Effects of a Series Resistor on Electron Emission Characteristics of a Dissimilar Metallic Nanogap

This study investigates the tunneling current in nanoscale asymmetric metal-insulator-metal (MIM) junctions integrated with a series resistor, with an emphasis on how geometric and material asymmetries, combined with quantum transport effects, shape the overall device response. Through a comprehensive parametric analysis, we identify the critical conditions under which the series resistor significantly alters device behavior—particularly in configurations with small insulator thickness and high bias voltage, where the intrinsic junction impedance approaches the resistor value. In these regimes, a transition emerges from nonlinear, quantum-tunneling limited [1],[2] transport to Ohmic-limited conduction. We show that the series resistor not only acts as a passive current limiter but also actively suppresses forward/reverse bias asymmetry and nonlinearity, effectively modulating transport symmetry. To quantitatively capture these effects, we introduce current reduction ratios and asymmetry indices, revealing how device behavior scales with key parameters such as barrier height, voltage, and work function difference. Contour plots of gap impedance/series resistance ratio Z/R as a function of barrier height and voltage reveal a clear transition boundary, whose position shifts with barrier height and material asymmetry—highlighting their exponential influence on transport. Our findings underscore the interplay between quantum tunneling and circuit-level resistance, demonstrating that the resistor can serve not merely as a parasitic element, but as a design lever for achieving controlled symmetry, stability[3],[4], and tunability in nanoelectronic devices. These insights contribute to a deeper understanding of how structural and electrical asymmetries govern quantum transport, informing the development of robust nanoscale switching and emission systems.