Wet Chemical Oxidation of Silicon Surfaces Prior to the Deposition of All-PECVD AlO<sub>x</sub>/<i>a</i>-SiN<sub>x</sub> Passivation Stacks for Silicon Solar Cells

Abstract

Aluminum oxide (AlO x ) is currently under intensive investigation for use in surface passivation schemes in solar cells. AlO x films contain negative charges and therefore generate an accumulation layer on p-type silicon surfaces, which is very favorable for the rear side of p-type silicon solar cells as well as the p + -emitter at the front side of n-type silicon solar cells. However, it has been reported that quality of an interfacial silicon sub-oxide layer (SiO x ), which is usually observed during deposition of AlO x on Silicon, strongly impacts the silicon/AlO x interface passivation properties [1]. The present work demonstrates that a convenient way to control the interface is to form thin wet chemical oxides of high quality prior to the deposition of AlO x / a -SiN x :H stacks by the plasma enhanced chemical vapor deposition (PECVD).