Accelerated deactivation of the boron?oxygen-related recombination centre in crystalline silicon
A significant acceleration of the permanent deactivation of the boron–oxygen-related recombination centre in crystalline silicon is observed if the samples are exposed to the plasma during plasma-enhanced chemical vapour deposition (PECVD) of a hydrogen-rich silicon nitride (SiNx) layer. Similar deactivation rate constants are measured in samples passivated with hydrogen-rich SiNx deposited without plasma exposure and hydrogen-lean aluminium oxide (Al2O3) deposited with plasma-assisted atomic layer deposition, suggesting that the critical parameter responsible for the acceleration is not the hydrogen content in the dielectric layer. Instead, we propose increased in-diffusion of hydrogen during or after the deposition of the PECVD SiNx layer, for example due to surface damage caused by plasma exposure, as the cause for the acceleration.