Cubic boron nitride (c-BN), hexagonal boron nitride (h-BN), and semiconducting diamond all have physical properties that make them ideal materials for applications in high power and high frequency electronics, as well as radiation detectors. However, there is limited research on the unique properties and growth of c-BN or h-BN thin films. This dissertation addresses the deposition of c-BN via plasma enhanced chemical vapor deposition (PECVD) on boron doped diamond substrates. In-Situ X-ray photoelectron spectroscopy (XPS) is used to characterize the thickness and hexagonal to cubic ratio of boron nitride thin films. The effects of hydrogen concentration during the deposition of boron nitride are investigated. The boron nitride deposition rate is found to be dependent on the hydrogen gas flow. The sp2 to sp3 bonding is also found to be dependent on the hydrogen gas flow. Preferential growth of h-BN is observed when an excess of hydrogen is supplied to the reaction, while h-BN growth is suppressed when hydrogen flow is reduced to be the limiting reactant. Reduced hydrogen flow is also observed to promote preferential growth of c-BN. The hydrogen limited reaction is used to deposit c-BN on single crystal (100) boron-doped diamond substrates. In-situ ultra-violet photoelectron spectroscopy (UPS) and XPS are used to deduce the valence band offset of the diamond/c-BN interface. A valence band offset of -0.3 eV is measured with the diamond VBM above the VBM of c-BN. This value is then discussed in context of previous experimental results and theoretical calculations. Finally, UPS and XPS are used to characterize the surface states of phosphorus-doped diamond. Variations within the processing parameters for surface preparation and the effects on the electronic surface states are presented and discussed.

In this project we are analyzing the diamond-titanium interface as it applies to diamond-based diode devices, including alpha particle, proton, and neutron detectors. This is done through the fabrication of an O-terminated B-doped diamond sample with a 20 Å Ti / 10 Å Pt overlayer which was then annealed and examined via X-ray photoelectron spectroscopy (XPS). It was discovered that after annealing the sample at temperatures ranging from 400 C - 900 C that TiC was not formed at any point during this experiment. Possible reasons for this include a lack of sufficient titanium in order to form TiC and over oxygenating the diamond surface before the metal was deposited.

This project details the learning of processes in nanofabrication and sensor detection fields. We sought to apply this knowledge to develop a processing procedure to fabricate sensors used to detect high energy protons.  We seek to create such a sensor to be applied to aid Mayo Clinic’s Proton Beam Therapy center for cancer treatment through providing beam detection measurements. Developed plans would allow for proton beam detectors to be able to measure beam intensity and direction which would allow for more accurate beam treatments. Current detectors require much calibration and solid state detectors can’t withstand the high-energy exposure of the proton beam for long durations. By fabricating pixelated diamond sensors we expect to produce sensitive beam readings, while extending detector length time due to diamonds durable crystalline lattice. We report processing procedures for simple 2-3 contact detectors as well as more complex multi-contact pixelated sensors used for spatial resolution of the beam. Testing of simple sensors is additionally reported with successful radioactive source detection.

Integration of dielectrics with graphene is essential to the fulfillment of graphene based electronic applications. While many dielectric deposition techniques exist, plasma enhanced atomic layer deposition (PEALD) is emerging as a technique to deposit ultrathin dielectric films with superior densities and interfaces. However, the degree to which PEALD on graphene can be achieved without plasma-induced graphene deterioration is not well understood. In this work, we investigate a range of plasma conditions across a single sample, characterizing both oxide growth and graphene deterioration using spectroscopic analysis and atomic force microscopy. Investigation of graphene and film quality produced by these conditions yields insight into plasma effects. Using a specially designed sample configuration, we achieve ultrathin (< 1 nm) aluminum oxide films atop graphene.