Laser annealing effects on the electrical characteristics of SOS transistors

Successful incorporation of laser annealing techniques into standard processing methods requires that the electrical characteristics of the devices not be degraded. In this work, a range of energy densities from pulsed u.v. and visible lasers which can be utilized in silicon on sapphire (SOS) technology to improve device performance without introducing any deleterious side effects is determined experimentally. Silicon islands were photolithographically defined and chemically etched (KOH) on standard SOS wafers which were subsequently exposed to pulsed (25 nsec) ruby ($\text{λ = 6943}\text{A}\text{?}$) and excimer ($\text{λ = 2490}\text{A}\text{?}$) laser radiation. Comparative studies of the effect of front and back side (through the sapphire) irradiation of the silicon on device performance were conducted. Using standard processing techniques, MOS transistors were fabricated after laser irradiation and electrically characterized. It was found that under certain conditions utilization of lasers in SOS processing, can result in an increase in the interface state density at both the top 〈100〉 Si-SiO₂ interface and the bottom Al₂O₃-Si interface. However, a set of conditions exists, in which it is possible to apply laser annealing to standard SOS processing so as to increase MOS/SOS transistor channel mobility by over 30% without causing any degradation of the device electrical characteristics.     

A new method for myocardial activation imaging

Noninvasive images of the myocardial activation sequence are acquired, based on a new formulation of the inverse problem of electrocardiography in terms of the critical points of the ventricular surface activation map. It is shown that the method is stable with respect to substantial amounts of correlated noise common in the measurements and modeling of electrocardiography and that problems associated with conventional regularization techniques can be circumvented. Examples of application of the method to measured human data are presented. This first invasive validation of results compares well to previously published results obtained by using a standard approach. The method can provide additional constraints on, and thus improve, traditional methods aimed at solving the inverse problem of electrocardiography     

Argon-ion bombardment effects on the electrical characteristics of platinum-silicon Schottky diodes

Before barrier metal evaporation, silicon Schottky diodes were cleaned by argon-ion bombardment. Some device series were evaporated just after the ion cleaning, whereas others were annealed beforehand. The electrical characteristics of the different series were checked by means of standard I/V and C/V measurements. Whereas the ideality coefficient and the barrier height obtained from I/V characteristics showed nearly complete recovery after heat treatment for 1 h at 700°C, the barrier height from C/V measurements did not recover.     

Metal nanocrystal memories-part II: electrical characteristics

This paper describes the electrical characteristics of the metal nanocrystal memory devices continued from the previous paper [see ibid., vol. 49, p. 1606-13, Sept. 2002]. Devices with Au, Ag, and Pt nanocrystals working in the F-N tunneling regime have been investigated and compared with Si nanocrystal memory devices. With hot-carrier injection such as the programming mechanism, retention time up to 10⁶ s has been observed and 2-bit-per-cell storage capability has been demonstrated and analyzed. The concern of the possible metal contamination is also addressed by current-voltage (I-V) and capacitance-voltage (C-V) characterizations. The extracted inversion layer mobility and minority carrier lifetime suggest that the substrate is free from metal contamination with continuous operations     

Hot carrier effects in polycrystalline silicon thin-film transistors: analysis of electrical characteristics and noise performance modifications

Hot-carrier effects on both the electrical characteristics and the noise performance in polycrystalline silicon thin film transistors are analysed. The devices were fabricated by using a combined solid phase crystallization (SPC) and excimer laser annealing (ELA) process, combining the beneficial aspects of the two techniques. Hot-carrier degradation results in the formation of both interface states, which have been evaluated through the analysis of the sheet conductance and of oxide traps near the insulator/semiconductor interface, as evidenced by the 1/f noise measurements. Oxide traps are calculated evaluating the flat band voltage spectral density associated with interface charge fluctuations in the damaged part of the interface. A strong correlation between interface state and oxide trap densities has been found, suggesting a common origin for the generation mechanism of the two types of defects.     

Combined shear-force/field emission microscope for local electrical surface investigation

In view of the rapid growth of interest in atomic force microscopy in the investigation of surface properties, the modular shear-force/field emission microscope is herein described. The electrochemically etched tungsten tip is used both as near field force detector and collector of tip-sample emission current. The setup allows to perform simultaneous measurement of the surface topography and field emission current. After the result is obtained, one can correlate presence of features on the surface with emission “map” which shows electrical surface properties. Presented setup is based on the fiber Fabry-Perot interferometer for the measurement of microtip oscillation. The optical detection allows one to apply voltage to the conductive tip. Moreover, the presented setup is extremely sensitive and compact.The presented preliminary results which were obtained by scanning HOPG (highly ordered pyrolytic graphite) and gold surface show the efficiency of the method and give perspectives for further applications.     

The effects of point defects on the electrical activation ofSi-implanted GaAs during rapid thermal annealing

The effects of point defects on the electrical activation of Si-implanted GaAs during rapid thermal annealing were investigated using slow positron beam, cross-sectional transmission electron microscopy, and Hall measurements. The increase of the Ga vacancy concentration in the GaAs substrate induced by the SiO₂ cap layer on the substrate during annealing was observed to decrease the activation efficiency and the number of extrinsic stacking faults via the recombination of interstitials with vacancies. It was found that the efficiency of the carrier creation is not dependent upon the Ga vacancy concentration during the rapid thermal annealing of Si-implanted GaAs. Hence, it is proposed that the electrical activation of Si-implanted GaAs is not due to implantation-induced vacancies but to the self-exchange of interstitial Si atoms with the host Ga substitutional atoms     

一种智能卡电性能可靠性的测试方法

随着智能卡以其自身高效、安全、便捷的特点在众多领域的应用,人们对其可靠性的要求也越来越高,因此有效的可靠性测试显得尤为重要.本文主要以接触式智能卡为例针对智能卡可靠性测试的一方面--电性能测试提出一种方便可行的测试方法.该方法在总结智能卡测试方法标准ISO/IEC10373的基础上,改进了相关测试项测试方法,根据实际情况补充了漏灌电流测试并详细说明其测试方法.根据测试需要设计了电性能全覆盖测试的程序,自动生成电性能测试报告.     

利用数字存储示波器测量特殊信号

随着数字化技术、集成电路的高速发展,数字存储示波器以其强大的测试能力、稳定的性能和更快捷的数据处理方式越来越多的应用于科研生产中,已成为检测电子线路最有效的工具之一.     

侧入式局域动态调光背光聚光特性研究

针对HDR技术在侧入式局域动态调光中的特殊要求,采用结构导光板搭配LED灯条进行聚光,以此提高背光对比度,实现液晶显示器的分区动态调光控制。首先,基于现有导光板出光面亮度分布,确定了导光板出光面微结构为锯齿形,然后利用光线追迹法对结构导光板进行仿真,分析了不同结构的导光板出光面微结构棱高、棱宽比和曲率对聚光性能的影响,结果表明,聚光性与导光板出光面结构直接相关,光学胶折射率为1.49,棱高为20μm,棱宽比为0.47时,聚光性能最佳;根据仿真结果开发了实际背光产品,并对此产品进行了测试,测试结果表明,与传统的导光板相比,使用结构导光板后,背光聚光效果显著,对比度由6.01提升到127.15,满足动态调光聚光性要求。     

Improvement of electrical characteristics for fluorine-ion-implanted poly-Si TFTs using ELC

The fluorine ion implantation applied to the polycrystalline silicon thin-film transistors (poly-Si TFTs) is investigated in this letter. Experimental results have shown that fluorine ion implantation effectively minimized the trap state density, leading to superior electrical characteristics such as high field-effect mobility, low threshold voltage, and high ON/OFF current ratio. Furthermore, the fluorine ions tended to segregate at the interface between the gate oxide and poly-Si layers during the excimer laser annealing, even without the extra deposition of pad oxide on the poly-Si film. The presence of fluorine obviously enhanced electrical reliability of poly-Si TFTs.     

The effects of grain boundaries in the electrical characteristics of large grain polycrystalline thin-film transistors

High-performance low-voltage thin-film transistors (TFTs) can be fabricated by grain-enhancement methods such as nickel-seeded metal-induced lateral crystallization (MILC). Electrical characteristics of the TFTs may vary due to the existence of the grain boundaries in the device active region. To obtain the best device characteristics, the effect of grain boundaries on the device must be investigated. In this paper, the cumulative distributions of the device properties such as leakage current, threshold voltage, subthreshold slope, and field-effect mobility as a function of different channel lengths and widths were studied. In general, the grain boundary effects decrease with device size. Devices with short channel lengths and wide channel widths may suffer from degradation due to large leakage current. Moreover, the effects due to the location of the nickel-seeding region on device characteristics were investigated. These include the effect of the longitudinal and lateral grain boundaries and the distance between the nickel seeding region and the device. Finally, a design guideline to reduce the grain boundary effect is presented.     

Long-term intramuscular electrical activation of the phrenic nerve:safety and reliability

The safety and reliability of a system for long-term intramuscular electrical activation of the phrenic nerve was evaluated in seven dogs. In this system, electrodes are implanted bilaterally into the diaphragm without directly contacting the phrenic nerve using a laparoscope to direct placement. Five dogs underwent chronic bilateral intramuscular diaphragm stimulation (IDS) for 61 to 183 days at stimulus parameters selected to evoke at least 120% of the animal's basal ventilation. Two dogs maintained as controls did not undergo chronic stimulation. The safety and reliability of the system was evaluated in terms of tissue responses to the electrode, alterations in diaphragm muscle, pulmonary function, electrode reliability, and cardiac activation. No adverse responses to the electrode or stimulation were found. The histochemistry of chronically stimulated diaphragm suggested transformation towards type I (oxidative metabolism) muscle fibers. Two IDS electrodes dislodged out of a total of 32 IDS electrodes implanted. Both electrodes dislodged within seven days of implant. All IDS electrodes had stable and repeatable recruitment properties. No IDS electrode mechanical failures were found and no electrode corrosion was observed. It is concluded from these experiments that intramuscular activation of the phrenic nerve will present a minimal risk to human patients who are good candidates for clinical studies using this technique     

Frequency-dependent electrical characteristics of GaAs MESFETs

Output resistance and transconductance of GaAs MESFETs have been observed to change significantly at very low frequencies. Extensive measurements of these characteristics as a function of device bias are reported. Direct measurements of the dispersive behavior between DC and 100 kHz and over a broad temperature range have been made on ion-implanted monolithic microwave IC (MMIC) devices. Conductance deep level transient spectroscopy (DLTS) and microwave S-parameter measurements have also been made to investigate this behavior. These measurements reveal that surface or channel-substrate interface traps in the material are most likely to be responsible for the observed behavior. A new equivalent-circuit model which accounts for many of the observed characteristics is developed. Unlike previously proposed equivalent circuits, the model does not rely on physically unrealistic circuit element values in order to obtain accurate performance predictions. The bias dependence of circuit element values is computed for one device. Effects not described by the model are also discussed     

The electrical characteristics of cermet-silicon contacts

The conductance and capacitance of metal/cermet/n-Si sandwiches has been found to be strongly dependent on the metal content of the cermet. Conductive cermets behave essentially as series resistors. Insulating cermets give rise to some Si surface inversion, and the surface minority carrier density varies with bias. This and the cermet capacitance results in a large dispersion of the measured capacitance with frequency and bias. In addition, metal particles in the cermet were found to trap charges, which then induced minority carrier charges at the interface and gave rise to a memory effect.     

The mosaic electrical characteristics of the skin

The authors constructed a suction microelectrode with a 200-μm internal diameter and performed several tests on two male subjects. It was found that the average skin impedance on the forearm was larger than the average impedance on the palm and that the ratio between the maximal and minimal skin impedance was larger for the forearm than for the palm. For both the magnitude and variance of skin impedance decreased with increasing stimulus frequency. The density of low-impedance points observed on the forearm and palm was consistent with the density of DC current pathways through the skin as indicated by traces left on 1-cm ² Ag electrodes. The ratio between the highest and lowest impedances decreased as temperature decreased. The authors were not able to break down the skin using the suction microelectrode. Tests suggest that breakdown is of thermal nature, and that the thermal capacitance of the saline in the suction microelectrode prevents the temperature of the underlying skin from increasing very rapidly, increasing the breakdown voltage     

Some electrical characteristics of the earth's crust

The electrical characteristics of the earth's crust and of the materials forming it are of great interest to those dealing with waves propagated over the earth's surface, particularly at frequencies below 10⁶cps. In addition, recent advances in geophysical prospecting have been made by employing electromagnetic techniques. Both of these facts indicated the importance of knowing the effects of earth's crust materials upon electromagnetic waves. An over-all picture of the earth and its environment is first presented including the types of materials involved. Techniques for measuring electrical properties of materials with emphasis on in situ methods are next given. The conductivity of numerous types of earth materials is considered and results presented in tabular form for ready reference. Finally, the likely variation in conductivity with depth below the surface is considered.     

Modeling of the electrical characteristics of an organic field effect transistor in presence of the bending effects

An analytical model incorporating the density of trap states for a bendable organic field effect transistor (OFET) is presented in this paper. The aim of this work is to propose a novel modeling framework to quantitatively characterize the bending effects on the electrical properties of an OFET in the linear and saturation regimes. In this model, the exponentially distributed shallow trap states are introduced into the Poisson equation to describe the carrier transports in the channel. The carrier mobility takes into account the low field mobility enhancement under gradual channel approximation and high field degradation. As a result, the generalized current-voltage transistor equations are derived for the first time to reflect the transconductance relationships of the OFET with trap states. In addition, an electro-mechanical coupling relationship is established per the metaphorical analogy between inorganic and organic semiconductor energy band models to quantify the stress-induced variations of the carrier mobility, and the threshold voltage. It is revealed that the before- and after-bending transconductances, predicted from the derived analytical model, are in good agreement with the experimental data measured from DNTT-based OFET bending tests.     

Long-term intramuscular electrical activation of the phrenic nerve:efficacy as a ventilatory prosthesis

The efficacy of a system for long-term intramuscular activation of the phrenic nerve as a ventilatory prosthesis was evaluated in seven dogs. Five dogs underwent chronic bilateral intramuscular diaphragm stimulation (IDS) for 61 to 183 days at stimulus parameters selected to evoke at least 120% of the animal's basal ventilation. Two dogs maintained as controls did not undergo chronic stimulation. The ability of IDS to provide long-term ventilation without diaphragm fatigue was evaluated in terms of the ventilatory capacity of IDS, the effects of chronic IDS on diaphragm contractile properties, and the phrenic nerve recruitment properties of chronic IDS electrodes. Hemi-diaphragms with electrodes placed within 2 cm of the phrenic nerve trunk could be completely activated by 25 mA pulses having a 100 μs pulse width. The tidal volume evoked by IDS in this study was 167% (±48 s.d.) of that required for full-time basal ventilation without diaphragm fatigue. Evoked tidal volume increased after 8 to 9 weeks of chronic IDS for stimulus pulse intervals longer than 50 ms. Electrode recruitment properties were stable for both active and passive implanted electrodes. It is concluded from these studies that with properly placed electrodes IDS is capable of providing reliable full-time ventilatory support without fatiguing the diaphragm