Surface photovoltage characterizations of Si nanopillar arrays for verifying field-effect passivation using a SiNx layer

•Surface photovoltage (SPV) characteristics of Si nanopillar arrays investigated.•SPV characterization with nanoscopic spatial resolution carried out using Kelvin probe force microscopy.•SPV of SiNx-coated nanopillars increased by positive fixed charges in the SiNx layer.•SPV measurements useful for quantitative investigation of surface electrical properties of the Si nanopillars.

The surface photovoltage (SPV) characteristics of periodic nanopillar (NP) arrays formed on Si wafers were investigated. The NP arrays exhibited broadband omnidirectional antireflection effects with Mie resonance. Kelvin probe force microscopy (KPFM) revealed that the positive fixed charges in SiNx layers induced band bending at the Si surface and increased surface photovoltage (SPV) at the NP top surface. Estimated SPV values, determined by the amount of surface band bending, were similar in NPs and planar counterparts. This finding suggests that field effect passivation by the dielectric layer coating could help improve photovoltaic performance of nanostructure-based Si solar cells and that KPFM may be a useful tool for the investigation of surface electrical properties of Si nanostructures.