Direct Measurement\nof Carrier Distribution in Perovskite\nby Scanning Capacitance Microscopy

This study successfully applies scanning capacitance\nmicroscopy\n(SCM) to organic–inorganic metal halide perovskite materials,\nproviding detailed insights into the microscopic distribution of carrier\nconcentrations and types. We developed and optimized an alumina (Al<sub>2</sub>O<sub>3</sub>) insulating layer using atomic layer deposition,\nwith a 5 nm thickness at 398.15 K proving optimal for minimizing defects\nat the Al<sub>2</sub>O<sub>3</sub>/perovskite interface. Further optimizations\nincluded selecting an appropriate probe for high-contrast SCM imaging,\nreducing stray capacitance by scanning at sample edges, and analyzing\nthe effects of light illumination. Our results show that perovskite\nfilms with excess PbI<sub>2</sub> in the precursor had a more uniform\ncarrier distribution and higher overall carrier concentration. Additionally,\nwe identified distinct p-type and n-type regions in perovskite materials\nmodified with polar molecular additives. This work enables SCM as\na robust technique for investigating complex carrier behaviors in\nperovskite materials.