Claus G. Zimmermann

Claus G. Zimmermann
  • Airbus

About

60
Publications
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630
Citations
Current institution
Airbus

Publications

Publications (60)
Article
Admittance spectroscopy combined with non-ionizing energy loss (NIEL) analysis is shown to be a powerful tool for analyzing solar cell radiation degradation, not relying on the change of macroscopic cell parameters. GaAs component cells, representative of the middle sub-cell in Ga0:5In0:5P/GaAs/Ge solar cells, were irradiated with protons and elect...
Preprint
Full-text available
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Applied Physics (Vol.128, Issue 19) and may be found at https://doi.org/10.1063/5.0028029
Article
The same amount of non-ionizing energy is deposited in GaAs solar cells through 1 MeV proton and electron radiation at specific fluence values. The defects created are detected and characterized via temperature-dependent dark I–V analysis, and the energy levels are correlated to trap states observed via admittance spectroscopy. A remarkable differe...
Article
Mechanical solar cell defects give rise to a characteristic contrast in luminescence imaging. In multijunction cell architectures, the current in each subcell can be adjusted individually in photoluminescence imaging in contrast to electroluminescence imaging. The contrast formation under these conditions is derived theoretically. The image contras...
Article
Full-text available
GaAs component cells, representative of the middle cell in Ga0.5In0.5P/GaAs/Ge triple junction solar cells, were irradiated with protons and electrons of various energies and fluences. The local ideality factor, calculated from the measured dark J‐V curves, exhibits a characteristic signature of the irradiating particle. With the help of an analyti...
Article
GaAs single junction cells, representative of the middle cell in triple junction Ga 0.5In 0.5P/GaAs/Ge cells, were irradiated with various fluences of 1- and 3-MeV electrons as well as 1-MeV protons. The light I-V curves measured at room temperature exhibit a voltage-dependent photocurrent. The photocurrent is modeled taking into account the voltag...
Conference Paper
The evolution of the subcell capacitance of triple junction solar cells upon 3 MeV electron irradiation is studied. Photocurrent is induced subcell specific using a sequence of spatially homogeneous, monochromatic light pulses. The used method is based on the externally measured transient voltage, which allows to calculate the depletion layer capac...
Article
Full-text available
A method for measuring subcell capacitance voltage (C–V) in a multijunction solar cell is introduced. The subcell of interest is illuminated by a monochromatic light pulse with a ns rise time. The subcell capacitance is calculated from the measured rise time of the solar cell voltage. The effect of optical coupling is eliminated by introducing a hi...
Article
Full-text available
Characteristic degradation curves for proton and electron induced degradation of triple junction (3J) and isotype Ga0.5In0.5P/GaAs/Ge solar cells were obtained. The displacement damage dose methodology in combination with a varying effective threshold energy for atomic displacement Td,eff was used to analyze 3G28 and 3G30 3J cell data. The nonioniz...
Article
The photocurrent versus open-circuit voltage characteristic of individual subcells in a multijunction solar cell can be measured by illuminating the subcell with a pulse sequence of spatially homogeneous laser light. In this paper, we demonstrate the applicability of this method for four junction solar cells. Furthermore, the degradation of triple...
Article
Full-text available
BepiColombo is the joint mission of the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) to explore the planet mercury. The European contributions, namely the mercury transfer module (MTM) and the mercury planetary orbiter (MPO), are both powered by deployable solar arrays. Many materials and technologies are at thei...
Article
Full-text available
Two ESA high temperature missions, BepiColombo and Solar Orbiter, are planned to start in 2018. Severe environmental conditions with sun intensities up to 10.6 resp. 12.8 solar constants will be encountered during both missions. Different tests have been performed to qualify the main component for the solar array, the solar cell. The key qualificat...
Article
Full-text available
Airbus is currently developing the Next Generation Solar Array (NGSA) for telecommunication satellites. It is based on a hybrid array concept which combines a conventional rigid panel array with lightweight, semi-rigid lateral panels. The main figures of merit power/mass and power/volume can be doubled through this concept. Mechanically, the semi-r...
Article
Results of making surfaces of flexible cable conductors, used for solar arrays in geostationary orbit, charge dissipative by a specially developed method of ion-beam surface treatment with simultaneous surface renewal are presented. All flexible cable conductor surfaces, including those with rough morphology and foreign inclusions, achieved surface...
Article
The open circuit voltages Voc of individual subcells in a multijunction solar cell are measured by illuminating a given subcell with a pulse of spatially homogeneous, nearly monochromatic light with a rising edge in the μs regime. The influence of luminescent coupling and semi-transparency on Voc is eliminated by over-illuminating all subcells belo...
Conference Paper
Full-text available
Several promising multi-junction solar cell concepts for space applications are currently under development worldwide. On-Orbit Verification on CubeSats is a cost-efficient method to gain data on critical hardware early in the design validation process. The MOVE-II CubeSat will be used for the verification of novel 4-6 junction solar cells. With a...
Conference Paper
Full-text available
We report on defect recovery of high energy proton irradiated GalnP 2 /GaAs/Ge triple junctions cells and related component cells by isothermal annealing. For systematically addressing the solar cell behavior all mission representative key parameters are varied: The energy of the impinging protons is 0.75 MeV, 2.0 MeV and 6.5 MeV; the particle flue...
Conference Paper
Full-text available
We report on design and qualification of solar array components such as solar cells, cell protection diodes, optical reflectors and wires for high temperature space missions. The ECSS standard ECSS-E-ST-20-08C and ESCC specification 3901 are appropriat baselines which have been tailored, in particular for long duration tests.
Article
Scanning transmission ion microscopy (STIM) has been applied to measure sputter yields of thin Kovar foil. The results have been found in very good agreement with values determined by the weight loss method, demonstrating STIM as a feasible alternative measurement technique for sputter yield estimation of thin material samples. Measurements have be...
Article
The open circuit voltage of a single subcell in a multijunction cell stack can be measured with the help of pulsed, millisecond illumination. This concept makes use of the fact that the charging of the non-illuminated cell capacitances takes place on a much longer timescale than of the illuminated one. Optical coupling introduces a photocurrent in...
Article
A method for the determination of the subcell I-V characteristics of multijunction solar cells in the presence of optical coupling is presented and applied to a Ga0.50In0.50P/Ga0.99In0.01As/Ge triple-junction solar cell. Each of the subcells is described by a two-diode model and can be illuminated by a narrowband light source externally. Optical co...
Conference Paper
In this paper a calibrated model of a III-V triple junction solar cell is presented. The simulations are carried out with a commercial TCAD software, and the model is validated by a comparison of the EQE and IV curve with experimental data. We perform an extensive simulation study of the geometry of the solar cell and of its behavior under differen...
Article
A small fraction of GaInP2/GaAs/Ge triple junction solar cells exposed to the 6× concentrated air mass zero spectrum at 523 K for 5 min was found to be severely shunted afterwards. A combination of electroluminescence imaging and focused ion beam cross sectioning revealed that pre-existing top-middle cell shunts were responsible for the observed de...
Article
A combined electroluminescence and photoluminescence setup for a fast, nondestructive, and high-resolution characterization of large-area lattice matched GaInP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Ga(In)As/Ge triple-junction space solar cells was developed. In contrast with electrol...
Article
A method to measure the series resistance of Ga0.5In0.5P/Ga(In)As/Ge triple-junction solar cells spatially resolved is developed, based on luminescence imaging. With the help of network simulations, the dependence of the local series resistance on the external subcell illumination intensities and biasing voltage is predicted and the optimum measure...
Patent
Full-text available
A method for screening of multi-junction solar cells to be operated in a high sun intensity and high temperature (HIHT) environment. An electroluminescence image of a homogeneous pn-junction at a predefined bias current is acquired for each of the solar cells. The spatial intensity distribution in the electroluminescence image is analyzed to determ...
Article
The harsh environment at mercury during the BepiColombo mission results in temperature ranges for the photovoltaic assembly (PVA) up to 200°C in combination with 5 to 11 times the air mass zero (AM0) solar spectrum. Standard solar cell assembly (SCA) technologies representative of the PVA materials and design could not met the required performance...
Conference Paper
Full-text available
We report on the isothermal annealing behavior of 1 MeV electron irradiated component cells of a GaInP2/GaAs/Ge triple-junction solar cell. The defect concentration as a function of annealing time and temperature is derived from the in-situ measured open circuit voltages. The time dependent behavior reveals the presence of partly overlapping expone...
Article
Polycrystalline Ag, covered with a nm thin siloxane layer, was irradiated with ultraviolet light in vacuum at 500 K. Ag particles of different aspect ratios, 50-1000 nm in size, formed on the surface, including a small fraction of nanorods. Pressurized water vapor bubbles are created in the subsurface region by hydrogen radicals photo-chemically re...
Article
Full-text available
Theoretical and experimental studies on joining thin silver foils by UV nanosecond and picosecond laser radiation were carried out for an application-orientated process design. Simulations of energy impact in the material at varying laser pulse energies, pulse durations and repetition rates were used to examine the feasibility of a laser-based join...
Article
The behavior of standard space photovoltaic assemblies in a high intensity, high temperature environment (HIHT) is addressed. Experimentally, an HIHT environment, typical for missions to the inner planets of the solar system such as Mercury, characterized by temperatures of 500K and 11 solar constant irradiance in the ultraviolet region below 400 n...
Article
An extensive set of environmental tests revealed that the standard solar cell design incorporated in the typical photovoltaic array configuration performs less than expected in the high intensity high temperature environment (HIHT) of the Bepi Colombo mission, characterized by temperatures between 200 and 230 °C and an incident irradiance of up to...
Article
. The sputter yield is an important material parameter not only for various surface treatment techniques, but also for electric spacecraft propulsion. Many satellite or thruster components might be subject of erosion due to energetic and/or related secondary ions. In order to estimate the lifetime of these components the sputter yield under xenon...
Article
The formation of epitaxial CoSi2 islands of nanoscopic dimensions is reported using the technique of reactive cluster deposition. Co clusters in the size range 5-50nm were synthesized by sputtering a high purity Co target inside a UHV sputtering chamber. The clusters were then deposited on the reconstructed Si (111) surface. Upon annealing the part...
Conference Paper
The potential of electroluminescence imaging is demonstrated for large area III-V triple junction solar cells. The cells are modeled as two dimensional diode networks and the emitted electroluminescence under forward bias is used as a measure of the local voltage. Mechanical cell defects introduce a discontinuity in this network which is shown to r...
Article
Virtually all spacecraft employ photovoltaic energy conversion for continuous power generation. Compared to their counterpart on Earth, photovoltaic modules in the space environment face a unique set of performance requirements. Among the most demanding ones are the need to have the highest possible specific power output with regard to mass and sur...
Article
To explore higher, farther, and faster, scientists and engineers have developed advanced materials for manned spacecraft and satellites for a range of sophisticated applications in transportation, global positioning, exploration, and communication. Materials used in space are exposed to vacuum, intense ultraviolet radiation from the sun, and ionizi...
Article
Electroluminescence intensity maps of all three subcells of space grade III-V multijunction cells were obtained with the help of dedicated imaging sensors at a range of different injection currents. Solely based on these data, making use of the homogeneity of one subcell, the local diode properties of an equivalent single junction cell were obtaine...
Article
Full-text available
For high efficiency silicone encapsulated solar modules for concentrator photovoltaic systems or space applications, the question of performance degradation due to long term exposure to ultraviolet (UV) light is addressed. The transparent silicones DC93-500 and Elastosil S690 and S695 were subjected to a time and wavelength resolved UV test with a...
Article
The space grade silicone elastomers Elastosil S-690 was subjected to the environmental loads experienced by a coverglass adhesive in a geostationary orbit environment. UV radiation, particle radiation as well as elevated temperatures all might impact the transmission of the silicone in orbit. In parallel with the established coverglass adhesives DC...
Article
The photodegradation behavior of three different transparent silicone elastomers, primarily used in space, was investigated experimentally. Samples were irradiated by an artificial ultraviolet (UV) light source, whose spectrum was split into five discrete wavelength bands in the range from 200 to 400 nm. The transmittance of the samples was measure...
Article
The space grade silicone elastomer Elastosil S-690 was subjected to the environmental loads experienced by a coverglass adhesive in a geostationary orbit environment. In parallel with the established coverglass adhesives DC93-500 and Elastosil S-695, Elastosil S-690 was subjected to 10000 equivalent sun hours of UV radiation, a total dose of 2.2 MG...
Article
A stable supply of electrical power is crucial for the success of space missions. Photovoltaic arrays are the most common means of in-orbit energy generation. Mechanical solar cell defects have the potential to impact their reliability considerably. In order to address this question, the environmental loads encountered in space were simulated exper...
Article
Full-text available
Lateral current transport in forward biased triple junction solar cells is analyzed. A model based on distributed sheet resistances in combination with ideal p-n junctions is developed. Experimentally, the spatial distribution of the electroluminescence radiation is recorded and used as a tool to deduce the current densities in the individual junct...
Article
We have investigated soft landings of Co nanoparticles on clean Cu(001) surfaces. The nanoparticles, ≈10 nm in size, were generated by dc magnetron sputtering in argon and transferred in the gas stream to an ultrahigh vacuum transmission electron microscope (TEM), where they were deposited on the thin-film substrate. The surface morphology created...
Article
The formation of epitaxial CoSi2 islands of nanoscopic dimensions is reported using the technique of reactive cluster deposition. Co clusters in the size range 5-50 nm were synthesized by sputtering of a high purity Co target inside a ultra high vacuum (UHV) sputtering chamber, using the technique of inert gas condensation. The clusters were then d...
Chapter
Surfaces with artificial roughness were generated by deposition of nanoparticles on single crystalline substrates. Nanoparticles with an average size of 15 nm were produced by inert gas condensation and deposited in situ on the substrate mounted inside a modified ultra-high vacuum transmission electron microscope. We investigated the smoothing beha...
Article
Full-text available
Metal nanoparticles can display a unique behavior when deposited on substrates with a significantly lower surface energy. Co nanoparticles in the 10 nm size regime burrow into clean Cu(100) and Ag(100) substrates when deposited at 600 K and also assume the substrate orientation. Deposition at room temperature fails to show either burrowing or reori...
Article
The energy and angular distributions of Ni and Al atoms sputtered from Ni3Al(100) by 8 keV Ar+ have been measured using multiphoton resonance ionization detection. The Al atoms, which originate entirely from the top atomic layer of Ni3Al(100), are predominantly sputtered along close packed 〈110〉 directions. On the other hand the sputtered Ni flux,...

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