Tunnelling is a quantum mechanical effect which becomes significant in plasmonic systems with nanogap regions. In a system of closely spaced metal nanoparticles plasmon tunnelling plays an important role in the transfer of energy and hence governs the optical properties of the system. Plasmon assisted tunnelling through a system depends on the skin depth of the material in consideration, which in turn is controlled by the wavelength of incident light. Here, we present, ‘gradient potential dependent skin-depth theory (GPST)’ explaining resonant plasmons assisted tunnelling through metal nanoparticles for the operating wavelength of 1.1 μm. For a system of silver nanodisk dimer with sub-nanometer interparticle distance, the nanogap region between adjacent nanodisks give rise to gradient potential forming the tunnelling zone and is verified by finite difference time domain computational method. The energy eigenvalues and corresponding eigen frequencies are obtained for the dimer system. The proposed GPST can predict the behaviour of plasmon tunnel diode, plasmonic Josephson junction assisted superconductivity, plasmon tunnelled field-effect transistors etc. significantly improving the performance of integrated circuits.

隧道效应是一种量子力学效应，在具有纳米间隙区域的等离子体系统中变得十分重要。在紧密间隔的金属纳米粒子系统中，等离激元隧穿在能量转移中起着重要作用，因此支配着系统的光学性质。通过系统的等离子辅助隧穿取决于所考虑材料的表皮深度，而表皮深度又由入射光的波长控制。在这里，我们介绍了“梯度势相关的趋肤深度理论（GPST）”，该信号解释了共振等离子体激元在1.1 nm的工作波长下辅助穿过金属纳米颗粒的隧穿。对于具有亚纳米粒子间距离的银纳米盘二聚体系统，相邻纳米盘之间的纳米间隙区域产生了形成隧道区的梯度电势，并通过时域有限差分计算方法进行了验证。获得了二聚体系统的能量本征值和相应的本征频率。所提出的GPST可以预测等离子体激元隧道二极管，等离子体激元约瑟夫逊结辅助超导，等离子体激元隧道效应场效应晶体管等的行为，从而显着提高集成电路的性能。