Depolarization-Field-Induced Retention Loss in Ferroelectric Diodes

$R\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n$ is of critical concern when a memory device stores data. While ferroelectric diodes continue to emerge as a promising memory technology, their retention behavior and underlying physics have not been well investigated. This paper proposes a theoretical model for retention loss in ferroelectric diodes, combining polarization relaxation kinetics and polarization-controlled Schottky emission. The model describes well the behavior of metal/BiFeO${}_{3}$/La${}_{0.7}$Sr${}_{0.3}$MnO${}_{3}$ diodes, and explains the dependences of retention-loss rate on BiFeO${}_{3}$ thickness and electrode screening. These findings should help to guide the development of reliable ferroelectric memory devices.