Publications by authors named "Giovanni Ghione"

Plasmonic organic hybrid electro/optic modulators are among the most innovative light modulators fully compatible with the silicon photonics platform. In this context, modeling is instrumental to both computer-aided optimization and interpretation of experimental data. Due to the large computational resources required, modeling is usually limited to waveguide simulations.

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We present three-dimensional simulations of HgCdTe-based focal plane arrays (FPAs) with two-color and dual-band sequential infrared pixels having realistic truncated-pyramid shape, taking into account also the presence of compositionally graded transition layers. After a validation against the spectral responsivity of two-color, mid-wavelength infrared detectors from the literature, the method is employed for a simulation campaign on dual-band, mid-, and long-wavelength infrared FPAs illuminated by a Gaussian beam. Simulation results underscore the importance of a full-wave approach to the electromagnetic problem, since multiple internal reflections due to metallizations and slanted sidewalls produce non-negligible features in the quantum efficiency spectra, especially in the long-wavelength band.

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Majority carrier depletion has been proposed as a method to suppress the dark current originating from quasi-neutral regions in HgCdTe infrared focal plane array detectors. However, a very low doping level is usually required for the absorber layer, a task quite difficult to achieve in realizations. In order to address this point, we performed combined electromagnetic and electric simulations of a planar $ 5 \times 5 $5×5 pixel miniarray with 5 µm wide square pixels, assessing the effect of the absorber thickness, its doping level in the interval $ {N_D}{ = [10^{14}}{,10^{15}}] \;{{\rm cm}^{ - 3}} $N=[10,10]cm, and temperature in the interval 140 K-230 K, both in the dark and under illumination.

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A numerical device-level model of dye-sensitized solar cells (DSCs) is presented, which self-consistently couples a physics-based description of the photoactive layer with a compact circuit-level description of the passive parts of the cell. The opto-electronic model of the nanoporous dyed film includes a detailed description of photogeneration and trap-limited kinetics, and a phenomenological description of nonlinear recombination. Numerical simulations of the dynamic small-signal behavior of DSCs, accounting for trapping and nonlinear recombination mechanisms, are reported for the first time and validated against experiments.

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