Charge trapping and storage in SiN<inf>x</inf> thin films deposited with Oxford PlasmaLab 100 system

Abstract

Negative charges in silicon nitride films are beneficial for surface passivation of rear side of p type solar cells.[1] Previous studies indicates that N-rich SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> films in an oxide-nitride-oxide structure display good charge trapping and storage ability. In this work, an Oxford PlasmaLab 100 PECVD system is used to vary the deposition conditions (temperature and RF power). SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> films deposited at 400°C and RF=60W show an initial negative charge density of 1.2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> after negative charge injection. Modeling results suggest that tunnel oxide may not be necessary for achieving good charge stability, which will make the application more flexible.