Investigation of the Trapping Mechanism for Transient Current-Voltage Behavior In CIGSS-Based Solar Cells

2001 ◽  
Vol 668 ◽  
Author(s):  
Pamela K. Johnson ◽  
James R. Sites ◽  
Dale E. Tarrant
Keyword(s):  
Elevated Temperatures ◽  
Light Exposure ◽  
Transient Behavior ◽  
Open Circuit ◽  
Trap Density ◽  
Transient Current ◽  
Photon Absorption ◽  
Cyclic Behavior ◽  
Zero Bias ◽  
Current Voltage

ABSTRACTSome thin-film CIS photovoltaic devices exhibit reversible transient behavior in their electrical properties induced by modestly elevated (70 - 100 °C) temperatures. This paper evaluates changes due to light exposure, thermal exposure, and applied bias in cells fabricated by Siemens Solar Industries (SSI). When a constant bias was maintained across cells subjected to elevated temperatures in the dark, and subsequent moderate- temperature light exposure, there was little reversible transient behavior. When the bias was cycled between zero and open-circuit voltage (VOC), independent of illumination, the fill factor (FF) decreased for zero bias and increased at VOC. Hence, it is the bias rather than photon absorption that drives the transient current-voltage behavior in these cells. Investigations of the relationship between trapping mechanisms and transient behavior using the frequency and temperature dependence of capacitance showed clear cyclic behavior in the trap-response frequency. Trap density profiles were found to be relatively independent of measurement temperature, and the total trap density varied only slightly with the bias cycle.

Novel Micro-Photodiodes for Retina Stimulation

2000 ◽  
Vol 609 ◽  
Author(s):  
M. Rojahn ◽  
M.B. Schubert
Keyword(s):  
Amorphous Silicon ◽  
Ganglion Cells ◽  
Light Exposure ◽  
Open Circuit ◽  
In Vitro Tests ◽  
Buffer Solution ◽  
Long Term Stability ◽  
Current Voltage

ABSTRACTWe present a new design of micro-photodiodes for in-vitro tests to electrically stimulate the ganglion cells of chicken and rat retinae upon light exposure of the photodiodes. Based on amorphous silicon, our laterally series connected double-stacked micro-photodiodes provide an open circuit voltage of 2.3 volts. Photolithographic steps as well as etching procedures for patterning the back contact, the amorphous silicon layers and the front contact are described. We analyse current- voltage-measurements performed with direct contact of the metal needles of a micro-positioning system to the device's electrodes. In order to test the performance of an individual micro-photodiode in an electrolyte environment, the stimulation electrode of the device is also contacted with a micro-droplet of buffer solution. Further improvement is needed, mainly addressing the problem of long-term stability of the device in electrolyte environments.

The Influence of Stressing at Different Biases on the Electrical and Optical Properties of CdS/CdTe Solar Cells

2001 ◽  
Vol 668 ◽  
Author(s):  
S. W. Townsend ◽  
T. R. Ohno ◽  
V. Kaydanov ◽  
A. S. Gilmore ◽  
J. D. Beach ◽  
...  
Keyword(s):  
Anomalous Behavior ◽  
Open Circuit ◽  
Trap Level ◽  
Doping Density ◽  
Zero Bias ◽  
Cdte Solar Cells ◽  
Current Voltage ◽  
Depletion Width ◽  
Capacitance Voltage ◽  
Iv Curves

ABSTRACTCadmium Sulfide/Cadmium Telluride (CdS/CdTe) devices are subject to stress under various biases. Striking differences are observed with the Current-Voltage, and Capacitance- Voltage measurements for cells degraded at 100°C in dark under forward (FB), open circuit (OC), and reverse (RB) biases. RB stress provides the greatest degradation, and the apparent doping density profile shows anomalous behavior at the zero bias depletion width. Thin films of CdS, both doped and undoped, with Cu are characterized with photoluminescence (PL). The PL spectra from the CdS films are correlated with the CdS spectra from stressed devices, revealing that Cu signatures in the CdS layer of stressed devices are a function of stress biasing. Device modeling using AMPS-1D produces IV curves similar to that in RB degraded devices, by only varying the trap level concentration in the CdS layer.

Space-charge-limited current theory for a spatially non-uniform trap distribution

1978 ◽  
Vol 31 (10) ◽  
pp. 2117 ◽  
Author(s):  
JS Bonham
Keyword(s):  
Space Charge ◽  
Low Voltage ◽  
Step Function ◽  
Open Circuit ◽  
Trap Density ◽  
Asymmetric Distribution ◽  
Space Charge Limited Current ◽  
Limited Current ◽  
Current Voltage ◽  
Space Charge Limited

The theory of space-charge-limited current, including diffusion, is discussed for an insulator containing a shallow or exponential distribution of traps whose concentration varies with position, being higher near the insulator surface than in the bulk. Two simple step- function spatial distributions are considered-one symmetric and one asymmetric. Analytic treatments are given for the open-circuit situation in both cases. For the symmetric case simple formulae are derived for the current-voltage relation. The current may be bulk- or surface-limited or there may be a transition from the former to the latter as the voltage is raised, giving rise to considerable structure in the current-voltage curves not predicted by theory which neglects diffusion. An asymmetric distribution may give rise to rectification at low voltages. This can be treated by considering the region of high trap density near one electrode to make an effectively blocking contact to the bulk of the insulator. Comparison of open-circuit potential profiles for the step-function and exponential spatial trap distributions suggests that the system is insensitive at low voltage to the nature of the spatial distribution; only the trap density in the vicinity of the surfaces is important.

Electrical Characterization of High Voltage 4H-SiC pin Diodes Fabricated Using a Low Basal-Plane Dislocations Process

2007 ◽  
Vol 556-557 ◽  
pp. 921-924 ◽  
Author(s):  
Pavel A. Ivanov ◽  
Michael E. Levinshtein ◽  
Mykola S. Boltovets ◽  
Valentyn A. Krivutsa ◽  
John W. Palmour ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Electrical Characterization ◽  
Open Circuit ◽  
Pin Diodes ◽  
Voltage Drops ◽  
Current Voltage ◽  
Lifetime Value ◽  
Deep Modulation ◽  
Base Width

Forward current-voltage (I-V) characteristics and non-equilibrium carrier lifetime, τ were measured in 4H-SiC pin diodes (10-kV rated, 100 μm base width). The τ value was found to be 3.7 μs at room temperature by measurements of open circuit voltage decay. To the best of the authors' knowledge, the above lifetime value is the highest reported for 4H-SiC. The forward voltage drops were measured to be 3.44 V at current density of 100 A/cm2 and 5.45 V at 1000 A/cm2 showing a very deep modulation of the blocking base by injected carriers. Diodes operated well at elevated temperatures up to 400oC. No essential forward degradation was detected after 300- A×min current stress at 400oC.

Metal Contacts on a-GaN

1996 ◽  
Vol 1 ◽  
Author(s):  
T. U. Kampen ◽  
W. Mönch
Keyword(s):  
Tight Binding ◽  
Image Force ◽  
Schottky Contacts ◽  
Metal Contacts ◽  
Zero Bias ◽  
Barrier Heights ◽  
Current Voltage ◽  
Optical Dielectric Constant ◽  
Optical Dielectric ◽  
Gap States

The Schottky barrier heights of silver and lead contacts on n-type GaN (0001) epilayers were determined from current-voltage characteristics. The zero-bias barrier heights and the ideality factors were found to be linearly correlated. Similar observations were previously reported for metal contacts on Si (111) and GaAs (110) surfaces. The barrier heights of ideal Schottky contacts are characterized by image force lowering of the barrier only. This gives an ideality factor of 1.01. From our data we obtain barrier heights of 0.82 eV and 0.73eV for ideal Ag and Pb contacts on GaN, respectively. The metal-induced gap states (MIGS) model predicts the barrier heights of ideal Schottky contacts on a given semiconductor to be linearly correlated with the electronegativities of the metals. The two important parameters of this MIGS-and-electronegativity model are the charge neutrality level (CNL) of the MIGS and a slope parameter. The CNL may be calculated from the dielectric band gap and using the empirical tight-binding method. The slope parameters are given by the optical dielectric constant of the respective semiconductor. The predictions of the MIGS model for metal/GaN contacts are confirmed by the results presented here and by barrier heights previously reported by others for Au, Ti, Pt, and Pd contacts on GaN.

scholarly journals The effects of electron irradiation and thermal dependence measurements on 4H-Sic Schottky diode

2017 ◽  
Vol 51 (12) ◽  
pp. 1721
Author(s):  
Sabuhi Ganiyev ◽  
M. Azim Khairi ◽  
D. Ahmad Fauzi ◽  
Yusof Abdullah ◽  
N.F. Hasbullah
Keyword(s):  
Barrier Height ◽  
Ideality Factor ◽  
Elevated Temperatures ◽  
Series Resistance ◽  
Schottky Diodes ◽  
High Energy ◽  
Bias Current ◽  
N Saturation ◽  
Saturation Current ◽  
Current Voltage

In this paper the effects of high energy (3.0 MeV) electrons irradiation over a dose ranges from 6 to 15 MGy at elevated temperatures 298 to 448 K on the current-voltage characteristics of 4H-SiC Schottky diodes were investigated. The experiment results show that after irradiation with 3.0 MeV forward bias current of the tested diodes decreased, while reverse bias current increased. The degradation of ideality factor, n, saturation current, Is, and barrier height, Phib, were not noticeable after the irradiation. However, the series resistance, Rs, has increased significantly with increasing radiation dose. In addition, temperature dependence current-voltage measurements, were conducted for temperature in the range of 298 to 448 K. The Schottky barrier height, saturation current, and series resistance, are found to be temperature dependent, while ideality factor remained constant. DOI: 10.21883/FTP.2017.12.45193.8646

scholarly journals Simulation of a perovskite sandwich solar cell with the p-CZTS / p-CH3NH3PbCI3 / p-CZTS absorber layers

2021 ◽  
Vol 877 (1) ◽  
pp. 012001
Author(s):  
Marwah S Mahmood ◽  
N K Hassan
Keyword(s):  
Solar Cell ◽  
Conversion Efficiency ◽  
Current Density ◽  
Short Circuit ◽  
Perovskite Solar Cells ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Current Voltage ◽  
Cell Capacitance

Abstract Perovskite solar cells attract the attention because of their unique properties in photovoltaic cells. Numerical simulation to the structure of Perovskite on p-CZTS/p-CH3NH3PbCI3/p-CZTS absorber layers is performed by using a program solar cell capacitance simulator (SCAPS-1D), with changing absorber layer thickness. The effect of thickness p-CZTS/p-CH3NH3PbCI3/p-CZTS, layers at (3.2μm, 1.8 μm, 1.1 μm) respectively are studied. The obtained results are short circuit current density (Jsc ), open circuit voltage (V oc), fill factor (F. F) and power conversion efficiency (PCE) equal to (28 mA/cm2, 0.83 v, 60.58 % and 14.25 %) respectively at 1.1 μm thickness. Our findings revealed that the dependence of current - voltage characteristics on the thickness of the absorbing layers, an increase in the amount of short circuit current density with an increase in the thickness of the absorption layers and thus led to an increase in the conversion efficiency and improvement of the cell by increasing the thickness of the absorption layers.

scholarly journals I-V measurements of Ge-Se-Sn chalcogenide glassy alloys

2015 ◽  
Vol 9 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Vandana Kumari ◽  
Anusaiya Kaswan ◽  
Dinesh Patidar ◽  
Narendra Saxena ◽  
Kananbala Sharma
Keyword(s):  
Elevated Temperatures ◽  
Low Voltage ◽  
Constant Load ◽  
Dc Conductivity ◽  
Voltage Range ◽  
Glassy Alloys ◽  
Current Voltage ◽  
Maximum Current ◽  
Current Voltage Characteristics ◽  
Minimum Resistance

Current-voltage characteristics and DC electrical conductivity were studied for Ge30-xSe70Snx (x = 8, 11, 14, 17 and 20) glassy thin pellets of diameter 12mm and thickness 1mm prepared under a constant load of 5 tons using a well-known melt quenching technique in bulk as a function of composition. The I-V characteristics were recorded at room temperature as well as elevated temperatures up to 300?C. The experimental data suggests that glass containing 20 at.% of Sn has the minimum resistance allowing maximum current through the sample as compared to other counterparts of the series. Therefore, DC conductivity is found to increase with increasing Sn concentration. Composition dependence of DC conductivity is discussed in terms of the bonding between Se and Sn. Plots between ln I and V1/2 provide linear relationship for both low and high voltage range. These results have been explained through the Pool-Frenkel mechanism. The I-V characteristics show ohmic behaviour in the low voltage range and this behaviour turns to non-ohmic from ohmic in the higher voltage range due to voltage induced temperature effects.

Metastable Variations of the Fill Factor in CIGS Thin Film Solar Cells

2009 ◽  
Vol 1165 ◽  
Author(s):  
Aleksander Urbaniak ◽  
Małgorzata Igalson
Keyword(s):  
Fill Factor ◽  
Elevated Temperatures ◽  
Reverse Voltage ◽  
Cell Behaviors ◽  
Cigs Thin Film ◽  
Current Voltage ◽  
Shallow Acceptors ◽  
Current Voltage Characteristics ◽  
Diode Behavior ◽  
Kinetics Of

AbstractWe investigate the origin of fill factor changes induced by reverse bias treatment. Evolution of current-voltage characteristics have been measured during application of reverse voltage bias. Two different cell behaviors have been identified. At elevated temperatures one kind of the devices strongly deteriorates and exhibit so called double diode behavior. On the other hand, in the same conditions another cells keep their fill factor almost constant. We correlate the fill factor changes with the kinetics of capacitance and show that although increased number of shallow acceptors itself cannot induce this severe FF deterioration, it may strongly influence position of the Fermi level at the heterointerface that in a presence of an electron barrier is crucial for the device behavior.

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