Defect engineering during the contact co‐firing step in an industrial belt furnace

Abstract

This work implements an optimization of the phosphorus gettering effect during the contact co‐firing step by means of both simulations and experiments in an industrial belt furnace. An optimized temperature profile, named ‘extended co‐firing step’, is presented. Simulations show that the effect of the short annealing on the final interstitial iron concentration depends strongly on the initial contamination level of the material and that the ‘extended co‐firing’ temperature profile can enhance the gettering effect within a small additional time. Experimental results using sister wafers from the same multicrystalline silicon ingot confirm these trends and show the potential of this new defect engineering tool to improve the solar cell efficiency (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Impact of Extended Contact Cofiring on Multicrystalline Silicon Solar Cell Parameters

“…1. Similar results were found studying the phosphorus gettering effect during the co-firing step without using screen-printed metal pastes [5], [6].…”

“…They have received a POCl 3 diffusion obtaining a sheet resistance of 35 Ω/ , HF-dip for phosphorus-silicate glass removal, silicon nitride (SiN x ) Plasma-Enhanced Chemical Vapor Deposition (PECVD) on the front surface, front Ag-paste and rear Al-paste screen-printing, and standard or extended co-firing (with a 100 seconds annealing) in an in-line belt furnace, using similar recipes as the temperature profiles presented in Ref. [6]. Reference samples for lifetime measurements follow the process, and after each step surface layers are etched, chemical cleaning is performed and fresh SiN x is deposited on both surfaces to evaluate the bulk quality.…”

“…Predictive Impurity-to-Efficiency simulations [5], [6] show a relative increase of dissolved iron during the standard co-firing step between 200% and 1000% for materials with high total contamination concentration (with initial total Fe concentrations between 10 15 and 10…”

Influence of Back Contact Annealing Temperature in the mc-Si Solar Cell Fabrication Process

“…Shiliang Wu et al investigated the electrical properties of mc-Si solar cell by the different front contact firing [7]. Extended co-firing was done by Ana Peral et al [8]. For all type of solar cell making optimization of the Series and Shunt resistance is needed.…”

Darwin at High Temperature: Advancing Solar Cell Material Design Using Defect Kinetics Simulations and Evolutionary Optimization

“…[ 1,[61][62][63] In this study, we focus on the process step with the largest potential for iron redistribution: phosphorus diffusion gettering, the process step with the largest thermal budget after crystallization. The primary purpose of phosphorus diffusion is forming the n + -type region of the n + -p junction, but this phosphorus-rich region simultaneously acts as an external gettering layer for many metal impurities, including iron.…”