Ozone-based Surface Conditioning Focused on an Improved Passivation for Silicon Heterojunction Solar Cells

Abstract Silicon Heterojunction (SHJ) solar cells represent a key technology to approach very high conversion efficiencies close to the theoretical limit of silicon solar cells. The main advantages of SHJ solar cells are a lean production chain with low temperature processes and the passivating hetero-structure contact which simultaneously fulfils the passivation and contacting role. For an improved passivation a smooth and low-defect concentration surface is required. This paper focuses on a new simple, cost effective and production-feasible ozone-based surface conditioning process for the controlled rounding and smoothing of textured surfaces applied in SHJ solar cells. The impact of surface conditioning on optical and morphological properties is analyzed for alkaline textured surfaces with small to medium and large size pyramids by reflection measurements and high resolution imaging methods as scanning electron microscopy (SEM) and atomic force microscopy (AFM).