of Silvaco ATLAS software under standard AM1.5G spectrum where thicknesses and doping levels of the top base layer were varied. The obtained optimal structure yields a power conversion efficiency of 41.65% with open circuit voltage of 1.78V, short circuit current of 35.72mA/ cm2and fill factor of 90.16%. The performance of the GaAs/GaSb dual-junction solar cell was further improved by using sunlight concentration. A conversion power efficiency of 45.78% at 60sun light concentration was attained. It was found also that above this level of concentration ratio the detriment effect of shunt resistance dominates.

A new optimization approach for high efficiency of FTO/InS/CIS heterojunction solar cells

ABSTRACT In this work, a new approach is developed to optimize FTO/InS/CIS hetero-junction solar cell using the Slivaco-Atlas software. Each single thin film was prepared by spray pyrolysis method on glass substrates in order to characterize its proper material parameters. Structural and morphological analysis confirmed the deposition of F-doped SnO2, In2S3 and CuInS2 films with porous structures. The extracted physical properties such as thickness, optical, and electrical parameters are considered as input data for Silvaco-Atlas software simulation. It was found that thickness layers and carrier concentration of CIS-based solar cell play an important role in determining solar cell performances. The combination of the optimum parameters enables to obtain the efficiency of 38.20%. The overall investigation on CIS solar cell gives potential suggestions that may lead to the fabrication of the high-efficiency CIS-based solar cell.

Numerical modeling of multi-junction solar cell-based CIGS with two sub-cells in parallel using silvaco TCAD

The multi-Junction solar cell technique was suggested for achieving high efficiency. This paper describes the simulation of a solar cell for double junction CGS/CIGS solar cell using Silvaco ATLAS software. The simulated device performance was demonstrated in the form of current-voltage (I-V) characteristics and quantum efficiency (QE). By simulation of the tow solar cell, we have obtained for solar the top cell maximum opencircuit voltage 1.15V, a short circuit current density of 18.74 mA, a fill factor (FF) of 87.79 % and an efficiency of 18.27% and for the bottom solar cell is maximum opencircuit voltage 0.57 V, a short circuit current density of 21.52 mA, a fill factor (FF) of 82.82% and an efficiency of 10.26%. For the Tandem whose sub-cells are tied in parallel, the maximum open-circuit voltage 1.16V, a short circuit current density of 29 mA, a fill factor (FF) of 83.06% and an efficiency of 28.11%.

Design and analysis of GaAs/AlAs asymmetric spacer layer tunnel diodes for high-frequency detection

Abstract In the present work, we have systematically investigated the design of Asymmetric SPAcer-layer Tunnel (ASPAT) diodes using numerical modeling employing SILVACO Atlas software. After reproducing and validating physical models using experimental data obtained from fabricated ASPAT diodes, a developed SILVACO model was used to evaluate the effect of different structure designs on two key parameters, namely the junction resistance and curvature coefficient at zero bias. The impact of the variation in the spacer layers thicknesses, emitter, collector, their doping profile, and the barrier width was thoroughly explored. It was found that the spacers and the barrier thickness are the most critical design parameters affecting the junction resistance and curvature coefficient. The insertion of an InxGa1-xAs QW layer adjacent to the AlAs barrier, combined with the appropriate choice of spacers and AlAs barrier thicknesses, contributed to an increase in the curvature coefficient by a factor of three while maintaining a low junction resistance. The cut-off frequency of a 4 × 4 μm2 ASPAT device is predicted to be > 500 GHz at zero bias. A comprehensive study is presented to guide researchers working on ASPAT devices, providing valuable prediction for appropriate design parameters toward maximizing the microwave/mm-wave device performance.

Numerical simulation and performance analysis of InGaP, GaAs, Ge single junction and InGaP/GaAs/Ge triple junction solar cells

Recent trends in the field of solar cells show that Multi-junction III-V semiconductor solar cells are an attractive option because of their high efficiency and cost effectiveness. As the first step to develop an InGaP/GaAs/Ge triple junction solar cell, we first simulated three individual InGaP, GaAs and Ge single junction solar cells using Silvaco ATLAS Software and obtained the efficiency of 13.42%, 12.99%, 3.37% for each cell respectively. Further in order to increase the efficiency of solar cell, we numerically simulated the InGaP/GaAs/Ge triple Junction solar cell by stacking InGaP, GaAs and Ge single junction solar cells and achieved high efficiency of 29.78%. The current–voltage curve, power-voltage curves and solar cell performance parameters and spectral response of each single junction solar cell as well as performance parameters and spectral response of InGaP/GaAs/Ge triple Junction solar cell have been extracted and analysed in detail. The aim of the study is to contribute to the investigation for experimental research work on the improvement of efficiency of InGaP/GaAs/Ge triple junction solar cell, through the numerical simulation, Since systematic cost of experimental investigation of the solar cell is very high and also it requires large time therefore technology computer aided design (TCAD) based simulation and performance optimization of the solar cells is important.

A new model of thermionic emission mechanism for non-ideal Schottky contacts and a method of extracting electrical parameters

In this paper, a new model of thermionic emission current for non-ideal Schottky contacts and a method of extracting electrical parameters are presented. The Au/n-GaAs Schottky structure is fabricated and simulated using Silvaco–Atlas software in a wide temperature range. The proposed method shows series resistance $$ R_{s} $$ values close to those obtained from ln(I)–V method and ideality factor n in good agreement with the reported experimental studies. The barrier height $$ \phi_{b} $$ extracted by our method is in good agreement with those extracted from the band diagram (BD) and capacitance–voltage (C–V) characteristics. It is increased with decreasing temperature, in accordance with the band gap variation with temperature and the reported negative temperature coefficient of the barrier height. Conversely, $$ \phi_{b} $$ obtained from the classical model using ln(I)–V method shows an abnormal behavior and discordance with the $$ \phi_{b} $$ extracted from the band diagram and C–V characteristics. Finally, the proposed model shows identical characteristics with the simulation and the experimental curves, in all temperature range, while the classic model shows large deviations at high bias voltages.

Effect of a Back-Surface Field and Passivation Layer on a Silicon Schottky Solar Cell

In this work, a numerical simulation of a silicon based solar cell (SC) is carried out using Silvaco-Atlas software. The back contact and the back surface field (BSF) combined with a passivation layer (PL) realized by using SiO2 tunneling layer, is addressed in this paper. It is demonstrated that a proper choice of the BSF and PL can enhance a Schottky back contact based solar cell compared to its ohmic counterpart. BSF has to be properly doped to reduce the barrier of the Schottky contact. The tunnel oxide is a vital part in this solar cell. It is required to achieve excellent interface passivation and has to have an optimum thickness and below this thickness, the SC performance is enhanced by a tunneling effect, while it is deteriorated by the fill factor reduction above this optimum thickness.