Identification of the nature of traps involved in the field cycling of Hf0.5Zr0.5O2-based ferroelectric thin films

Bulk Depolarization Fields as a Major Contributor to the Ferroelectric Reliability Performance in Lanthanum Doped Hf0.5Zr0.5O2 Capacitors

“…Moreover, our cycling frequency of 100 kHz also increases the overall stress time substantially compared to former reports where a cycling frequency of 600 kHz is applied . A ferroelectric material typically shows fatigue (decrease of P r with field cycling) before hard breakdown and the effect was explained recently by Islamov et al as generation of additional oxygen vacancies with field cycling which initially trap charges leading to pinning of the domains (fatigue) and eventually when the defect concentration reaches a critical value initiate hard breakdown. Umezawa et al calculated the oxygen vacancy formation energy by first principal simulations in HfO 2 based materials and reported a vacancy formation energy increase from 5.73 to 6.29 eV if the vacancy is in the vicinity of a La atom.…”

“…The endurance characteristics of a ferroelectric capacitor (FeCAP) can be improved by reducing the generation of defects caused by the field cycling stress in the material. Recent literature has revealed oxygen vacancies as the nature of these defects whereby field cycling causes oxygen vacancies to increase in concentration, leading to an increase in leakage current density followed by hard breakdown . Doping the material with La results in a suppression of the generation of oxygen vacancies due to an increase in the oxygen vacancy formation energy, hence the endurance can be improved by La incorporation .…”

A Comprehensive Study on the Effect of TiN Top and Bottom Electrodes on Atomic Layer Deposited Ferroelectric Hf0.5Zr0.5O2 Thin Films

“…This phenomenon, known as oxygen scavenging, can occur further during the RTA process. On the other hand, the oxygen vacancies remaining in the ferroelectric HZO film may degrade the reliability of the fabricated device [ 14 , 22 , 23 ]. Therefore, in order to obtain excellent reliability while maintaining a large ferroelectric polarization, an increase in oxygen vacancies at the interface is not necessarily desirable.…”

Interplay between oxygen defects and dopants: effect on structure and performance of HfO2-based ferroelectrics

“…generalized gradient approximation (GGA) or local density approximation (LDA)], but differences calculated with the same method are more accurate. The hypothesis that neutrally charged defects are predominant and that a lower concentration of charged defects is present has recently been investigated by Islamov et al 22 by combining optical and transport experiments with ab initio simulations and transport modelling. Also in this case, a comparison between calculated and measured optical trap energies confirmed a predominant presence of neutral oxygen vacancies.…”