Defining electronic materials

Group lib elements form compound semiconductors with the chalcogenides and have a variety of other uses. The most common conductors are the group Ib elements Cu and Au with Ag also occasionally used. Transition metals are commonly used in compound form either as silicides or nitrides, primarily as stable contact materials bridging between Si and a highly conductive metal, or as diffusion barriers. The rare 

In some cases the Ila elements such as calcium are used as conductors or contacts, although their reactivity makes them too unstable in many cases. Finally, the group la alkali metals are rarely used because of their reactivity and rapid diffusion rates in many materials, although these too are becoming more common. Both group la and Ila elements are increasingly used, for example, in organic electronic devices. 

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TT-Electron materials, which are defined as those having extended Jt-electron clouds in the solid state, have various peculiar properties such as high electron mobility and chemical/biological activities. We have developed a set of techniques for synthesizing carbonaceous K-electron materials, especially crystalline graphite and carbon nanotubes, at temperatures below 1000°C. We have also revealed new types of physical or chemical interactions between Jt-electron materials and various other materials. The unique interactions found in various Jt-electron materials, especially carbon nanotubes, will lay the foundation for developing novel functional, electronic devices in the next generation. 

Nigeria has as well its Harmful Wastes Act, which, rather than listing banned substances, broadly bans materials by their effects, defining such materials as those which ... subject a person to risk of death or... incurable impairment. Trading in such can be punished by life imprisonment [39]. Nigeria s more recent National Environmental Regulations (Electronics Sector) explicitly prohibits unusable electronic goods [40]. 

Metals are defined as materials in which the uppermost energy band is only partly filled. The uppermost energy level filled is called the Fermi energy or the Fermi level. Conduction can take place because of the easy availability of empty energy levels just above the Fermi energy. In a crystalline metal the Fermi level possesses a complex shape and is called the Fermi surface. Traditionally, typical metals are those of the alkali metals, Li, Na, K, and the like. However, the criterion is not restricted to elements, but some oxides, and many sulfides, are metallic in their electronic properties. 

This volume can best be understood by considering the olfactory senses of animals. Everyone has witnessed the ability of a dog to use its nose with its superb olfactory sense to detect trace odors. A holy grail of detection science has been to duplicate a dog s nose electronically. Dr. Woodfin s volume tries to assess where the scientific community stands in its search for this holy grail. The authors of this volume are using this chemical sensing approach to detect explosives. Explosives, as used in this context, are defined as materials that concentrate releasable energy controllable or uncontrollable. 

These materials feature a well-defined electronic structure that is consistent with (but does not prove) quantum confinement derived from the very thin wall thickness (Fig. 13). The optical absorption spectra of NU-GeSi-1 show sharp absorption onsets in the energy range from 2.04 to 2.12 eV. Crystalline and amorphous bulk Si have a band gap of 1.1 and 1.5 eV, respectively [54], The energy band gap... 

Work Function (WF) plays a key role in the physics and chemistry of materials. Phenomena such as the semiconductor field effect, photo- and thermionic electron emission (Allen and Gobelli, 1962), catalysis (Vayenas et al 1996), and the like are dominated by the WF. This fundamental property of electronic materials is defined as the minimum work required to extract an electron from the Fermi level Ep of a conducting phase, through the surface and place it in vacuum just outside the reach of the electrostatic forces of that phase (Trasatti and Parsons, 1986). The reference level for this transfer is thus called the vacuum reference level. Because even a clean surface is a physical discontinuity, a surface dipole t] with its associated electric field always appears at the surface of the condensed phase. Thus, the work of extracting the electron can be conceptually divided between the work required to... 

In recent years much effort has been spent on the development of experimental techniques to grow well defined nanoscale materials, due to their possible applications in nanometric electronic devices. Indeed the creation of nanowire field effect transistors [128-132], nano-sensors [133,134], atomic scale light emitting diodes and lasers [135,136], has been made possible by the development of new techniques, which allow one to control the growth processes of nanotubes, nanowires and quantum dots. Of particular importance, among the different atomic scale systems experimentally studied, are... 

The synthesis of pure precursor molecules is crucial, e.g., Ln(OR)3 or Ln(SeR)2. Well-defined compounds which contain specific element compositions are attractive for ceramic and electronic materials or catalysts in organic transformations. Hitchcock et al. reported the synthesis of monomeric homo-leptic lanthanide(III) aryloxides according to this route for the first time in 1983... 

At first, by injeetion-free TOF speetroseopy transients for eleetrons and holes were observed between 300 K and 420 K, i.e. above the struetural phase transition. The two eharge earrier types obey a thermally aetivated transport behaviour with mobility maxima of 0.03 emWs for holes and 0.2 em A s for electrons both at 400 K. The detection of well-defined electron transients in a sublimation purified material aheady indicates its aforementioned chemical stability. For many polyaromatic materials the formation of the respective quinones, e.g. upon (photo-)oxidation, shifts the molecular levels to lower energies because of the higher electronegativity and causes stronger binding of electrons on the molecular skeleton [2]. The LUMO (lowest unoccupied molecular orbital) of those oxidation-products is often positioned below the... 

Two of the major branches of chemistry have traditionally been defined by the elements that each studies. Organic chemistiy studies the compounds of carbon, specifically those that contain hydrogen and often oxygen, nitrogen, and a few other elements. This branch is concerned with fuels, drugs, dyes, polymers, and the like. Inorganic chemistry, on the other hand, focuses mainly on the compounds of all the other elements. It is concerned with catalysts, electronic materials, metal alloys, mineral salts, and the like. With the explosive growth in biomedical and materials research, the line between these branches has all but disappeared. 

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