Multiple negative-differential-resistance (MNDR) phenomena of ametal-insulator-semiconductor-insulator-metal (MISIM)-like structurewith step-compositioned InxGa1-xAs quantum wells

In this paper, a new multiple negative-differential-resistance (MNDR) device based on a metal-insulator-semiconductor-insulator-metal (MISIM)-like structure with step-compositional In_xGa_1-x As quantum wells has been fabricated and demonstrated. The interesting MNDR phenomena are found in the current-voltage (I-V) characteristics of this device. At room temperature, the triple switching behaviours and quadruple stable operation states are obtained. In addition, the sixfold switching behaviors and a staircase-shaped I-V characteristic are observed at -105°C. A sequential carrier accumulation at InGaAs subwells and the potential lowering process are used to qualitatively explain the interesting MNDR phenomena. From the experimental results, it is shown that the studied device has good potential in multiple-valued logic applications     

Conference key agreement protocol with non-interactive fault-tolerance over broadcast network

Most conventional conference key agreement protocols have not been concerned with a practical situation. There may exist some malicious conferees who attempt to block conference initiation for some purposes, e.g. commercial, political or military benefit. Instances where conference must be launched immediately due to emergency, efficient detection of malicious behavior would be needed. Recently, Tzeng (IEEE Trans. Comput. 51(4):373–379, 2002) proposed a fault-tolerant conference key agreement protocol to address the issue where a conference key can be established among conferees even though malicious conferees exist. However, his protocol might be complex and inefficient during fault-detection. In the case where a malicious conferee exists and a fault-tolerant mechanism is launched, complicated interactions between conferees will be required. In this paper, we introduce a novel strategy, where any malicious conferee may be identified and removed from the conferee list without any interaction. With such a non-interactive fault-tolerance, conferences could be established and started efficiently. A complete example of our protocol will be given to describe the fascinating fault-tolerance. We analyse the security of our protocol regarding four aspects, i.e. correctness, fault-tolerance, active attack and passive attack. The comparisons of performance between our protocol and that of Tzeng are also shown. As a whole, the advantage of our protocol is superior to that of Tzeng under the situation where malicious conferees exist.

ECC-based lightweight authentication protocol with untraceability for low-cost RFID

Due to the potential wide deployment of Radio Frequency Identification (RFID), the security of RFID systems has drawn extensive attention from both academia and industry, and the RFID authentication protocol is an important mechanism in the security of RFID systems. The desired security requirements of RFID authentication protocols include privacy, integrity, authentication, anonymity/untraceability, and even availability. To design an efficient protocol that satisfies all the requirements with limited resources is a challenge. This paper proposes a new RFID authentication protocol based on Error Correction Codes (ECC). The proposed scheme has excellent performance in terms of security, efficiency, server’s maintenance, robustness, and cost. The tag only performs simple operations, such as random number generation and simple bitwise computations. The lightweight feature makes it attractive to those low-cost RFIDs that support only simple operations.     

A Practical Algorithm for Computing Multi-State Two-Terminal Reliability

A practical, important system performance index for analyzing real world systems is NP-hard multi-state two-terminal reliability. Contributions of this paper are 1) it presents a direct, correct decomposition method for solving NP-hard multi-state two-terminal reliability, and 2) it does not require a priori the multi-state minimal paths/cuts of the system. Because all the exact methods solve the multi-state two-terminal reliability problem in terms of two/three NP-hard problems, excluding the impractical complete enumeration method, and Doulliez & Jamoulle's popular but incorrect decomposition method, development of such an exact, direct, and practical algorithm is thus worthwhile. Computational experiments verify that the proposed method is practical, fast, and efficient in comparison with the complete enumeration method.     

Preparation of kanamycin powder by an optimized spray freeze-drying method

The physical and antibiotic properties of kanamycin powders obtained by spray freeze drying (SFD) were compared with those of raw kanamycin. The SFD procedures were optimized to prepare kanamycin for use as an inhaled drug. Scanning electron microscopy (SEM) and a laser particle size analyzer were applied to estimate physical structure and properties of the particle. In addition, the disk diffusion method was used to compare the antibiotic activity of raw kanamycin and that produced by SFD. According to SEM, the kanamycin particles had various sizes and shapes with porous structures at different SFD conditions. The diameters of the kanamycin powders were between 13.5 μm and 21.8 μm, and their aerodynamic particle sizes were between 3.58 μm and 6.39 μm. The antibiotic activities of the raw and spray freeze-dried kanamycin samples were not significantly different (P > 0.05). The optimized conditions for annealing temperature, annealing time, kanamycin concentration, pressure, and nozzle tip lift were ? 15 °C, 5 h, 10% kanamycin, 100 kPa, and, 1 mm, respectively.     

As/sup +/-implanted AlGaAs oxide-confined VCSEL with enhanced oxidation rate and high performance uniformity

We report the utilization of an As/sup +/-implanted AlGaAs region and regrowth method to enhance and control the wet thermal oxidation rate for 850-nm oxide-confined vertical-cavity surface-emitting laser (VCSEL). The oxidation rate of the As/sup +/-implanted device showed a four-fold increase over the nonimplanted one at the As/sup +/ dosage of 1/spl times/10/sup 16/ cm/sup -3/ and the oxidation temperature of 400/spl deg/C. 50 side-by-side As/sup +/-implanted oxide-confined VCSELs fabricated using the method achieved very uniform performance with a deviation in threshold current of /spl Delta/I/sub th//spl sim/0.2 mA and slope-efficiency of /spl Delta/S.E./spl sim/3%.     

A novel InGaP/GaAs S-shaped negative-differential-resistance (NDR)switch for multiple-valued logic applications

In this paper, a novel InGaP/GaAs multiple S-shaped negative-differential-resistance (NDR) switch based on a heterostructure-emitter bipolar transistor (HEBT) structure is fabricated and demonstrated. An interesting multiple NDR phenomenon resulting from an avalanche multiplication and successive two-stage barrier lowering process is observed under the inverted operation mode. The three-terminal-controlled and temperature-dependent NDR characteristics are also investigated. In addition, a typical transistor performance is found under the normal operation mode. Consequently, owing to the presented different stable operation points and transistor action, the studied device shows a good potential for multiple-valued logic and analog amplification circuit applications     

Fabrication and Characteristics of high-speed oxide-confined VCSELs using InGaAsP-InGaP strain-compensated MQWs

This paper presents the fabrication and characteristics of high-performance 850-nm InGaAsP-InGaP strain-compensated multiple-quantum-well (MQW) vertical-cavity surface-emitting lasers (VCSELs). The InGaAsP-InGaP MQW's composition was optimized through theoretical calculations, and the growth condition was optimized using photoluminescence. These VCSELs exhibit superior performance with characteristics threshold currents /spl sim/0.4 mA and slope efficiencies /spl sim/0.6 mW/mA. The threshold current change with temperature is less than 0.2 mA, and the slope efficiency drops less than /spl sim/30% when the substrate temperature is raised from room temperature to 85/spl deg/C. A high modulation bandwidth of 14.5 GHz and a modulation current efficiency factor of 11.6 GHz/(mA)/sup 1/2/ are demonstrated. The authors have accumulated life test data up to 1000 h at 70/spl deg/C/8 mA.     

Multiple-route current-voltage (I-V) characteristics of GaAs-InGaAsmetal-insulator-semiconductor-like (MIS) structure for multiple-valuedlogic applications

A new GaAs-In_xGa_1-xAs metal-insulator-semiconductor-like (MIS) device with the interesting dual-route and multiple-negative-differential-resistance (MNDR) current-voltage (I-V) characteristics has been fabricated and demonstrated. These performances are caused by the successive barrier lowering and potential redistribution effect. A novel multiple-route I-V characteristic is obtained in the studied device at low temperature (-130°C). This performance is different from the previously reported NDR switching device and has not yet been found in other devices. The interesting property of the studied structure provides a promising candidate for switching device applications     

On the multiple negative-differential-resistance (MNDR) InGaP-GaAsresonant tunneling bipolar transistors

Two InGaP/GaAs resonant tunneling bipolar transistors (RTBTs) with different superlattice (SL) structures in the emitters are fabricated and studied. The uniform and modulated widths of barriers are respectively utilized in the specific SL structures. Based on the calculations, the ground state and first excited state minibands are estimated from the transmission probability. The electron transport of RT through SL structures is significantly determined by the electric field behaviors across the barriers. Experimentally, the excellent transistor characteristics including the small saturation voltage, small offset voltage and high breakdown voltages are obtained due to the insertion of δ-doping sheet at the base-collector (B-C) heterointerface. Furthermore, at higher current regimes, the double- and quaternary-negative difference resistance (NDR) phenomena are observed in agreement with the theoretical prediction at 300 K