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4 Oct 1999

Volume 75, Issue 14, pp. 1999-2151

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Device degradation of polymer light emitting diodes studied by electroabsorption measurements

C. Giebeler, S. A. Whitelegg, D. G. Lidzey, P. A. Lane, and D. D. C. Bradley

Appl. Phys. Lett. 75, 2144 (1999); http://dx.doi.org/10.1063/1.124944 (3 pages) | Cited 19 times

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We have studied the device degradation of single layer poly(2,5-dialkoxy-p-phenylenevinylene) light emitting diodes by electroabsorption spectroscopy. The applied direct current (dc) bias generates an opposing internal field. This internal field rises as the applied dc bias is increased. The development of the internal field is less pronounced in vacuum than in an ambient atmosphere and is no longer apparent for devices that were prepared and tested under an inert atmosphere in a glovebox. For the devices that were tested in air and under dynamic vacuum conditions we have also observed a change in the flat band voltage of the devices due to an aging effect on the electrodes. The combination of these two processes leads to an increase in the device turn-on voltage with increasing operating time. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.20.Jq Electro-optical effects
78.66.Qn Polymers; organic compounds
78.40.Me Organic compounds and polymers
42.70.Jk Polymers and organics

Microelectronic cooling using the Nottingham effect and internal field emission in a diamond (wide-band gap material) thin-film device

N. M. Miskovsky and P. H. Cutler

Appl. Phys. Lett. 75, 2147 (1999); http://dx.doi.org/10.1063/1.124945 (3 pages) | Cited 16 times

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We propose a method for heat dissipation in microelectronic devices which uses internal field emission through the interface of a composite thin-film device {i.e., metal [semiconductor (S)]/ chemical vapor deposition doped diamond [wide-band gap (WBG) material]} in conjunction with a heat sink. These composite thin-film devices are of micron to submicron dimensions and composed of materials which can be integrated with existing semiconductor technology. As distinct from conventional field emission into vacuum and thermionic devices, the relatively high metallic (S) work function (>2 eV) is here circumvented by use of internal field emission through a Schottky barrier at a metal/diamond (WBG) interface. It is the large band gap in these materials which introduces a filtering effect on the injected electrons which allows one to restrict the tunneling of electrons through the Schottky barrier from states below the Fermi energy, ϵF. For applied fields below a certain value, the average energy of the field-emitted electrons is greater than the average energy of the electrons which replace them, leading to the so-called Nottingham cooling. It has recently been shown that the replacement electrons have an energy up to 100 meV or more lower than ϵF, enhancing the cooling process by field emission. Using a kinetic field emission formalism, a tip density of 107/cm2, a local electron gas temperature of 500 K, and a tip radius of 50 nm (blunt tip), an average cooling rate per area of 1.6 W/cm2 can be achieved. Higher tip densities lead to average heat dissipation rates which can scale up to 100 W/cm2 or higher, rates competitive with or exceeding other techniques for thermal dissipation (i.e., thermoelectric and thermionic). © 1999 American Institute of Physics.
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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
73.40.Ns Metal-nonmetal contacts
73.40.Gk Tunneling
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
44.10.+i Heat conduction
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
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