Determination of the Series Resistance of a Series Vertical-Junction Silicon (N+/P/P+) Solar Cell under Polychromatic Illumination and Magnetic Field: Effect of Optimum Thickness

By solving the magneto-transport equation for excess minority charge carriers in the base of the series vertical-junction silicon cell, the phenomenological parameters of the cell can be determined from the boundary conditions. Photocurrent density and photovoltage are determined for each value of applied magnetic field and corresponding optimum thickness, to establish the current-voltage characteristic (Jph(Sf, Sb, z, B, Hop)-Vph(Sf, Sb, z, B, Hop) of the silicon cell under polychromatic illumination. This study will make it possible to reduce the material used (by reducing the optimum thickness), which will help to lower prices. It will also enable us to reduce betting effects (lower series resistance), thereby boosting solar cell efficiency.

Directly extracting both threshold voltage and series resistance from the conductance-voltage curve of an AlGaN/GaN Schottky diode

An Ni/Au Schottky contact on an AlGaN/GaN heterostructure has been prepared. By using the peak-conductance model, the threshold voltage and the series resistance of the AlGaN/GaN diode are simultaneously extracted from the conductance-voltage （G-V） curve and found to be in good agreement with the ones obtained by using the capacitance-voltage （C-V） curve integration and the plot of dV/d（ln I） versus current I. Thus, a method of directly and simultaneously extracting both the threshold voltage and the series resistance from the conductance-voltage curve for the AlGaN/GaN Schottky diode is developed.

Theoretical and experimental analysis of the effects of the series resistance on luminous efficacy in GaN-based light emitting diodes

In this paper, a new equivalent circuit model of GaN-based light emitting diodes （LEDs） is established. The impact of the series resistance to luminous efficacy is simulated using the MATLAB software. GaN-based LEDs with different n- contact electrode materials （LEDs with Ni/Au and LEDs with Cr/Au） are fabricated. By comparing and analyzing the results of performances, we concluded that both the series resistance and the carrier loss could affect the luminous efficacy severely. LEDs with lower series resistance have higher luminous efficacy and its efficiency droop is alleviated simultaneously. To improve luminous efficacy, the fabrication process should be optimized for lower series resistance.

Corrective Effect of the Angle of Incidence of the Magnetic Field Intensity on the Performance (Series and Shunt Resistances) of a Bifacial Silicon Solar Cell

This article presents a three-dimensional analysis of the impact of the angle of incidence of the magnetic field intensity on the electrical performance (series resistance, shunt resistance) of a bifacial polycrystalline silicon solar cell. The cell is illuminated simultaneously from both sides. The continuity equation for the excess minority carriers is solved at the emitter and at the depth of the base respectively. The analytical expressions for photocurrent density, photovoltage, series resistance and shunt resistance were deduced. Using these expressions, the values of the series and shunt resistances were extracted for different values of the angle of incidence of the magnetic field intensity. The study shows that as the angle of incidence increases, the slopes of the minority carrier density for the two modes of operation of the solar cell decrease. This is explained by a drop in the accumulation of carriers in the area close to the junction due to the fact that the Lorentz force is unable to drive the carriers towards the lateral surfaces due to the weak action of the magnetic field, which tends to cancel out as the incidence angle increases, and consequently a drop in the open circuit photovoltage. This, in turn, reduces the Lorentz force. These results predict that the p-n junction of the solar cell will not heat up. The study also showed a decrease in series resistance as the incidence angle of the magnetic field intensity increased from 0 rad to π/2 rad and an increase in shunt resistance as the incidence angle increased. His behaviour of the electrical parameters when the angle of incidence of the field from 0 rad to π/2 rad shows that the decreasing magnetic field vector tends to be collinear with the electron trajectory. This allows them to cross the junction and participate in the external current. The best orientation for the Lorentz force is zero, in which case the carriers can move easily towards the junction.

Series resistance influence on performance of waveguide-type germanium photodetectors on silicon

We investigate influences of series resistances on the performance of 1.55 μm waveguide-type germanium photodetectors（Ge-PDs） on a silicon-on-insulator substrate. The current-voltage characteristics, responsivities,saturation photo-current characteristics, electrical reflection coefficients, and photodetection frequency responses of Ge-PDs, having different series resistances, are measured, and their equivalent circuit models are established. By analyzing the resulting circuit model parameters, we determine how much Ge-PD series resistances influence Ge-PD saturation photo-currents and photodetection bandwidth. These results should be of great use for optimization of Ge-PD fabrication processes and device parameters for target applications.

Effect of single walled carbon nanotubes on series resistance of Rose Bengal and Methyl Red dye-based organic photovoltaic device

The influence of single walled carbon nanotube（SWCNT）on the series resistanceof Rose Bengal（RB）and Methyl Red（MR）dye-based organic diodes has been studied.It has been revealed from experimental results that SWCNT has a significant effect on Rs.The values of Rs are measured from current–voltage（I–V）characteristics and also by utilizing the Cheung method.Obtained values from the Cheung method have been verified using H（I）–I plots for all dye-based devices.The extracted values using these two processes show a good consistency with each other.It is observed that Rs is reduced significantly by incorporating SWCNT for both dyes.The estimated amounts of reduction of Rs using SWCNT are 76.08%and 64.23%obtained from the I–V relationship whereas the value of Rs shows a reduction of 83.5%and 67.1%when measured by using the Cheung method for RB and MR dyes respectively.The ideality factor and barrier height of the diodes have also been extracted.The ideality factor has decreased with incorporation of SWCNT.A reduction in barrier height for the devices has also been observed in the presence of SWCNT.

On the profile of frequency dependent interface states and series resistance in Au/p-InP SBDs prepared with photolithography technique

The frequency dependent of the forward and reverse bias capacitance-voltage （C-V） and conductance-voltage （G/w-V） charac- teristics of Au/p-InP SBDs have been investigated in the frequency range of 20 kHz-10 MHz and voltage range of-5 - 5 V at room temperature. The effects of surface states （Nss） and series resistance （R0 on C-V and G/w-V characteristics have been in- vestigated in detail. The frequency dependent Nss and Rs profiles were obtained for various applied bias voltages. The experi- mental results show that the main electrical parameters of Au/p-InP SBD such as barrier height （gOB）, the density of acceptor concentration （NA）, Nss and Rs were found strongly frequency and voltage dependent. The values of C and G/w decrease with increasing frequency due to a continuous distribution of Nss localized at the metal/semiconductor （M/S） interface. The effect of Rs on C and G is found considerably high especially at high frequencies. Therefore, the high frequencies of the values of C and G were corrected for the effect of Rs in the whole measured bias range to obtain the real diode capacitance Cc and conductance Gc using the Nicollian and Goetzberger technique. The distribution profile of Rs-V gives a peak depending on the frequency especially at low frequencies and disappears with increasing frequencies due to the existence of Nss at the M/S interface.

Series resistance effect on time zero dielectrics breakdown characteristics of MOSCAP with ultra-thin EOT high-k/metal gate stacks

The time zero dielectric breakdown characteristics of MOSCAP with ultra-thin EOT high-k metal gate stacks are studied. The TZDB results show an abnormal area dependence due to the series resistance effect. The series resistance components extracted from the Fowler-Nordheim tunneling relation are attributed to the spreading resistance due to the asymmetry electrodes. Based on a series model to eliminate the series resistance effect, an area acceleration dependence is obtained by correcting the TZDB results. The area dependence follows Poisson area scaling rules, which indicates that the mechanism of TZDB is the same as TDDB and could be considered as a trap generation process.

Impact of Parasitic Resistances on the Output Power of a Parallel Vertical Junction Silicon Solar Cell

This paper describes the theoretical model for calculating IV-curve of parallel vertical silicon solar cells (SCs) based on solving diffusion-recombination equation for such SC, which was suggested that two IV curve zones (those which are close to the short current and open circuit points) can be linearized. This linearalization allows obtaining the values of shunt (Rsh) and series (Rs) resistances. The evolution of the electric power based on these resistances was illustrated to show the values that shunt and series resistances must have to obtain a good efficiency.

Determination of the Electrical Parameters of a Solar Cell in Steady State

Photovoltaic solar energy can be obtained by using several types of technologies, including silicon solar cells. The characterization of its solar cells makes it possible to know them better. This article presents, on the one hand, the work that has been carried out on these cells. On the other hand, a theoretical study of the cell under illumination using Lambert’s W function. On the basis of the electrical parameters provided by the manufacturer, the parameters such as the series and shunt resistances and the electrical quantities such as the photocurrent and the photovoltage, are determined and studied according to the ideality factor of the diode. From the results obtained the shunt resistance increases when the ideality factor increases, the series resistance decreases very weakly.

Performance Analysis of a Radial N+/P Silicon Solar Cell in Steady State and Monochromatic Illumination

In this paper, we investigate theoretically a radial n+/p silicon solar cell in steady state and monochromatic illumination. The purpose of this work is to analyze the effect of the cell base radius on its electrical parameters. The continuity equation in cylindrical coordinates is established and solved based on Bessel functions and boundaries conditions;this led us to the photovoltage and photocurrent density in the cell. The open circuit voltage and the short circuit current density are then deduced and analyzed considering the base radius. Based on J-V and P-V curves, series and shunt resistances, fill factor and maximum power point are derived and the conversion efficiency of the cell is deduced. We showed that short circuit current density, maximum power, conversion efficiency and shunt resistance decrease with increasing base radius contrary to the open circuit voltage, the fill factor and the series resistance.

Study of Electron Mobility in 4H-SiC Buried-Channel MOSFETs

The effects of several factors on mobility in 4H-SiC buried-channel （BC） MOSFETs are studied,A simple model that gives a quantitative analysis of series resistance effects on the effective mobility and field-effect mobility is proposed.A series resistance not only decreases field-effect mobility but also reduces the gate voltage corresponding to the peak field-effect mobility. The dependence of the peak field-effect mobility on series resistance follows a simple quadratic polynomial. The effects of uniform and exponential interface state distributions in the forbidden band on field-effect mobility are analyzed with an analytical model. The effects of non-uniform interface states can be ignored at lower gate voltages but become more obvious as the gate bias increases.

Effect of hole-transporting materials on the photovoltaic performance and stability of all-ambient-processed perovskite solar cells

High-efficiency perovskite solar cells（PSCs） reported hitherto have been mostly prepared in a moisture and oxygen-free glove-box atmosphere, which hampers upscaling and real-time performance assessment of this exciting photovoltaic technology. In this work, we have systematically studied the feasibility of allambient-processing of PSCs and evaluated their photovoltaic performance. It has been shown that phasepure crystalline tetragonal MAPbI;perovskite films are instantly formed in ambient air at room temperature by a two-step spin coating process, undermining the need for dry atmosphere and post-annealing.All-ambient-processed PSCs with a configuration of FTO/TiO;/MAPbI;/Spiro-OMeTAD/Au achieve opencircuit voltage（990 mV） and short-circuit current density（20.31 mA/cm;） comparable to those of best reported glove-box processed devices. Nevertheless, device power conversion efficiency is still constrained at 5% by the unusually low fill-factor of 0.25. Dark current–voltage characteristics reveal poor conductivity of hole-transporting layer caused by lack of oxidized spiro-OMe TAD species, resulting in high seriesresistance and decreased fill-factor. The study also establishes that the above limitations can be readily overcome by employing an inorganic p-type semiconductor, copper thiocyanate, as ambient-processable hole-transporting layer to yield a fill-factor of 0.54 and a power conversion efficiency of 7.19%. The present findings can have important implications in industrially viable fabrication of large-area PSCs.

Detection of finger interruptions in silicon solar cells using photoluminescence imaging

Finger interruptions are common problems in screen printed solar cells, resulting in poor performance in efficiency because of high effective series resistance. Electroluminescence（EL） imaging is typically used to identify interrupted fingers. In this paper, we demonstrate an alternative method based on photoluminescence（PL） imaging to identify local series resistance defects, with a particular focus on finger interruptions. Ability to detect finger interruptions by using PL imaging under current extraction is analyzed and verified. The influences of external bias control and illumination intensity on PL images are then studied in detail. Finally, in comparison with EL imaging, the using of PL imaging to identify finger interruptions possesses the prominent advantages： in PL images, regions affected by interrupted fingers show higher luminescence intensity, while regions affected by recombination defects show lower luminescence intensity. This inverse signal contrast allows PL imaging to more accurately identify the defect types.

Modeling capacitance voltage characteristic of TiW/p-InP Schottky barrier diode

The capacitance-voltage（C-V） characteristic of the TiW/p-InP Schottky barrier diodes（SBDs） is analyzed considering the effects of the interface state（N（ss））, series resistance（Rs）, and deep level defects. The C-V of the Schottky contact is modeled based on the physical mechanism of the interfacial state and series resistance effect. The fitting coefficients α andβ are used to reflect the N（ss） and Rs on the C-V characteristics, respectively. The α decreases with the increase of frequency,while β increases with the increase of frequency. The capacitance increases with the increase of α and the decrease of β.From our model, the peak capacitance and its position can be estimated. The experimental value is found to be larger than the calculated one at the lower voltage. This phenomenon can be explained by the effect of deep level defects.

A DESIGN OF 0.25μm CMOS SWITCH

Single-Pole Double-Throw （SPDT） broadband switch has been designed in a 0.25gm Complementary Metal Oxide Semiconductor （CMOS） process. To optimize the performance of isolation and insertion loss, based on normal design, the effects of Gate Series Resistances （GSR） on insertion loss and switching time are analyzed for the first time. The compatible GSRs are chosen by the analyses. The fabricated chips were tested and the results show the switch isolation from DC （Direct Current） to 1GHz exhibits 55dB and insertion loss lower than 2.1 dB.

P-type AlAs/[GaAs/AlAs] Semiconductor/Superlattice DBR Grown by MBE

A p-type AlAs(70.2 nm)/16.5 period [GaAs(3 nm)/AlAs(0.7 nm)] semiconductor/superlatice distributed Bragg reflector (DBR) has been grown on n +-GaAs(100) substrate by V80H molecular beam epitaxy system. Experimental reflection spectrum shows that its central wavelength is 820 nm, with the peak reflectivity for 10-pair DBR of as high as 96 %, and the reflection bandwidth of as wide as 90 nm. We formed a 20×20 μm 2 square mesa to measure the series resistance using wet chemical etching. From the measurement result, the series resistance of about 50 Ω is obtained at a moderate doping (3×10 18 cm -3 ). Finally, the dependence of the resistance of the DBR on the temperature is analyzed. From the experimental result, it is found that the mechanism of the low series resistance of this kind of DBR may increase the tunneling current in the semiconductor/superlattice mirror structure, which will result in a decrease in series resistance.

Design of a fast-transient and high-stabilized GPS low dropout regulator

A high stabilized low dropout(LDO) voltage regulator fabricated for GPS radio frequency(RF) chip in SMIC 0.18μm CMOS technology is presented.The LDO mainly consists of bandgap reference,error amplifier,resistive feedback network and AC current path.A fast current path is added to improve the performance of LDO's transient response.Equivalent series resistance(ESR)compensation and internal Miller compensation are used to constitute the frequency compensation.The measurement results of the transient response of the output voltage show that it can recover within 2μs with less than 120 mV ripple when the load current is changed from 0 to 100 mA.The total quiescent current of LDO and bandgap reference(without load) is 260 μA.

Optimization of Electrics Parameters CdS/CdTe Thin Film Solar Cell Using Dielectric Model

Abstract *Corresponding author. In this paper, the electrical properties of heterojunction solar cells thin film n-CdS/p-CdTe from dielectric model have been studied. Based on the expression of the minority, carriers density in the p-CdTe base of solar cell, the photocurrent density and that of the photo voltage are determined according to the cell dimensions, doping levels, the absorption coefficient, the solar irradiance and the temperature, etc. Fitting using Mathcad and Origin Lab software on the photocurrent and the photovoltage of the n-CdS/p-CdTe enabled to determine the series, shunt resistance and the maximum power point. The results obtained, in good agreement with experimental results, allow operating simulations for optimizing maximum outputs parameters (Ip, Vp). Thereafter, it is proposed a type of photovoltaic generator module with a good command of the design parameters for better efficiency.

A Simplified Simulation Procedure and Analysis of a Photovoltaic Solar System Using a Single Diode Model

A single diode model for a photovoltaic solar module is the most ideal and quick way of analyzing the module characteristics before implementing them in a solar plant. Solar modules manufacturers provide information for three critical points that are essential in I-V, P-V or P-I curves. In this study, we propose four separate simulation procedures to estimate the five-model parameters of an analogous single diode equivalent circuit by utilizing three cardinal points of the photovoltaic module I-V curve, described from experimental data using a solar simulator and manufacturer’s datasheet. The main objective is to extract and use the five unknown parameters of a single diode model to describe the photovoltaic system using I-V ad P-V plots under different environmental conditions. The most influential parameters that greatly alter the cardinal points defined at short circuit point (SCP), the maximum power point (MPP) and the open circuit point(OCP) are the ideality factor (n) and the diode saturation current (Io). For a quick and fast convergence, we have determined the optimal ideality factor (no) and optimal saturation current (Ioopt) as the primary parameters by first assuming the optimal values of Rsh, Rs and Iph at standard test conditions (STC). Further, we evaluated the effects of Iph, Rs and Rsh on I-V and P-V curves by considering the values of n below no. We have evaluated different iterative procedures of determining Rsh and Rs at open-circuit, short-circuit point and the maximum-power points. These procedures have been classified into four approaches that guarantees positive shunt and series resistance for n ≤ no. These approaches have been categorized by deriving the saturation current as a dependent variable at each cardinal point with or without Rs and Rsh pair. The values obtained for the five parameters have been used to simulate the photovoltaic solar module characteristic curves with great precision at different air temperatures and irradiances, considering the effect of Nominal Operating Cell Temperature (NOCT).