Physical Modeling of Resonant Tunneling in Ferroelectric Tunnel Junctions With Multiple Quantum Well Superlattice Heterostructures

Resonant tunneling (RT) in ferroelectric tunnel junction (FTJ) with multiple quantum well (QW) superlattice heterostructures are elucidated by physical modeling of quantum transport and ferroelectric polarization in single-, double-, and triple QW cases. The quasi-bound states can form in the QW structure and can give rise to the RT phenomenon. The ferroelectric polarization switchable by an applied electric field can shift the discrete energy levels. Compared with conventional bilayer FTJ, the FTJs with QWs provide RT-enhanced tunneling electroresistance effect, negative differential resistance (NDR), and rectification properties. The dependence of current-voltage characteristics on the QW number, sweep bias range, and film thicknesses are explained through a competition between RT and direct tunneling. Within these structures, due to a broken symmetry along the transport direction stemming from the asymmetry of the polarization charges and device structure, electrons undergo highly asymmetric RT injection that depends on the direction of the applied electric field and ferroelectric polarization. These theoretical predications shed light on the design of advanced ferroelectric HfO2-based FTJ as required for emerging memory technologies.