Molecular diamonds enabled synthesis and growth [electronic resource]

Diamond has amazing bulk properties including extreme hardness, the highest thermal conductivity of any solid and high refractive index. Furthermore, wide band gap with the possibility of doping offer potential for power electronics. Hydrogen-terminated diamond surface exhibits negative electron affinity (NEA), which enables its use as a cathode for energy conversion or for electron emission devices. Recent developments in diamond research have focused on diamond nanoparticles which have shown a wide range of new applications including quantum computing, drug delivery, biomarkers and biosensors. Molecular diamonds, also known as "diamondoids" are the smallest possible forms of hydrogen-terminated diamond. The smallest diamondoid is an adamantane which consists of a single diamond cage composed of ten carbons terminated with hydrogen at the surface. Diamondoids offers a unique research platform in which diamond and diamond-surface properties can be explored at the molecular level. Fundamental properties of diamondoids, such as photoluminescence of the solid and gas phases, dielectric constants, ionization potentials, band structure etc. have been discussed in previous published papers. This thesis focuses primarily on three topics: 1) The use of diamondoid monolayers to obtain 10nm resolution on X-ray Photoemission Electron Microscope (XPEEM) images. 2) Identification of critical nucleation size for CVD diamond nucleation using diamondoid seeds of various sizes and shapes. 3) Symmetrical structure offered by SiV- color center was used for production of photonic nanocrystal structure with SiV- center to obtain identical emission spectrum. The first part of this thesis discusses applications of diamondoids for X-ray imaging. X-ray Photoemission Electron Microscope (XPEEM) is extremely useful for obtaining chemical and magnetic images. Typical XPEEM resolution is limited due the wide range of electron energies emitted from the target. To overcome this limitation, expensive focusing apparatus are generally necessary for best resolution. Taking advantage of the monochromatic nature of electrons photo-emitted through a diamondoid monolayer (FWHM of 0.3eV), we were able to overcome XPEEM resolution limitations by simply coating sample with a diamondoid monolayer. Using this technique, we were able to obtain the 10nm resolution XPEEM image. We found diamondoid monolayers minimized chromatic aberration by a factor of 10 and increased contrast by a factor of two for samples ranging from 100nm to 10nm. We achieved this resolution by simply dipping the sample in a solution containing diamondoids with functional groups (linkers) designed to form Self Assembled Monolayers on the sample surface. The second part of this thesis describes use of diamondoid seeds of various sizes and shapes can lead to a better understanding of the critical nucleation size of diamond nanoparticles in CVD diamond growth. By comparing diamond growth from various pure seeds including diamantane of different chemical funcationalization configuration, two different tetramantane isomers and two pentamantane isomers, a critical nucleation size at sub 1nm, smaller than previously thought, was determined. Critical nucleation size was determined by an exponential increase in nucleation rate as thermal activation is no longer required for a post-critical size particle. In addition, this study found the critical nuclei depend on both size and structure of the molecule. The third topic of this thesis revolves around the development of a bottom-up method for growing diamond nanoparticles with Silicon-Vacancy (SiV)- color centers. SiV− centers have emerged as promising candidates for quantum information processing applications and possibly as biosensors. The inversion symmetry of SiV− centers provide superior spectral stability and narrow inhomogeneous broadening with linewidths of a few nanometers and nearly transform-limited linewidths at low temperature. We demonstrate stability of SiV- color center by forming nanophotonic crystal structure on SiV film and SiC using diamondoids as seeds for diamond nucleation. The resulting nanopillars contain high quality SiV− centers with very narrow linewidths and very low inhomogeneous broadening, thereby enabling implementation of quantum photonic devices containing identical quantum emitters, as needed for quantum simulations and quantum network.

Keywords: Electrical Engineering.
Advisor: Shen Zhi-Xun primary advisor. Thesis advisor
Melosh Nicholas A. advisor. Thesis advisor
Vuckovic Jelena advisor. Thesis advisor