Propagation losses were measured for surface plasmon-polariton (SPP) modes at metal waveguides on semiconductor substrates. The waveguides are simple strips of Au or Al deposited on InP substrates or 300-nm-thick SiO2 film covering the InP substrates. We used a direct method that can clearly discriminate SPP modes in vidicon-camera images, thereby allowing quantitative measurements. The loss coefficients measured at a wavelength of 1.55 μm were, as predicted by theory, in the range of 8.5–17 dB/mm, which shows the waveguides are feasible for practical applications.
Laser induced molecular implantation technique (LIMIT) has been used for site-controlled fabrication of pixel arrays of organic light-emitting diodes in a form of dots with a diameter of several micrometers. N,N 0 -Bis(3-methylphenyl)-N,N 0diphenylbenzidine (TPD) dots, which were implanted into the poly(3,4-ethylene dioxythiophene)-poly(styrene sulphonate) (PEDOT-PSS) layer, act as recombination centers between the hole-and electron-transport layers in the indium tin oxide (ITO)/PEDOT-PSS/TPD dots /tris(8-hydroxyquinoline) aluminum (Alq 3 )/Mg-Ag sandwich structure, and illuminate intense green light. We studied fluorescence spectra of the implanted TPD dots and the dependence of their size and morphology on the intensity of a laser pulse, as well as the electroluminescence resulted from the organic light-emitting device (OLED) arrays. The site-controlled fabrication of such small OLEDs opens up an opportunity for production of electroluminescent devices with ultrahigh resolution.
By using a bottom-gate top-contact field-effect transistor structure, the field effect of graphite-rich carbon nanocrystallite thin films deposited by electron cyclotron resonance sputtering was investigated. An appreciable ambipolar field effect was observed at the film edge where the thickness was vanishing. On-off current ratios of 2 and 7 were attained at 294 and 150 K, respectively.
The organic field-effect transistor (OFET) properties of conducting polymers bearing a tetrathiafulvalene (TTF) unit in the backbone whose termini are capped with functional groups were investigated. The OFET devices were fabricated by a solution process under various fabrication conditions. All the devices showed typical p-type semiconducting behavior as expected from the electron-donating properties of TTF derivatives. Cast films exhibited higher field-effect mobilities than spin-coated films. Surface treatment with organic silane molecules produced no noticeable effects. When using thioacetyl-capped polymer, treatment of the OFET device in an ammonia atmosphere resulted in a field-effect mobility one order of magnitude higher than that of the pristine film. By contrast, there was no such enhancement with ethyl acetate-capped polymer. Atomic force microscopy observations revealed that the ammonia treatment promoted the ordering of the polymer chain, which resulted in improved electronic conduction.
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