Optical properties and passivation effects of silicon nitride three layer stacks deposited by plasma enhanced chemical vapor deposition

In this work, we investigate the optical properties and passivation effects of silicon nitride stacks deposited by the plasma enhanced chemical vapor deposition (PECVD) system. A stack of three SiNx:H layers with different refractive indices were deposited at 310 °C using silane (SiH4) and ammonia (NH3) as precursor gases. The chemical composition of the films was modulated by varying the gas flow ratio r = [NH3]/[SiH4]. Details of the optical optimization procedure are presented. Thanks to spectrophotometric and spectroscopic ellipsometry measurements we confirmed the suitability of a three layered SiNx:H stack for antireflective coating. Passivation effects were evaluated by measurements of effective carrier lifetimes. Simulated short‐circuit currents were also calculated for two fixed internal quantum efficiency IQE spectra. It was found that a triple‐layered silicon nitride coating provides lower optical reflection and better passivation for silicon p‐type than those of a single‐layered silicon nitride coating.