CSG Solar AG

Thalheim, Germany

CSG Solar AG

Thalheim, Germany
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Boostandoost M.,TU Berlin | Friedrich F.,PVcomB | Kerst U.,TU Berlin | Boit C.,TU Berlin | And 3 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2011

Three different optical interaction techniques have been employed to characterise the electrical and material parameters of polycrystalline silicon (poly-Si) thin-film solar cells with an interdigitated mesa structure. First, Light Beam Induced Current (LBIC) in the infrared range was used to locally analyse the light collection properties. Second, electroluminescence in forward bias (EL) yielding information on band to band recombination was performed. Third, electroluminescence in reverse bias (ELR) was utilized to gain information on the intraband relaxation. The EL and ELR measurements were performed using cooled Si-CCD (Silicon-based Charge Coupled Device) and InGaAs (Indium Gallium Arsenide) detectors. The high resolution IR-LBIC measurement equipped with a 1,064 nm wavelength laser has been applied to investigate the grain boundary characteristics in the absorber layer. Additionally, the local electrical characteristics of the absorber layer (diffusion length, doping concentration and built-in potential) have been extracted by performing a bias-dependent IR-LBIC measurement based on a simple theoretical model with the assumption of relatively small diffusion length compared to the absorber layer thickness. The local/spatial distribution of the diffusion length in the absorber layer of the thin-film solar cell has been extracted. Furthermore, the temperature dependence of the photocurrent of thin-film solar cells in a temperature range of -25 to +70 °C has been locally investigated using IR-LBIC. Additionally, the temperature dependence of the reverse bias characteristics of the poly-Si thin-film solar cell is analysed and compared with that of monocrystalline Si solar cell. For the EL and ELR measurements a spectral analysis of the emitted light has been performed. From the EL results material properties like diffusion length and process induced defects have been deduced and insights on the quality of production processes like metallization and etching were gained. The complementary information from the ELR measurements provides access to additional types of defects resulting from generation centres, such as lattice disorder, crystal defects and charged coulomb centers. © 2011 Springer Science+Business Media, LLC.


Lausch D.,Fraunhofer Center for Silicon Photovoltaics | Werner M.,Fraunhofer Center for Silicon Photovoltaics | Naumann V.,Fraunhofer Center for Silicon Photovoltaics | Schneider J.,CSG Solar AG | Hagendorf C.,Fraunhofer Center for Silicon Photovoltaics
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2011

In this paper a method for studying p-n junctions is described. Different electron and ion beam charactersiation methods are introduced to determine the p-n-junction position using two different examples from Crystalline Silicon on Glass (CSG) thin film technology. In a first example lateral and cross section electron beam induced current (EBIC) measurements revealed that oxygen rich columnar growth at textured substrates disturbs strongly the p-n junction. In a second example diffusion from glass specimen is identified by TOF-SIMS to influencing the electrical and structural characteristics of the thin Si layer are responsible for the modified p-n junction. A model describing the formation of both defect structures is introduced. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Chowdhury A.,French National Center for Scientific Research | Schneider J.,CSG Solar AG | Schneider J.,Fraunhofer Center for Silicon Photovoltaics | Dore J.,CSG Solar AG | And 3 more authors.
Applied Physics A: Materials Science and Processing | Year: 2012

Thin film polycrystalline silicon films grown on glass substrate were irradiated with an infrared continuous wave laser for defects annealing and/or dopants activation. The samples were uniformly scanned using an attachment with the laser system. Substrate temperature, scan speed and laser power were varied to find suitable laser annealing conditions. The Raman spectroscopy and Suns-V ∞c analysis were carried out to qualify the films quality after laser annealing. A maximum enhancement of the open circuit voltage V ∞c of about 100 mV is obtained after laser annealing of as-grown polysilicon structures. A strong correlation was found between the full width half maximum of the Si crystalline peak and V ∞c. It is interpreted as due to defects annealing as well as to dopants activation in the absorbing silicon layer. The maximum V ∞c reached is 485 mV after laser treatment and plasma hydrogenation, thanks to defects passivation. © 2012 Springer-Verlag.


Straube H.,Max Planck Institute of Microstructure Physics | Straube H.,Sovello AG | Wagner J.-M.,Max Planck Institute of Microstructure Physics | Wagner J.-M.,University of Kiel | And 3 more authors.
Journal of Applied Physics | Year: 2011

We describe the measurement and modeling of lock-in thermograms for three differently processed crystalline silicon on glass thin film silicon solar modules. For the purpose of defect impact evaluation, a bias series of lock-in thermograms for a single cell in each module is measured. The resulting images around maximum power point bias show pronounced Peltier heat redistribution inside the cell, which needs to be taken into account for quantitative evaluation of the thermography results. This is done using a finite differences electronics simulation of the current flow inside the module and convolution of the heat distribution patterns with the thermal blurring. The procedure makes it possible to extract relevant cell performance parameters like the area diode dark saturation current and nonlinear edge shunting current densities as well as to evaluate the relative impact of these on the efficiency under simulated illumination. © 2011 American Institute of Physics.


Lausch D.,Fraunhofer Center for Silicon Photovoltaics | Werner M.,Fraunhofer Center for Silicon Photovoltaics | Naumann V.,Fraunhofer Center for Silicon Photovoltaics | Schneider J.,CSG Solar AG | Hagendorf C.,Fraunhofer Center for Silicon Photovoltaics
Journal of Applied Physics | Year: 2011

In this paper various methods for studying p-n junctions in thin film solar cells are applied with the aim to localize and investigate defects on a microscopic scale. Different electron and ion beam characterization methods are introduced to determine the p-n junction position using two different examples from crystalline silicon on glass thin film technology. In a first example, planview and cross section electron beam induced current measurements revealed that oxygen rich columnar growth at textured substrates strongly disturbs the p-n junction. In a second example, diffusion from glass substrate is identified by ToF-SIMS to influence the electrical and structural characteristics of the thin Si layer resulting in a modified p-n junction. A model describing the formation of both defect structures is introduced. © 2011 American Institute of Physics.


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2009.2.1.1 | Award Amount: 6.30M | Year: 2009

The aim of this project is to improve the efficiency and the cost-effectiveness of thin-film polysilicon solar modules. Thin-film polysilicon solar cells have recently emerged as a promising thin-film alternative to bulk crystalline Si. With Solid Phase Crystallization (SPC) of amorphous Si, CSG Solar AG recently achieved mini-modules with an efficiency of around 10%, matching the efficiencies of the best European micromorph mini-modules. The efficiency of polysilicon modules will be enhanced in this project by improvement of the crystallographic and electronic quality of the polysilicon material and by the develoment of advanced new methods for light confinement. By in-depth characterization of the polysilicon material, a better understanding of the relationship between the processing parameters, the electrical and optical properties of the material and the resulting device properties will be obtained. The main goals are to have large-area polysilicon modules with an efficiency of 12% and with a cost of 0.7 Euro per Watt peak at the end of the project. The active participation of CSG within this project will allow the consortium to produce module demonstrators by using the pilot line of CSG and also to accurately determine the effect of newly developed process steps on the cost-effectiveness of polysilicon modules. This makes sure that there is a good chance to bring the developed technologies directly into real mass production at the end of the project. These objectives fit very well in the topic ENERGY.2009.2.1.1 - Efficiency and material issues for thin-film photovoltaics. The expected impact of the proposed project is to enhance the efficiency of polysilicon modules, thereby increasing their cost-effectiveness. Since all the main European institutes working on thin-film polysilicon solar cells are joining forces within this project, a substantial acceleration in the improvement of the cost-effectiveness of polysilicon modules is expected.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: ENERGY-2007-2.1-06 | Award Amount: 4.47M | Year: 2008

HIGH-EF will provide the silicon thin film photovoltaic (PV) industry with a unique process allowing for high solar cell efficiencies (potential for >10%) by large, low defective grains and low stress levels in the material at competitive production costs. This process is based on a combination of melt-mediated crystallization of an amorphous silicon (a-Si) seed layer (<500 nm thickness) and epitaxial thickening (to >2 m) of the seed layer by a solid phase crystallization (SPC) process. Melting the a-Si layer and solidifying large grains (about 100 m) will be obtained by scanning a beam of a diode laser array. Epitaxial thickening of the large grained seed layer (including a pn-junction) is realized by deposition of doped a-Si atop the seed layer and a subsequent SPC process by way of a furnace anneal. Such a combined laser-SPC process represents a major break-through in silicon thin film photovoltaics on glass as it will substantially enhance the grain size and reduce the defect density and stress levels of multi-crystalline thin layers on glass compared e.g. to standard SPC processes on glass, which provide grains less than 10 m in diameter with a high density of internal extended defects, which all hamper good solar cell efficiencies. It is, however, essential for the industrial laser-SPC implementation that such a process will not be more expensive than the established pure SPC process. A low cost laser processing will be developed in HIGH-EF using highly efficient laser diodes, combined to form a line focus that allows the crystallization of an entire module (e.g. 1.4 m x 1 m in the production line or 30 cm x 39 cm in the research line) within a single scan. Specific attention has been given to identify each competence needed for the success of the project and to identify the relevant partners forming a balanced, multi-disciplinary consortium gathering 7 organizations from 4 different member states with 1 associated country.


Steffens S.,Helmholtz Center Berlin | Becker C.,Helmholtz Center Berlin | Zollondz J.-H.,CSG Solar AG | Chowdhury A.,LInstitut dElectronique du Solide et des Systemes | And 5 more authors.
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2013

A variety of defect healing methods was analyzed for optimization of polycrystalline silicon (poly-Si) thin-film solar cells on glass. The films were fabricated by solid phase crystallization of amorphous silicon deposited either by plasma enhanced chemical vapor deposition (PECVD) or by electron-beam evaporation (EBE). Three different rapid thermal processing (RTP) set-ups were compared: A conventional rapid thermal annealing oven, a dual wavelength laser annealing system and a movable two sided halogen lamp oven. The two latter processes utilize focused energy input for reducing the thermal load introduced into the glass substrates and thus lead to less deformation and impurity diffusion. Analysis of the structural and electrical properties of the poly-Si thin films was performed by Suns-VOC measurements and Raman spectroscopy. 1 cm2 cells were prepared for a selection of samples and characterized by I-V-measurements. The poly-Si material quality could be extremely enhanced, resulting in increase of the open circuit voltages from about 100 mV (EBE) and 170 mV (PECVD) in the untreated case up to 480 mV after processing. © 2012 Elsevier B.V. All rights reserved.


Mchedlidze T.,TU Brandenburg | Schneider J.,CSG Solar AG | Arguirov T.,TU Brandenburg | Arguirov T.,Ihp Microelectronics | And 2 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2011

Thin film of amorphous Si deposited on glass substrate was crystallized at 600 °C using solid phase crystallization and further processed for PV application using Crystalline Silicon on Glass technology. The resulting film was polycrystalline and contained dislocations in large density. Photoluminescence (PL) and SunsVoc measurements were applied for characterization of the material properties. The intensity of radiative transitions related to dislocations (DRL) measured at room temperature supplied information about specificities of non-radiative recombination in the material and nicely correlated with open circuit voltage, measured using SunsVoc method. The PL measurements at room temperature showed a capability of fast and reliable prediction of PV performance of the film. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


McHedlidze T.,TU Brandenburg | Zollondz J.-H.,CSG Solar AG | Kittler M.,TU Brandenburg | Kittler M.,Ihp Microelectronics
Solid State Phenomena | Year: 2011

Thin crystalline silicon films on glass substrate, fabricated using solid phase crystallization for application in thin-film solar cells, were investigated by deep level transient spectroscopy (DLTS). The analyses of the DLTS spectra obtained during temperature scans revealed presence of carrier traps related to dislocations in silicon. Other carrier traps of yet unknown nature were detected as well. Variations of electrical activity of the traps were achieved applying variations in the process of the film formation. These changes were also detected during DLTS measurements, suggesting a possibility for applying of DLTS for the investigation and characterization of the thin-film Si material on glass. © (2011) Trans Tech Publications, Switzerland.

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