Sample holder development for in-situ EBAC mapping of the uniformity of thin-film conductivity

Electron beam absorbed current (EBAC) microscopy can provide spatially resolved electrical information that conventional probe methods and local scanning probes often miss in nanoparticulate thin films. Here we present the development of a practical scanning electron microscopy (SEM)-based methodology to qualitatively assess conductivity uniformity and electrical continuity in thin films spanning two electrodes using TiO₂ films as a model system. The approach combines a purpose-built insulating holder, readily made without clean-room and advanced lithography access, with embedded electrodes and a measurement configuration to visualize current pathways and identify electrically disconnected regions that may not be apparent from morphology alone. Line scans and 2D maps enable rapid screening of film quality, highlighting cracks, and poor particle connectivity. The workflow is designed for reproducibility and can be adapted to other semiconducting or weakly conducting thin films where microscale continuity is critical to device performance. Fabricate a biasable dual-electrode SEM holder by embedding bent copper plates in an insulating resin body and machining a defined deposition channel (drilled to expose copper + resin in one plane), enabling repeatable electrode gaps and robust external connections for EBAC measurements. Prepare thin films that reliably bridge the electrode gap by using a diluted, well-dispersed nanoparticle suspension (e.g., TiO₂ in IPA) and controlled drop-casting into the channel; confirm continuous coverage using standard SEM imaging before electrical mapping. Map conductivity uniformity in situ using EBAC (line scans and 2D maps under applied voltage) to rapidly locate conductive pathways and diagnose electrically disconnected regions that may appear morphologically continuous, providing a reproducible screening workflow adaptable to other weakly conducting thin films.