Silicon Solar Cells using Silicon Oxynitride (SIO2:N) for Emitter Surface Passivation

Abstract

Surface passivation in silicon solar cells is an important step for achieving high efficiencies as a consequence of a reduced dark saturation current density simultaneously with an increased illumination current density. One of the methods more often used to achieve such surface passivation is the deposition of thin silicon oxide films on the top surface of the emitter of silicon solar cells. More recently, silicon nitride has been also used, but the reduction of the surface density of states has not been as good as with high quality thermal silicon oxide layers. On the other hand, it has been shown that small quantities of nitrogen introduced in the silicon oxide films may help to reduce such density of states. In this work, we compare the results for silicon solar cells prepared without any silicon oxide layer, cells with a thermal silicon oxide film on the emitter and cells prepared with a passivating silicon oxynitride layer (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> :N), showing that the best efficiency is achieved in the last case