Influence of heating atmosphere on the properties of stannous phosphate glass

A low-viscosity 60 SnO–40 P₂O₅ (mol%) glass was reheated at 280 °C (about 45 °C above the glass-transition temperature) for 20 min in various atmospheres (Ar, air, and O₂), then the structure- and surface-related properties were examined. It was found that increase in textP_{textO 2} {text{P}}_{{{text{O}}_{ 2} }} increases surface hardness, reduces optical transmittance, and improves chemical durability. The above phenomena are explained in terms of the increased oxidation tendency of Sn²⁺ to Sn⁴⁺ on the glass surface during reheating in increased textP_{textO 2} {text{P}}_{{{text{O}}_{ 2} }} .     

Characteristics of self-induced lightly-doped-drain polycrystallinesilicon thin film transistors with liquid-phase deposition SiO2 as gate-insulator and passivation-layer

As the passivation layer on the top of undoped offset region for offset-gate structured poly-Si TFTs is exposed to hydrogen plasma, a lightly-doped-like drain region could be equivalently self-induced. The hydrogenated polycrystalline silicon thin-film transistor of this structure, named self-induced lightly-doped-drain (SI-LDD) poly-Si TFTs, was first developed with liquid-phase deposition oxide as both the gate insulator and the passivation layer. This paper describes the optimum hydrogenation condition, and the electrical characteristics for the novel SI-LDD poly-Si TFTs. The effects of DC electrical stress on SI-LDD poly-Si TFTs are also described. Finally a model is proposed to explain the degradation phenomena observed in our SI-LDD devices     

Cluster-based blind nonlinear-channel estimation

A cluster-based maximum-likelihood sequence estimator (MLSE) for nonlinear channels was described, which consists of a clustering network and an MLSE implemented by the Viterbi algorithm. The cluster-based MLSE can be used for digital communication through nonlinear finite-length channels because channel mapping estimation is used instead of channel estimation in the conventional MLSE. The clustering network of the cluster-based MLSE, which estimates the channel mapping between the signal input vectors and the noiseless channel outputs, is a supervised network and requires a training sequence. We propose a blind channel mapping estimator to estimate the channel mapping without using the training sequence. The blind channel mapping estimator has a clustering block and a mapping block. The clustering block estimates the channel outputs, which represent the channel mapping, subject to an unknown permutation operation because no training sequence is utilized. That permutation operation is resolved by the mapping block, and therefore, the channel mapping is obtained. Introducing the blind channel mapping estimator into the cluster-based MLSE, a blind cluster-based MLSE for nonlinear channels can be done. Computer simulations of the blind channel mapping estimator and the blind MLSE for nonlinear channels are presented     

A maintenance model for two-unit redundant system

In this paper, a maintenance model for two-unit redundant system with one repairman is studied. At the beginning, unit 1 is operating, unit 2 is the standby unit. The costs include the operating reward, repair cost and replacement cost, besides, a penalty cost is incurred if the system breaks down. Two kinds of replacement policy, based on the number of failures for two units and the working age, respectively are used. The long-run average cost per unit time for each kind of replacement policy is derived. Also, a particular model in which the system is deteriorative, two units are identical and the penalty cost rate is high, is thoroughly studied.     

Design and fabrication of deep submicron CMOS technology compatible suspended high-Q spiral inductors

In this paper, deep submicron complementary metal-oxide-semiconductor (CMOS) process compatible high-Q suspended spiral on-chip inductors were designed and fabricated. In the design, the electromagnetic solver, SONNET, and the finite element program, ANSYS, were used for electrical characteristics, maximum endurable impact force, and thermal conduction simulations, respectively. Based on the design, suspended spiral inductors with different air cavity structures, i.e., diamond opening, circle opening, triangle opening, and full suspended with pillar supports were developed for various applications. Among these structures, the suspended inductor with pillar support possesses the highest Q/sub max/ (maximum of quality factor) of 6.6 at 2 GHz, the least effective dielectric constant of 1.06, and the lowest endurable impact force 0.184 Newton. On the other hand, the spiral inductor with diamond opening has a lowest Q/sub max/ of 4.3, the largest effective dielectric constant of 3.44 and highest endurable impact force 4 Newton. The former is suitable for station telecommunication applications in which the mechanical vibration is not a serious concern, while the latter can be used for mobile telecommunication applications subject to strong mechanical vibrations. Additionally, the conventional on-chip spiral inductor embraced by SiO/sub 2/ with a dielectric constant of 4 was prepared for comparison and found its Q/sub max/ is 3.8 at 1.2 GHz.     

Schottky barrier thin-film transistor (SBTFT) with silicidedsource/drain and field-induced drain extension

A novel Schottky barrier thin-film transistor (SBTFT) with silicided source/drain and field-induced drain (FID) extension is proposed and demonstrated. In the new device configuration, a metal field-plate (or sub-gate) lying on the passivation oxide is employed to induce a sheet of carriers in a channel offset region located between the silicided drain and the active channel region underneath the main gate. The new device thus allows ambipolar device operation by simply switching the polarity of the bias applied to the field plate. In contrast to the conventional SBTFT that suffers from high GIDL (gate-induced drain leakage)-like off-state leakage current, the new SBTFT with FID is essentially free from the GIDL-like leakage current. In addition, unlike the conventional SBTFT that suffers from low on-off current ratio, the new device exhibits high on/off current ratio up to 10⁶ for both n- and p-channel modes of operation. Moreover, the implantless feature and the ambipolar capability of the new device also result in extra low mask count for CMOS process integration. These excellent device characteristics, coupled with its simple processing, make the new device very promising for future large-area electronic applications     

Influence of La substitution on the electrical properties of metal-ferroelectric (BiFeO3)-insulator (CeO2)-semiconductor nonvolatile memory structures

Metal-multiferroic (La-substituted BiFeO₃)-insulator (CeO₂)-semiconductor (MFIS) capacitors has been fabricated. The crystalline phase and amount of La³⁺ substitution at Bi-site were investigated by XRD and XPS in the postannealing temperature range from 500 to 700 °C, respectively. The microstructure and interfacial layer between CeO₂ and Si substrate were characterized by HRTEM. The memory windows as functions of insulator film thickness and DC power for La were measured. The maximum memory window is about 1.9 V under ±6 V applied voltage. The ferroelectric polarization increases with increasing substitution amount. The morphologies of La-substituted BiFeO₃ films were also studied by AFM.     

The impacts of high tensile stress CESL and geometry design on device performance and reliability for 90 nm SOI nMOSFETs

The thickness effects of high-tensile-stress contact etch stop layer (HS CESL) and impact of layout geometry (length of diffusion and gate width) on mobility enhancement of 100/(100) 90 nm SOI nMOSFETs were studied in detail. Additionally, we also inspected the low frequency characteristic with low-frequency noise investigation for FB-SOI nMOSFETs. Experimental results show that devices with 1100 Å HS CESL possess worse characteristics and hot-carrier-induced degradations than devices with 700 Å HS CESL due to serious stress-induced defects happen. The lower plateau of Lorentzian noise spectrum observed from input-referred voltage noise (S_vg) implies higher leakage current for the devices with 1100 Å HS CESL. On the other hand, we found that devices with narrow gate widths possess higher driving capacity because of larger fringing electric fields and higher compressive stress in direction perpendicular to the channel. Owing to the more serious impact of compressive stress in direction parallel to the channel, the device performance was degraded particularly for devices with shorter LOD.     

Required bandwidth, unwanted emission, and data power efficiencyfor residual and suppressed carrier systems-a comparative study

This paper presents a new concept for required bandwidth along with a method for computing this bandwidth and the associated undesired emission for the classes of PCM/PSK/PM, PCM/PM and BPSK signals. The PCM/PSK/PM signals considered here employ either a square wave or sine-wave subcarrier with NRZ data format. On the other hand, the PCM/PM and BPSK signals use either a Bi-phase or an NRZ data format. Furthermore, the maximum allowable required bandwidth in the presence of noise and the data power efficiency for these modulation schemes will also be investigated. The term “data power efficiency” as considered in this paper consists of two principal components, namely, the amount of power contained in the data channel, and the symbol signal-to-noise ratio (SSNR) degradation due to the presence of intersymbol interference (ISI) for a specified required bandwidth. This paper evaluates both of these components numerically for the modulation schemes considered and the results are then compared. Furthermore, the impact of baseband filtering on the required bandwidth is also investigated in this paper     

Motor control and torque coordination of an electric vehicle actuated by two in-wheel motors

In this research, an electric vehicle actuated by two in-wheel DC motors is developed. By properly coordinating the motor torques, both drive-by-wire and electrical steering can be achieved. Two critical issues respectively related to the design of motor controllers and the coordination of the two motor torques under control saturation are investigated in this study. Firstly, as for the in-wheel motors that are used for driving and steering simultaneously, their operation covers a wider dynamic range that forward acceleration (deceleration), and reverse acceleration (deceleration) may occur alternately. To perform driving and steering smoothly and efficiently, each motor should be switched to an appropriate mode to generate the torque demanded. Secondly, during the high-speed maneuvering, the high back-emf voltage in the motor coil substantially reduces the motor’s torque generating capability. Since the electrical steering depends on the differential torque of two wheels, when electrical steering is demanded in this case, torque/current saturation may occur in either one of the motors and the electrical steering performance could be seriously degraded. To address these issues, controllers of two levels are proposed. For the low-level controller (the motor controller), it operates the motor automatically in an appropriate mode for performance and efficiency consideration. An input transformation is introduced to cancel the nonlinearity in current dynamics so as to control the motor torque easily and precisely regardless of mode switching. For the high-level controller (the torque coordination controller), besides generating reference commands to the low-level controllers, during control saturation it can also properly re-distributes control signals to maintain consistent steering performance and provides compensation for integrator windup. The control system is implemented and the performance is experimentally and numerically validated.