© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Phys. Status Solidi RRL, 1–4 (2014) / DOI 10.1002/pssr.201409295 The effect of annealing ambient on carrier recombination in boron implanted silicon Thomas Ratcliff *, 1 , Kean Chern Fong 1 , Avi Shalav 2 , Robert Elliman 2 , and Andrew Blakers 1 1 Centre for Sustainable Energy Systems, Australian National University, Building 32 North Road, ACT 0200, Australia 2 Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, ACT 0200, Australia Received 23 June 2014, revised 1 August 2014, accepted 6 August 2014 Published online 12 August 2014 Keywords ion implantation, boron, annealing, oxidation, carrier recombination, silicon solar cell emitters, sheet resistance * Corresponding author: e-mail tom.ratcliff@anu.edu.au, Phone: +612 6125 0078 © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction The use of ion implantation for the formation of heavily doped regions in silicon solar cells of- fers significant process simplification compared with tradi- tional diffusion-based processes, especially for advanced Si solar cell structures that require patterned doping such as interdigitated back contact cells [1]. The application of ion implantation in industrial Si solar cell manufacturing has also been shown to yield improved uniformity and con- trol [2]. Following implantation, high temperature process- ing is required to electrically activate dopant atoms and re- pair implantation damage. However, secondary defects are likely to form during annealing and may cause increased Shockley–Read–Hall recombination of minority carriers reducing the overall conversion efficiency of the device. For boron implantation, defects such as dislocation loops and boron-interstitial clusters have been identified as pos- sible causes of high recombination [3, 4]. Boron-interstitial clusters (BICs) are comprised of electrically inactive boron atoms and silicon interstitials and can form at concentrations below the boron solid solu- bility limit [5]. Extrinsic dislocation loops are also known to form during annealing of Si that has been implanted beyond a critical implant fluence [6, 7]. Both BICs and dislocation loops form due to a local supersaturation of interstitial silicon atoms resulting from implantation dam- age. The selection of either an oxidising or inert ambient during high temperature annealing is shown to affect dopant activa- tion and electron–hole recombination in boron implanted silicon samples. Samples implanted with B at fluence be- tween 3 × 10 14 cm –2 to 3 × 10 15 cm –2 are shown to have lower dopant activation after oxidation at 1000 °C compared to an equivalent anneal in an inert ambient. In addition, emitter re- combination is shown to be up to 15 times higher after oxida- tion compared with an inert anneal for samples with equiva- lent passivation from deposited Al 2 O 3 films. The observed in- crease in recombination for oxidised samples is attributed to the enhanced formation of boron-interstitial defect clusters and dislocation loops under oxidising conditions. It is also shown that an inert anneal for 10 minutes at 1000 °C prior to oxidation has no significant impact on sheet resistance or re- combination compared with a standard oxidation process. J 0p+ as a function of sheet resistance for Al 2 O 3 passivated samples after 1000 °C anneal for 70 minutes.