Alfredo Rubino

Amorphous silicon waveguides and light modulators for integrated photonics realized by low-temperature plasma-enhanced chemical-vapor deposition.

A new amorphous silicon waveguide is realized by use of amorphous silicon carbon as cladding material. The structure is characterized both experimentally and theoretically, and its application for optical interconnections in photonic integrated circuits on silicon motherboards is proposed. The fabrication process is based on low-temperature (220 degrees C) plasma-enhanced chemical-vapor deposition and is compatible with standard microelectronic processes. Propagation losses of 1.8 dB/cm have been measured at the fiber-optic wavelength of 1.3 microm. A strong thermo-optic coefficient has been measured in this material at this wavelength and exploited for the realization of a light-intensity modulator based on a Fabry-Perot interferometer that is tunable by temperature.

Stream Processor for Real-Time Inverse Tone Mapping of Full-HD Images

In this paper, an architecture design of a hardware accelerator capable to expand the dynamic range of low dynamic range images to the 32-bit high dynamic range counterpart is presented. The processor implements on-the-fly calculation of the edge-preserving bilateral filtering and luminance average, to elaborate a full-HD (1920

On the electrical behavior of V2O5/4H-SiC Schottky diodes

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Effect of PEDOT:PSS ratio on the electrical and optical properties of OLEDs

1080 pixels) image in 16.6 ms (60 frames/s) on field-programmable logic (FPL), by processing the incoming pixels in streaming order, without frame buffers. In this way, the design avoids the use of external DRAM and can be tightly coupled with acquiring devices, thus to enable the implementation of smart sensors. The processor complexity can be configured with different area/speed ratios to meet the requirements of different target platforms from FPLs to ASICs, obtaining, in both implementations, state-of-the-art performances.

A Model of Electric Field Distribution in Gate Oxide and JFET-Region of 4H-SiC DMOSFETs

A complete analysis of the rectifying behavior of V2O5/4H-SiC (divanadium pentoxide/4H polytype of silicon carbide) junction is reported. The analysis of forward and reverse JD−VD curves of samples fabricated with 5 nm-thick V2O5 films shows that the carrier transport across junction is dominated by the field enhanced thermionic emission mechanism. All the physical and electrical parameters, such as Schottky barrier height, ideality factor, and series resistance, have been evaluated from temperature behavior of JD−VD curves in the range 100–425 K and from CD−VD measurements. It is shown that the barrier height extracted from measurements can be justified in terms of inhomogeneities localized at the interface.

Effect of electrodes properties on OLED performances

We report on the employ of several kinds of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) dispersions as hole injection layer to increase the stability and the charge injection in organic light emitting diodes (OLEDs). The PEDOT:PSS dispersions are different for PEDOT:PSS ratios and their properties were characterized by contact angle measurement, UV-Vis-IR transmittance and I-V characteristics. Multi layer ITO-PEDOT:PSS-PF6-Alq3- Al OLEDs have been manufactured and the electrical and optical properties have been extensively investigated and discussed in function of PEDOT:PSS ratio. We have found that a major quantity of PEDOT induces a decrement of ITO hole barrier and so an increment of OLED current and luminance. Performed transport analysis have pointed out that PEDOT:PSS carrier density ND has a notable role in electrical transport at high bias.

Optimized Design for 4H-SiC Power DMOSFET

For the first time, a full analytical model of the electric field in the gate oxide of 4H-polytype silicon carbide (4H-SiC) power double-implanted MOSFET devices is shown. It takes into account all the relevant physical and geometrical parameters of the device and avoids the use of any fitting parameters. To validate the results of the full-analytical model, comparisons with numerical simulations are reported for device structures having different values of the drift doping concentration and drift thickness as well as of the junction FET (JFET)-region width. Moreover, because the model equations are in closed form, they can be used to derive an adequate JFET-region geometry by fixing the maximum electric field in the oxide and the maximum blocking voltage for a given drift region.

Multiplier-Less Stream Processor for 2D Filtering in Visual Search Applications

The effects induced by different electrical contacts, both for the anode and for the cathode, have been analyzed in Organic Light Emitting Diodes (OLEDs). The properties of anode electrode, Indium Tin Oxide (ITO), have been varied through different surface treatments allowing roughness control, carbon impurity removal, spikes decrement. These induce changes of ITO surface chemical-physical characteristics as roughness, surface energy and surface polarity. OLEDs manufactured employing treated ITO have showed an improvement of 25 times in luminance. Thermionic injection model has been used to estimate decrement in effective hole barrier at ITO-organic layer. It is shown that this effect is correlated to ITO surface energy. The second step of process optimization has concerned the cathode electrode investigation. In order to perform this task, Al, Ca/Al, Ag, Mg/Ag have been used to realize different ITO/PEDOT:PSS/PF6/Alq3/Metal OLEDs. Measurements of electrical and optical behaviour have been performed. A thermionic injection model, with and without Schottky barrier decrement, has been used to calculate the change of the cathode electrical barrier.

Admittance spectroscopy of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) based organic light emitting diodes

An optimized tradeoff between blocking voltage and specific ON-resistance for 4H-silicon carbide power vertical double-implanted metal-oxide-semiconductor field-effect transistor (DMOSFET) is exclusively obtained as a function of doping concentration in the drift region. Based on a novel analytical model of the electric field in the gate oxide of 4H-SiC DMOSFETs, we propose a closed-form equation of the Junction FET (JFET) region width and the drift thickness as function of doping concentration without using fitting and empirical parameters to obtain the maximum figure of merit. Model results are successfully verified with TCAD numerical simulations, covering a wide range of device performances, and experimental results.

Photosensing Properties of Pentacene OFETs Based on a Novel PMMA Copolymer Gate Dielectric

A new 2D convolution-based filter is presented, which is specifically designed to improve visual search applications. It exploits a new radix-3 partitioning method of integer numbers, derived from the weight partition theory, which allows substituting multipliers with simplified floating point (FP) adders, working on 32-b FP filter coefficients. The memory organization allows elaborating the incoming data in raster scan order, as those directly provided by an acquisition source, without frame buffers and additional aligning circuitry. Compared with the existent literature, built around conventional arithmetic circuitry, the proposed design achieves state-of-the-art performances in the reduction of the mapped physical resources and elaboration velocity, achieving a critical path delay of about 4.5 ns both with a Xilinx Virtex-7 field-programmable gate array and CMOS 90-nm std_cells.