ABSTRACT We report on the one-pot synthesis and characterization of pure cubic and monoclinic pha... more ABSTRACT We report on the one-pot synthesis and characterization of pure cubic and monoclinic phase HfO2 nanoparticles. An average particles size of 2.6 nm was estimated from transmission electron microscopy studies. The equivalent synthesis conditions of the two polymorphs provided means for direct comparison of their optical absorption and emission properties, which are found to exhibit different behaviors as a function of temperature and ambient environment. The origin of the strong visible luminescence observed from both cubic and monoclinic HfO2 is discussed in terms of surface-defects and nanosize of the particles. The comparative analysis of the PL responses of the two polymorphs suggests that emission at 3.1 eV originates from the oxygen vacancy related defects.
ABSTRACT The flat-band voltage shift of bilayer SiO2/HfO2 MOS structures is investigated as a fun... more ABSTRACT The flat-band voltage shift of bilayer SiO2/HfO2 MOS structures is investigated as a function of the structural properties of the HfO2 films. It was demonstrated that for amorphous HfO2 films, the flat-band voltage vs HfO2 thickness relationship is well described by a second-order polynomial resulting from a bilayer model including two interfacial charge densities and bulk high-k charges. When the crystalline structure of HfO2 is stabilized in a monoclinic phase, the flat-band voltage is shifted to positive voltages and becomes nearly independent on the HfO2 thickness. These results confirm that the high-k/SiO2 interface can significantly contribute to the flat-band voltage shift. However, this contribution appears greatly dependent on the microstructural properties of HfO2.
Perovskite compounds are among the most interesting mixed metal oxide materials in terms of their... more Perovskite compounds are among the most interesting mixed metal oxide materials in terms of their optical, magnetic, ferroelectric and multiferroic properties. The synthesis of these compounds as nanoparticles is of fundamental importance as size reduction and shape engineering allow modification and tuning of their fundamental properties, 1 thus opening new possibilities for micro-, opto-and nanoelectronic applications. 2 Hafnia perovskite nanoparticles with size as small as 1.6nm in diameter were synthesized via a non-aqueous sol-gel process. 3 The synthesis procedures were carried out in a glove box using metallic strontium (Sr) or calcium methoxide (Ca(OCH 3) 2) and hafnium (IV) tert-butoxide (Hf(O t Bu) 4) mixed into benzyl alcohol. The mixture was transferred into a stainless steel autoclave, carefully sealed and then heated in a furnace at 300ºC for 2 days. An important advantage of this method is the possibility to synthesize pure and highly crystalline nano-sized perovskite...
Hafnia is one of the most widely used wide gap materials in the microelectronic industry. Stemmin... more Hafnia is one of the most widely used wide gap materials in the microelectronic industry. Stemming from the need to miniaturize electronic devices, high κ materials such as hafnia-based compounds replace SiO2 in gate oxides, thereby decreasing the equivalent oxide thickness of the gate dielectric. On the other hand, scaling down deteriorates the physical properties of the latter viz., leakage current and carrier mobility. By increasing κ or the electric constant of the material, these losses can nevertheless be compensated for. Doping of HfO2 is known to increase its κ; these dopants include mostly divalent elements such as Mg or trivalent elements such as Y, Al and La. Multivalent elements such as V and Ta are also used as dopants but their oxidation state depends upon the growth conditions. Doping via elements with +2 and +3 oxidation states, has a propensity to introduce oxygen vacancies and stabilize higher symmetry phases of HfO2 i.e. cubic, tetragonal and even orthorhombic whi...
Silver nanoparticles (AgNPs) have been widely used in biomedical fields because of their intrinsi... more Silver nanoparticles (AgNPs) have been widely used in biomedical fields because of their intrinsic therapeutic properties. Here, we introduce methods of synthesizing AgNPs and discuss their physicochemical, localized surface plasmon resonance (LSPR) and toxicity properties. We also review the impact of AgNPs on human health and the environment along with the underlying mechanisms. More importantly, we highlight the newly emerging applications of AgNPs as antiviral agents, photosensitizers and/or radiosensitizers, and anticancer therapeutic agents in the treatment of leukemia, breast cancer, hepatocellular carcinoma, lung cancer, and skin and/or oral carcinoma.
ABSTRACT We report on the one-pot synthesis and characterization of pure cubic and monoclinic pha... more ABSTRACT We report on the one-pot synthesis and characterization of pure cubic and monoclinic phase HfO2 nanoparticles. An average particles size of 2.6 nm was estimated from transmission electron microscopy studies. The equivalent synthesis conditions of the two polymorphs provided means for direct comparison of their optical absorption and emission properties, which are found to exhibit different behaviors as a function of temperature and ambient environment. The origin of the strong visible luminescence observed from both cubic and monoclinic HfO2 is discussed in terms of surface-defects and nanosize of the particles. The comparative analysis of the PL responses of the two polymorphs suggests that emission at 3.1 eV originates from the oxygen vacancy related defects.
ABSTRACT The flat-band voltage shift of bilayer SiO2/HfO2 MOS structures is investigated as a fun... more ABSTRACT The flat-band voltage shift of bilayer SiO2/HfO2 MOS structures is investigated as a function of the structural properties of the HfO2 films. It was demonstrated that for amorphous HfO2 films, the flat-band voltage vs HfO2 thickness relationship is well described by a second-order polynomial resulting from a bilayer model including two interfacial charge densities and bulk high-k charges. When the crystalline structure of HfO2 is stabilized in a monoclinic phase, the flat-band voltage is shifted to positive voltages and becomes nearly independent on the HfO2 thickness. These results confirm that the high-k/SiO2 interface can significantly contribute to the flat-band voltage shift. However, this contribution appears greatly dependent on the microstructural properties of HfO2.
Perovskite compounds are among the most interesting mixed metal oxide materials in terms of their... more Perovskite compounds are among the most interesting mixed metal oxide materials in terms of their optical, magnetic, ferroelectric and multiferroic properties. The synthesis of these compounds as nanoparticles is of fundamental importance as size reduction and shape engineering allow modification and tuning of their fundamental properties, 1 thus opening new possibilities for micro-, opto-and nanoelectronic applications. 2 Hafnia perovskite nanoparticles with size as small as 1.6nm in diameter were synthesized via a non-aqueous sol-gel process. 3 The synthesis procedures were carried out in a glove box using metallic strontium (Sr) or calcium methoxide (Ca(OCH 3) 2) and hafnium (IV) tert-butoxide (Hf(O t Bu) 4) mixed into benzyl alcohol. The mixture was transferred into a stainless steel autoclave, carefully sealed and then heated in a furnace at 300ºC for 2 days. An important advantage of this method is the possibility to synthesize pure and highly crystalline nano-sized perovskite...
Hafnia is one of the most widely used wide gap materials in the microelectronic industry. Stemmin... more Hafnia is one of the most widely used wide gap materials in the microelectronic industry. Stemming from the need to miniaturize electronic devices, high κ materials such as hafnia-based compounds replace SiO2 in gate oxides, thereby decreasing the equivalent oxide thickness of the gate dielectric. On the other hand, scaling down deteriorates the physical properties of the latter viz., leakage current and carrier mobility. By increasing κ or the electric constant of the material, these losses can nevertheless be compensated for. Doping of HfO2 is known to increase its κ; these dopants include mostly divalent elements such as Mg or trivalent elements such as Y, Al and La. Multivalent elements such as V and Ta are also used as dopants but their oxidation state depends upon the growth conditions. Doping via elements with +2 and +3 oxidation states, has a propensity to introduce oxygen vacancies and stabilize higher symmetry phases of HfO2 i.e. cubic, tetragonal and even orthorhombic whi...
Silver nanoparticles (AgNPs) have been widely used in biomedical fields because of their intrinsi... more Silver nanoparticles (AgNPs) have been widely used in biomedical fields because of their intrinsic therapeutic properties. Here, we introduce methods of synthesizing AgNPs and discuss their physicochemical, localized surface plasmon resonance (LSPR) and toxicity properties. We also review the impact of AgNPs on human health and the environment along with the underlying mechanisms. More importantly, we highlight the newly emerging applications of AgNPs as antiviral agents, photosensitizers and/or radiosensitizers, and anticancer therapeutic agents in the treatment of leukemia, breast cancer, hepatocellular carcinoma, lung cancer, and skin and/or oral carcinoma.
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