Entity

Time filter

Source Type

Boulder, CO, United States

Hameiri Z.,Solar Energy Research Institute of Singapore | Trupke T.,University of New South Wales | Trupke T.,BT Imaging Pty Ltd | Gao N.,University of New South Wales | And 2 more authors.
Progress in Photovoltaics: Research and Applications | Year: 2013

The effective doping concentration of the bulk of a silicon wafer is an important material parameter for photovoltaic applications. The techniques commonly used to measure the effective doping concentration are based on conductance or resistivity measurements and include both contacted methods, such as the four-point probe, and contactless approaches, such as eddy current measurements. Applying these techniques to diffused wafers is complicated by the fact that the total conductance is the sum of the bulk conductance and the diffused layer conductance. Without further information about the emitter properties, a clear separation of these two parameters is not possible. This paper demonstrates a contactless method for specifically measuring the effective doping concentration of the bulk without significant influence from diffused layers. Copyright © 2012 John Wiley & Sons, Ltd. A new contactless method to detrmine the bulk doping concentration is presented. The method can be used throughout the solar cell fabrication process and on a wide variety of silicon substrates, without being affected by diffused or passivation layers. An excelent agreement was demonstrated between the post-diffusion doping concentration as obtained by the new method and the pre-diffusion doping concentration from dark conductance measurements. Copyright © 2012 John Wiley & Sons, Ltd. Source


Bothe K.,Institute for Solar Energy Research Hamelin | Krain R.,Institute for Solar Energy Research Hamelin | Falster R.,MEMC Electronic Materials | Sinton R.,Sinton Instruments
Progress in Photovoltaics: Research and Applications | Year: 2010

The determination of the bulk lifetime of bare multicrystalline silicon wafers without the need of surface passivation is a desirable goal. The implementation of an in-line carrier lifetime analysis is only of benefit if the measurements can be done on bare unprocessed wafers and if the measured effective lifetime is clearly related to the bulk lifetime of the wafer. In this work, we present a detailed experimental study demonstrating the relationship between the effective carrier lifetime of unpassivated wafers and their bulk carrier lifetime. Numerical modelling is used to describe this relationship for different surface conditions taking into account the impact of a saw damage layers with poor electronic quality. Our results show that a prediction of the bulk lifetime from measurements on bare wafers is possible. Based on these results we suggest a simple procedure to implement the analysis for in-line inspection. Copyright © 2010 John Wiley &Sons, Ltd. Source


Sinton R.A.,Sinton Instruments
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2010

The excess carrier recombination lifetime in silicon solar cells is a critical indicator of material and passivation quality. This property can be measured on silicon crystals and then at every stage of production. As the silicon PV field has developed, many methods of measuring this carrier lifetime are coming into use, including mapping methods such as microwave- photoconductance decay, imaging methods including infra-red carrier density imaging and photoluminescence, as well as the methods that measure lifetime vs. carrier density such as Quasi-Steady-State Photoconductance, (QSSPC). This paper will focus on efforts to define standards for the measurement of carrier lifetime in silicon that will allow for the comparison of results between these varied methods. As an example of the importance of comparisons between methods, the "trapping" signature often seen in photoconductance measurements is briefly discussed. © 2010 IEEE. Source


Sinton R.A.,Sinton Instruments | Haunschild J.,Fraunhofer Institute for Solar Energy Systems | Demant M.,Fraunhofer Institute for Solar Energy Systems | Rein S.,Fraunhofer Institute for Solar Energy Systems
Progress in Photovoltaics: Research and Applications | Year: 2013

Wafer quality is extremely important in determining yield and efficiency of solar cells. Ideally, this wafer quality should be determined for incoming wafers before solar cell fabrication based on the electronic quality of the wafers. Recent papers have discussed methodologies for doing this by using lifetime measurement and pattern recognition of photoluminescence (PL) images. This paper compares results from quasi-steady-state photoconductance (QSSPC) lifetime measurements with PL imaging pattern recognition of dislocations. By using a more complete analysis of the lifetime and the PL data than performed in some recent publications, a more detailed physical picture is presented here, which reconciles contradictions between previous results. In particular, the differences between PL and QSSPC lifetime measurements on as-cut wafers are discussed. The trends in voltage prediction based on measured lifetime, doping, and PL-determined dislocation densities are shown. Copyright © 2012 John Wiley & Sons, Ltd. Wafer quality is extremely important in determining yield and efficiency of solar cells. Ideally, this wafer quality should be determined for incoming wafers before solar cell fabrication based on the electronic quality of the wafers. This paper compares results from quasi-steady-state photoconductance lifetime measurements with photoluminescence (PL) imaging pattern recognition. A detailed physical picture is presented here that reconciles contradictions between previous results. The trends in voltage prediction based on measured lifetime, doping, and PL-determined dislocation densities are shown. Copyright © 2012 John Wiley & Sons, Ltd. Source


Sinton R.A.,Sinton Instruments | Trupke T.,BT Imaging NSW
Progress in Photovoltaics: Research and Applications | Year: 2012

Comparison of minority carrier lifetime measurements carried out in transient mode with measurements performed under steady-state conditions allows determination of the calibration constants needed in non-transient measurements. In this letter, we point out practical scenarios in which the assumptions underlying this approach break down, resulting in significant experimental errors. Specific examples for crystalline silicon wafers will be discussed to provide some guidelines on practical limitations of this calibration approach. Large errors are possible for wafers with high surface recombination velocity as might be the case for incoming wafers for a solar cell production line. Copyright © 2011 John Wiley & Sons, Ltd. Source

Discover hidden collaborations