L. Faraone

University of Western Australia, Perth City, Western Australia, Australia

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Publications (372)439.94 Total impact

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    ABSTRACT: Multi-carrier transport in planar fully-depleted silicon-on-insulator (FD-SOI) MOSFETs has been investigated employing magnetic-field dependent geometrical magnetoresistance measurements and high-resolution mobility spectrum analysis. The results indicate that electronic transport in the 10 nm thick Si channel layer is due to two distinct and well-defined electron species. Although self-consistent Schrödinger–Poisson numerical calculations indicate significant localization of the total electron population near the back and front interfaces, the results of mobility spectrum analysis suggest that the mobility distributions associated with these spatially localized populations are strongly coupled through carrier scattering processes, and do not have independent and distinguishable mobility distributions. The two detected electron mobility distributions are thus evidence of sub-band modulated transport in 10-nm thick Si planar FD-SOI MOSFETs. The mobility maximum of the dominant carrier was found to occur under gate bias conditions that result in a minimum perpendicular effective electric field.
    Solid-State Electronics 06/2015; DOI:10.1016/j.sse.2015.05.022 · 1.51 Impact Factor
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    ABSTRACT: Magnetic-field dependent resistivity and Hall-effect measurements combined with high resolution mobility spectrum analysis (HR-MSA) were employed to study room-temperature electronic transport in 4H-SiC metal–oxide–semiconductor field-effect transistor (MOSFET) structures. It is shown that the mobility distribution for electrons at the SiO2/SiC interface is significantly broader than expected for quantum confined carriers, exhibiting Hall scattering factors significantly greater than the generally assumed unity value. The interfacial electron mobility and Hall scattering factor are likely to be determined by potential fluctuations arising from a disordered transition layer on the SiC side of the SiO2/SiC interface. For the MOSFET structures studied, charge trapping at the SiO2/SiC interface was found to determine the interfacial free electron sheet density, in agreement with prior studies on similar device structures. HR-MSA has enabled unambiguous discrimination between electrons in the ion-implanted buried channel layer and at SiO2/SiC interface in a depletion-mode MOSFET structure.
    Microelectronic Engineering 04/2015; 147. DOI:10.1016/j.mee.2015.04.017 · 1.34 Impact Factor
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    ABSTRACT: We report a theoretical study of mercury cadmium telluride (HgCdTe) unipolar n-type/barrier/n-type (nBn) detectors for midwave infrared (MWIR) applications at elevated temperatures. The results obtained indicate that the composition, doping, and thickness of the barrier layer in MWIR HgCdTe nBn detectors can be optimized to yield performance levels comparable with those of ideal HgCdTe p-n photodiodes. It is also shown that introduction of an additional barrier at the back contact layer of the detector structure (nBnn+) leads to substantial suppression of the Auger generation-recombination (GR) mechanism; this results in an order-of-magnitude reduction in the dark current level compared with conventional nBn or p-n junction-based detectors, thus enabling background-limited detector operation above 200 K.
    Journal of Electronic Materials 04/2015; DOI:10.1007/s11664-015-3764-y · 1.68 Impact Factor
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    ABSTRACT: In this paper, we report results of a study of SiN x thin films for surface passivation of HgCdTe epitaxial layers. The hydrogenated amorphous SiN x films under study were deposited by a SENTECH SI500D inductively coupled plasma-enhanced chemical vapor deposition (ICPECVD) system with a high-density and low-ion-energy plasma source at relatively low substrate temperatures (80°C to 100°C). A series of SiN x films were first deposited on CdTe/GaAs and Si substrates under different deposition conditions to examine the influence of ICP power, deposition temperature, and NH3/SiH4 ratio on properties of the SiN x films. To investigate SiN x deposition conditions suitable for surface passivation of HgCdTe, the SiN x /n-Hg0.68Cd0.32Te interface characteristics were investigated employing capacitance–voltage measurements, and the corresponding interface trap densities D it were extracted from the high-frequency and low-frequency characteristics. Analysis of SiN x /n-Hg0.68Cd0.32Te metal–insulator–semiconductor (MIS) structures indicated that Si-rich SiN x films deposited at 100°C by ICPECVD exhibit electrical characteristics suitable for surface passivation of HgCdTe-based devices, that is, interface trap densities in the range of mid-1010 cm−2 eV−1 and fixed negative interface charge densities of ∼1011 cm−2. In addition, the relationship between bond concentration and surface passivation performance has been explored based on infrared (IR) absorbance spectra. The Si–H and N–H bond concentrations were found to be directly correlated with passivation performance, such that SiN x films with a combination of high [Si–H] and low [N–H] bond concentrations were found to be suitable as electrical passivation layers on HgCdTe.
    Journal of Electronic Materials 03/2015; DOI:10.1007/s11664-015-3703-y · 1.68 Impact Factor
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    ABSTRACT: In this paper, we present a theoretical study of mercury cadmium telluride (HgCdTe)-based unipolar n-type/barrier/n-type (nBn) infrared (IR) detector structures for midwave IR and longwave IR spectral bands. To achieve the ultimate performance of nBn detectors, a bandgap engineering method is proposed to remove the undesirable valence band discontinuity that is currently limiting the performance of conventional HgCdTe nBn detectors. Our proposed band engineering method relies on simultaneous grading of the barrier composition and doping density profiles, leading to efficient elimination of the valence band discontinuity. This allows the detector to operate at |V-bias| < 50 mV, rendering all tunneling-related dark current components insignificant and allowing the detector to achieve the maximum possible diffusion current limited performance.
    IEEE Transactions on Electron Devices 03/2015; 62(3):722-728. DOI:10.1109/TED.2015.2389229 · 2.36 Impact Factor
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    ABSTRACT: n this work, we report results of a study of electronic transport in nominally undoped p-type GaSb wafers typically employed as substrate material for the epitaxial growth of InAs/GaInSb type-II superlattices. Magnetic field dependent Hall-effect measurements and high-resolution mobility spectrum analysis clearly indicate p-type conductivity due to carriers in both the heavy and light hole bands. The extracted hole concentrations indicate a thermal activation energy of 17.8 meV for the dominant native acceptor-like defects. A temperature-independent effective mass ratio of 9.0 ± 0.8 was determined from the ratio of measured heavy and light hole concentrations. Over the 56 K–300 K temperature range, the light hole mobility was found to be 4.7 ± 0.7 times higher than the heavy hole mobility. The measured room temperature mobilities for the light and heavy holes were 2550 cm2/Vs and 520 cm2/Vs, respectively.
    Applied Physics Letters 01/2015; 106(3):032103. DOI:10.1063/1.4906489 · 3.52 Impact Factor
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    ABSTRACT: Monitoring the nanomechanical movement of suspended cantilever structures has found use in applications ranging from biological/chemical sensing to atomic force microscopy. Interrogating these sensors relies on the ability to accurately determine the sub-nanometre movements of the cantilever. Here we investigate a technique based on the combination of integrated silicon photonics and microelectromechanical systems (MEMS) to create an optically resonant microcavity and demonstrate its use for monitoring of the position of cantilevers on the picometer scale under ambient conditions with dynamic range extending over several microns. The technique is interferometric, and we show it to be sufficiently sensitive to measure both the first and second modes of cantilever Brownian motion. We anticipate that application of this technique will provide a physically robust, picometer precision, integrated cantilever movement read-out technology which can take cantilever sensors from laboratory controlled environments into real world conditions, allowing everyday applications.
    Nanoscale 12/2014; 7(5). DOI:10.1039/c4nr05419a · 6.74 Impact Factor
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    ABSTRACT: Iodine (I) doping in mercury cadmium telluride (Hg1-xCdxTe) grown by molecular beam epitaxy (MBE) on CdZnTe substrates with cadmium-iodide (CdI2) as the dopant source was investigated. I doping concentration in the samples was controlled by CdI2 source temperature that varied in 110°C-150°C range. Depending upon I doping concentration, the electrical conductivity at 77K for as grown films varied in the 3×103 Ω-1m-1 - 6×104 Ω-1 m-1 range and was about of six to ten orders of magnitude higher than those of non-doped HgCdTe films. The Hall coefficient showed classical n-type extrinsic behavior. The electron mobility for lower doping level was observed to be as high as that in an indium-doped material reported in literature [1]. The x-ray diffraction (XRD) studies revealed that there was no prominent change in crystal structure with increasing doping concentration. However, atomic force microscopy (AFM) measurements showed that dislocation densities and consequently defect concentration and size increased with increasing doping concentration.
    Conference on Optoelectronic and Microelectronic Materials & Devices (COMMAD), 2014, Perth, WA, Australia; 12/2014
  • Optoelectronic and Microelectronic Materials & Devices (COMMAD), Perth, WA; 12/2014
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    ABSTRACT: We report on the deposition, crystallization, and magnetic properties of cerium-substituted europium iron garnet having the general form of (CeEu) 3 (FeGa) 5 O 12 . The films were deposited on gallium gadolinium garnet and fused quartz substrates using biased target ion beam deposition at a rate of 2.7 nm/min. The Ce:EIG thin film has a composition of Ce 1.3 Eu 1.7 Fe 3 Ga 1.6 O 12 , with 30% of the Ce in the 4+ oxidation state and the remainder as Ce 3+ . The film exhibits the primary peaks of the garnet phase in X-ray diffraction patterns. In the visible part of the electromagnetic spectrum, the film on GGG exhibits a Faraday rotation of 3.3°/µm with coercivity of 0.58 kOe, whereas the film on fused quartz exhibits 1.1°/µm with a coercivity of 0.8 kOe. The film on the fused quartz substrate has a saturation magnetization of 17 emu/cm 3 at room temperature. Index Terms— Biased target ion beam deposition, cerium substituted europium iron garnets, crystallization, grazing angle X-ray diffraction (XRD), magnetic and magneto-optical (MO) properties, X-ray photoelectron spectroscopy (XPS).
    IEEE Transactions on Magnetics 12/2014; 50(12). DOI:10.1109/TMAG.2014.2331016 · 1.21 Impact Factor
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    ABSTRACT: Design of practically realizable unipolar HgCdTe nBn photodetectors has been studied in detail by numerical analysis. The simulations reported herein reveal that, by optimization of barrier doping, dark current levels can be reduced and collection efficiency substantially improved. It is shown that p-type doping of the barrier layer can significantly reduce the effective potential barrier arising from the valence band offset between the absorber and barrier regions, thus enabling HgCdTe nBn detector operation under near zero-bias conditions. However, relatively high electric fields in the space charge regions near the barrier/absorber interface result in enhanced trap-assisted Shockley–Read–Hall thermal generation. Our calculations indicate that nBn HgCdTe detectors with barriers engineered by use of HgTe/Hg0.05Cd0.95Te superlattices have, potentially, substantially better valence band alignment without the need for p-type doping.
    Journal of Electronic Materials 12/2014; 44(1). DOI:10.1007/s11664-014-3511-9 · 1.68 Impact Factor
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    ABSTRACT: This paper presents the results of experimental work on a low temperature through-wafer reactive ion etching (RIE) technique obtained in the course of development of a process that can be used in small sample processing for microelectromechanical systems (MEMS). Low temperature RIE are a crucial step for many dry MEMS fabrication processes, where can be used to fabricate silicon vias, trenches, and to perform dry release of membranes and other devices. The through-wafer etch developed here can be used also to separate fabricated devices, especially when it is desirable to produce non-rectangular shapes, which cannot be cut using a dicing saw. The presented process works with large silicon wafers as well as with small samples. In this work we developed a method which allows for stabilization of the sample temperature at the correct level during the entire process, which allows through wafer etch of thick silicon samples. The results obtained indicate that there is no universal process suited to all applications. Here we present three different recipes suitable for various applications.
    Optoelectronic and Microelectronic Materials Devices (COMMAD), 2014 Conference on; 12/2014
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    ABSTRACT: Crystallization of germanium (Ge) thin films was investigated by depositing Ge on glass and silicon substrates using electron beam (e-Beam) evaporation. The hole carrier concentration in Ge thin films deposited on glass substrates was found to decrease slightly with increasing annealing temperature, whereas its Hall mobility was found to increase monotonically. For all crystallized Ge thin films herein reported, the conductivity was found to be dominated by holes (p-type). This characteristic was then exploited to fabricate p-Ge/n-Si heterojunction diodes on n-type silicon substrates, which were then investigated by analysis of their current–voltage and capacitance–voltage characteristics. It was found that increasing annealing temperatures lead to significant improvements in on/off ratio and ideality factor, as well as increased built-in voltage. After crystallization of the top p-Ge layer through annealing at 600 °C, the devices indicated an on/off ratio of 106, an ideality factor of 1.25 and a built-in potential of 0.58 eV. The improvement in device performance is correlated with the crystallization of the Ge thin films, as confirmed by Hall effect and X-ray diffraction measurement, which indicated increases in hole mobility and improved solid-phase crystallization with increases in annealing temperature. The photoresponse of the devices was characterized employing a two-dimensional mapping approach, which provides insight into the optical generation and recombination processes at the Ge/Si heterojunction. The results herein presented indicate that thermally crystallized Ge thin films may be of significant promise for electronic and optoelectronic device applications.
    Materials Science in Semiconductor Processing 12/2014; 30:413. DOI:10.1016/j.mssp.2014.10.041 · 1.76 Impact Factor
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    ABSTRACT: Modern devices consisting of multiple semiconductor layers often result in the population of numerous distinct carrier species. Conventional Hall measurements at a single-magnetic-field strength provide only a weighted average of the electron mobility and carrier concentration of a semiconductor structure and, therefore, are of limited use for the extraction of carrier transport information. In recent years, mobility spectrum analysis techniques, which have been developed to extract a mobility spectrum from magnetic field-dependent conductivity-tensor measurements, have been applied in the analysis of carrier conductivity mechanisms of numerous semiconductor structures and devices. Currently there is a severe lack of reported studies on theoretical calculations of the mobility distribution of semiconductor structures or devices. In addition, the majority of reports on experimental mobility spectrum analysis are of complex, multi layered structures such as type-II superlattices, and the interpretation of the mobility spectra has been difficult. Therefore, a good understanding of the mobility spectrum has yet to be developed. For example, it is often assumed that distinct peaks of a mobility spectrum result from fundamentally different conduction mechanisms such as the bulk and surface conduction of narrow-band-gap semiconductors. In this article, we present calculations of the electron mobility distribution of bulk GaAs, which predict the existence of multiple mobility spectrum peaks that result from electron conductivity in the Γ conduction band. This report serves as an important and simple test case upon which experimentally measured mobility spectra can be compared. It also presents insight into the general nature of electron mobility distributions.
    New Journal of Physics 11/2014; 16(11):113033. DOI:10.1088/1367-2630/16/11/113033 · 3.67 Impact Factor
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    ABSTRACT: Modulation of the sub-band electron population in the inversion channel of 10-nm planar fully depleted silicon-on-insulator MOSFETs is evidenced by the bias dependence of inversion layer transport parameters. Two distinct inversion-layer electron species were detected by magnetic-field-dependent magnetoresistance measurements and high-resolution mobility spectrum analysis. According to self-consistent Poisson–Schrödinger calculations, these species correspond to carriers in distinct sub-bands within the Si channel region. The mobility peak of the carrier with the highest sheet density occurs under gate bias conditions that result in a minimum perpendicular effective electric field.
    IEEE Electron Device Letters 09/2014; 35(11). DOI:10.1109/LED.2014.2358201 · 3.02 Impact Factor
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    ABSTRACT: A method is described where the valence band discontinuity in HgCdTe-based nBn detectors will be eliminated. The method relies on doping modulation technique, where grading the material composition and doping concentration of the barrier layer at the same time will lead to elimination of the valence band discontinuity in HgCdTe-based nBn detectors. The method is not limited to the nBn structure and can be applied to any barrier detector structure with xBx (with x = n, p) to eliminate the energy band discontinuity in the valence band or conduction band.
    Applied Physics Letters 09/2014; 105(12):121110. DOI:10.1063/1.4896577 · 3.52 Impact Factor
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    ABSTRACT: Three-dimensional (3D) topological insulators (TI) are a new state of quantum matter in which surface states reside in the bulk insulating energy bandgap and are protected by time-reversal symmetry. It is possible to create an energy bandgap as a consequence of the interaction between the conduction band and valence band surface states from the opposite surfaces of a TI thin film, and the width of the bandgap can be controlled by the thin film thickness. The formation of an energy bandgap raises the possibility of thin-film TI-based metal-oxide-semiconductor field-effect-transistors (MOSFETs). In this paper, we explore the performance of MOSFETs based on thin film 3D-TI structures by employing quantum ballistic transport simulations using the effective continuous Hamiltonian with fitting parameters extracted from ab-initio calculations. We demonstrate that thin film transistors based on a 3D-TI structure provide similar electrical characteristics compared to a Si-MOSFET for gate lengths down to 10 nm. Thus, such a device can be a potential candidate to replace Si-based MOSFETs in the sub-10 nm regime.
    Journal of Applied Physics 08/2014; 116(8):084508-084508-8. DOI:10.1063/1.4894152 · 2.19 Impact Factor
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Publication Stats

2k Citations
439.94 Total Impact Points

Institutions

  • 1900–2015
    • University of Western Australia
      • School of Electrical, Electronic and Computer Engineering
      Perth City, Western Australia, Australia
  • 2010
    • University of Southampton
      Southampton, England, United Kingdom
  • 2006
    • DRS Technologies
      Парсиппани, New Jersey, United States
  • 2004
    • University of California, Santa Barbara
      • Department of Electrical and Computer Engineering
      Santa Barbara, California, United States
  • 1999
    • Vigo System S.A.
      Ożarów-Franciszków, Masovian Voivodeship, Poland
  • 1984
    • University of Bradford
      Bradford, England, United Kingdom
  • 1981–1982
    • Lehigh University
      Bethlehem, Pennsylvania, United States
    • University of Toronto
      • Department of Electrical and Computer Engineering
      Toronto, Ontario, Canada