Reutlingen, Germany
Reutlingen, Germany

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Baier T.,Manz Automation AG | Schulz-Ruthenberg M.,Fraunhofer Institute for Laser Technology | Ametowobla M.,Manz Automation AG | Schlenker T.,Manz Automation AG | Manz D.,Manz Automation AG
Progress in Photovoltaics: Research and Applications | Year: 2010

This paper presents a simple method for estimating the ablation rate during drilling processes in crystalline silicon wafers. Using data from literature, the physical process of material heating, melting, and ejection can be estimated on a time scale and leads to a temporal separation of the pulse duration in two parts. The latter one offers a theoretical determination of the expected average ablation rate. The results of this approximation coincide with experimental values and offer solutions to increase drilling efficiency. The experiments were done with a q-switched solid-state laser emitting at 1064 nm wavelength at pulse durations between 810 ns and 1440 ns. © 2010 John Wiley & Sons, Ltd.


Schulz-Ruhtenberg M.,Fraunhofer Institute for Laser Technology | Baier T.,Manz Automation AG | Boeckler E.-W.,SCANLAB AG | Siebert C.,TRUMPF Laser und Systemtechnik GmbH
29th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2010 - Congress Proceedings | Year: 2010

A major breakthrough on the way to cheap sustainable solar electricity generation is the back contact solar cell. By moving both terminals to the back of the solar cell shading losses can be reduced or eliminated, which leads to higher cell efficiencies. One concept to achieve this, the emitter wrap-through (EWT) solar cell, requires holes drilled through the silicon wafer with a density of up to one hole per mm2, i.e. up to 24,000 holes on a 6″ wafer. The present situation of the solar cell industry demands high processing speeds and a high production throughput. For an industrial EWT solar cell production line, a throughput of 10,000 vias/sec and more is essential and this depends heavily on the laser performance. In this work, this is tackled by developing optical concepts such as beam splitting and the combination of ultra-fast scanning and simultaneous movement of a linear axis. Also, the selection of the proper laser source and processing parameters has proven to be crucial to successfully achieve the desired drilling rates. Of course, other applications, such as laser drilling of filters can benefit from these developments.


Trusheim D.,Fraunhofer Institute for Laser Technology | Schulz-Ruhtenberg M.,Fraunhofer Institute for Laser Technology | Baier T.,Manz Automation AG | Krantz S.,Solland Solar Cells BV | And 2 more authors.
Physics Procedia | Year: 2011

Lasers as production tools offer several advantages, which are especially relevant for the production of solar cells. The contactless and localized nature of the energy deposition allows new processes, such as laser selective emitter doping, laser ablation of dielectric coatings and via drilling for back contact cell concepts. A critical factor is the selection of suitable laser sources and parameters in a manner that adapts the laser process to the requirements of the material, the process nature and the solar cell properties. In this paper three laser processes are investigated with the goal to identify the most suitable laser source. © 2011 Published by Elsevier Ltd.


Jager U.,Fraunhofer Institute for Solar Energy Systems | Thaidigsmann B.,Fraunhofer Institute for Solar Energy Systems | Okanovic M.,Fraunhofer Institute for Solar Energy Systems | Okanovic M.,MANZ Automation AG | Preu R.,Fraunhofer Institute for Solar Energy Systems
Energy Procedia | Year: 2011

The increase of solar cell efficiency via the implementation of a selective emitter in crystalline silicon solar cells is currently under research and partly in transition into production. The choice of the doping profile underneath the contacts can have significant impact on cell efficiency. In this work, the quantum efficiency of highly doped areas and its impact on the short circuit current are investigated. The aim of this work is to asses the influence of highly doped illuminated areas, which can possibly diminish the gain of the selective emitter structure regarding JSC. Areas of high doping are created by the technique of laser induced diffusion. The doping profile is varied by adjusting the laser pulse energy. The IV characteristics and spectral response of finished solar cells are measured. The internal quantum efficiency is analyzed using a model proposed by Fischer. Deeper diffused profiles are found to have larger dead layers and a linear correlation between the dead layer thickness and the resultant short circuit current is observed. The impact on solar cells with selective emitter is discussed. © 2011 Published by Elsevier Ltd.


Germershausen S.,Conergy | Bartholomaus L.,Conergy | Seidel U.,Conergy | Hanisch N.,Conergy | And 6 more authors.
Energy Procedia | Year: 2011

The selective emitter formation by laser doping is a well known process to increase the efficiency of silicon solar cells [1], [2]. For the characterization of laser doped emitters, SIMS (Secondary Ion Mass Spectroscopy) and ECV (Electrochemical Capacitance Voltage Measurement) techniques are used to analyze the emitter profile [3]. It is very difficult to get acceptable result by SIMS on a textured surface, so only ECV can be used. It has been shown, that a charge carrier depth profile can be measured on a homogeneous emitter only by ECV. The use of laser doping results in a non-homogeneous emitter. We have shown that the emitter depth is not just a function of the pulse power, but in addition of the surface structure of the wafer. The texture seems responsible for a strong variability in the doping profile. It has been shown, that the ECV measurement is not applicable to characterize the emitter depth on laser doped areas, because of the microscopic inhomogeneities in the emitter on the macroscopic measurement area. The real emitter profiles are to complex to be characterized by SIMS or ECV. We have shown that the variation in the emitter profile is resulting from the texture in the laser-doped regions. © 2010 Published by Elsevier Ltd.


Patent
Manz Automation AG | Date: 2010-11-29

In a method for removing at least sections of at least one semiconductor layer (4) of a layer stack (1), an optically dense metallisation layer (3) is heated such that the semiconductor layer located on top is detached.

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