Recombination and Contact Properties in Metallised Rear Side Regions of PERC Cells

We study the laser contact opening as used in industrial PERC solar cells. We open Al2O3/SiN multilayer with a nanosecond Flat-Top laser and apply Al screen printing and firing. As already published, we confirm that the surface recombination velocity decreases with increasing line width. Accordingly, with the ns laser we achieve Scont values as low as 400 cm/s for line widths above 100 µm, and Scont values of 600 cm/s for 40 µm wide lines. On the contrary, the contact resistance tends to increase slightly with the line width to values around 10 Ω cm 2 . Low values of these two parameters are due to an Al-BSF layer, either grown after Al-Si re-solidification after firing or by laser doping before firing. We show evidences of laser doping for ns laser, whereas this effect for ps laser seems to play a very minor role, if any.

[1]  R. Brendel,et al.  Inductively coupled plasma chemical vapour deposited AlOx/SiNy layer stacks for applications in high-efficiency industrial-type silicon solar cells , 2013 .

[2]  Isidro Martín García,et al.  Low Recombination n+ Regions Created by n+ c-Si Epitaxial Layers and Laser Processing of Phosphorus-Doped SiCx Films , 2012 .

[3]  T. Pernau,et al.  Advanced Anti-Reflection and Passivation Layer Systems Produced by High-Power Plasma in the New Manz PECVD System , 2012 .

[4]  Hartmut S. Leipner,et al.  Proof of damage-free selective removal of thin dielectric coatings on silicon wafers by irradiation with femtosecond laser pulses , 2012 .

[5]  K. Bothe,et al.  Modeling the formation of local highly aluminum‐doped silicon regions by rapid thermal annealing of screen‐printed aluminum , 2012 .

[6]  K. Bothe,et al.  Contact Formation and Recombination at Screen-Printed Local Aluminum-Alloyed Silicon Solar Cell Base Contacts , 2011, IEEE Transactions on Electron Devices.

[7]  Andreas Wolf,et al.  Comprehensive analytical model for locally contacted rear surface passivated solar cells , 2010 .

[8]  Ulrich Klug,et al.  Laser ablation of SiO2 for locally contacted Si solar cells with ultra‐short pulses , 2007 .

[9]  R. Sinton,et al.  Contactless determination of current–voltage characteristics and minority‐carrier lifetimes in semiconductors from quasi‐steady‐state photoconductance data , 1996 .

[10]  B. Wolff-Rottke,et al.  Nanosecond and femtosecond excimer-laser ablation of oxide ceramics , 1995 .

[11]  K. Ramspeck,et al.  Industrial high performance crystalline silicon solar cells and modules based on rear surface passivation technology , 2014 .

[12]  Jens Müller,et al.  Analysis and optimization of the bulk and rear recombination of screen-printed PERC solar cells , 2012 .

[13]  Minghui Hong,et al.  Rear-Side Contact Opening by Laser Ablation for Industrial Screen-Printed Aluminium Local Back Surface Field Silicon Wafer Solar Cells , 2012 .