Gotowa bibliografia na temat „Multiferroics - Microelectronic Devices”

The phenomenal growths of information technology and related fields have warranted the development of new class of materials. Multifunctional oxides, magnetic-semiconductors, multiferroics and smart materials are just a few examples of such materials. They are needed for the development of novel technologies such as spintronics, magneto-electronics, radhard electronics, and advanced microelectronics. For these technologies, of particular interest are some solid solutions of ilmenite-hematite (IH) represented by (1-x) FeTiO3.xFe2O3 where x varies from 0 to 1; Mn-doped ilmenite (Mn+3-FeTiO3) and Mn-doped pseudobrookite, Mn+3-Fe2TiO5 (PsB). These multifunctional oxides are ferromagnetic with the magnetic Curie points well above the room temperature as well as wide bandgap semiconductors with band gap Eg > 2.5 eV. This paper outlines: (a) processing of device quality samples for structural, electrical and magnetic characterization, (b) fabrication and evaluation of an integrated structure for controlled magnetic switching, and (c) the response of the two terminal non-linear current-voltage (I-V) characteristics when biased by a dc voltage. Subsequently, we will identify a few microelectronic applications based on this class of oxides.

Multiferroics are currently of great interest for applications in microelectronics namely in future data storage and spintronic devices. These materials couple simultaneously ferroelectric and ferromagnetic properties and have potentially different applications resulting from the coupling between their dual order parameters. A true multiferroic material is single phase. However, the known true multiferroic materials possess insufficient coupling between the two phenomena or their magnetoelectric response occurs at temperatures too low to be useful in practical applications. But a tremendous progress in the field of microelectronics can be expected if one is able to design an effective multiferroic material with ideal coupling of the ferromagnetic and ferroelectric properties to suit a particular application. Within this context composite structures are gaining considerable interest and different strategies in terms of materials microstructure have been proposed including horizontal multilayers and vertical heterostructures. In the horizontal multilayer heterostructures, the alternating layers of conventional ferro/ferrimagnetic and ferroelectric phases are grown, while in the vertical heterostructures nanopillars of the ferro/ferrimagnetic phase are embedded in a ferroelectric matrix. The later structures show advantages over the first ones because promote larger interfacial surface area and are intrinsically heteroepitaxial in three dimensions; which is expected to allow a stronger coupling between ferroelectric and ferromagnetic components.

The electron devices in which electrons do not collide with other particles or in which the collision probability is very small in the transport process can be theoretically regarded as general vacuum electron devices. General vacuum electron devices include microfabricated vacuum nano-electronic devices, which can work in atmosphere, and some solid-state electron devices with nanoscale channel for electrons whose material characteristics are close to those of vacuum channels. Vacuum nano-electron devices (e.g., nanotriodes) are expected to be the fundamental elements for high-speed, radiation-resistant large-scale vacuum integrated circuits. The solid-state electron devices with spin semiconductor materials, multiferroics or topological crystal insulators are quite different from traditional semiconductor devices and are expected to operate under novel principles. Understanding vacuum electron devices from a microcosmic perspective and understanding solid-state electron devices from a vacuum perspective will promote a union of vacuum electronics and microelectronics, as well as the formation and development of general vacuum electronics.

In this work, PbFe1/2Nb1/2O3 (PFN) ceramic samples synthesized by chemically wet method (precipitation from the solution) were obtained. Due to the tendency to form powder agglomerates, the synthesized powder was subjected to ultrasound. The sintering was carried out under various technological conditions, mainly through controlling the sintering temperature. -X-ray powder-diffraction (XRD), scanning electron microscope (SEM) microstructure analysis, as well as the examinations of dielectric, ferroelectric, and magnetic properties of the PFN ceramics were carried out. Studies have shown that hard ceramic agglomerates can be partially minimized by ultrasound. Due to this treatment, closed porosity decreases, and the ceramic samples have a higher density. Optimization and improvement of the technological process of the PFN material extends the possibility of its use for the preparation of multiferroic composites or multicomponent solid solutions based on PFN. Such materials with functional properties find applications in microelectronic applications, e.g., in systems integrating ferroelectric and magnetic properties in one device. The optimal synthesis conditions of PFN ceramics were determined to be 1050 °C/2 h.

In this chapter, we have report a list of synthesis methods (including both synthesis steps & heating conditions) used for thin film fabrication of perovskite ABO3 (BiFeO3, BaTiO3, PbTiO3 and CaTiO3) based multiferroics (in both single-phase and composite materials). The processing of high quality multiferroic thin film have some features like epitaxial strain, physical phenomenon at atomic-level, interfacial coupling parameters to enhance device performance. Since these multiferroic thin films have ME properties such as electrical (dielectric, magnetoelectric coefficient & MC) and magnetic (ferromagnetic, magnetic susceptibility etc.) are heat sensitive, i.e. ME response at low as well as higher temperature might to enhance the device performance respect with long range ordering. The magnetoelectric coupling between ferromagnetism and ferroelectricity in multiferroic becomes suitable in the application of spintronics, memory and logic devices, and microelectronic memory or piezoelectric devices. In comparison with bulk multiferroic, the fabrication of multiferroic thin film with different structural geometries on substrate has reducible clamping effect. A brief procedure for multiferroic thin film fabrication in terms of their thermal conditions (temperature for film processing and annealing for crystallization) are described. Each synthesis methods have its own characteristic phenomenon in terms of film thickness, defects formation, crack free film, density, chip size, easier steps and availability etc. been described. A brief study towards phase structure and ME coupling for each multiferroic system of BiFeO3, BaTiO3, PbTiO3 and CaTiO3 is shown.