Structural, optical and electrical properties of nanocrystalline TiO2 -- HfO2 thin films
In the present work the properties of mixed HfxTi1-xO2 solid solution thin films in metal-oxide-semiconductor (MOS) configuration have been studied. Thin films, were grown on monocrystalline silicon substrates using the low pressure hot target reactive sputtering from the Ti:Hf mosaic target. From optical transmission measurements the 3.42 (eV) bandgap of the thin films has been estimated. Electrical characterization of the prepared MOS structures shows classical capacitance- and current-voltage behaviors indicating medium-k gate oxide properties with the low leakage current
Microstructure and Optical Properties of TiO2 Thin Films Prepared by Low Pressure Hot Target Reactive Magnetron Sputtering
Abstract Thin films of TiO2 were deposited onto (1 0 0) oriented silicon and glass substrates using modified magnetron sputtering method. The method, among the others, consisted in employing low pressure of reactive gas (
Ancient Origin of the Modern Deep-Sea Fauna
The origin and possible antiquity of the spectacularly diverse modern deep-sea fauna has been debated since the beginning of deep-sea research in the mid-nineteenth century. Recent hypotheses, based on biogeographic patterns and molecular clock estimates, support a latest Mesozoic or early Cenozoic date for the origin of key groups of the present deep-sea fauna (echinoids, octopods). This relatively young age is consistent with hypotheses that argue for extensive extinction during Jurassic and Cretaceous Oceanic Anoxic Events (OAEs) and the mid-Cenozoic cooling of deep-water masses, implying repeated re-colonization by immigration of taxa from shallow-water habitats. Here we report on a well-preserved echinoderm assemblage from deep-sea (1000–1500 m paleodepth) sediments of the NE-Atlantic of Early Cretaceous age (114 Ma). The assemblage is strikingly similar to that of extant bathyal echinoderm communities in composition, including families and genera found exclusively in modern deep-sea habitats. A number of taxa found in the assemblage have no fossil record at shelf depths postdating the assemblage, which precludes the possibility of deep-sea recolonization from shallow habitats following episodic extinction at least for those groups. Our discovery provides the first key fossil evidence that a significant part of the modern deep-sea fauna is considerably older than previously assumed. As a consequence, most major paleoceanographic events had far less impact on the diversity of deep-sea faunas than has been implied. It also suggests that deep-sea biota are more resilient to extinction events than shallow-water forms, and that the unusual deep-sea environment, indeed, provides evolutionary stability which is very rarely punctuated on macroevolutionary time scales.