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We report on measurements and modeling of FE HfZrO/SiO2 Ferroelectric-Dielectric (FE-DE) FETs which indicate that many of the phenomena attributed to Negative Capacitance can be explained by a delayed response of ferroelectric domain switching - referred to as Transient Negative Capacitance (TNC). No traversal of the stabilized negative capacitance branch is required. Modeling is used to correlate the hysteretic properties of the ferroelectric material to the measured transient and subthreshold slope (SS) behavior. It is found that steep SS can be understood as a transient phenomenon, present when significant polarization changes occur. The experimental signature of TNC is investigated, and guidelines for detecting it in measured data are outlined. The technological implications of FE polarization switching are investigated, and it is found that NCFETs relying on it are not suitable for high performance CMOS logic, due to voltage, frequency, and hysteresis limitations. Requirements for experimental evidence of stabilized S-curve behavior are summarized., Comment: 8 pages, 14 figures

A multi-bit digital weight cell for high-performance, inference-only non-GPU-like neuromorphic accelerators is presented. The cell is designed with simplicity of peripheral circuitry in mind. Non-volatile storage of weights which eliminates the need for DRAM access is based on FeFETs and is purely digital. The Multiply-and-Accumulate operation is performed using passive resistors, gated by FeFETs. The resulting weight cell offers a high degree of linearity and a large ON/OFF ratio. The key performance tradeoffs are investigated, and the device requirements are elucidated., Comment: 9 pages, 15 figures

In this letter, we show that conventional III–V MOSFETs with moderate/high In content channels (In0.53Ga0.47As or In0.70Ga0.30As) at scaled nodes are incompatible with mobile SoC designs, which often operate at intermediate/high ${V_{{\mathrm {dd}}}}$ (0.7 V to $\geq 1$ V) to achieve high frequency including during burst-mode. The incompatibility is due to conventional III–V FETs having too small bandgap, and thus too high leakage when operated at the increased voltages. We show that FETs with a more optimal lower In content, In0.35Ga0.65As, have the necessary combination of larger bandgap (~Si) and sufficiently high injection velocity (~2.5 times Si) to enable both low leakage and high performance (versus Si), across the entire ${V_{{\mathrm {dd}}}}$ range of mobile SoC operation. We report for the first time the growth and characterization of ultra-thin In0.35Ga0.65As FETs with a standard 1nm EOT gate dielectric. Calibrated models show that In0.35Ga0.65As enables the highest performance at very low leakages at intermediate/high ${V_{{\mathrm {dd}}}}$ in short channel FETs.

We demonstrate an SoC logic compatible ferroelectric-metal field effect transistor (FeMFET) digital 2-bit weight cell by monolithic BEOL integration of a ferroelectric (FE) capacitor with the gate of a conventional Si HK/MG MOSFET. Through optimization of the area ratio between the FE capacitor and the MOSFET, we show: 1) program/erase write voltages can be scaled down to logic compatible level, ±1.8 V, simplifying write circuitry; 2) write speed of 100ns; 3) write endurance $> 10^{10}$ cycles without degradation due to elimination of charge trapping in FE; 4) 2 bits/cell achieving software levels of accuracy for inference on MNIST training database; 5) state retention approaching 104 s for a depolarization field of 0.3 MV/cm; 6) Multi-port (independent read and write) operations.

We report on measurements and modeling of FE HfZrO/SiO 2 Ferroelectric-Dielectric (FE-DE) FETs which indicate that phenomena attributed to Negative Capacitance can be explained by a delayed response of ferroelectric domain switching. No traversal of the stabilized negative capacitance branch is required. Modeling is used to correlate the hysteretic properties of the ferroelectric material to the measured transient and subthreshold slope (SS) behavior. It is found that steep SS can be understood as a transient phenomenon, present only when significant polarization changes occur. The technological implications of this finding are investigated, and it is found that NCFETs are most likely not suitable for high-performance CMOS logic, due to voltage, frequency, and voltage polarity limitations.

The observation of room temperature sub-60 mV/dec subthreshold slope (SS) in MOSFETs with ferroelectric (FE) layers in the gate stacks or in series with the gate has attracted much attention. Recently, we modeled this effect in the framework of a FE polarization switching model. However, there is a large amount of literature attributing this effect to a stabilization of quasi-static (QS) negative capacitance (NC) in the FE. The technological implications of a stabilized non-switching (NS) QSNC model vs a FE switching model are vastly different; the latter precluding applications to sub-60 mV/dec SS scaled CMOS due to speed limitations and power dissipated in switching. In this letter, we provide a thorough analysis assessing the foundations of models of QSNC, identifying which specific assumptions (ansatz) may be unlikely or unphysical, and analyzing their applicability. We show that it is not reasonable to expect QSNC for two separate capacitors connected in series (with a metal plate between dielectric (DE) and FE layers). We propose a model clarifying under which conditions a QS "apparent NC" for a FE layer in a FE-DE bi-layer stack may be observed, quantifying the requirements of strong interface polarization coupling in addition to capacitance matching. In this regime, our model suggests the FE layer does not behave as a NC layer, simply, the coupling leads to both the DE and FE behaving as high-k DE with similar permittivities. This may be useful for scaled EOT devices but does not lead to sub-60 mV/dec SS., Comment: Version published in Appl. Phys. Lett

A user-friendly behavioral macromodel for biological response of FET-based transistors has been developed for use with commercial SPICE versions and will enable circuit level analysis of biosensor chips. The model is based on the physically realistic representation of biological layers using an ion-permeable charged membrane model. Simulations demonstrate good agreement to experimental results. Logarithmic increments in bound membrane charge result in linear threshold voltage shifts. The model accounts for phenomena such as Debye screening of biomolecules resulting in reduced sensor response to increments in salt concentration. Additionally, the presence of site binding charge on oxide surfaces is shown to severely deteriorate sensitivity.

The simulation of dynamic loads and required power is essential for the design of any morphing wing aircraft, since it ultimately determines the feasibility of a given morphing configuration. In this paper a methodology suitable for numerical calculation of the dynamic loads for a morphing-wing aircraft is presented. The approach taken is one of extending Rigid Body Dynamics to include time-varying terms. The dynamic loads are derived from Lagrange’s Equations of a morphing aircraft, modeled as a system of rigid bodies connected by actuated rotational and translational joints. The overall flight dynamics are also treated using the Extended Rigid Body Dynamics approach, introducing morphing forces and moments to model the correct dynamics for a morphing aircraft. Aerodynamic loads are computed using a Vortex-Lattice method. The overall model is applied to a gullwing aircraft performing a set of morphing-induced maneuvers. The resulting loads are analyzed, and the strict power requirements of the gull-wing aircraft are explained.

Aircraft with variable wing geometry (morphable wings) are of considerable interest, not only formission-specific optimization but for enhanced maneuverability as well. In the nascent field of mini or micro unmanned aerial vehicles, large and rapid changes inwing geometry are achievable, resulting in significant changes of the dynamics of the vehicle. In this paper, a simulationmethodology suitable for such aircraft is presented, accounting for the changes in both the aerodynamic and inertial properties. Because of the complexity of the possible wing configurations, the aerodynamics are simulated using an unsteady vortex-lattice approach, solved concurrently with six-degree-offreedom ( ) nonlinear equations of motion. The time dependence of the inertia tensor andmotion ofmass within the body frame are explicitly taken into account, resulting in additional body-frame forces andmoments. The simulation methodology is applied to various gull-wing configurations, and the flight dynamics are analyzed through nonlinear simulation.

Germanium is one of the promising materials for future CMOS technologies, due to its high carrier mobility and low Schottky barrier height (for PMOS). However, the presence of a small direct gap (in addition to the main indirect gap at the L-point) can result in significant band-to-band tunneling (BTBT), even at low voltages. If not remedied, it is easily the dominant BTBT mechanism. In this letter, the dependence of BTBT on the alloy composition in Ge-rich SiGe is studied using detailed simulation of the bandstructure. It is shown that even a very low stoichiometric fraction of Si in a FinFET results in a dramatic reduction of direct BTBT, much more so than in a corresponding p-i-n diode.

Due to the success of using strain for performance gain in advanced logic technologies, strain engineering has become an important part of advanced transistor design. This paper presents process and device models that are used to provide understanding of process-induced stress such as the stress due to epitaxial SiGe source drains and nitride capping films and how that stress affects device performance.

A bio-inspired energy-optimizing control methodology for a formation of rotary-wing Micro Air Vehicles (MAVs) is proposed. The key idea is that the recirculating airflow induced by each vehicle can be used to provide an upward airflow to a neighbor in the formation. The recirculating airflow around each vehicle is modeled using a doublet field, and the effects of recirculation on each vehicle in the formation are accounted for. A separation-bearing controller is implemented for a leader-follower formation, and the optimal formation is determined. It is found that the effects of recirculation are relatively weak, and only a single vehicle at a time can be the beneficiary of the recirculating flow of the rest of the formation. Within the optimal configuration, significant reduction in hover power can be realized for the lead vehicle.

We present novel and cost effective integration schemes with high performance analog and high voltage components to enable system-on-chip (SOC) designs in advanced CMOS technologies. The new transistors have superior analog performance compared to the standard logic devices resulting in significant area savings and greater analog functionality. The new high voltage (HV) transistors enable reliable 6V capability with high performance for direct battery connection circuits and other high voltage applications. Additional cost-free components are also provided including fully isolated CMOS; ppoly-pwell capacitors and varactors; and high-gain npn and pnp bipolar transistors. All of these components are implemented in a standard digital process without mask adders like deep nwell (DNWELL), silicide block (SIBLK), or dedicated high voltage (HV) transistor implants that are commonly used in the industry for deep sub-micron SOC implementation.

We report on reliability properties of MOCVD PZT ferroelectric capacitors as a function of film thickness. Data is presented for fatigue, thermal depolarization, and imprint. It is important to be able to model these parameters as they can significantly affect the switching polarization, which in turn affects the signal margin of an FRAM circuit. A ferroelectric SPICE model is presented that can be used to accurately simulate hysteresis and switching polarization behavior. This model agrees with experimental data and can be used to simulate FRAM circuit behavior through Ȝend of lifeȝ.

Aircraft with variable wing geometry (morphable wings) are of considerable interest, not only for mission-speciflc optimization, but for enhanced maneuverability as well. In the nascent fleld of mini- or micro-Unmanned Aerial Vehicles (UAVs), large and rapid changes in wing geometry are achievable, resulting in signiflcant changes of the dynamics of the vehicle. In this paper, we present a simulation methodology suitable for such aircraft, accounting for the changes in both the aerodynamic and inertial properties. Due to the complexity of the possible wing conflgurations, the aerodynamics are simulated using an unsteady Vortex-Lattice approach, solved concurrently with six(+) degrees of freedom (DOF) nonlinear equations of motion. The time dependence of the inertia tensor and motion of mass within the body frame are explicitly taken into account, resulting in additional body frame forces and moments. The simulation methodology is applied to several morphing wing conflgurations. The aerodynamic loads of each conflguration are obtained and the ∞ight dynamics analyzed through non-linear simulation.

Mobile system-on-chip (SoC) technologies require high-quality analog active and passive components along with low-power CMOS and dense SRAM. However, area scaling for both the SRAM bit cell and analog CMOS circuits is becoming increasingly difficult due to the impact of transistor random variation. To avoid added cost, co-optimizing the process for low random variation along with high performance and low power is required. We report a 45 nm lowpower technology with significantly reduced random variation for high yielding 0.255 mum2 SRAM arrays and analog transistors. Flexible RF and passive components for mobile SoCpsilas are also described. These process techniques enable continued 50% area scaling at 45 nm and beyond.

Electronic properties of graphene (carbon) nanoribbons are studied and compared to those of carbon nanotubes. The nanoribbons are found to have qualitatively similar electron band structure which depends on chirality but with a significantly narrower band gap. The low- and high-field mobilities of the nanoribbons are evaluated and found to be higher than those of carbon nanotubes for the same unit cell but lower at matched band gap or carrier concentration. Due to the inverse relationship between mobility and band gap, it is concluded that graphene nanoribbons operated as field-effect transistors must have band gaps