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

• Introduced a novel hyperspectral conductive AFM technique for studying single electron tunneling in ultrathin films. • Demonstrated sensor potential of Pd-ZrO 2 nanogranular films by controlling single-electron tunneling. • Combined experimental data with theoretical models to explain tunneling mechanisms in sensor applications. This study maps the electrical behavior across a 7 × 7 μm 2 nanogranular ultrathin Pd-ZrO 2 film, revealing nonlinear I-V characteristics indicative of single-electron tunneling. Following the Coulomb blockade power law I ∼ (V − V t ) ξ with a scaling exponent ξ ≈ 1.2, these characteristics appear above the threshold voltage V t . By modeling the nanogranular structure as a 1D array of multitunnel junctions, we demonstrate a linear relationship between V t and tunnel channel length, allowing for a better understanding of nanoscale electrical properties and supporting the development of sensitive sensors.