Evaluation of HfO-Based Ferroelectric Resonant Tunnel Junction by Band Engineering

The HfO2-based ferroelectric (FE) tunnel junction (FTJ) and its crossbar array are promising for energy-efficient computing. However, its limited ON- current (JON) and ON/OFF tunneling electroresistance (TER) ratio become a bottleneck for large array circuits. We theoretically propose using a low-barrier Ta2O5 dielectric to enhance the device asymmetry, instead of SiO2 or Al2O3. Through resonant band engineering by inserting Ta2O5 between two FE HfO2 barriers, both JON and TER ratio are enhanced by several orders of magnitude, while a good retention is maintained benefiting from high permittivity of Ta2O5; besides, high current rectification ratio and negative differential resistance are observed. These abundant physical effects in HfO2/Ta2O5/HfO2 based MFIFM resonant FTJ may enable selector-less crossbar.