Resonant tunneling properties of inverse parabolic multibarrier structures: a non-equilibrium green’s function approach

Abstract

We present a theoretical investigation aimed at understanding how external electric fields influence resonant tunneling and quantum transport in inverse parabolic multibarrier semiconductor heterostructures. The main problem addressed is the lack of comprehensive studies describing field-induced localization and miniband modulation in smoothly varying potential profiles. The analysis is carried out using the non-equilibrium Green’s function formalism with the finite element method, which allows accurate determination of transmission spectra, resonant energy levels, and current density-voltage characteristics. Our results highlight the strong dependence of resonant tunneling features on the structural parameters of the system, including the number of barriers, as well as the width of wells and height of barriers. It is found that increasing the number of barriers enhances the complexity of the transmission spectrum, leading to sharper resonant peaks and modified miniband formation. Furthermore, the application of an external electric field introduces a substantial shift in the resonant energy levels and significantly alters the transmission probability. Numerical results indicate that for a field-free structure, unity transmission occurs at specific resonance energies (E 20–250 meV for NB = 2 and 5), while under a high electric field (F = 50 kV/cm), the transmission significantly decreases and resonance peaks vanish due to wave localization. The calculated current–voltage characteristics reveal a pronounced negative differential resistance behavior. As the barrier height increases from 250 meV to 500 meV, the NDR region broadens while the peak-to-valley current ratio decreases. These findings emphasize the tunability of inverse parabolic multibarrier structures and their potential applications in high-frequency nanoelectronic and quantum device technologies.