All ETDs from UAB

Advisory Committee Chair

Yogesh K Vohra

Advisory Committee Members

Shane A Catledge

Mohammad R Haider

Joseph G Harrison

Samuel T Weir

Document Type

Dissertation

Date of Award

2017

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

This work encompasses the development and construction of a state of the art Microfabrication facility to produce diamond-based sensors for applications in extreme environments. The facility utilizes maskless lithography housed in a class 7000 clean room and DC-sputter deposition, along with a 1.2 kW Chemical Vapor Deposition system for the encapsulation of metallic micro-probes in single crystal diamond. Extensive research and development has been applied to developing a novel and reproducible method for fabrication of designer diamond anvils, that feature sensing probes integrated into the diamond anvil and are capable of unobtrusively measuring resistivity of a material whilst simultaneously compressing it to large pressures. Diamond sensors fabricated in the Microfabrication laboratory have been used successfully in numerous high-pressure experiments. We have applied the resistance sensing technology to study various 1-2-2 iron based superconductors, demonstrating that our sensors function extremely well at both high pressures and low temperatures. The sensors have also been implemented in a prototype wireless data transmission diamond anvil cell design for the study of insulator to metal phase transition in GaAs at 17 GPa. In addition to fabricating designer diamond anvils, a novel process for creating two-stage diamond anvils has been developed and has shown promising and reproducible results. Two-stage anvils, in which a small secondary diamond structure is placed on the culet of a traditional primary anvil is a new and pioneering area of significant interest in the high-pressure research community. Two-stage anvils offer the potential of consistently generating ultra-high static pressures in the terapascal regime. We have produced two-stage anvils with a single crystal second stage morphology that have generated pressures as high as 172 GPa, and have more recently adapted the technology to create a nanocrystalline second-stage morphology, with these anvils producing pressures as high as 516 GPa. Extensive research and development has been conducted throughout this dissertation to optimize the fabrication process of diamond based sensors for use in extreme environments. Various characterization techniques have been used to assess sensor quality and efficacy. Reproducibility of our fabrication methods has been demonstrated, indicating that there is commercial viability for this technology. The diamond anvil technology lends itself to far reaching fields of interest, from industry and space exploration, to biomedical and environmental applications; essentially anywhere that extreme environments or conditions are present and durable sensors are required.

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