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Tunnelling in rare-earth nitride structures

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thesis
posted on 23.11.2021, 19:50 by Jackson MillerJackson Miller

GdN thin film device structures, including magnetic tunnel junctions (MTJs), were grown by physical vapour deposition and their electrical properties were investigated. Growth compatibility between GdN and various contact metals (Al, Au, Gd and Nb) was assured using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. I developed a photomask and lithographic process to isolate electrical behaviour perpendicular to the plane of the films. Al and Au were confirmed to make ohmic contact to GdN, while Gd and Nb both formed Schottky-like barriers at the interface with GdN. In MTJ structures, device electrical characteristics were dominated by tunnelling behaviour through the GaN barrier layer. The Simmons model was successfully applied to tunnelling measurements of Al/GdN/GaN/GdN/Gd structured MTJs to determine the barrier properties. MTJs grown with Al bottom contacts were grown with 1.5eV potential barrier height and 2.5 nm width. Finally, MTJs contacted with Nb exhibited a large magnetoresistance (> 500%), greater than GdN-based MTJs recorded in the literature [Warring et al. ”Magnetic Tunnel Junctions Incorporating a Near-Zero-Moment Ferromagnetic Semiconductor”, Phys. Rev. Appl., vol.6, p.044002, 2016].

History

Copyright Date

01/01/2018

Date of Award

01/01/2018

Publisher

Te Herenga Waka—Victoria University of Wellington

Rights License

Author Retains Copyright

Degree Discipline

Physics

Degree Grantor

Te Herenga Waka—Victoria University of Wellington

Degree Level

Masters

Degree Name

Master of Science

ANZSRC Type Of Activity code

970102 Expanding Knowledge in the Physical Sciences

Victoria University of Wellington Item Type

Awarded Research Masters Thesis

Language

en_NZ

Victoria University of Wellington School

School of Chemical and Physical Sciences

Advisors

Natali, Franck