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Showing papers on "Equivalent series resistance published in 1993"


Journal ArticleDOI
TL;DR: In this paper, the frequency dependence of forward capacitance-voltage characteristics of Schottky barrier diodes were investigated by considering the series resistance effect, and the peak value of the capacitance was found to vary with series resistance, interface state density and the frequency of the a.c. signal.
Abstract: The frequency dependence of forward capacitance-voltage characteristics of Schottky barrier diodes were investigated by considering the series resistance effect. It is seen that in presence of a series resistance, the capacitance-voltage plot exhibits a peak. The peak value of the capacitance is found to vary with series resistance, interface state density and the frequency of the a.c. signal. The effect of series resistance on the capacitance is found appreciable at higher frequencies when capacitance decreases rapidly with frequency. On the other hand, the conductance of the diode increases with frequency in the high frequency limit. Such a variation in conductance limits the use of well known conductance technique to determine interface state density.

219 citations


Journal ArticleDOI
TL;DR: In this article, a new deterioration diagnosis method for the electrolytic capacitor is proposed for a forward-type converter and a buck-boost converter, which is valid for any load condition, no matter whether the circuit has feedback control.
Abstract: A new deterioration diagnosis method for the electrolytic capacitor is proposed for a forward-type converter and a buck-boost converter. It was observed that the ESR (equivalent series resistance) of the electrolytic capacitor increases as it deteriorates, and the knowledge that ripple varies proportionally to the ESR increase was used. With this method, the electrolytic capacitor life-cycle aging rate can be projected for the active circuit over the system life. This approach to deterioration is valid for any load condition, no matter whether the circuit has feedback control or not. >

214 citations


Proceedings ArticleDOI
10 May 1993
TL;DR: In this paper, the authors used the measured "J/sub SC/-V/sub OC/ curve" of a solar cell as an approximation to the unknown R/sub S/-corrected I-V curve and determined the "lumped series resistance" in dark and illuminated operating conditions (R/sub s.dark/ and R/ sub s.light/) from the voltage shift between the "J /sub SC/V/ sub O/C curve" and the dark and illumination I -V curve, respectively.
Abstract: Measurements of the series resistance R/sub S/ are important for the localisation of dominant loss mechanisms in photovoltaic devices. The new measurement technique presented in this work uses the measured "J/sub SC/-V/sub OC/ curve" of a solar cell as an approximation to the unknown R/sub S/-corrected I-V curve and determines the "lumped series resistance" in dark and illuminated operating conditions (R/sub s.dark/ and R/sub s.light/) from the voltage shift between the "J/sub SC/-V/sub O/C curve" and the dark and illuminated I-V curve, respectively. Owing to multidimensional effects in practical devices, the lumped series resistance depends on the operating condition of the cell (i.e., dark or illuminated I-V measurements) and on the current density flowing through the device. This work not only provides a new, powerful method for the determination of the lumped series resistance of photovoltaic devices, but also considerably improves the general understanding of ohmic power loss effects in silicon solar cells. >

192 citations


Journal ArticleDOI
TL;DR: In this paper, the circuit properties of networks which include multiterminal quantum Hall effect (QHE) devices are discussed, and it is shown that QHE devices can be placed in a series or in parallel using multiple links to give equivalent fourterminal quantized resistances which are in practice, to a high degree of accuracy, independent of contact resistances to the twodimensional electron gas in the samples and of series resistances in the links.
Abstract: The circuit properties of networks which include multiterminal quantum Hall‐effect (QHE) devices are discussed. It is shown that QHE devices can be placed in a series or in parallel using multiple links to give equivalent four‐terminal quantized resistances which are in practice, to a high degree of accuracy, independent of contact resistances to the two‐dimensional electron gas in the samples and of series resistances in the links. The same technique of multiple links can also be used to incorporate QHE devices in resistance or impedance bridges, resulting in a balance condition which is practically unaffected by contact or series resistances. These properties are established using calculations based on equivalent circuits of QHE devices. Metrological applications include the obtainment of accurate reference standards of resistance with values which are multiples or submultiples of individual quantized Hall resistances (QHRs) and, using a resistance bridge, the precise comparison of QHRs. An experimental verification is reported, demonstrating that the effective equivalent resistance of two QHE devices connected in parallel does not differ from nominal by more than a few parts in 109.

165 citations


Journal ArticleDOI
TL;DR: Analysis of measured illuminated and dark I-V characteristics of PERL cells reveals that the AM1.5 efficiency is mainly limited by recombination losses at the rear oxidized surface, as opposed to the ideal theoretical limit of 85-86% for silicon cells operating in low injection conditions.
Abstract: Despite exceptionally high open-circuit voltages, record high-efficiency PERL (passivated emitter, rear locally diffused) silicon solar cells recently developed at the University of New South Wales demonstrate relatively low fill factors. This behaviour is shown to result from a surface recombination velocity at the rear Si-SiO2 interface that increases with reducing voltage across the cell, leading to non-ideal I-V curves with high ideality factors (>1.3) near the maximum power point. When corrected for series resistance losses, the Air Mass 1.5 (AM1.5) fill factor of actual PERL cells is found to be limited to values below 82.9%, as opposed to the ideal theoretical limit of 85-86% for silicon cells operating in low injection conditions. Relatively large series resistance losses (Rs > 0.35 ω cm2) further reduce this value to the experimentally observed fill factors below 81.4%. Analysis of measured illuminated and dark I-V characteristics of PERL cells reveals that the AM1.5 efficiency is mainly limited by recombination losses at the rear oxidized surface. Optimum PERL cell resistivity is about 2 ω cm. Owing to increased rear surface recombination velocity, lower resistivity material shows no advantage in open-circuit voltage and suffers from short-circuit current losses, while a strong reduction in the surface recombination velocity above the maximum power point results in smaller fill factors. High-resistivity cells do show an improved short-cuircuit current but suffer from voltage and fill factor losses.

74 citations


Journal ArticleDOI
TL;DR: In this article, a method for determining the intrinsic drain-and-source series resistance and the effective channel length of LDD MOSFET's is proposed, based on the experimentally measured device I-V characteristics and a new parameter extraction procedure.
Abstract: A method for determining the intrinsic drain-and-source series resistance and the effective channel length of LDD MOSFET's is proposed. The method is based on the experimentally measured device I-V characteristics and a new parameter extraction procedure. A consistent set of the effective channel length and the gate-voltage-dependent drain-and-source series resistance was thus determined. The comparison between the measured and experimental drain current characteristics shows excellent agreement using the present model values. >

45 citations


Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the reduction in the series resistance of the distributed Bragg reflector by introducing quasi-graded superlattices at the heterointerfaces.
Abstract: Surface emitting optical devices with a vertical cavity have been investigated for applications in optical interconnections. To integrate these devices into a two‐dimensional array, it is necessary to improve the conversion efficiency from electrical power to optical power. To meet this requirement, the series resistance of the distributed Bragg reflectors that form the vertical cavity must be reduced. This article demonstrates the reduction in the series resistance of the distributed Bragg reflector by introducing quasi‐graded superlattices at the heterointerfaces. By using this structure, we obtain a low series resistance distributed Bragg reflector without compromising the high reflectivity. The mechanism of the reduction in the series resistance is studied and it is found that an increase in tunneling current leads to a decrease in the resistance. The dependence of tunneling current on doping concentration of the distributed Bragg reflector and the superlattice structure is also discussed.

43 citations


Journal ArticleDOI
TL;DR: In this article, the Schottky varactor frequency multiplier at submillimeter wavelengths can be improved by cooling the diode, and the maximum output power near 1 THz is calculated to increase by about 10 dB from 50 mu W to 500 mu W when the multiplier chain is cooled to 77 K.
Abstract: The efficiency of a Schottky varactor frequency multiplier at submillimeter wavelengths can be increased by cooling the diode. The increased mobility of the free carriers causes the series resistance to decrease, and the efficiency can increase as much as a few dB at low input power levels. At high output frequencies and at high power levels the efficiency of the multiplication is decreased by the current saturation, because the junction capacitance cannot be pumped effectively. When the diode is cooled, the maximum current of the diode increases and much more output power can be expected. There are also slight changes in the I-V characteristic and in the diode junction capacitance, but they have a negligible effect on the efficiency of the multiplier. The theoretical maximum output power near 1 THz is calculated to increase by about 10 dB from 50 mu W to 500 mu W, when the multiplier chain is cooled to 77 K. However, considerable improvement in the efficiency can be achieved by cooling to 150 K, which is easily attained in space by passive cooling. >

41 citations


Proceedings ArticleDOI
05 Dec 1993
TL;DR: In this article, the optimization of device series resistance in ultra-thin film SOI devices is studied through 2D simulations and process experiments, where very thin silicides that do not fully consume the SOI film are needed.
Abstract: The optimization of device series resistance in ultra-thin film SOI devices is studied through 2-D simulations and process experiments. To achieve low series resistance, very thin silicides that do not fully consume the SOI film are needed. A novel cobalt salicidation technology using titanium/cobalt laminates is used to demonstrate sub-0.2 /spl mu/m, thin-film SOI devices with excellent performance and very low device series resistance. >

39 citations


Journal ArticleDOI
TL;DR: In this article, a low resistance ohmic contact is required to minimize current losses due to series resistance; e.g. in Schottky diodes, in order to minimize the series resistance.
Abstract: We report here on the optimization of ohmic contacts to p-CuInSe2 (CISe) single crystals. A low resistance ohmic contact is required to minimize current losses due to series resistance; e.g. in Schottky diodes. Both In-Ga (eutectic)/CISe and gold (evaporatedVCISe contacts have been fabricated on crystals with different orientations and bulk properties. Gold contacts were found to have a lower resistance and to be more stable than In-Ga ones, from the slope of the linear current-voltage plot of the junctions. The resistance of the Au/CISe ohmic contact was decreased by etching the CISe crystal surface chemically in a 0.5% solution of Br2 in methanol for 30 sec at room temperature, prior to gold deposition, while that of the In-Ga contact increased by this etch. Wetting experiments and contact angle measurements showed evidence for changes in the polarity of the surface due to chemical etches.

38 citations


Journal ArticleDOI
TL;DR: In this paper, the external resistance of the self-aligned silicided source/drain structure is examined by two-dimensional simulation considering recession of the contact interface due to the consumption of silicon during the silicidation process.
Abstract: The external resistance of the self-aligned silicided source/drain structure is examined by two-dimensional simulation considering recession of the contact interface due to the consumption of silicon during the silicidation process. It is observed that the recessed contact interface forces a significant amount of current to flow into the high-resistivity part of the junction, resulting in an increase of resistance as large as several hundred ohms-micrometers in comparison with the surface contact structure. The increase scales up with the scaledown of the minimum feature size, and the expected benefits of the salicide structure diminish for the sub-half-micrometer devices. A simple analytical explanation is proposed. By considering the recession of the contact interface, the reported high external resistance of short-channel MOSFETs is explained. Different source/drain contact types are compared, and it is concluded that the conventional salicide process should be modified for sub-half-micrometer devices. >

Patent
24 Sep 1993
TL;DR: In this article, the equivalent circuit parameters of a piezoelectric resonator are measured in order to precisely control the amplitude and/or frequency of oscillation of an oscillator including the resonator.
Abstract: Equivalent circuit parameters of a piezoelectric resonator are measured in order to precisely control the amplitude and/or frequency of oscillation of an oscillator including the resonator, or to compensate for variations in the amplitude and/or frequency of oscillation. Significant variations are caused by shunt capacitance, and to a lesser degree, series resistance. The equivalent circuit parameters are measured by exciting the resonator at a plurality of frequencies, measuring responses of the resonator at the frequencies, including a complex response at one of the frequencies, and determining a value of the shunt capacitance from the responses. Preferably, the resonator is simultaneously and continuously excited at three different frequencies, one of which is approximately the resonant frequency of the resonator. The complex responses are measured by complex demodulation, and the circuit parameters are computed from the responses by solving simultaneous equations resulting by setting each complex response equal to the admittance of the equivalent circuit at each different frequency. In this fashion, the equivalent circuit parameters are measured periodically during continuous operation of the oscillator for correction or compensation of the amplitude and/or frequency of oscillation.

Journal ArticleDOI
01 Jun 1993
TL;DR: In this article, a distributed parameter analysis of the p-n junction solar cell in the current-induced case at low level injection is presented, taking into account the metal-semiconductor contact resistance, along with the base bulk resistance and the diffused layer shear resistance.
Abstract: The present investigation deals with the distributed parameter analysis of the p–n junction solar cell in the current-induced case at low level injection. The theory, for the first time, takes into account the metal–semiconductor contact resistance, along with the base bulk resistance and the diffused layer shear resistance. The transcendentally nonlinear differential equations for the emitter layer current and voltage have been solved analytically. Additionally, expressions for the I–V characteristic and equivalent ‘lumped’ series resistance have been established. Such physical parameters are very useful in the optimisation of the contact finger width and separation. Inclusion of the contact resistance, even for very small values, corresponds to the nonuniform carrier generation within the metallic grid. Therefore, the results are affected both qualitatively and quantitatively. The most important effect has been calculated in the I–V characteristics resulting from an additional contribution to the series resistance. Analysis reveals that the series resistance and the diode quality factor vary with applied current.

Journal ArticleDOI
TL;DR: In this paper, the fabrication and properties of a light-emitting porous silicon device incorporating a p-n junction are presented. But they do not describe the internal quantum efficiency.

Proceedings ArticleDOI
10 May 1993
TL;DR: In this paper, the authors have performed basic characterization studies of thin-film GaAs n/p and p/n solar cells made by epitaxial lift-off and found that the internal quantum efficiency is enhanced by as much as 71% in these cells after liftoff due to the presence of a back reflector.
Abstract: The authors have performed basic characterization studies of thin-film GaAs n/p and p/n solar cells made by epitaxial lift-off. They find that the internal quantum efficiency is enhanced by as much as 71% in these cells after lift-off due to the presence of a back reflector. An unalloyed, low series resistance back contact can be made with proper contacting techniques and using only van der Waals bonding to gold or palladium. These preliminary results show that thin-film solar cells can be processed without loss of film quality, and suggest that successful implementation of this design concept should lead to increased conversion efficiencies. >

Proceedings ArticleDOI
27 Sep 1993
TL;DR: In this paper, a new variable capacitance device for use in power electronics is proposed, constructed by ceramic capacitors, four well-balanced capacitors are bridge-connected, and the series resistance for suppressing the leakage current can be removed unlike the former three-terminal device.
Abstract: A new variable capacitance device for use in power electronics is proposed. The capacitance of this device can be varied by DC control voltage. In the new device, constructed by ceramic capacitors, four well-balanced capacitors are bridge-connected. Therefore, the AC leakage current which flows from the control voltage terminals becomes extremely small. The series resistance for suppressing the leakage current can be removed unlike the former three-terminal device. This brings a marked decrease in the time constant as seen from the control voltage terminals. The transient response times are investigated in the case when this device is used as the resonant capacitor of resonant power converters. >

Journal ArticleDOI
TL;DR: A theoretical study of the relationship between the electrical series resistance (R/sub s/) of an IMPATT diode and the threshold current for oscillation and the corresponding frequency has been carried out, considering the inequality of the ionization rates and drift velocities of the two types of charge carriers in silicon.
Abstract: A theoretical study of the relationship between the electrical series resistance (R/sub s/) of an IMPATT diode and the threshold current for oscillation and the corresponding frequency has been carried out, considering the inequality of the ionization rates and drift velocities of the two types of charge carriers in silicon. The series resistance has been obtained experimentally by measuring the threshold current for oscillation and the corresponding oscillation frequency with an X-band silicon SDR device embedded in a resonant-cap cavity. The results indicate that the method is a suitable one for determining R/sub s/, and they agree with the manufacturer's data. The method would be suitable for determining R/sub s/ for millimeter-wave diodes with appropriate values of the ionization rate ratios at maximum electric field. >

Journal ArticleDOI
TL;DR: In this article, the Schottky collector contact was scaled to submicron dimensions to increase the periphery-to-area ratio, decreasing the periphery dependent components of the parasitic resistance, and substantially increasing the device's maximum frequency of oscillation.
Abstract: The Schottky-collector resonant-tunnel-diode (SRTD) is an resonant-tunnel-diode with the normal N + collector layer and ohmic contact replaced by direct Schottky contact to the space-charge layer, thereby eliminating the associated parasitic series resistance R ins. By scaling the Schottky collector contact to submicron dimensions, the device periphery-to-area ratio is increased, decreasing the periphery-dependent components of the parasitic resistance, and substantially increasing the device's maximum frequency of oscillation. We report measured d.c. and microwave parameters of planar SRTDs fabricated with 1 μm-geometries in AlAs/GaAs.

Proceedings ArticleDOI
04 Oct 1993
TL;DR: In this paper, an equivalent model of inductors at high frequencies is developed taking into account equivalent series resistance (ESR) and the parallel equivalent resonant capacitance, and an expression representing the equivalent inductance (L/sub s/) of an inductor is derived.
Abstract: An equivalent model of inductors at high frequencies is developed taking into account equivalent series resistance (ESR) and the parallel equivalent resonant capacitance. An expression representing the equivalent inductance (L/sub s/) of an inductor is derived. It is shown that an inductor behaves like a capacitor beyond its resonant frequency. Various parameters such as inductance, capacitance, quality factor (Q), ESR, impedance (Z), and phase angle (/spl phi/) are measured over a wide range of frequency for the pot core and toroidal core inductors. Then graphs of these parameters are plotted and interpreted.

Proceedings ArticleDOI
05 Oct 1993
TL;DR: A new Recess-Channel technology has been developed which significantly reduces the source/drain series resistance and is potentially very useful for ultra-thin-film fully depleted SOI MOSFET fabrication with arbitrary silicon film thickness.
Abstract: A new Recess-Channel technology has been developed which significantly reduces the source/drain series resistance. This technology is potentially very useful for ultra-thin-film fully depleted SOI MOSFET fabrication with arbitrary silicon film thickness. Silicide technology may also be used in conjunction with the Recess-Channel technique to further reduce the source/drain series resistance and increase the current drive. >

Journal ArticleDOI
TL;DR: In this article, a numerical model of the currentvoltage characteristics of standard and heteroepitaxial Schottky-barrier diodes is presented, and the model considers quantum-mechanical tunneling and is therefore applicable to highly doped devices.
Abstract: A numerical model resulting in the current-voltage characteristics of standard and heteroepitaxial Schottky-barrier diodes is presented. Simulations of GaAs diodes, as well as InGaAs diodes grown on GaAs and InP substrates, are presented. The model considers quantum-mechanical tunneling, and is therefore applicable to highly doped devices. A self-consistent drifted-Maxwellian distribution is used to model the electron energy distribution at high current densities. The assumption of a drifted-Maxwellian distribution is shown to lead to higher current at high bias than predicted with the assumption of a Maxwell-Boltzmann or Fermi-Dirac distribution. The presence of a heterojunction at the InGaAs-substrate interface is predicted to lead to an additional series resistance component. >

Journal ArticleDOI
TL;DR: In this article, the carrier injection and transport in bulk Si-porous Si-metal diodes was studied by impedance and photoresponse spectroscopy, and the independence of the diode prefactor from the metal contact work function and the spatially resolved photocurrent identify the rectification as occurring at the bulk Si/porous si interface.

Journal ArticleDOI
TL;DR: In this article, the application of thin (∼1000-5000 A) layers of low-temperature (LT) molecular beam epitaxially (MBE) grown AlGaAs as current blocking layers is investigated.
Abstract: The application of thin (∼1000–5000 A) layers of low‐temperature (LT) molecular beam epitaxially (MBE) grown AlGaAs as current blocking layers is investigated. Data are presented regarding the current–voltage characteristics of resistors incorporating such layers, and it is shown that layers as thin as 1000 A are highly resistive when biased to less than 8 V. Lateral current confinement is demonstrated for both surface‐emitting light‐emitting diodes and vertical‐cavity surface‐emitting laser (VCSEL) diodes through the use of MBE regrowth over a patterned layer of LT AlGaAs. The VCSEL devices exhibit low series resistance with only 1.8 V at a threshold current of 1.9 mA for 10‐μm‐diam devices.

Journal ArticleDOI
TL;DR: In this article, the frequency-dependent admittance of Al-GaAs Schottky diodes with nonideal ohmic contacts is tested, using a simple three-component small-signal equivalent circuit model.
Abstract: The frequency-dependent admittance of Al-GaAs Schottky diodes with nonideal ohmic contacts is tested, using a simple three-component small-signal equivalent circuit model. Both the ohmic and the rectifying contacts of this diode are produced during one process step. This simplifies the formation procedure and saves testing time and costs. However, the nonalloyed ohmic contacts lead to a high series resistance, minority carrier injection, and deep level influence. All of these effects give a frequency-dependent diode admittance. Frequency-dependent admittance analysis in a certain frequency range using the three-component equivalent circuit model leads to the space-charge capacitance of the diode reflecting only the free majority carriers. The method is highly suitable for the automatic routine control of semiconductor material properties, diode, or gate capacitances. >

Proceedings ArticleDOI
05 Oct 1993
TL;DR: In this paper, a contact silicide in a TiSi/sub 2/ layer followed by Al(Cu) metal interconnect lines is investigated for CMOS device structures built on SIMOX only.
Abstract: As semiconductor device dimensions shrink and packing-densities rise, issues of parasitic capacitance and circuit speed become increasingly important. The use of Thin-Film Silicon-On-Insulator (TFSOI) substrates for device fabrication is being explored in order to reduce power consumption and increase performance. SIMOX (Silicon separation by Implanted OXygen) and BESOI( Bond and Etch back Silicon On Insulator) can be used for device fabrication at this time, however the subject of this study will be CMOS device structures built on SIMOX only. Fabrication of modern MOSFET's requires formation of a silicide in both the poly gate and mono-silicon Source/Drain regions. In our case the contact silicide under investigation is a TiSi/sub 2/ layer followed by Al(Cu) metal interconnect lines. TiSi/sub 2/ has a relatively low contact resistance and reduces the series resistance of both source/drain as well as gate regions. >

Journal ArticleDOI
TL;DR: In this paper, a zero-voltage-ripple (ZVR) rectifier is introduced to suppress the output voltage ripple in DC/DC power converters, which can be used for noise-sensitive high-output-current applications.
Abstract: Class E zero-voltage-ripple (ZVR) rectifiers are introduced. The proposed circuits offer a new means of a significant improvement in suppressing the output voltage ripple compared with their predecessors. Therefore, the size of the output filter can be considerably reduced, the rI/sub rms//sup 2/ conduction power loss in the equivalent series resistance of the filter capacitor can be lowered, aluminum or tantalum electrolytic capacitors may be entirely eliminated, filter capacitors with low capacitances and thereby high self-resonant frequencies can be used, and a faster dynamic response becomes achievable. ZVR is accomplished by reducing the AC component of the current at the input of the output filter. Class E/sup 2/ and Class D-E ZVR resonant DC/DC power converters are derived using the Class E ZVR rectifiers. An experimental prototype of a Class E/sup 2/ 30 W/500 kHz DC/DC converter was built and tested. Its output voltage ripple was as much as 20 times lower than that of the corresponding conventional converter. The new converters are suitable for noise-sensitive high-output-current applications. >

Journal ArticleDOI
TL;DR: In this article, a design and fabrication process for the realization of low-threshold, high-output vertical-cavity surface-emitting laser diodes with low series resistance is presented.
Abstract: Data are presented demonstrating a design and fabrication process for the realization of low‐threshold, high‐output vertical‐cavity surface‐emitting laser diodes with low series resistance Lateral current confinement is achieved in the laser structures through the use of molecular‐beam epitaxial regrowth over a 1000‐A‐thick patterned layer of low growth temperature AlGaAs incorporated into the p‐type top mirror A maximum cw output power in excess of 57 mW, at 300 K is demonstrated for 15‐μm‐diam devices With increased top mirror reflectivity (through the addition of dielectric layers), the low series resistance of the design results in a bias voltage of only 18 V at a threshold current of 19 mA for 10‐μm‐diam devices

Journal ArticleDOI
TL;DR: In this paper, a complex impedance diagram for dysprosium oxide thin films sandwiched between aluminium electrodes is presented for presentation and analysis of experimental data in the frequency range from 10−4 to 107 Hz.
Abstract: The complex impedance diagrams for dysprosium oxide thin films sandwiched between aluminium electrodes are shown. The logarithmic complex impedance graphs (Z″-Z′ plots) are used for presentation and analysis of experimental data in the frequency range from 10−4 to 107 Hz. The influence of temperature, insulator thickness, and measurement voltage is examined. A detailed analysis shows clearly the existence of two regions in the impedance graphs. The high-frequency “arc” is assigned to the volume of Dy2O3, whereas the low-frequency “spur” is connected with M/I barriers. In the radio-frequency region the influence of the series resistance of electrodes and leads is observed. Results presented in this paper enable to estimate the resistance and capacitance of the volume of Dy2O3, the resistance of leads and electrodes as well as the capacitance and resistance of M/I interfaces.

Journal ArticleDOI
TL;DR: In this paper, the double-velocity avalanche transit-time (DOVATT) diode was examined in detail using a series of GaAs/AlxGa1-xAs devices grown by molecular beam epitaxy.
Abstract: The authors' present the results of a study into the potential benefits of including heterostructures within single-drift impact avalanche transit-time (IMPATT) diodes. One particular heterostructure device, which exploits the change in saturated drift velocity in going from one material to another (the double-velocity avalanche transit-time (DOVATT) diode), is examined in detail using a series of GaAs/AlxGa1-xAs devices grown by molecular beam epitaxy. Contrary to claims in the literature, they conclude that there is little prospect for realizing high-performance DOVATT diodes using this materials system. The authors' note, however, that a novel InxGa1-xAs heterojunction technique to reduce series resistance appears promising and is deserving of further study.

Journal ArticleDOI
TL;DR: In this article, an analysis of solar cell distributed sheet resistance is performed by solving the nonlinear Poisson equation for the surface potential, and two different approaches to lumped series resistance are discussed: equivalent series resistance R Seq obtained from the cell's equivalent circuit that satisfies the actual current of the cell (all other parameters in the equivalent circuit except the series resistance were kept constant).
Abstract: An analysis of solar cell distributed sheet resistance is performed by solving the nonlinear Poisson equation for the surface potential. Two different approaches to lumped series resistance are discussed: equivalent series resistance R Seq obtained from the cell's equivalent circuit that satisfies the actual current of the cell (all other parameters in the equivalent circuit except the series resistance are kept constant) and Joule series resistance R SJ obtained from the Joule losses in the emitter of the cell. It is observed that the I ( U ) characteristic obtained from the equivalent circuit that includes R SJ generally disagrees with the actual I ( U ) characteristic of the solar cell. An additional series resistance R Sadd should be introduced in series with R SJ . Series resistances R SJ , Sadd and R Seq are analyzed numerically in one and two dimensions for different conditions of terminal voltage, illumination and weighted sheet resistance R sh b 2 , where b is related to the geometry of the analyzed cell. Following the derivations and the results of the numerical analysis it can be concluded that wherever R SJ varies as a function of terminal voltage, R Sadd should be taken into consideration.