trolled using a closed-cycle Helium cryostat (Cryogenic Technology Inc., model 501A).Theoretical Methodology: The geometry of all compounds was fully optimized with the semiempirical PM3 (Parametric Method 3) Hamiltonian [26], which yields a coplanar structure. The vibrational frequencies were also computed at this level of theory and confirm the global minimum of the equilibrium geometry by the absence of negative frequencies. The geometric relaxation taking place in the lowest excited state has been described by coupling the PM3 method to a full CI (configuration interaction) expansion involving a limited number of orbitals (as implemented in the AMPAC package) [27]. The size of the CI active space is chosen in order to ensure the convergence of the geometric parameters. On the basis of the PM3-optimized structures, the transition energy and transition dipole moment associated to the lowest excited state of the compounds have been estimated with the help of the spectroscopic version of the semiempirical These efforts span not only layer-structured materials, but also metallic, semiconducting, and even strongly ionic bonded oxide materials. The latter, however, have often been found as nanosized tubular materials. Nanotubes and/or nanotubular oxide (and, in particular, functional oxide) materials that have particularly promising physical properties and potential applications in nanoelectronics, however, are rarely found or synthesized. Nanotubes of SiO 2 , TiO 2 , and vanadium oxides have been synthesized, using several different processing techniques. Among these, nanotubes of TiO 2 have been the most intensively investigated, since their superior catalytic properties are combined with nanotubular forms of high surface area. Much effort has been devoted to forming TiO 2 nanotubes, and nanotubular COMMUNICATIONS

We report on atomic layer deposited Hf0.5Zr0.5O2 (HZO)-based capacitors which exhibit excellent ferroelectric (FE) characteristics featuring a large switching polarization (45 μC/cm2) and a low FE saturation voltage (∼1.5 V) as extracted from pulse write/read measurements. The large FE polarization in HZO is achieved by the formation of a non-centrosymmetric orthorhombic phase, which is enabled by the TiN top electrode (TE) having a thickness of at least 90 nm. The TiN films are deposited at room temperature and annealed at 400 °C in an inert environment for at least 1 min in a rapid thermal annealing system. The room-temperature deposited TiN TE acts as a tensile stressor on the HZO film during the annealing process. The stress-inducing TiN TE is shown to inhibit the formation of the monoclinic phase during HZO crystallization, forming an orthorhombic phase that generates a large FE polarization, even at low process temperatures.

A template-directed synthesis strategy is an ideal tool to fabricate oxide nanotubes in that their physical dimensions can be precisely controlled and monodisperse samples can be harvested in large quantity. The wall thickness of the oxide nanotubes is controllable by varying the deposition conditions, and the length and diameter can be tailored in accordance with the templates used. A wealth of functional oxide materials with the controlled polymorphs can be deposited to be nanotubular structures by various synthesis methods. This short review article describes the recent progress made in the field of the template synthesis of oxide nanotubes. We begin this review with the comprehensive survey on the research activities of the template-directed oxide nanotubes. We then focus on the template synthesis that combines porous membrane templates with various deposition techniques and discuss the processing issues associated with coating inside nanoscale pores, selective etching of oxide nanotubes from the templates, and dispersion against the formation of nanotubes’ bundle-up. Structures and physical properties of the oxide nanotubes prepared by template synthesis are also summarized. Their potential for application in drug-delivery systems, sensors, and solar energy conversion devices, which could be facilitated by the template synthesis, is discussed. Finally, we conclude this review as providing our perspectives to the future directions in the template-directed oxide nanotubes.

Effects of interface oxidation on the transport behavior of the two-dimensional-electron-gas in AlGaN/GaN heterostructures by plasma-enhanced-atomic-layer-deposited AlN passivation