BBr3 Boron Diffusion Process for p+-Emitter Formation of n-Type Silicon Solar Cells

Autor: Michael Kessler

ISBN: 978-3-944586-18-2

Dissertation, Leibniz Universität Hannover, 2013

Herausgeber der Reihe: Rolf Brendel

Umfang: 147 Seiten, 55 Abbildungen

Schlagworte: BBr3 boron diffusion, boron emitter, boron-rich layer (BRL)

Kurzfassung: The liquid-source BBr₃ technology to diffuse a boron p⁺-emitter is the state-of-the-art laboratory technology for p-type emitter formation and is a feature of the current world record silicon solar cell with η = 25.0%. Nevertheless the BBr₃ boron diffusion process for p⁺-emitter formation is little spread in industrial cell manufacturing due to technological challenges.
A detailed experimental study shows the implications of the formation of an undesirable boron-rich layer (BRL) during the boron diffusion process. The passivation of boron emitter surfaces is investigated experimentally and using numerical simulations. Based on an industrial manufacturing scheme an n-type solar cell with boron emitter and in-line evaporated aluminum grid is developed and reaches a conversion efficiency of η = 19.6%. The results of this work can help to accelerate the industrial implementation of boron p⁺-emitters for n-type silicon solar cells.