Papers by Author: Lucia Calcagno

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Authors: Vito Raineri, Lucia Calcagno, Filippo Giannazzo, D. Goghero, F. Musumeci, Fabrizio Roccaforte, Francesco La Via
375
Authors: Gaetano Izzo, Grazia Litrico, Lucia Calcagno, Gaetano Foti, Francesco La Via
Abstract: The defects produced by irradiation with 7 MeV C+ induce a change in the electrical properties of 4H-SiC Schottky diodes. Capacitance-voltage and Current-voltage characteristics of the diodes fabricated in epilayers doped with different nitrogen concentrations were monitored before and after irradiation with different fluences. The Capacitance-voltage curves show free carrier compensation after low fluence irradiation and it was found that the reduction of carriers per ion induced vacancy increases with nitrogen content. The forward current-voltage characteristics of the diodes show an increase in the series resistance after irradiation. This change is mainly related to the high compensation occurring around the end of the ion range.
619
Authors: Vito Raineri, Fabrizio Roccaforte, Sebania Libertino, Alfonso Ruggiero, V. Massimino, Lucia Calcagno
Abstract: The defects formation in ion-irradiated 4H-SiC was investigated and correlated with the electrical properties of Schottky diodes. The diodes were irradiated with 1 MeV Si+-ions, at fluences ranging between 1×109cm-2 and 1.8×1013cm-2. After irradiation, the current-voltage characteristics of the diodes showed an increase of the leakage current with increasing ion fluence. The reverse I-V characteristics of the irradiated diodes monitored as a function of the temperature showed an Arrhenius dependence of the leakage, with an activation energy of 0.64 eV. Deep level transient spectroscopy (DLTS) allowed to demonstrate that the Z1/Z2 center of 4H-SiC is the dominant defect in the increase of the leakage current in the irradiated material.
1167
Authors: Alfonso Ruggiero, M. Zimbone, Fabrizio Roccaforte, Sebania Libertino, Francesco La Via, Ricardo Reitano, Lucia Calcagno
Abstract: Deep-Level Transient Spectroscopy and room temperature photoluminescence were used to characterise a 6H-SiC epitaxial layer irradiated with 10 MeV C+ and to follow the defect annealing in the temperature range 300-1400 °C. The intensity of luminescence peak at 423 nm, related to band to band transitions, decreases after irradiation and it is slowly recovered after annealing in the temperature range 1000-1400 °C. The DLTS spectra of low temperature annealed samples show the presence of several overlapping traps, which anneal and evolve at high temperatures. After 1200 °C a main level at Ec-0.43 eV (E1/E2) is detected. The comparison between luminescence and DLTS results indicates that the defect associated with the E1/E2 level is mainly responsible for the luminescence quenching after irradiation.
485
Authors: Alfonso Ruggiero, Sebania Libertino, Marco Mauceri, Ricardo Reitano, Paolo Musumeci, Fabrizio Roccaforte, Francesco La Via, Lucia Calcagno
493
Authors: Gaetano Izzo, Grazia Litrico, Andrea Severino, Gaetano Foti, Francesco La Via, Lucia Calcagno
Abstract: The defects produced by 7.0 MeV C+ irradiation in 4H-SiC epitaxial layer were followed by Deep Level Transient Spectroscopy, current-voltage measurements and Transmission Electron Microscopy in a large fluence range (109-51013 ions/cm2). At low fluence (109 -1010 ions/cm2), the formation of three main level defects located at 0.68 eV, 0.98 eV and 1.4 eV below the conduction band edge is detected. The trap concentration increases with ion fluence suggesting that these levels are associated to the point defects generated by ion irradiation. In this fluence range the leakage current of the diodes does not change. At higher fluence an evolution of defects occurs, as the concentration of traps at 0.68 eV and 1.4 eV decreases, while the intensity of the level at 0.98 eV remains constant. In this fluence range complex defects are formed and an increase of a factor five in the leakage current is measured.
397
Authors: Francesco La Via, Fabrizio Roccaforte, Salvatore di Franco, Alfonso Ruggiero, L. Neri, Ricardo Reitano, Lucia Calcagno, Gaetano Foti, Marco Mauceri, Stefano Leone, Giuseppe Pistone, Giuseppe Abbondanza, Gian Luca Valente, Danilo Crippa
Abstract: The effects of the Si/H2 ratio on the growth of the epitaxial layer and on the epitaxial defects was studied in detail. A large increase of the growth rate has been observed with the increase of the silicon flux in the CVD reactor. Close to a Si/H2 ratio of 0.05 % silicon nucleation in the gas phase occurs producing a great amount of silicon particles that precipitate on the wafers. The epitaxial layers grown with a Si/H2 ratio of 0.03% show a low defect density and a low leakage current of the Schottky diodes realized on these wafers. For these diodes the DLTS spectra show thepresence of several peaks at 0.14, 0.75, 1.36 and 1.43 eV. For epitaxial layers grown with higher values of the Si/H2 ratio and then with an higher growth rate, the leakage current of the Schottky diodes increases considerably.
429
Authors: Fabrizio Roccaforte, Francesco La Via, A. Baeri, Vito Raineri, Lucia Calcagno, F. Mangano
865
Authors: Fabrizio Roccaforte, Francesco La Via, Vito Raineri, Paolo Musumeci, Lucia Calcagno
893
Authors: Francesco La Via, G. Galvagno, A. Firrincieli, Fabrizio Roccaforte, Salvatore di Franco, Alfonso Ruggiero, Milo Barbera, Ricardo Reitano, Paolo Musumeci, Lucia Calcagno, Gaetano Foti, Marco Mauceri, Stefano Leone, Giuseppe Pistone, F. Portuese, Giuseppe Abbondanza, Giovanni Abagnale, Gian Luca Valente, Danilo Crippa
Abstract: The growth rate of 4H-SiC epi layers has been increased by a factor 3 (up to 18μm/h) with respect to the standard process with the introduction of HCl in the deposition chamber. The epitaxial layers grown with the addition of HCl have been characterized by electrical, optical and structural characterization methods. An optimized process without the addition of HCl is reported for comparison. The Schottky diodes, manufactured on the epitaxial layer grown with the addition of HCl at 1600 °C, have electrical characteristics comparable with the standard epitaxial process with the advantage of an epitaxial growth rate three times higher.
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