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Device Research Conference (DRC), 2012 70th Annual

Date 18-20 June 2012

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Displaying Results 1 - 25 of 143
  • 70th Device Research Conference Digest [front matter]

    Publication Year: 2012 , Page(s): 1 - 3
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  • Officers

    Publication Year: 2012 , Page(s): ii
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  • [Title page]

    Publication Year: 2012 , Page(s): iii
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  • Schedule of events

    Publication Year: 2012 , Page(s): iv - v
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  • Table of contents

    Publication Year: 2012 , Page(s): vi - xvii
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  • Plenary session [breaker page]

    Publication Year: 2012 , Page(s): 1 - 2
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  • Mapping a path to the beyond-CMOS technology for computation

    Publication Year: 2012 , Page(s): 3 - 6
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    This paper describes a methodology for benchmarking beyond CMOS exploratory devices for computation using metrics that can provide insights about the device fundamental operation. A more detailed investigation of circuits based upon two beyond-CMOS devices is given in the paper. First tunneling FET (TFET) circuits are compared to low power CMOS circuits. Then the All-Spin Logic device (ASLD) is described and a spin circuit theory based simulator is used to show the functional transient operation of an all spin logic circuit. View full abstract»

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  • Solid-state electronics and single-molecule biophysics

    Publication Year: 2012 , Page(s): 7 - 8
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    Biomolecular systems are traditionally studied using ensemble measurements and fluorescence-based detection. Among the most common in vitro applications are DNA microarrays to identify target gene expression profiles [1] and enzyme-linked immunosorbent assays (ELISA) to identify proteins [2]. While much can be determined with ensemble measurements, scientific and technological interest is rapidly moving to single-molecule techniques. When probing at the single-molecule level, observations can be made about the inter- and intramolecular dynamics that are usually hidden in ensemble measurements. In molecular diagnostic, single-molecule techniques often do not require amplification and simplify sample preparation. The most popular single-molecule techniques based on fluorescence [3, 4] are fundamentally limited in resolution and bandwidth by the countable number of photons emitted by a single fluorophore (typically on the order of 2500 photons/sec). Instrumentation is complex, expensive, and large-form-factor. Furthermore, most optical probes photobleach, limiting observation times and pump powers. Single-molecule measurements of the kinetics of fast biomolecular processes are often unavailable through fluorescent techniques, as they lack the required temporal resolution. View full abstract»

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  • Advanced device technologies for defense systems

    Publication Year: 2012 , Page(s): 9 - 12
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    The performance requirements of defense systems to detect small signals in the presence of clutter or large interferers, to see further than the adversary, and discriminate between targets in a complex environment, has driven the need for ever more capable device technologies for focal plane arrays (FPAs) and monolithic microwave integrated circuits (MMICs). This paper discusses the history, and current state, of several key technologies developed at Raytheon to enable our systems to meet mission needs. The technologies include Gallium Nitride (GaN) MMICs and Mercury Cadmium Telluride (MCT) Infrared Focal Plane Arrays (FPAs). Emerging technologies for heterogeneous integration and Short Wave Infrared (SWIR) FPAs are also discussed. View full abstract»

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  • Mems, sensors and harvestors [breaker page]

    Publication Year: 2012 , Page(s): 13 - 14
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  • High performance miniaturized NEMS sensors Toward co-integration with CMOS?

    Publication Year: 2012 , Page(s): 15 - 16
    Cited by:  Papers (2)
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    In this paper, we will present some possible emerging applications for Nano-Electro-Mechanical Systems (NEMS) and the interest of their co-integration with CMOS. We will compare some integration schemes and present mass sensing as a possible emerging application. In particular, experimental results on complex gas measurements with NEMS will be introduced. We will show that multi-physics simulations and compact modelling of NEMS components (including chemical and physical effects) can be efficiently used in circuit simulations standard tools for such system optimization. View full abstract»

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  • Silicon monolithic MEMS + photonic systems

    Publication Year: 2012 , Page(s): 17 - 18
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    Opto-mechanical systems offer one of the most sensitive methods for detecting mechanical motion using shifts in the optical resonance frequency of the optomechanical resonator. Presently, these systems are used for measuring mechanical thermal noise displacement or mechanical motion actuated by optical forces. Meanwhile, electrostatic capacitive actuation and detection is the main transduction scheme used in RF MEMS resonators. The use of electrostatics is convenient as it allows direct integration with electronics used for processing the RF signals. In this presentation, the author will introduce a method for actuating an opto-mechanical resonator using electrostatic forces and sensing of mechanical motion by using the optical intensity modulation at the output of an optomechanical resonator, integrated into a monolithic system fabricated on a silicon-on-insulator (SOI) platform. The author will discuss new applications enabled by this hybrid system including opto-acoustic oscillators and opto-mechanical accelerometers. View full abstract»

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  • Highly sensitive III–V nitride based piezoresistive microcantilever using embedded AlGaN/GaN HFET as ultrasonic detector

    Publication Year: 2012 , Page(s): 19 - 20
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    Summary form only given.We report, for the first time, an ultra high gauge factor of more than 3500 observed using AlGaN/GaN Heterostructure Field Effect Transistor (HFET) embedded GaN piezoresistive microcantilever. In addition, the deflection transduction signal from the HFET was utilized to determine dynamic bending as well as AC frequency response of the cantilever. Finally, the piezoresistive microcantilver was used to detect very small acoustic pressure waves generated by a piezo chip oscillated at sub nm amplitude at the resonance frequency of the cantilever positioned 1 cm away, highlighting the utility of these cantilevers as highly sensitive ultrasonic transducers. FET embedded microcantilevers are ideal for developing integrated electronic detection platform for biological and chemical analytes. GaN microcantilever with integrated AlGaN/GaN HFET deflection transducer offers very high mechanical, thermal, and chemical stability, in addition to extraordinary deflection sensitivity due to its strong piezoelectric properties. The piezoelectric property of III-V Nitrides causes a highly mobile (>;1500 cm2/Vs) two dimensional electron gas (2DEG) to form at the AlGaN/GaN interface, which gets strongly affected by the deflection induced strain. In addition, the electron mobility also changes due to the change in effective mass. The combined changes in 2DEG and mobility offer very high deflection sensitivity, verified through COMSOL finite element simulations and experimental observations. The effect of mechanical strain caused by microcantilever bending on the 2DEG and the AlGaN/GaN HFET characteristics has been reported experimentally [1] and theoretically [2] earlier, but this for the first time we have obtained such a high Gauge Factor. Microcantilevers were fabricated using III-V Nitride layers on Si(111). The layer structure consisted of i-GaN (2 nm)/ AlGaN (17.5 nm, 26% Al)/i-GaN (1 μm)/Transition layer (1.1 μm)/Si (111) subs- rate (500 μm). Fig. 1 (a) shows the SEM image of the fabricated device with the HFET shown in the inset. The HFET was fabricated with initial 200 nm mesa etching, followed by Ti(20 nm)/Al(100 nm)/Ti(45 nm)/Au(55 nm) metal stack deposition and rapid thermal annealing for ohmic contact formation. For gate contact, Ni(25 nm)/Au(375 nm) Schottky barrier was used. The fabricated microcantilever dimension is 350×50×2 μm. The GaN cantilever pattern was etched down using Ch based inductively coupled plasma etch process. Fig. 1 (b) shows the schematics of the experimental setup using our wire bonded device (shown as inset in Fig. 2) and Nanopositioner's (PI-611 Z). Fig. 2 shows the Id-V d characteristics of one of our best devices for different gate bias. In Fig. 3 the static bending performance is shown where the drain current is found to change by 6.3 % in magnitude, which gives a gauge factor of 3532. Both the downward and upward bending of cantilever exhibited similar changes. The movement of the nanopositioner was controlled using a Labview program, which was modified to also perform low frequency dynamic bending (up to 40 Hz). Fig. 4 shows the low frequency (0.5 Hz) response of a more typical device when the bending magnitude (both downward and upward) was 25 μm. We found that the low frequency upward and downward bending does not alter the gauge factor, and the response up to 40 Hz is also quite similar. We previously reported [3] a gauge factor of -38 (at Vg=0 V) and -860 in steady state and transient conditions, respectively. But our second generation devices consistently exhibit much higher gauge factor in both static and dynamic bending conditions at zero gate bias. We also extracted the AC response of the cantilevers using a miniature peizoactuator (PL055.31 from PI) and a lock-in amplifIer (SR 850). The ac response of the microcantilever, determined from direct contact oscillation of the piezo chip revealed a View full abstract»

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  • Nanostructured thermoelectric energy conversion and refrigeration devices

    Publication Year: 2012 , Page(s): 21 - 22
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    Energy consumption in our society is increasing rapidly. A significant fraction of the energy is lost in the form of heat. In this talk we introduce thermoelectric devices that allow direct conversion of heat into electricity. A key requirement to improve the efficiency is to increase the Seebeck coefficient (S) and the electrical conductivity (σ) while reducing the electronic and lattice contributions to thermal conductivity (κeL). Some new physical concepts and nanostructures make it possible to modify the trade-offs between the bulk material properties through the changes in the density of states, scattering rates and interface effects on the electron and phonon transport. We will review recent experimental and theoretical results on nanostructured materials of various dimensions: superlattices, nanowires, nanodots, as well as solid-state thermionic power generation devices [1]. Most of the recent success has been in the reduction of lattice thermal conductivity while maintaining good electrical conductivity. Several theoretical and experimental results to improve the thermoelectric power factor (S2σ) and reduce Lorenz number (σ/κe) are presented. Novel metal-semiconductor nanocomposites are developed where the heat and charge transport are modified at the atomic level. Theory and experiment are compared for several III-V and nitride nanocomposites and multilayers [2]. Potential to increase the energy conversion efficiency and bring the cost down to $0.1-0.2/W will be discussed [3]. We also describe how similar principles can be used to make micro refrigerators with cooling power densities exceeding 500 watts per centimeter square [4] in order to selectively remove dynamic hot spots and decrease significantly the requirements for overall cooling of the chip. We also describe some recent advances in nanoscale thermal characterization. Thermoreflectance imaging is used to- measure the transient temperature distribution in power transistors. Resolution down to 100ns in time, submicron spatial and 0.1C in temperature are achieved using megapixel CCDs. Finally, the transition between energy and entropy transport in nanoscale devices will be briefly discussed. View full abstract»

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  • Piezotronics and piezo-phototronics

    Publication Year: 2012 , Page(s): 23 - 24
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    Piezoelectricity, a phenomenon known for centuries, is an effect that is about the production of electrical potential in a substance as the pressure on it changes. The most well known material that has piezoelectric effect is the provskite structured Pb(Zr, Ti)O3 (PZT), which has found huge applications in electromechanical sensors, actuators and energy generators. But PZT is an electric insulator and it is less useful for building electronic devices. Wurtzite structures, such as ZnO, GaN, InN and ZnS, also have piezoelectric properties but they are not extensively used as much as PZT in piezoelectric sensors and actuators due to their small piezoelectric coefficients. In fact, due to the polarization of ions in a crystal that has non-central symmetry, a piezoelectric potential (piezopotential) is created in the crystal by applying a stress. For materials such as ZnO, GaN, InN in the wurtzite structure family, the effect of piezopotential to the transport behavior of charge carriers is significant due to their multiple functionalities of piezoelectricity, semiconductor and photon excitation. By utilizing the advantages offered by these properties, a few new fields have been created. Electronics fabricated by using inner-crystal piezopotential as a “gate” voltage to tune/control the charge transport behavior is named piezotronics, with applications in strain/force/pressure triggered/controlled electronic devices, sensors and logic units. Piezo-phototronic effect is a result of three-way coupling among piezoelectricity, photonic excitation and semiconductor transport, which allows tuning and controlling of electro-optical processes by strain induced piezopotential. The objective of this talk is to introduce the fundamentals of piezotronics and piezo-phototronics and to give an updated progress about their applications in energy science (LED, solar cell), electronics and sensors. View full abstract»

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  • Alternative graphene devices: beyond field effect transistors

    Publication Year: 2012 , Page(s): 24a - 24b
    Cited by:  Papers (1)
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    The future manufacturability of graphene devices depends on the availability of large-scale graphene fabrication methods. While chemical vapor deposition and epitaxy from silicon carbide both promise scalability, they are not (yet) fully compatible with silicon technology. Direct growth of graphene on insulating substrates would be a major step, but is still at a very early stage [1]. This has implications on potential entry points of graphene as an add-on to mainstream silicon technology, which will be discussed in the talk. View full abstract»

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  • Alternate transistor concept [breaker page]

    Publication Year: 2012 , Page(s): 25 - 26
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  • Novel double layer graphene transistors-bilayer pseudospin FETs and 2D-2D tunnel FETs

    Publication Year: 2012 , Page(s): 27 - 28
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    In this paper, bilayer pseudospin FET (BiSFET) is fabricated and tested for the condensate using Coulomb drag measurements in the double layer graphene system. The basic BiSFET structure can also be used as 2D-2D single particle tunnel FET, and the single particle h-h and e-e 2D-2D tunnel FETs, which is graphene's single-atom thickness could lead to more ideal interlayer tunneling characteristics provided the layers can be aligned. Single particle tunneling current calculations have been performed which show NDR characteristics, reminiscent of the BiSFET, albeit with higher operating powers. View full abstract»

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  • Effect of interfacial phonon-plasmon modes on electrical transport in supported graphene

    Publication Year: 2012 , Page(s): 29 - 30
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    This paper discusses the effects of interfacial phonon-plasmon modes on electrical transport in supported graphene. The mobility in graphene supported on an insulating dielectric substrate (such as SiO2) is typically due to scattering by charged impurities, surface roughness and surface polar phonon (SPP) modes. Although impurity scattering is the dominant factor limiting electron mobility it can be reduced experimentally. Coupling between the SPP and graphene plasmon modes leads to the formation of interfacial phonon-plasmon (lPP) modes which can also be interpreted as screened SPP modes. IPP dispersion and electron-IPP scattering rates were used for different substrates (SiO2, h-BN, HfO2 and Al2O3) to calculate the substrate-limited conductivity and field mobility of supported graphene. View full abstract»

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  • Possible applications of topological insulator thin films for tunnel FETs

    Publication Year: 2012 , Page(s): 31 - 32
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (694 KB) |  | HTML iconHTML  

    We have begun to explore the possibility of thin film three dimensional (3D) topological insulator (TI) based tunnel FETs (TFETs), specifically Bi2Se3 here, using quantum ballistic transport simulations with a tight-binding Hamiltonian in the atomic orbital basis including spin degrees of freedom. TI-based TFETs would be analogous in some ways to graphene nanoribbon TFETs, but without the sensitivity to ribbon width and edge roughness, and in some ways to narrow gap III-V TFETs but with substantially thinner quantum well widths. View full abstract»

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  • SymFET: A proposed symmetric graphene tunneling field effect transistor

    Publication Year: 2012 , Page(s): 33 - 34
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (781 KB) |  | HTML iconHTML  

    The expressions given in previous section, is for T = 0K. The room temperature results need to consider the Fermi distribution with integral over energy. The corresponding device parameters are labeled in the figures. A graphene length L = 100 nm is assumed. When the tunnel barrier is thicker, the resonant peak current decreases as expected (Figure 2 (a)). Thinner tgate offers better gate control and higher gate induced doping (and more resonant current). The corresponding resonance peaks increase and shift to higher bias (Figure 2 (b)). Figure 3 explores the entire bias phase space of the I-V characteristics. Though the on/off ratio of the SymFET is not a true performance metric, from equation (1) and (3) we find it is given by Ion/Ioff ≈ LΔE/ħvF, (~100 for L ~ 100nm, ~1000 for L ~ 1 μm). It is independent of temperature and increases with size. The ID-VDS characteristics at fixed VG are shown in Figure 4(a). In Figure 4(b), the ID-VG curve shows strong non-linear behavior. The transconductance can be large in the bias range where the resonant current peak exists. The ID-VDS curve (e.g. resonant width) is insensitive to the temperature (Figure 5), because of tunneling mechanism, except for Fermi function smearing. The slight difference at low VDS, is due to the Fermi function varying with temperature. The increase of resonant peak current is because Fermi tail extends to high energy with larger density of states. The nonlinear symmetric ID-VDS behavior can also be used for purposes of frequency multiplication; if a dc voltage bias at the current peak VDSp is superposed with an ac signal, the frequency of the output current will be doubled (Figure 6 schematic). The SymFET is expected to be intrinsically fast since it relies entirely on tunneling; high frequency digital operation and a host of analog appl- cations such as frequency multiplication are thus possible by exploiting the symmetry of the bandstructure of 2D graphene. View full abstract»

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  • Hybrid straintronics and spintronics: An ultra energy-efficient paradigm for logic and memory

    Publication Year: 2012 , Page(s): 35 - 36
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    Excessive energy dissipation during switching of logic and memory bits is the primary impediment to continued downscaling of electronic devices predicted by Moore's law. Nanomagnetic logic and memory switches are innately more energy-efficient than electronic switches because of correlated switching of spins that does not happen when charges are “switched” by moving them into and out of a transistor's channel. Furthermore, magnets do not “leak” unlike transistors. This results in much lower energy dissipation in a nanomagnetic switch compared to an electronic switch. However, this advantage is usually squandered in nanomagnetic logic (NML) paradigms because of very inefficient magnet switching schemes that result in mammoth dissipation in the switching circuit. View full abstract»

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  • Graphene and topological insulator based transistors: Beyond computing applications

    Publication Year: 2012 , Page(s): 37 - 38
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    Silicon based field effect transistors (FET) have been the foundation of computing industries for decades. As we approach the end of the Moore's law scaling, there have been increasing interests and efforts to explore transistors based on many "emerging" (non-Si) materials that may replace or supplement Si in future electronics and computing devices. However, Si and Si-MOSFETs remain exceptionally competitive and hard to beat by most "emerging" contenders. On the other hand, many of the non-Si based "emerging transistors" have novel physical properties that may make them highly attractive for various non-computing applications. In this talk, I will discuss transistors based on graphene and topological insulators, two classes of materials that have attracted much recent attention in physics and nanoelectronics communities. While both materials feature many novel electronic properties related to the unique Dirac electronic bandstructure, the lack of band gap brings challenges in applying them as digital electronic switches in conventional computing applications. After a brief review of graphene and TI based transistors and their prospects for digital computing applications, I will focus on two examples of exploiting the unique physical properties of these transistors for non-computing applications, particularly sensing and energy conversion. View full abstract»

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  • Poster session [breaker page]

    Publication Year: 2012 , Page(s): 39 - 44
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  • Al2O3/InSb/Si quantum well MOSFETs having an ultra-thin InSb layer

    Publication Year: 2012 , Page(s): 45 - 46
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    The fabrication and the properties of Al2O3-InSb-Si QW MOSFETs having an ultra thin InSb channel layer is reported. The good characteristic of ID-VD with an transconductance of 67 mS/mm demonstrates that the ultra thin InSb channel layer grown directly on Si can be used for MOSFET channels. The results show that the InSb/Si pseudomorphic quantum well MOSFETs is a promising candidate for future VLSIs. View full abstract»

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