C. Berge

Bio: C. Berge is an academic researcher from University of Stuttgart. The author has contributed to research in topics: Monocrystalline silicon & Wafer. The author has an hindex of 5, co-authored 6 publications receiving 554 citations.

Generalized analysis of quasi-steady-state and quasi-transient measurements of carrier lifetimes in semiconductors

Abstract: Recently, a simple yet powerful carrier lifetime technique for semiconductor wafers has been introduced that is based on the simultaneous measurement of the light-induced photoconductance of the sample and the corresponding light intensity [Appl. Phys. Lett. 69, 2510 (1996)]. In combination with a light pulse from a flash lamp, this method allows the injection level dependent determination of the effective carrier lifetime in the quasi-steady-state mode as well as the quasi-transient mode. For both cases, approximate solutions (those for steady-state and transient conditions) of the underlying semiconductor equations have been used. However, depending on the actual lifetime value and the time dependence of the flash lamp, specific systematic errors in the effective carrier lifetime arise from the involved approximations. In this work, we present a generalized analysis that avoids these approximations and hence substantially extends the applicability of the quasi-steady-state and quasi-transient methods beyond their previous limits.

Injection level dependence of the defect-related carrier lifetime in light-degraded boron-doped Czochralski silicon

Abstract: The carrier recombination lifetime in light-degraded boron-doped 1 Ω cm Czochralski-grown silicon wafers is measured as a function of the bulk excess carrier concentration Δn. The measurements are performed with the quasi-steady state photoconductance method and cover a large injection level range between 1013 and 1.5×1017 cm−3. We observe a very strong increase of the carrier lifetime in the Δn range between 1014 and 2×1016 cm−3, which is attributed to boron–oxygen (BiOi) defect pairs. The observed strong increase of the defect-related carrier lifetime allows us to determine the previously unknown hole capture cross section σp of the BiOi pair. Our analysis gives a σp value of (0.45–1.2)×10−15 cm2, which is 2–3 orders of magnitude smaller than the corresponding electron capture cross section.

Recent progress on transfer-Si solar cells at ipe Stuttgart

Abstract: This work reports first results on flexible crystalline thin film Si solar cells prepared by transferring single crystalline Si films onto transparent plastic foils. Despite the high absorbance of the plastic superstrates, our very first cells of 4 cm/sup 2/ size show AM 1.5G efficiencies above 14%, for cell thicknesses of 40 /spl mu/m. For cells transferred behind glass superstrates, we have brought the Si-transfer technique to cell efficiencies above 16%. As a new market for flexible solar cells, we identify solar cells integrated into clothing, for the supply of personal electronics such as personal digital assistants, intelligent wrist watches, radios, compact disc players, mobile phones, and other consumer electronics. Here, we report first results on so-called clothing integrated photovoltaics (ipv) of the ipe Stuttgart.

Solar cell efficiency tables (version 37)

Abstract: Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells andmodulesarepresented.GuidelinesforinclusionofresultsintothesetablesareoutlinedandnewentriessinceJune2010arereviewed. Copyright # 2010 John Wiley & Sons, Ltd. KEYWORDSsolar cell efficiency; photovoltaic efficiency; energy conversion efficiency*CorrespondenceMartin A. Green, ARC Photovoltaics Centre of Excellence, University of New South Wales, Sydney 2052, Australia.E-mail: m.green@unsw.edu.auReceived 12 October 2010 1. INTRODUCTION Since January 1993, ‘Progress in Photovoltaics’ haspublished six monthly listings of the highest confirmedefficiencies for a range of photovoltaic cell and moduletechnologies [1–3]. By providing guidelines for theinclusion of results into these tables, this not only providesan authoritative summary of the current state of the art butalso encourages researchers to seek independent confir-mation of results and to report results on a standardisedbasis. In a recent version of these tables (Version 33) [2],results were updated to the new internationally acceptedreferencespectrum(IEC60904–3,Ed.2,2008),wherethiswas possible.Themostimportantcriterionforinclusionofresultsintothe tables is that they must have been measured by arecognised test centre listed elsewhere [1]. A distinction ismade between three different eligible areas: total area;aperture area and designated illumination area [1]. ‘Activearea’ efficiencies are not included. There are also certainminimum values of the area sought for the different devicetypes (above 0.05cm

Status and prospects of Al2O3-based surface passivation schemes for silicon solar cells

Abstract: The reduction in electronic recombination losses by the passivation of silicon surfaces is a critical enabler for high-efficiency solar cells. In 2006, aluminum oxide (Al2O3) nanolayers synthesized by atomic layer deposition (ALD) emerged as a novel solution for the passivation of p- and n-type crystalline Si (c-Si) surfaces. Today, high efficiencies have been realized by the implementation of ultrathin Al2O3 films in laboratory-type and industrial solar cells. This article reviews and summarizes recent work concerning Al2O3 thin films in the context of Si photovoltaics. Topics range from fundamental aspects related to material, interface, and passivation properties to synthesis methods and the implementation of the films in solar cells. Al2O3 uniquely features a combination of field-effect passivation by negative fixed charges, a low interface defect density, an adequate stability during processing, and the ability to use ultrathin films down to a few nanometers in thickness. Although various methods can be used to synthesize Al2O3, this review focuses on ALD—a new technology in the field of c-Si photovoltaics. The authors discuss how the unique features of ALD can be exploited for interface engineering and tailoring the properties of nanolayer surface passivation schemes while also addressing its compatibility with high-throughput manufacturing. The recent progress achieved in the field of surface passivation allows for higher efficiencies of industrial solar cells, which is critical for realizing lower-cost solar electricity in the near future.

Solar cell efficiency tables (version 44)

Abstract: Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since January 2010 are reviewed. Copyright # 2010 John Wiley & Sons, Ltd.