Improved Ferroelectric Performance of Mg-Doped LiNbO3 Films by an Ideal Atomic Layer Deposited Al2O3 Tunnel Switch Layer

Yan Zhang,Jun Jiang,Qing Hua Ren,Xiao Jie Chai,Jian Guo Yang,An Quan Jiang

doi:10.1186/s11671-019-2970-6

Abstract

Bilayer structures composed of 5% Mg-doped LiNbO3 single-crystal films and ultrathin Al2O3 layers with thickness ranging from 2 to 6 nm have been fabricated by using ion slicing technique combined with atomic layer deposition method. The transient domain switching current measurement results reveal that the P-V hysteresis loops are symmetry in type II mode with single voltage pulse per cycle, which may be attributed to the built-in electric field formed by asymmetric electrodes and compensation of an internal imprint field. Besides, the inlaid Al2O3, as an ideal tunnel switch layer, turns on during ferroelectric switching, but closes during the post-switching or non-switching under the applied pulse voltage. The Al2O3 layer blocks the adverse effects such as by-electrode charge injection and improves the fatigue endurance properties of Mg-doped LiNbO3 ferroelectric capacitors. This study provides a possible way to improve the reliability properties of ferroelectric devices in the non-volatile memory application.

Highlights

Lithium niobate (LN) single-crystal films, due to their excellent physical properties, [1–6] have been widely used in surface acoustic wave oscillators, electro-optic modulators, and data storage based on the domain switching
The imprint hysteresis loop originated from preferred orientations and the poor fatigue endurance of LN films, due to by-electrode charge injection, destabilize the retention of polarization reversal, which limits their application in non-volatile memory devices [10–13]
The thinner lithium niobate single crystal thin films on silicon substrates are the promising materials for integrated ferroelectric domain-wall memories and its retention and fatigue endurance properties can be improved by design of Al2O3/ lithium niobate bilayer

Summary

Background

Lithium niobate (LN) single-crystal films, due to their excellent physical properties, [1–6] have been widely used in surface acoustic wave oscillators, electro-optic modulators, and data storage based on the domain switching. Wafer-scale lithium niobate-on-insulator (LNOI), which has great potential application for high-density integrated circuits in electro-optic, acousto-optic, and data storage devices, is fabricated by an ion implantation and wafer bonding technology. This technology allows for a wide variety of substrates, such as LN, silicon, and even the CMOS circuit [3, 7–9]. The imprint hysteresis loop originated from preferred orientations and the poor fatigue endurance of LN films, due to by-electrode charge injection, destabilize the retention of polarization reversal, which limits their application in non-volatile memory devices [10–13]. It proves that the inlaid Al2O3 layer plays as a tunnel switch layer, which can turn up during the ferroelectric switching and close after completed polarization switching or no switching operation

Methods

Conclusions