Comprehensive model for interface recombination at a‐Si:H/c‐Si interfaces based on amphoteric defects

Abstract

AbstractToday, most fabricated solar cells are made of crystalline Silicon (c‐Si) wafers. Electronic passivation of defect states at interfaces is a major issue in recent cell development. A current topic is surface passivation using hydrogenated amorphous Silicon (a‐Si:H). The purpose of this paper is to describe recombination at the a‐Si:H/c‐Si interface by a comprehensive model considering recombination via amphoteric defects. The density of defect states at the interface (Dit) is modeled via the Defect‐Pool‐Model(DPM), adapted to a‐Si:H/c‐Si interfaces by fitting to published experimental data. Since our model accounts for the amphoteric nature of defects at the hetero‐interface, and approximates Dit by a physical model, parameters are physical more meaningful and allow for an investigation of measured recombination properties. A numerical comparison between different recombination models shows that using amphoteric recombination statistics is more generally applicable. The purpose is to apply the model in numerical semiconductor device simulators for accurate modeling of a‐Si:H passivated c‐Si solar cells. Limitations of cell performance due to interface recombination can then be traced back to physical parameters which helps to optimize cell designs (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)