Zirconium doping has a dramatically different influence on Ce reduction in the bulk than on the surface of ceria–zirconia.
Articles you may be interested inIonic conductivity and thermal stability of magnetron-sputtered nanocrystalline yttria-stabilized zirconia Stress evolution as a function of substrate bias in rf magnetron sputtered yttria-stabilized zirconia films Epitaxial La 0.7 Sr 0.3 Mn O 3 thin films with two in-plane orientations on silicon substrates with yttria-stabilized zirconia and Y Ba 2 Cu 3 O 7 − δ as buffer layers J. Appl. Phys. 97, 073905 (2005); 10.1063/1.1876577 Large low-field magnetoresistance observed in twinned La 2 ∕ 3 Ca 1 ∕ 3 MnO 3 thin films epitaxially grown on yttria-stabilized zirconia-buffered silicon on insulator substrates Appl. Phys. Lett. 86, 112514 (2005); 10.1063/1.1875766High-rate deposition of biaxially textured yttria-stabilized zirconia by dual magnetron oblique sputteringUnderstanding and controlling growth stress is a requisite for integrating oxides with Si. Yttria stabilized zirconia (YSZ) is both an important functional oxide and a buffer layer material needed for integrating other functional oxides. Stress evolution during the growth of (100) and (111) oriented YSZ on Si (100) by radio frequency and reactive direct current sputtering has been investigated with an in-situ monitor and correlated with texture evolution. Films nucleated at rates <5 nm/min are found to be (111) oriented and grow predominantly under a compressive steady state stress. Films nucleated at rates >20 nm/min are found to be (100) oriented and grow under tension. A change in growth rate following the nucleation stage does not change the orientation. The value of the final steady state stress varies from À4.7 GPa to 0.3 GPa. The in-situ studies show that the steady state stress generation is a dynamic phenomenon occurring at the growth surface and not decided at film nucleation. The combination of stress evolution and texture evolution data shows that the adatom injection into the grain boundaries is the predominant source of compressive stress and grain boundary formation at the growth surface is the source of tensile stress. V C 2012 American Institute of Physics. [http://dx.
We present a study of co-sputtered VO2-SiO2 nanocomposite dielectric thin-film media possessing continuous temperature tunability of the dielectric constant. The smooth thermal tunability is a result of the insulator-metal transition in the VO2 inclusions dispersed within an insulating matrix. We present a detailed comparison of the dielectric characteristics of this nanocomposite with those of a VO2 control layer and of VO2/SiO2 laminate multilayers of comparable overall thickness. We demonstrated a nanocomposite capacitor that has a thermal capacitance tunability of ∼60% between 25 °C and 100 °C at 1 MHz, with low leakage current. Such thermally tunable capacitors could find potential use in applications such as sensing, thermal cloaks, and phase-change energy storage devices.
It is demonstrated here that growth stress has a substantial effect on the dielectric constant of ZrO 2 thin films. The correct combination of parameters -phase, texture and stress -is shown to yield films with high dielectric constant and best reported equivalent oxide thickness of 0.8 nm. The stress effect on dielectric constant is twofold, firstly, by the effect on phase transitions and secondly by the effect on interatomic distances. We discuss and explain the physical mechanisms involved in the interplay between the stress, phase changes and the dielectric constant in detail.KEYWORDS: High-k dielectrics, in situ stress study in thin films, effect of stress on high-k dielectric, oxides thin films on germanium, reactive sputter deposition of oxides
Conventional epitaxy plays a crucial role in current state-of-the art semiconductor technology, as it provides a path for accurate control at the atomic scale of thin films and nanostructures, to be used as the building blocks in nanoelectronics, optoelectronics, sensors, etc. Four decades ago, the terms "van der Waals" (vdW) and "quasi-vdW (Q-vdW) epitaxy" were coined to explain the oriented growth of vdW layers on 2D and 3D substrates, respectively. The major difference with conventional epitaxy is the weaker interaction between the epi-layer and the epi-substrates. Indeed, research on Q-vdW epitaxial growth of transition metal dichalcogenides (TMDCs) has been intense, with oriented growth of atomically thin semiconductors on sapphire being one of the most studied systems. Nonetheless, there are some striking and not yet understood differences in the literature regarding the orientation registry between the epi-layers and epi-substrate and the interface chemistry. Here we study the growth of WS 2 via a sequential exposure of the metal and the chalcogen precursors in a metal−organic chemical vapor deposition (MOCVD) system, introducing a metal-seeding step prior to the growth. The ability to control the delivery of the precursor made it possible to study the formation of a continuous and apparently ordered WO 3 mono-or few-layer at the surface of a c-plane sapphire. Such an interfacial layer is shown to strongly influence the subsequent quasi-vdW epitaxial growth of the atomically thin semiconductor layers on sapphire. Hence, here we elucidate an epitaxial growth mechanism and demonstrate the robustness of the metal-seeding approach for the oriented formation of other TMDC layers. This work may enable the rational design of vdW and quasi-vdW epitaxial growth on different material systems.
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