Study of Plasmonic and Magneto-optical Properties of Transition Metal Doped Indium Oxide Nanocrystals - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Study of Plasmonic and Magneto-optical Properties of Transition Metal Doped Indium Oxide Nanocrystals write by Yi Tan. This book was released on 2019. Study of Plasmonic and Magneto-optical Properties of Transition Metal Doped Indium Oxide Nanocrystals available in PDF, EPUB and Kindle. Plasmonic nanostructure materials have been widely investigated recently because of their considerable potential for applications in biological and chemical sensors, nano-optical devices and photothermal therapy. Compared to metal nanocrystals (NCs), doped semiconductor NCs with tunable localized surface plasmon resonance (LSPR) from near-infrared (NIR) mid-infrared (MIR) region bring more opportunities to the applications of plasmonics. Magnetoplasmonic nanostructures which could be utilized in multifunctional devices also have attracted attention due to the combination of plasmonic and magnetic properties and the manipulation of light with external magnetic fields. In this research, indium oxide (In2O3) as a typical n-type semiconductor with high mobility and carrier concentration is selected as the host lattice for doping, and molybdenum (Mo) and tungsten (W) which are transition metal elements from the same group as dopants. Colloidal molybdenum-doped indium oxide (IMO) NCs and tungsten-doped indium oxide (IWO) NCs with varying doping concentrations have been successfully synthesized, and their plasmonic and magneto-optical properties have been explored. Similarities and differences between IMO NCs and IWO NCs were discussed. Both IMO and IWO NCs have shown good tunability of plasmon resonance in the MIR range approximately from 0.22 eV to 0.34 eV. 9.2 % IMO NCs show the strongest LSPR at 0.34 eV and the maximum free electron concentration of 1.1x1020 cm-3, and 1.5 % IWO NCs exhibit the strongest LSPR at 0.33 eV with the free electron concentration of 0.94x1020 cm-3. The magneto-optical properties were studied by magnetic circular dichroism (MCD) spectroscopy. The variable-temperature-variable-field MCD spectra that coincide with the band gap absorption, indicate the excitonic splitting in the NCs. A robust MCD intensity at room temperature suggests intrinsic plasmon-exciton coupling and carrier polarization induced by plasmon, which might be phonon-mediated. A decrease in MCD signal with temperature and the saturation-like field dependence of MCD intensity for IMO and IWO NCs may related to the different oxidation states of the dopant ions since the reduced 5+ oxidation states can exhibit the Curie-type paramagnetism. IMO and IWO NCs show the coupling between exciton and plasmon in a single-phase which opens a possibility for their application in electronics and photonics. Moreover, magnetoplasmonic modes provide a new degree of freedom for controlling carrier polarization at room temperature in practical photonic, optoelectronic and quantum-information processing devices.
Studies in Pure and Transition Metal Doped Indium Oxide Nanocrystals
Studies in Pure and Transition Metal Doped Indium Oxide Nanocrystals - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Studies in Pure and Transition Metal Doped Indium Oxide Nanocrystals write by Lisa Nicole Hutfluss. This book was released on 2015. Studies in Pure and Transition Metal Doped Indium Oxide Nanocrystals available in PDF, EPUB and Kindle. Controlling the crystal structure of transparent metal oxides is essential for tailoring the properties of these polymorphic materials to specific applications. Structural control is usually achieved via solid state phase transformation at high temperature or pressure. The first half of this work is a kinetic study of in situ phase transformation of In2O3 nanocrystals from metastable rhombohedral phase to stable cubic phase during their colloidal synthesis. By examining the phase content as a function of time using the model fitting approach, two distinct coexisting mechanisms are identified - surface and interface nucleation. It is shown that the mechanism of phase transformation can be controlled systematically through modulation of temperature and precursor to solvent ratio. The increase in both of these parameters leads to gradual change from surface to interface nucleation, which is associated with the increased probability of nanocrystal contact formation in the solution phase. The activation energy for surface nucleation is found to be 144±30 kJ/mol, very similar to that for interface nucleation. In spite of the comparable activation energy, interface nucleation dominates at higher temperatures due to increased nanocrystal interactions. The results of this work demonstrate enhanced control over polymorphic nanocrystal systems, and contribute to further understanding of the kinetic processes at the nanoscale, including nucleation, crystallization, and biomineralization. The ability to further modify the properties of transparent metal oxides through doping of transition metal ions into the host lattice offers a world of possibilities in terms of viable systems and applications. In particular, the use of transition metal dopants to induce room temperature ferromagnetic behaviour in non-magnetic transparent metal oxides is highly desirable for applications such as spintronics. Thus, the second half of this study is concerned with the doping of Fe into nanocrystalline In2O3 via colloidal synthesis and the fundamental characterization of the nanocrystals in anticipation of further development of these materials for potential spintronics applications. Focus is placed on the relationship between the doping concentration, observed phase of the host lattice, and nanocrystal growth and properties. Structural characterizations determine that Fe as a dopant behaves quite unlike previously studied dopants, Cr and Mn, establishing a positive correlation between increasing nanocrystal size and increasing doping concentration; the opposite was observed in the aforementioned previous systems. Through analysis of X-ray absorption near edge structure spectra and the pre-edge feature, it is found that ca. 10% of the assimilated Fe is reduced to Fe2+ during synthesis. Magnetization measurements reveal that these nanocrystals are weakly ferromagnetic at room temperature, suggesting the possibility of an interfacial defect mediated mechanism of magnetic interactions. With increasing doping concentration, the decrease in saturation magnetization suggests a change in the magnetic exchange interaction and a consequential switch from ferromagnetic to antiferromagnetic behaviour. It is clear from this work that colloidal Fe-doped In2O3 nanocrystals are a promising species, prompting further investigation using additional spectroscopic and magneto-optical techniques to increase understanding of the origin of the observed properties. A thorough understanding of this system in conjunction with other transition metal doped transparent conducting oxides will enable enhanced control in the materials design process and effectively allow tailoring of these materials for specific applications, such as spintronics.
Magnetic and Magneto-optical Properties of Doped Oxides
Magnetic and Magneto-optical Properties of Doped Oxides - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Magnetic and Magneto-optical Properties of Doped Oxides write by Mohammed Alqahtani. This book was released on 2012. Magnetic and Magneto-optical Properties of Doped Oxides available in PDF, EPUB and Kindle. This thesis describes the growth, structural characterisation, magnetic and magneto-optics properties of lanthanum strontium manganite (LSMO), GdMnO3 and transition metal (TM)-doped In2O3 thin films grown under different conditions. The SrTiO3 has been chosen as a substrate because its structure is suitable to grow epitaxial LSMO and GdMnO3 films. However, the absorption of SrTiO3 above its band gap at about 3.26 eV is actually a limitation in this study. The LSMO films with 30% Sr, grown on both SrTiO3 and sapphire substrates, exhibit a high Curie temperature (Tc) of 340 K. The magnetic circular dichroism (MCD) intensity follows the magnetisation for LSMO on sapphire; however, the measurements on SrTiO3 were dominated by the birefringence and magneto-optical properties of the substrate. In the GdMnO3 thin films, there are two well-known features in the optical spectrum; the charge transfer transition between Mn d states at 2 eV and the band edge transition from the oxygen p band to d states at about 3 eV; these are observed in the MCD. This has been measured at remanence as well as in a magnetic field. The optical absorption at 3 eV is much stronger than at 2 eV, however, the MCD is considerably stronger at 2 eV. The MCD at 2 eV correlates well with the Mn spin ordering and it is very notable that the same structure appears in this spectrum, as is seen in LaMnO3. The results of the investigations of Co and Fe-doped In2O3 thin films show that TM ions in the films are TM2+ and substituted for In3+. The room temperature ferromagnetism observed in TM-doped In2O3 is due to the polarised electrons in localised donor states associated with oxygen vacancies. The formation of Fe3O4 nanoparticles in some Fe-doped films is due the fact that TM-doped In2O3 thin films are extremely sensitive to the growth method and processing condition. However, the origin of the magnetisation in these films is due to both the Fe-doped host matrix and also to the nanoparticles of Fe3O4.
Plasmonic and Magneto-Optical Properties of Nonstoichiometric Indium Nitride Nanostructures
Plasmonic and Magneto-Optical Properties of Nonstoichiometric Indium Nitride Nanostructures - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Plasmonic and Magneto-Optical Properties of Nonstoichiometric Indium Nitride Nanostructures write by Shuoyuan Chen. This book was released on 2019. Plasmonic and Magneto-Optical Properties of Nonstoichiometric Indium Nitride Nanostructures available in PDF, EPUB and Kindle. Localized surface plasmon resonance (LSPR) in semiconductor nanostructures have attracted intense attention recently for its broad application in bio-imaging, chemical sensing, photocatalysis, and photovoltaics. Compared to the LSPR in metallic nanocrystals (NCs), LSPR in semiconductor NCs is highly tunable in the infrared region by tailoring chemical composition and stoichiometry. Moreover, LSPR along with external magnetic field allows the exploration of magneto-plasmonic coupling in single-phase semiconductors, opening up the magneto-optical ways to control charge carriers. In this thesis, we focus on the LSPR as well as magneto-optical properties of indium nitride (InN), providing valuable insights into the insufficiently researched III-V group semiconductors. Wurtzite phase InN NCs were successfully synthesized using the low-temperature colloidal method, and the plasmon intensity is tunable by changing the synthesis environment and varying doping concentrations of aluminum and titanium ions. Due to the combined effects of conduction band non-parabolicity and intraband transition, our InN NCs with different plasmon intensities have an almost fixed plasmonic energy of 0.37 eV. Besides, the optical bandgap of pure InN NCs ranges from 1.5 to 1.75 eV, depending on the reaction conditions, while that of the Al and Ti-doped InN varies from 1.65 to 1.85 eV. The plasmon-dependent phonon change is evaluated by the Raman spectroscopy. Differences in the longitudinal-optical (LO) phonon mode was observed for InN with high and low plasmon intensity. The magneto-optical properties of InN NCs were measured by the magnetic circular dichroism (MCD). The field-dependence and temperature-independence of the measured MCD spectra were investigated, and the plasmon-induced polarization of carriers was demonstrated. Tuning of the carrier polarization by varying LSPR and external magnetic field corroborates the hypothesis of non-resonant coupling between plasmons and excitons in a single-phase semiconductor. The results of this work demonstrate that LSPR can act as a degree of freedom in manipulating electrons in technologically-important III-V nanostructures and lead to potential applications in photonics and quantum computing at room temperature. Finally, InN nanowires (NWs) with LSPR were fabricated via low-temperature chemical vapor deposition (CVD) approach, laying the groundwork for the future research of LSPR and magneto-plasmonics in a one-dimensional system.
Manipulation of the Plasmonic Properties of N-type Doped Colloidal Indium Oxide Nanocrystals
Manipulation of the Plasmonic Properties of N-type Doped Colloidal Indium Oxide Nanocrystals - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Manipulation of the Plasmonic Properties of N-type Doped Colloidal Indium Oxide Nanocrystals write by Hanbing Fang. This book was released on 2017. Manipulation of the Plasmonic Properties of N-type Doped Colloidal Indium Oxide Nanocrystals available in PDF, EPUB and Kindle. Plasmonic nanocrystals (NCs) have been a focus of intense research over the past decade due to their unique optical properties and wide applications. Indium (III) oxide (In2O3) is an ideal host lattice for plasmonic NCs, owing to its high charge carrier concentration and mobility. In this project, one pot colloidal synthesis has been utilized to prepare antimony-doped In2O3 (AIO) NCs and titanium-doped In2O3 (TIO) NCs. It is shown that both of these doped NC samples exhibit the tunability of the plasmon resonance in the mid-infrared (MIR). For AIO NCs, it is revealed that the plasmon resonance can be well-tuned from 0.25 eV to 0.37 eV, with the maximum electron concentration of ca. 1.24 x 10^20 cm^-3 determined for 10.6 % of Sb. Compared to the broad plasmon of AIO NCs, relatively narrow plasmon of TIO NCs can be tuned from 0.13 eV to 0.28 eV by varying the doping concentration of Ti from 1.12 % to 7.8 %. Furthermore, the highest electron concentration determined for TIO NCs (7.8 % of Ti) is ca. 6.85 x 10^19 cm^-3. Both XRD patterns and high-resolution TEM images indicate that all synthesized AIO and TIO NCs retain the body-centered cubic (bcc)-In2O3 structure. UV-visible absorption spectra confirm the blue shift of the band gap for both AIO NCs and TIO NCs, because of the Burstein-Moss effect. Post treatment of as-synthesized NCs by rapid annealing under H2 or Ar illustrates that the intensity of the plasmon band can be improved appreciably. Finally, electronic and optical properties of AIO and TIO NCs were further investigated by the Density Functional Theory (DFT) calculations. It is expected that AIO and TIO NCs broadly tunable in the MIR can be employed in a variety of potential applications, including sensing, enhanced spectroscopy, and thermal imaging.
