Unveiling Resistance Switching Mechanisms in Undoped HfOx Ferroelectric Tunnel Junction Using Low-Frequency Noise Spectroscopy

We demonstrate that the resistance switching (RS) of an undoped hafnium oxide (HfOx)-based ferroelectric tunnel junction (FTJ) is affected not only by ferroelectric domain switching of HfOx but also by the redistribution of oxygen vacancies inside HfOx, known as the working principle of resistive random-access memory. It is revealed that the RS mechanism varies depending on the program bias applied to FTJ. Through low-frequency noise spectroscopy, a precise method for distinguishing two distinct RS processes intrinsic to FTJ is presented.