In this paper, we design and optimize a mechanically stacked dual-junction Si/Ge solar cell, focusing on the thicknesses and doping concentrations that yield the best photovoltaic output parameters. Specifically, this study provides a theoretical analysis of the technological parameters necessary to achieve a high-efficiency tandem solar cell using silicon and germanium, materials that benefit from well-established and controllable manufacturing technologies. The aim of our work is to simulate the electrical behavior of each cell separately: the upper Si cell (Top-cell) and the lower Ge cell (Bottom-cell), using SCAPS-1D simulation software. This is achieved through numerical simulations of the current-voltage (J-V) characteristic and the spectral response curve. We estimated an efficiency ranging from 21.63 to 30.62

In the present paper, we have conducted both theoretical and experimental investigations on thin films of lead sulfide (PbS). The structural and morphological properties of these films, which were prepared using the spray pyrolysis method, were analyzed utilizing Xray diffraction (XRD) and scanning electron microscopy (SEM). Theoretical calculations were performed employing the first principles full potential linearized augmented plane wave (FP-LAPW) approach. The findings of this study reveal that the PbS film that was deposited is polycrystalline and possesses a rock-salt structure. The SEM image depicts a planar structure with dimensions ranging from 480 to 930 nm. The results obtained through energy dispersive spectroscopy (EDS) indicate high crystalline quality, and the film surface exhibits a rough texture and a dense morphology. In terms of its behavior, PbS acts as a semiconductor with a direct optical band gap situated at the L point of the Brillouin zone (BZ). The density of states on both sides of the band gap is primarily of s-p character. The ionic nature of PbS can be attributed to charge transfer. A substantial level of agreement has been observed between the experimental and theoretical results. Our ongoing research endeavors aim to explore biosensors and their various applications. The novelty of this work lies in the combined study of the structural and morphological properties of PbS films grown using the spray pyrolysis technique, employing both experimental and theoretical approaches. This paper describes a comprehensive approach to understanding bulk and thin-film PbS materials through theory and experimentation.

In this paper we present an optimization analysis of the doping of the intrinsic layer of an In 0.3 Ga 0.7 N PIN solar cell conducted experimentally. This analytical approach aims to determine the optimal doping value for the intrinsic layer, which may not always be experimentally determined in certain cases. Subsequently, this determined value will be utilized in calculating the output parameters, particularly focusing on enhancing the conversion efficiency of the solar cell. To comprehensively evaluate the photovoltaic characteristics of the In 0.3 Ga 0.7 N PIN homojunction solar cell, we used numerical simulation with PC1D software. This simulation aims to ensure the achievement of both short-circuit current, open-circuit-voltage and high conversion efficiency. Specifically, we have simulated the current-voltage (I-V) characteristic of this cell under AM1.5G solar illumination conditions, just as we also simulated the quantum efficiency (QE) curve. The influence of carrier lifetime and front surface recombination velocity on photovoltaic quantities has been investigated.

The ternary (ABX2) semiconductors have wide optical band gaps range and motilities of carrier, has led to their appearance importance device materials, including solar cells of photovoltaic and light-emitting diodes. In accordance with this, AgInTe(2)solar cells have proved to be the next big advancement in the field of solar energy. In this work, different numerical simulations were performed using SCAPS. The doping density and layer thickness are investigated under solar illumination of AM1.5 for optimised performance of solar cell. Thus, starting fromJ-Vcurves, we have calculated the short-circuit current densityJ(sc), the open-circuit voltageV(oc), the fill factor and the efficiency conversion. This structure can also provide a fundamental solar cell unit for developing very high efficiency solar cell.

The GaAsN alloy has a great potential in the manufacture of the photovoltaic devices. A simple optimized GaAsN junction can reach conversion efficiency from > 20%, comparable with that reached by the best cells of die CISGS. Because the band gap of GaAsN can be modified from 1.4 eV to 3.4 eV by increasing the nitrogen content with multi-junction cells, it is theoretically possible to achieve the record performance 70% with this only material system, whereas the theoretical record in technology GaAs multi-junctions is less than 50%. The work presented in this paper concerns the study of photovoltaic cells based on GaAsN nitrided materials. The main objective is to optimize the front and base with their thickness and doping, on the electrical characteristic of the photovoltaic cell and subsequently its output parameters under solar illumination of AM1.5G. 54.1 % efficiency is predicted for this new GaAs1-xNx based on a simple single solar cell. This structure can also provide a fundamental solar cell unit for developing very high efficiency IBSC solar cell.

The current–voltage (I–V) characteristics of Schottky diodes on free-standing GaN substrate are investigated by using electrical characterization and analytical modelling calculation. We have calculated the electrical parameters from experimental current-voltage curve by two methods: ln(I) and Cheung. So, we calculated different electrical parameters using experimental I-V curve such as saturation current, ideality factor, series resistance and barrier height. We have found from the first method, the ideality factor n (1.02), the barrier height fb (0.65 eV) and a series resistance Rs (84 Ω). From the second method, we have found, n (1.09), fb (0.79 eV) and Rs (79.58 Ω - 79.73 Ω). Using analytical approach, we plotted the theoretical curves for comparison with the experimental characteristic and also to determine the dominant current transport mechanism. The results found support an assumption that the dominant current mechanism in Au/n-GaN (free-standing substrate) Schottky diode is the thermionic current.

Dilute nitride semiconductors, such as GaAs1-xNx alloys, have attracted considerable attention due to their unique physical properties and wide range of their possible application in optoelectronics. In this report, a comprehensive numerical simulation under solar illumination of AM1.5G with SCAPS software, is used to find the optimum geometrical and physical parameters that yield the best efficiency of an n-GaAsN-based Schottky solar cell. This optimisation task is a function of the nitrogen concentration, the metal work function, the doping and the thickness of the GaAsN layer. According to our results, the choice of metal that allows to have a high barrier height while controlling the doping and the thickness of the GaAsN active layer allows the development of high quality GaAs1-xNx based SJSCs. Efficiency greater than 27% is expected with a nitrogen concentration of x = 0.004 for this new design of the n-GaAsN Schottky solar cell.

Intermediate band solar cells are one type of third generation photovoltaic devices. Indeed, the increase in the power conversion efficiency is achieved through the absorption of low energy photons while preserving a large band gap that determines the open circuit voltage. The ability to absorb photons from different parts of the solar spectrum originates from the presence of an intermediate energy band located within the band gap of the material. This intermediate band, acting as a stepping stone allows the absorption of low energy photons to transfer electrons from the valence band to the conduction band by a sequential two photons absorption process. In This work, a numerical simulation is performed using Analysis of Microelectronic and Photonic Structure (AMPS) simulator to explore the possibility of higher efficiency of intermediate band solar cell (IBSC) based on GaAs1-xNx material (x=0.04). The doping density and layer thickness are investigated for optimized the performance of solar cell under solar illumination of AM1.5G. An 24.94% efficiency is determined for this new structure IBSC (GaAs0.96N0.04).

In this paper, we have studied Au/n-GaN freestanding Schottky structures. The growth technique of GaN used is the HVPE (Hybrid Vapor Phase Epitaxy) method. The frequency dependent capacitance-voltage (C-V-f) and conductance-voltage (G-V-f) characteristics of Au/n-GaN freestanding/Ag Schottky diodes has been investigated in the frequency range of 100 Hz-1MHz at room temperature. The higher values of C and G at low frequencies were attributed to the native oxide layer thickness and surface states. From the C-f and G-f characteristics, the energy distribution of surface states (N-ss) and their relaxation time (s) have been determined in the energy range of (E-c-0.648) eV- (E-c-1.35) eV taking into account the forward bias I-V data. The values of N-ss and tau(ss) change from 6.18x10(13) eV(-1) cm(-2) to 9.37x10(12) eV(-1) cm(-2) and 6.3x10(-4) s to 3.6x10(-7) s, respectively.

We report on the photovoltaic characteristics of solar cells based on GaAs1-xNx grown on gallium arsenide. The GaAsN is a recently developed novel solar cell material for its promising tunable band gap of 1.42 eV to 3.4 eV for the realization of high efficiency solar cells. We have conducted numerical simulation of GaAs1-xNx single junction solar cell. The doping density, layer thickness, and the stoichiometric coefficient are investigated for optimized performance of solar cell under solar illumination of AM1.5G. Thus starting from I-V curves, we have calculated the short-circuit current I-CC, the open-circuit voltage V-OC and the efficiency conversion. This structure can also provide a fundamental solar cell unit for developing very high efficiency MQW solar cell.

Numerical calculations based on first principles are applied to study the structural, electronic and optical properties of zinc blende indium gallium phosphide alloys InxGa1-xP (for x = 0.00, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1.00); we calculated lattice parameters and bulk modulus as well as its first pressure derivative. The exchange-correlation contribution is described within the generalized gradient approximation (GGA) in the new form PBEsoland the local density approximation (LDA). For the band structure calculations, the generalized gradient approximation suggested by Engel and Vosko (EVGGA) and the modified Becke-Johnson exchange correlation (mBJ) have been used to obtain an accurate bandgap and also to provide a good description of the optical properties, The imaginary part of dielectric function, reflectivity, refractive index, absorption coefficients and optical conductivity are investigated well and provide reasonable results for optoelectronic devices applications. The calculated results are in good agreement with the available computational works.

In this paper we present an optimization analysis for estimating energy level position of the IB and concentration of oxygen doping in ZnTeO thin film solar cells. ZnTe and ZnTeO layers have to be very thin, optimized thicknesses are 0.08 mu m and 0.34 mu m, respectively. Though, the current thickness of a typical absorbers ZnTeO layer is about 1 mu m. However, on the path toward mass production, it will be necessary to decrease the thickness even further. Consequently, the production cost can be reduced in comparison with conventional ZnTeO intermediate band solar cell. It is shown that by optimizing the considered structure, oxygen concentration higher than 10(19) cm(-3) with energy level position of the IB in the range of 0.4-0.8 eV below the conduction band edge enhance the performance of ZnTeO photovoltaic solar cells. We observed that when the open circuit voltage (VOC) and fill factor (FF) decrease, the short circuit current (JSC) is increased by more than 100% and we have a significant improvement in the conversion efficiency compared to the ZnTe heterojunction without oxygen.

ZnTe homojunction diode doped with oxygen is a very promising material for photovoltaic applications. It is shown, by numerical optimization, that the properties of an intermediate band solar cell present in the ZnTe:O (Energetic position of the IB, oxygen doping concentration...) play a crucial role in its performance. In the present study the intermediate band solar cell (IBSC) parameters are optimized using a solar cell device simulator (SCAPS). We have considered the parasitic effects such as the shunt resistance and series resistance which dramatically influence the performance of the cell. We observed that when the open circuit voltage and fill factor decrease, the short circuit current is increased by more than 100% and we have an improvement of approximately 30% in the conversion efficiency compared to the ZnTe homojunction without oxygen.

In this paper, the high efficiency Cu(In,Ga)Se2 (CIGS)-based solar cells solar cells was analyzed and designed by SCAPS-1D software. This paper deals with the influence of a buffer layer on the performance of the CIGS-based solar cells. The photovoltaic parameters have been calculated in different buffer layer materials (CdS, ZnS, ZnSe), we give great alternative for Cadmium sulphide (CdS). Starting with a good structure, we simulated the J-V characteristics and showed how the absorber and buffer layers thickness, defect density influence the short-circuit current density (Jsc), open-circuit voltage (Vco), fill factor (FF), and efficiency (η) of solar cell. The optimized solar cell shows an efficiency of > 22% under the AM1.5G spectrum and one sun.

In this study, the forward bias current-voltage-temperature (I-V-T) characteristics of (Mo/Au)–AlGaN/GaN high electron mobility transistors (HEMTs) have been investigated over the temperature range of 100-450K. The barrier height (Fb), ideality factor (n), series resistance (Rs) and shunt resistance (Rp) of (Mo/Au)–AlGaN/GaN HEMTs have been calculated from their experimental forward bias current–voltage-temperature (I-V-T). The capacitance–voltage (C–V) of (Au/Mo)- AlGaN/GaN HEMTs were investigated at room temperature. The doping concentration (Nd) and the bi- dimensional sheet carrier density (ns) were evaluated from C–V data. The experimental results show that all forward bias semilogarithmic I-V curves for the different temperatures have a nearly common cross point at a certain bias voltage, even with finite series resistance (Rs). We found that the value of Fb and Rs increases by cons n and Rp decreases with increasing temperature. The values of Nss obtained by taking into account the Rs are about one order lower than those obtained without considering the Rs.

In this work we investigate AlGaN/GaN HEMTs structures grown by Low Pressure Metal Organic Chemical Vapour Depostion on SiC substrate. The aim of our work is to study anomalous behavior of the performance results of the characteristics I-V and C-V of (Mo/Au)-AlGaN/GaN HEMTs structure at room temperature. The experimental data were analyzed considering different current-transport mechanisms, such as thermionic emission, generation-recombination, tunneling and leakage currents. The barrier height (phi(bn)), ideality factor (n) and series resistance (R-s) of (Mo/Au)-AlGaN/GaN HEMTs have been calculated from their experimental forward bias current-voltage-temperature (I-V). The capacitance-voltage (C-V) of (Au/Mo)-AlGaN/GaN HEMTs were investigated at room temperature.

In this paper, electrical characterisation and analytical modelling of current-voltage ( I - V ) and capacitance-voltage ( C - V ) for Hg/InN/n-InP Schottky structures are investigated. We have studied electrically thin InN films realised by the nitridation of InP(100) substrates using a glow discharge source (GDS) in ultra high vacuum. So, we have calculated, using I - V and C - V measurements, the ideality factor n , the saturation current I s , the barrier height

The current-voltage (I-V) characteristics of Pt/(n.u.d)-GaN and Pt/Si-doped-GaN diodes Schottky are investigated. Based on these measurements, physical mechanisms responsible for electrical conduction have been suggested. The contribution of thermionic-emission current and various other current transport mechanisms were assumed when evaluating the Schottky barrier height. Thus the generation-recombination, tunneling and leakage currents caused by inhomogeneities and defects at metal-semiconductor interface were taken into account.

In this paper, we have studied the Schottky contact of Ni/Au/AlInN/GaN HEMTs. The current–voltage Igs (Vgs) of Ni/Au/AlInN/GaN structures were investigated at room temperature. The electrical parameters such as ideality factor (2.3), barrier height (0.72 eV) and series resistance (33 W) were evaluated from I(V) data, the threshold voltage (-2.42 V), the 2D gas density (1.35 ´ 1013 cm-2) and barrier height (0.94 eV) were evaluated from C(V) data.

In this work, electrical characterization of the current-voltage and capacitance-voltage curves for the Metal/InN/InP Schottky structures are investigated. We have studied electrically thin InN films realized by the nitridation of InP (100) substrates using a Glow Discharge Source (GDS) in ultra high vacuum. The I (V) curves have exhibited anomalous two-step (kink) forward bias behaviour; a suitable fit was only obtained by using a model of two discrete diodes in parallel. Thus, we have calculated, using I(V) and C(V) curves of Hg/InN/InP Schottky structures, the ideality factor n, the saturation current Is, the barrier height φ B , the series resistance Rs, the doping concentration Nd and the diffusion voltage Vd. We have also presented the band diagram of this heterojunction which indicates the presence of a channel formed by holes at the interface InN/InP which explain by the presence of two-dimensional electron gas (2-DEG) and this was noticed in the presentation of characteristics C(V). Copyright © 2014 IFSA.