Solid-state lighting is a rapidly evolving, emerging technology whose efficiency of conversion of electricity to visible white light is likely to approach 50% within the next several years. This efficiency is significantly higher than that of traditional lighting technologies, giving solid-state lighting the potential to enable significant reduction in the rate of world energy consumption. Further, there is no fundamental physical reason why efficiencies well beyond 50% could not be achieved, which could enable even more significant reduction in world energy usage. In this article, we discuss in some detail: (a) the several approaches to inorganic solid-state lighting that could conceivably achieve "ultra-high," 70% or greater, efficiency, and (b) the significant research questions and challenges that would need to be addressed if one or more of these approaches were to be realized.

Single-crystal epitaxial thin films of the isotropic metallic oxides Sr1-xCaxRuO(3) (0

The important changes produced on the electroluminescence characteristics of organic materials due to planar microcavity effects are examined in detail. The photon density of states is redistributed such that only certain wavelengths, which correspond to allowed cavity modes, are emitted in a given direction. This enables us to realize color selectivity over a large wavelength (and color coordinate) range with broadband emitters such as 8-hydroxyquinoline aluminum (Alq), and intensity enhancement in narrow band emitters. The intensity enhancement in Alq-based cavity light emitting diodes (LEDs) is extensively evaluated both experimentally and theoretically. The design considerations for and device characteristics of a novel multiple emissive layer LED are also described.

Colossal magnetoresistance with more than a thousandfold change in resistivity (ΔR/RH=127 000% at 77 K, H=6 T) has been obtained in epitaxially grown La-Ca-Mn-O thin films. This magnetoresistance value is about three orders of magnitude higher than is typically seen in the giant-magnetoresistance-type metallic, superlattice films. The temperature of peak magnetoresistance is located in the region of metallic resistivity behavior. As the magnetoresistance peak occurs not at the temperature of magnetic transition but at a temperature where the magnetization is still substantial, the spin-disorder scattering is not likely to be the main mechanism in these highly magnetoresistive films. The peak can be shifted to near room temperature by adjusting processing parameters. Near-room-temperature ΔR/RH values of ∼1300% at 260 K and ∼400% at 280 K have been observed. The presence of grain boundaries appears to be very detrimental to achieving large magnetoresistance in the lanthanum manganite compounds. The fact that the electrical resistivity of a material can be manipulated by magnetic field to change by orders of magnitude could be useful for various device applications.

Epitaxial ferroelectric SrRuO3/Pb(Zr0.52Ti0.48)O3/SrRuO3 heterostructures have been fabricated employing isotropic metallic oxide electrodes on (100) SrTiO3 and (100) Si with an yttria stabilized zirconia buffer layer. The structures have been grown in situ by 90° off-axis sputtering, which allows the growth of uniform stoichiometric films over large areas with excellent step coverage. X-ray diffraction, Rutherford backscattering spectroscopy, and cross-sectional transmission electron microscopy reveal high crystalline quality and coherent interfaces. They exhibit superior fatigue characteristics over those made with metal electrodes, showing little degradation over 1010 cycles, with a large remnant polarization.

Highly conductive indium zinc oxide prepared by reactive magnetron cosputtering technique using indium and zinc metallic targets J. Vac. Sci. Technol. A 28, 425 (2010); 10.1116/1.3372806 Effects of Zn content on structural and transparent conducting properties of indium-zinc oxide films grown by rf magnetron sputtering High mobility undoped amorphous indium zinc oxide transparent thin films J. Appl. Phys. 98, 073703 (2005); 10.1063/1.2060957 Transparent conducting zinc oxide and indium-tin oxide films prepared by modified reactive planar magnetron sputtering J.

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Epitaxial yttria-stabilized zirconia films were grown on Si (100) and Si (111) by pulsed laser deposition. Rutherford backscattering spectroscopy indicates a high degree of crystalline perfection with a channeling minimum yield of 5.3%. A necessary predeposition process is removal of native silicon oxide from the Si prior to film growth. This is done outside the deposition chamber at 23 °C using a wet-chemical hydrogen-termination procedure. Epitaxial YBa2Cu3O7−δ films have been grown on these films.