F.A. Marino

Arizona State University, Mesa, AZ, United States

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Publications (22)18.1 Total impact

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    ABSTRACT: Ultrashort gate length pseudomorphic highelectron-mobility transistors (p-HEMTs) based on an InP substrate and featuring a InAs/In0.053Ga0.47As composite channel have been modeled using a full-band Cellular Monte Carlo simulator. The affects of pair generation by impact ionization are included and we have incorporated a model to allow carriers to tunnel into and out of the channel. Using a gate length scaling analysis, we can obtain a theoretical upper limit for the cut-off frequency, fT, which we find to be 1.7 THz for this specific type of structure. We also examine factors that may be preventing actual devices from achieving such high frequency operation.
    Nanotechnology (IEEE-NANO), 2012 12th IEEE Conference on; 01/2012
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    ABSTRACT: The effect of the passivation layer dielectric constant and T-gate geometry on the performance of millimeter-wave high-power GaN HEMTs is investigated through a nanoscale carrier dynamics description obtained by full-band cellular Monte Carlo simulation. The effective gate length is found to be increased by fringing capacitances and enhanced by the dielectric constant of the passivation layer in the regions adjacent to the gate for layers thicker than about 5 nm. Detailed simulation results are shown for the carrier energy, velocity, scattering, and electric field profiles along the channel. The output impedance under small- and large-signal operations is also discussed. Our results indicate that the effect of the passivation layer dielectric constant changes the nanoscale carrier dynamics and can strongly affect the radio-frequency performance of deep submicrometer devices.
    IEEE Transactions on Electron Devices 12/2011; · 2.06 Impact Factor
  • F.A. Marino, G. Meneghesso
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    ABSTRACT: A multifunctional field-effect transistor (FET) for the manufacturing of high-density integrated circuits (ICs) has been developed and fabricated. Furthermore, an extensive numerical device simulation campaign has been carried out in order to characterize the new structure. Such device is a metal-oxide-semiconductor (MOS) FET that simultaneously performs the functions of two traditional FETs (an n-channel MOS and a p-channel MOS), working as one or as the other according to the voltage applied to the gate's terminal. Combinational and sequential circuits employing the new technology introduce, with respect to the standard complementary MOS (CMOS) ones, a drastic reduction of both the required device number and the parasitic capacitances. This leads to a significant increase in the circuit's speed. Furthermore, the ICs obtained with these transistors are fully compatible with the standard CMOS technology and fabrication process.
    IEEE Electron Device Letters 04/2011; · 2.79 Impact Factor
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    ABSTRACT: We provide design guidelines for InGaAs HEMT nanoscale scaling from the analysis of results obtained through our full band Cellular Monte Carlo simulator. In particular, improved RF performance can be obtained preserving a minimum aspect ratio of 5, limiting in such way short channel effects and reducing the electron transit time through the reduction of the effective gate length. Further improvement can be obtained reducing the source-gate access region lentgh. Thus, the effective gate length relative increase and the parasitic intrinsic access region resistance are found to be the main factors limiting nanoscale scaling in THz InGaAs HEMTs. Index Terms—Aspect ratio, effective gate length, InGaAs, nanoscale devices, nanoscale gate length, Terahertz.
    01/2011;
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    ABSTRACT: We report the simulation of the large-signal performance of mm-wave FET power amplifiers obtained for the first time through Full Band Monte Carlo particle-based device simulation self-consistently coupled with a Harmonic Balance (HB) frequency domain circuit solver. Due to the iterative nature of the HB algorithm, this FET simulation approach is possible only due to the computational efficiency of our Cellular Monte Carlo (CMC), which uses pre-computed scattering tables. On the other hand, a frequency domain circuit solver such as HB allows the simulation of the steady-state behavior of an external passive reactive network without the need for simulating long transient time (i.e. RC, L/C time constants) typical of time domain solutions. By exploiting this newly developed self-consistent CMC/HB code, we were able to time-efficiently characterize the mm-wave power performance of a state-of-the-art 30-nm gate-length InAlN/GaN HEMT.
    Electron Devices Meeting, 1988. IEDM '88. Technical Digest., International 01/2011;
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    ABSTRACT: We report for the first time the simulation of the large-signal dynamic load-line of high-Q matched mm-wave power amplifiers obtained through a Monte Carlo particle-based device simulator. Due to the long transient time of large reactive circuit elements, the time-domain solution of power amplifier high-Q matching networks requires prohibitive simulation time for the already time-consuming Monte Carlo technique. However, by emulating the high-Q matching network and the load impedance through an active load-line, we show that, in combination with our fast Cellular Monte Carlo algorithm, particle-based accurate device simulations of the large signal operations of AlGaN/GaN HEMTS are possible in a time-effective manner. Reliability issues and parasitic elements (such as dislocations and contact resistance) are also taken into account by, respectively, exploiting the accurate carrier dynamics description of the Monte Carlo technique and self-consistently coupling a Finite Difference Time Domain network solver with our device simulator code.
    Simulation of Semiconductor Processes and Devices (SISPAD), 2011 International Conference on; 01/2011
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    ABSTRACT: We compare the performance of GaN HEMT devices based on the established Ga-face technology and the emerging N-face technology. Starting from a state-of-the-art N-face device, we obtain the analogous Ga-face layout imposing the constraint of the same channel charge in both structures, and then, we simulate both the configurations with our full-band cellular Monte Carlo simulator, which includes the full details of the band structure and the phonon spectra. Moreover, we define a modeling approach based on gate-to-2-D electron gas distance and capacitance discussions, which allows a fair comparison between the N- and Ga-face technologies. Full direct current and RF simulations were performed and compared with available experimental data for the N-face device in order to calibrate the few adjustable simulator parameters. Our simulations indicate that N-face GaN HEMTs exhibit improved RF performance with respect to Ga-face devices. Furthermore, the use of an AlN layer in N-face devices results in a reduced alloy scattering and offers a strong back-barrier electron confinement to mitigate short-channel effects, thus improving the cutoff frequency for highly scaled devices.
    IEEE Transactions on Electron Devices 01/2011; · 2.06 Impact Factor
  • Fabio Alessio Marino, Gaudenzio Meneghesso
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    ABSTRACT: In this paper, an extensive description of the main characteristics and possible applications of a double-halo metal-oxide-semiconductor (MOS) device is presented. In partic- ular, the details concerning the prototype fabrication through a standard complementary MOS (CMOS) process and the obtained experimental results are reported. Extensive numerical device sim- ulation has been carried out in order to deeply understand the new structure. Furthermore, to gain insight on the device behavior, an electrical model to be used in SPICE-like circuit simulation tools has been developed and verified. As shown by our analysis, digital integrated circuits employing the new technology introduce, with respect to standard CMOS ones, a drastic reduction of both the device number and the parasitic capacitances, leading to a significant improvement of the circuit performance.
    IEEE Transactions on Electron Devices 01/2011; 58(12):4226-4234. · 2.06 Impact Factor
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    ABSTRACT: We report a comparison between state-of-the-art GaN and InGaAs HEMTs in terms of the minimum aspect ratio required to limit short-channel effects. DC and RF simulations were carried out through our full-band cellular Monte Carlo simulator, which includes the full details of the band structure and the phonon spectra. Our results indicate that the minimum aspect ratio for GaN devices is 15 for negligible short-channel effects and 10 for reduced short-channel effects. On the other hand, InGaAs devices perform well for lower aspect ratio values such as 7.5 and 4-5 for negligible and reduced effects, respectively. The origin of this difference between GaN and InGaAs HEMTs is believed to be related to the different dielectric constants of the two materials and the corresponding difference in the electric field distributions related to short-channel effects.
    IEEE Electron Device Letters 12/2010; · 2.79 Impact Factor
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    ABSTRACT: This paper aims to investigate the potential of the emerging N-face technology with respect to both the direct current and radio frequency performance of GaN high electron mobility transistor (HEMT) devices. High-frequency high-power state-of-the-art HEMTs were investigated with our full-band cellular Monte Carlo simulator, which includes the full details of the band structure and the phonon spectra. A complete characterization of these devices was performed using experimental data to calibrate the few adjustable parameters of the simulator. The effect of scaling the device dimensions, such as the gate length and the access region lengths, on the device performance was analyzed. In addition, the enhancement-mode configuration of the N-face structure was investigated. Our simulations showed that N-face devices represent an important step in engineering HEMT devices for delivering high power density and efficiency at microwave and millimeter-wave frequencies.
    IEEE Transactions on Electron Devices 11/2010; · 2.06 Impact Factor
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    ABSTRACT: Here we report simulation results for high-frequency, high-power state-of-the-art GaN High Electron Mobility Transistors (HEMTs), using a full band Cellular Monte Carlo simulator, which includes the full details of the band structure and the phonon spectra, in order to study the RF performance of the new promising technology available nowadays.A complete characterization of an InGaN back – barrier device has been performed using experimental data to calibrate the few adjustable parameters of the simulator. Furthermore, a study on a device structure based on the N-face configuration was performed. Finally, threading dislocation effects on HEMT device transport properties were investigated (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    physica status solidi (c) 07/2010; 7(10):2445 - 2449.
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    ABSTRACT: The effects of polarization charge on the electrostatic potential distribution across the heterostructure of a AlGaN/GaN high electron mobility transistor device have been investigated. Simulations were performed using a full-band cellular Monte Carlo simulator, which included electronic dispersion and the phonon spectra. Quantum effects were taken into account using the effective potential method. Experimental extraction of potential profiles across the device was carried out using off-axis electron holography. Based on comparison to simulations, the differences between the theoretical predictions and experimental results could be explained, thereby providing better understanding of device operation.
    Journal of Applied Physics 04/2010; · 2.21 Impact Factor
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    ABSTRACT: This brief aims to show the effects of threading edge dislocations on the DC and RF performance of GaN high-electron mobility transistor (HEMT) devices. A state-of-the-art high-frequency and high-power HEMT was investigated with our full-band cellular Monte Carlo (CMC) simulator, which includes the full details of the band structure and the phonon spectra. A complete characterization of the device has been performed using experimental data to calibrate the few adjustable parameters of the simulator. Thermal simulations were also carried out with commercial software in order to operate the corrections needed to model thermal effects. The approach of Weimann based on the results of Read, Bonch-Bruevich and Glasko, and Po¿do¿r was then used to model with our CMC code the dislocation effects on the transport properties of HEMT devices. Our simulations indicate that GaN HEMT performance exhibits a fairly large dependence on the density of thread dislocation defects. Furthermore, we show that a threshold concentration exists, above which a complete degradation of the device operation occurs.
    IEEE Transactions on Electron Devices 02/2010; · 2.06 Impact Factor
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    ABSTRACT: Quantum well field effect transistors have been proposed as promising device candidates for future high-speed and low-power logic applications due to their high electron mobility. This paper aims to study InAs and InGaAs state-of-the-art QWFETs, investigating both RF and DC performance through our full band Cellular Monte Carlo simulator, which includes the full details of the band structure and the phonon spectra. A complete characterization of these devices has been performed using experimental data to calibrate the simulation parameters.
    01/2010;
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    ABSTRACT: An investigation of RF short-channel effects in state-of-the-art GaN and InGaAs HEMTs, in relation to effective gate length and aspect ratio, is performed through our full band Cellular Monte Carlo simulator. In particular, the short-circuit current gain cut-off frequency, fT, is extracted using two different methods for several gate lengths. The first method relates fT to the electron transit time in the gate region, and from the electron velocity profile allows a direct estimation of fT, the effective gate length Leff, and the investigation of the nananoscale carrier dynamics in the channel. The second extraction methods derives fT through small-signal analysis. Our results indicates that the increasing difference between effective gate length and metallurgical gate length, as the device is scaled, plays a major role in limiting the RF performance. Moreover, maintaining a minimum aspect ratio of 5 for InGaAs HEMTs, and 10 for GaN devices, helps mitigating the short-channel effects.
    01/2010;
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    ABSTRACT: Here we discuss how Monte Carlo Simulations can be exploited to investigate reliability issues in GaN high electron mobility transistor (HEMT) devices. In particular, we report simulation results for high-frequency, high-power state-of-the-art GaN HEMTs focusing our analysis on the effects of that threading edge dislocations on the DC and RF performance of state of the art technologies. A complete characterization of an InGaN back - barrier device has been performed, and the influence of dislocation density on device performance analyzed. Furthermore, a device structure based on the N-face configuration is analyzed.
    01/2010;
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    ABSTRACT: The most important metrics for the high-frequency and high-power performance of microwave transistors are the cut-off frequency fT, and the Johnson figure of merit FoMJohnson. We have simulated a state-of-the-art, high-frequency and high-power GaN HEMT using our full band Cellular Monte Carlo (CMC) simulator, in order to study the RF performance and compare different methods to obtain such metrics. The current gain as a function of the frequency, was so obtained both by the Fourier decomposition (FD) method and the analytical formula proposed by Akis. A cut-off frequency fT of 150 GHz was found in both the transit time analysis given by the analytical approach, and the transient Fourier analysis, which matches well with the 153 GHz value measured experimentally. Furthermore, through some physical considerations, we derived the relation between the FoMJohnson as a function of the breakdown voltage, VBD, and the cut-off frequency, fT . Using this relation and assuming a breakdown voltage of 80V as measured experimentally, a Johnson figure of merit of around 20 × 1012V/s was found for the HEMT device analyzed in this work.
    Journal of Physics Conference Series 11/2009; 193(1):012040.
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    ABSTRACT: Buffer traps can induce ldquofalserdquo surface-trap signatures in AlGaN-GaN HEMTs, namely the same type of current-mode DLTS peaks and pulse responses that are generally attributed to surface traps. Device simulations are adopted to clarify the underlying physics. Being aware of the above phenomenon is important for both reliability testing and device optimization, as it can lead to erroneous identification of the degradation mechanism, thus resulting in inappropriate correction actions on the technological process.
    Reliability Physics Symposium, 2009 IEEE International; 05/2009
  • F.A. Marino, G. Meneghesso
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    ABSTRACT: We have developed and analyzed two alternative devices for the manufacture of high-density ICs, each of which is a FET that develop contemporarily the function of two classical transistors, allowing notably advantages in the realization of SRAM and logic circuits. We tested the effective functionality of these devices through Synopsys TCAD tools. We also extracted for each one of these a full set of electrical equations.
    Semiconductor Device Research Symposium, 2007 International; 01/2008
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    ABSTRACT: A new silicon controlled rectifier low voltage triggered (SCR-LVT), to be adopted as protection structure against electrostatic discharge (ESD) events, has been developed and characterized. A high holding voltage has been obtained thanks to the insertion of two parasitic bipolar transistors, achieved adding a n-buried region to a conventional SCR structure. These two parasitic transistors partially destroy the loop feedback gain of the two main npn and pnp BJTs, resulting in an increase of the sustaining (holding) voltage during the ESD event. A strong dependence of the holding voltage with the ESD pulse width has also been observed, caused by self-heating effects. 2D device simulations (DESSIS Synopsys) have been performed obtaining results that perfectly fit the measurements over a wide temperature range (25 degC-125 degC). Using device simulation results , the factors that influence the holding voltage, in terms of temperature dependence, but also in the behavior of the parasitic BJTs, are explained. A guideline to change the SCR holding voltage, related to the SCR design layout without any change to process parameters, is also proposed.
    Reliability Physics Symposium, 2008. IRPS 2008. IEEE International; 01/2008