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Parreira, P., G. Lavareda, J. Valente, F. T. Nunes, A. Amaral, and C. Nunes de Carvalho. "Undoped InOx Films Deposited by Radio Frequency Plasma Enhanced Reactive Thermal Evaporation at Room Temperature: Importance of Substrate." JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 10 (2010): 2701-2704. Abstract

Conductive and transparent undoped thin films of indium oxide (InOx), 120 nm average thick, were deposited by radio frequency plasma enhanced reactive thermal evaporation (rf-PERTE) of indium in the presence of oxygen at room temperature. Several substrates were used in order to study their influence on the main properties of these films: alkali free (AF) glass, fused silica, crystalline silicon and polyethylene terephthalate (PET). Surface morphology of the InOx films as a function of the substrates was observed by SEM and showed that the undoped InOx films obtained are nano-structured. For the c-Si substrate, InOx films with increased grain size are obtained, induced by the crystalline substrate. Films deposited on fused silica and AF glass substrates show a nano-grainy surface with similar surface morphologies. The InOx films deposited on AF glass show the highest values of both: electrical conductivity of about 1100 (Omega cm)(-1) and visible transmittance of 85%. The substrate has a greater influence on the surface morphology of the films when a polymer (PET) is used. InOx films deposited on PET show a decrease in the electrical conductivity (90 (Omega cm)(-1)) and a slight decrease in the average visible transmittance (78%).

Ribeiro, Celso, Pedro Brogueira, Guilherme Lavareda, Carlos Nunes de Carvalho, Ana Amaral, Luis Santos, Jorge Morgado, Ulrich Scherf, and Vasco D. B. Bonifacio. "Ultrasensitive microchip sensor based on boron-containing polyfluorene nanofilms." BIOSENSORS & BIOELECTRONICS 26 (2010): 1662-1665. Abstract

A fluorene-based pi-conjugated copolymer with on-chain dibenzoborole units was used in the development of a nanocoated gold interdigitated microelectrode array device which successfully detects fluoride in a broad range of concentrations (10(-11)-10(-4) M) in aqueous solution, upon impedance spectroscopy measurements. A calibration curve obtained over this range of concentrations and a new analytical method based on impedance spectroscopy measurements in aqueous solution is proposed. The sensor nanofilm was produced by spin-coating and diagnosed via spectroscopic ellipsometry, AFM, and electrically conductivity techniques. Changes in the conductivity due to the boron-fluoride complex formation seem to be the major mechanism behind the dependence of impedimetric results on the fluoride concentration. (C) 2010 Elsevier B.V. All rights reserved.