Tuning Plasmonic and Magneto-Plasmonic Behavior in 4-d Transition Metal Doped Indium Oxide

Florida State University, Tallahassee FL

Investigators

Abstract

Incorporation of atoms that donate electrons into metal oxide nanocrystals leads to new properties. These nanocrystal metal oxides are important for optics, photocatalysis, quantum computing, and flexible electronics. Computational, synthetic, and optical techniques will be employed to control the interaction of light (photons) and electrons in a magnetic field. The intentional placement of magnetic and electron donating atoms within a metal oxide nanocrystal will lead to an ability to intentionally control carrier densities within the metal oxide using light. Light will cause the electrons to oscillate. This oscillation will allow the electrons to be coupled with a magnetic field providing a route to materials for quantum computing. The choice of the donor atom, its concentration, and its location within the nanocrystal controls the color of the light used to couple the electrons. The effort will train students at the forefront of electronic and photonic materials. A collaborative educational experience for undergraduate students from universities focused on underrepresented students will be established. Research into electronic and photonic materials will be explored jointly with the investigators at Florida State University and the collaborative schools through distance-learning. Emergent plasmonic and magneto plasmonic properties will arise from changes in carrier mobility and densities near the Fermi level in metal oxide semiconductor quantum dots. The changes are size and site (core vs. surface) dependent. The research addresses three prevailing questions in regards to plasmonic quantum dots (QDs), 1) Will a plasmonic response be observed when 4d n-type donors are incorporated into In2O3 QDs and will the effective mass be systematically tuned as a function of 4d energy level? 2) What is the role of donor site location on the plasmonic activation or deactivation of an aliovalent dopant? and 3) Can the electronic and magnetic properties for QDs co-doped with electronic and magnetic dopants be coupled? Aim 1 interrogates the impact on carrier densities and carrier mobilities arising from the 4d donor orbital energy levels relative to the conduction band minimum (CBM) in In2O3. It is anticipated the plasmonic response will be Type I for Mo, Type II for Nb, and Type III for Zr donors. In Aim 2, measurement of the carrier densities and the influence of site of donor incorporation will be evaluated using solid-state magic angle spinning (MAS) NMR techniques correlated with optical methods. The aim will evaluate the prediction that the carrier density at the Fermi level and plasmon properties arise primarily from dopants within the core of the QD. In Aim 3, perturbation of magnetic exchange interactions in Sn,Cr:In2O3 will be investigated for a system co-incorporating an electronic (n-donor) and a paramagnetic (Cr(III)) donor. The aim will test the computational hypothesis that coupling of the magnetic exchange and plasmonic features can arise for shallow donors. The application of experimental and computational modeling methods (density field theory), will lead to the development of rational design criteria for producing new plasmonic and magneto-plasmonic responses in these new materials. The activities will train students at the forefront of research and develops the educational and research infrastructure for students at all levels. A research collaboration using distance-learning strategies will be established to enhance the educational experience of undergraduate researchers from University of North Georgia and Florida A&M University. The distance learning approach includes remote access to instrumentation and remote meetings with the principle investigator to review research performance and results. The effort is termed the Plasmonic Army and uses distance learning strategies to share research and to improve the learning outcome for undergraduates interested in advanced research activities in areas typically not found at a small University. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.