Date of Award

1-1-2017

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Nanoscale Science and Engineering

Program

Nanoscale Sciences

Content Description

1 online resource (ii, xvii, 89 pages) : illustrations (some color)

Dissertation/Thesis Chair

Hassaram Bakhru

Committee Members

Vincent LaBella, Ji Ung Lee, Toh-Ming Lu

Keywords

Device physics, Ion beam analysis, Ion implantation, Magnetic nanoparticles, Magnetoresistance, Silicon Spintronics, Annealing of crystals, Ferromagnetism, Nanostructured materials, Spintronics, Trapped ions

Subject Categories

Materials Science and Engineering | Nanoscience and Nanotechnology | Physics

Abstract

Integrating magnetic functionalities with silicon holds the promise of developing, in the most dominant semiconductor, a paradigm-shift information technology based on the manipulation and control of electron spin and charge. Here, we demonstrate an ion implantation approach enabling the synthesis of a ferromagnetic layer within a defect free Si environment by exploiting an additional implant of hydrogen in a region deep below the metal implanted layer. Upon post-implantation annealing, nanocavities created within the H-implanted region act as trapping sites for gettering the implanted metal species, resulting in the formation of metal nanoparticles in a Si region of excellent crystal quality. This is exemplified by the synthesis of magnetic nickel nanoparticles in Si implanted with H+(range: ~850 nm; dose: 1.5×1016 cm-2)and Ni+ (range: ~60 nm; dose:2×1015 cm-2).Following annealing, the H implanted region populated with Ni nanoparticles of size (~ 10-25 nm) and density (~ 1011/cm2) typical of those achievable via conventional thin film deposition and growth techniques. In particular, a maximum amount of gettered Ni atoms occurs after annealing at 900 C, yielding strong ferromagnetism persisting even at room temperature, as well as fully recovered crystalline Si environments adjacent to these Ni nanoparticles. Furthermore, Ni nanoparticles capsulated within a defect-free crystalline Si layer exhibit a very high magnetic switching energy barrier of ~ 0.86 eV, an increase by about one order of magnitude as compared to their counterparts on a Si surface or in a highly defective Si environment.

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