Terahertz Sensing of Å‐scale Thin Dielectric Film Via Electron Tunnelling

Abstract Precise sensing of ultrathin dielectric films is paramount in various fields including nanoscale dielectric characterization, advanced material development, and quality control in microelectronics manufacturing. However, achieving this with conventional detection techniques within the terahertz (THz) frequency range has remained challenging due to their limited sensitivity and resolution. In this study, a novel approach is reported that utilizes Fowler‐Nordheim (FN) tunnelling at a metal‐dielectric junction, which drastically improves the sensitivity to changes in dielectric film thickness down to the Angstrom scale. Through a detailed analysis of both experimental and simulated data, it is demonstrated that the FN tunnelling‐based THz sensing technique exhibits exceptional sensitivity. This finding not only overcomes the limitations of traditional detection techniques, but also paves the way for novel ultrathin film sensing capabilities in the rapidly advancing field of THz technology.