Mechanisms, Conditions and Applications of Filament Formation and Rupture in Resistive Memories

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dc.contributor.authorKang, Yuhongen
dc.contributor.committeechairOrlowski, Mariusz Kriysztofen
dc.contributor.committeememberAgah, Masouden
dc.contributor.committeememberHeremans, Jean J.en
dc.contributor.committeememberGuido, Louis J.en
dc.contributor.committeememberManteghi, Majiden
dc.contributor.departmentElectrical and ComputerEngineeringen
dc.date.accessioned2017-05-07T06:00:16Zen
dc.date.available2017-05-07T06:00:16Zen
dc.date.issued2015-11-13en
dc.description.abstractResistive random access memory (RRAM), based on a two-terminal resistive switching device with a switching element sandwiched between two electrodes, has been an attractive candidate to replace flash memory owing to its simple structure, excellent scaling potential, low power consumption, high switching speed, and good retention and endurance properties. However, due to the current limited understanding of the device mechanism, RRAMs research are still facing several issues and challenges including instability of operation parameters, the relatively high reset current, the limited retention and the unsatisfactory endurance. In this study, we investigated the switching mechanisms, conditions and applications of oxygen vacancy (Vo) filament formation in resistive memories. By studying the behavior of conductive Vo nanofilaments in several metal/oxide/metal resistive devices of various thicknesses of oxides, a resulting model supported by the data postulates that there are two distinct modes of creating oxygen vacancies: i) a conventional bulk mode creation, and ii) surface mode of creating oxygen vacancies at the active metal-dielectric interface. A further investigation of conduction mechanism for the Vo CF only based memories is conducted through insertion of a thin layer of titanium into a Pt/ Ta2O5/Pt structure to form a Pt/Ti/ Ta2O5/Pt device. A space charge limited (SCL) conduction model is used to explain the experimental data regarding SET process at low voltage ranges. The evidence for existence of composite copper/oxygen vacancy nanofilaments is presented. The innovative use of hybrid Vo/Cu nanofilament will potentially overcome high forming voltage and gas accumulation issues. A resistive floating electrode device (RFED) is designed to allow the generation of current/voltage pulses that can be controlled by three independent technology parameters. Our recent research has demonstrated that in a Cu/TaOx/Pt resistive device multiple Cu conductive nanofilaments can be formed and ruptured successively. Near the end of the study, quantized and partial quantized conductance is observed at room temperature in metal-insulator-metal structures with graphene submicron-sized nanoplatelets embedded in a 3-hexylthiophene (P3HT) polymer layer. As an organic memory, the device exhibits reliable memory operation with an ON/OFF ratio of more than 10.en
dc.description.degreePh. D.en
dc.format.mediumETDen
dc.identifier.othervt_gsexam:6560en
dc.identifier.urihttp://hdl.handle.net/10919/77593en
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectresistive memoryen
dc.subjectnonvolatile memoryen
dc.subjectoxideen
dc.subjectconductive filamenten
dc.subjectoxygen vacancyen
dc.subjectgrapheneen
dc.subjectquantum conductanceen
dc.subjectspace charge limited conductionen
dc.titleMechanisms, Conditions and Applications of Filament Formation and Rupture in Resistive Memoriesen
dc.typeDissertationen
thesis.degree.disciplineElectrical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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