Unveiling single-electron tunneling in nanogranular ultrathin films for sensor applications via hyperspectral conductive AFM

Abstract

This study maps the electrical behavior across a 7 × 7 μm2 nanogranular ultrathin Pd-ZrO2 film, revealing nonlinear I-V characteristics indicative of single-electron tunneling. Following the Coulomb blockade power law I ∼ (V − Vt)ξ with a scaling exponent ξ ≈ 1.2, these characteristics appear above the threshold voltage Vt. By modeling the nanogranular structure as a 1D array of multitunnel junctions, we demonstrate a linear relationship between Vt and tunnel channel length, allowing for a better understanding of nanoscale electrical properties and supporting the development of sensitive sensors.