title: In Situ Control of Oxygen Vacancies in TaOxThin Films via Plasma-Enhanced Atomic Layer Deposition for Resistive Switching Memory Applications.
abstract: The plasma-enhanced atomic layer deposition (PEALD) process using Ta(OC2H5)5as a Ta precursor and plasma-activated hydrogen as a reactant for the deposition of TaOxfilms with a controllable concentration of oxygen vacancies (VO) is reported herein. The VOconcentration control was achieved by varying the hydrogen volume fraction of the hydrogen-argon mixture in the plasma, allowing the control of the leakage current density in the tantalum oxide films within the range of 5 orders of magnitude compared with the Ta2O5film grown via thermal ALD using the identical Ta precursor and H2O. Temperature-dependent current-voltage measurements combined with Poole-Frenkel emission modeling demonstrated that the bulk trap depth decreases with the increasing hydrogen volume fraction, which could be attributed to the increase of the VOconcentration. The possible chemical change in the PEALD TaOxfilms grown under different hydrogen volume fractions was confirmed by the in situ X-ray photoelectron spectroscopy (XPS) measurements of the Ta 4f core and valence band spectra. The comparison of the XPS-measured nonstoichiometry and the secondary ion mass spectrometry analysis of the hydrogen content allowed this study to conclude that the nonstoichiometry is largely related to the formation of Ta-VOsites rather than of Ta-H sites. Such oxygen-deficient TaOxlayers were studied for application as an oxygen-deficient layer in a resistance switching random access memory stack (Ta2O5/TaOx) where the actual switching occurred within the stoichiometric Ta2O5layer. The bilayer memory stack showed reliable resistance switching up to ∼106switching cycles, whereas the single-layer Ta2O5memory showed only several hundred switching cycles.
authors.affiliation: Moscow Institute of Physics and Technology , Institutskii Lane 9, 141700 Dolgoprudny, Russian Federation.
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Egorov
authors.affiliation: Moscow Institute of Physics and Technology , Institutskii Lane 9, 141700 Dolgoprudny, Russian Federation.
authors.forename: Dmitry S
authors.initials: DS
authors.lastname: Kuzmichev
authors.affiliation: Chemistry Department, Moscow State University , Leninskie Gory 1, 119992 Moscow, Russian Federation.
authors.forename: Pavel S
authors.initials: PS
authors.lastname: Chizhov
authors.affiliation: Moscow Institute of Physics and Technology , Institutskii Lane 9, 141700 Dolgoprudny, Russian Federation.|National Research Nuclear University , Moscow Engineering Physics Institute, Kashirskoye Shosse 31, 115409 Moscow, Russian Federation.
authors.forename: Yuri Yu
authors.initials: YY
authors.lastname: Lebedinskii
authors.affiliation: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 08826, Republic of Korea.
authors.forename: Cheol Seong
authors.identifier: http://orcid.org/0000-0002-6254-9758
authors.initials: CS
authors.lastname: Hwang
authors.affiliation: Moscow Institute of Physics and Technology , Institutskii Lane 9, 141700 Dolgoprudny, Russian Federation.
authors.forename: Andrey M
authors.initials: AM
authors.lastname: Markeev
keywords: PEALD; ReRAM; TaOx; hydrogen plasma; reliability