DC and AC characteristics of sub-50-nm MOSFETs with source/drain-to-gate nonoverlapped structure

A MOSFET structure with a nonoverlapped source/drain (S/D) to gate region was proposed to overcome the challenges in sub-50-nm CMOS devices. Key device characteristics were investigated by extensive simulation study. Fringing gate electric field through the spacer induces an inversion layer in the nonoverlap region to act as an extended S/D region. An oxide spacer is used to reduce parasitic gate overlap capacitance. A reasonable amount of inversion electrons were induced under the spacers. Internal physics, speed characteristics, short channel effects, and RF characteristics were studied with the nonoverlap distance at a fixed metallurgical channel length of 40 nm. The proposed structure had good drain-induced barrier lowering and V/sub T/ rolloff characteristics and showed reasonable intrinsic gate delay and cutoff frequency compared to those of an overlapped structure.     

A typed functional extension of logic programming

A logic language is suitable for specification if it is equipped with features for data abstraction and modularization. In this paper, an effective mechanism to incorporate function and type into logic programming is presented as the means to embed data abstraction mechanism into logic programming. This incorporation is essentially based on Horn clause logic with equality and a polymorphic type system that is an extension of Mycroft and O’Keefe’s system. This paper also presents an implementation based on Warren Abstract Machine (WAM) and shows the performance, along with a comparison with WAM.     

Synthesis and characterization of poly(siloxane-urethane)s

A series of polyurethane block copolymers based on hydroxy-terminated polydimethylsiloxane and poly(propylene glycol) soft segments of molecular weights 1818 and 2000, respectively, were synthesized. The hard segments consisted of 4,4′-diphenylnethane diisocyanate and 1,4-butanediol as the chain extender. Samples with different molar ratios were prepared. We tried to synthesize polydimethylsiloxane-based polyurethanes (PDMS-PU) containing a hard block as major fraction and a soft block as minor fraction for preparing toughened rigid systems. After a study of the pure polydimethylsiloxane-based polyurethane and poly(propylene glycol)-based polyurethane (PPG-PU), (mixed polyol)-based block copolymers and blends of PDMS-PU and PPG-PU were synthesized, and characterized by means of differential scanning calorimetry, tensile testing and scanning electron microscopy. In (mixed polyol)-based copolymers and lower hard-segment content blends, macro-phase separation occurred, but blends with higher hard-segment contents showed significant reduction in amounts of phase separation.     

Simple ASK transmitter using a 790 nm self-pulsating laser diodefor local area networks

A simple amplitude shift keying (ASK) optical link is demonstrated by using a low-cost self-pulsating laser diode and an envelope detector for a low-cost broadband local area network. A link sensitivity of -22 dBm was achieved at 200 Mbit/s. Because the self-pulsation frequency can be tuned by the bias current, frequency division multiplexing can be simply implemented for multiuser applications     

InSb,GaSb, and GaInSb grown using trisdimethylaminoantimony

GalnSb alloys as well as the constituent binaries InSb and GaSb have been grown by organometallic vapor phase epitaxy using the new antimony precursor trisdimethylaminoantimony (TDMASb) combined with conventional group III precursors trimethylindium (TMIn) and trimethylgallium (TMGa). InSb layers were grown at temperatures between 275 and 425°C. The low values of V/III ratio required to obtain good morphologies at the lowest temperatures indicate that the pyrolysis temperature is low for TDMASb. In fact, at the lowest temperatures, the InSb growth efficiency is higher than for other antimony precursors, indicating the TDMASb pyrolysis products assist with TMIn pyrolysis. A similar, but less pronounced trend is observed for GaSb growth at temperatures of less than 500°C. No excess carbon contamination is observed for either the InSb or GaSb layers. Ga_1-xIn_xSb layers with excellent morphologies with values of x between 0 and 0.5 were grown on GaSb substrates without the use of graded layers. The growth temperature was 525°C and the values of V/III ratio, optimized for each value of x, ranged between 1.25 and 1.38. Strong photoluminescence (PL) was observed for values of x of less than 0.3, with values of halfwidth ranging from 13 to 16 meV, somewhat smaller than previous reports for layers grown using conventional precursors without the use of graded layers at the interface. The PL intensity was observed to decrease significantly for higher values of x. The PL peak energies were found to track the band gap energy; thus, the luminescence is due to band edge processes. The layers were all p-type with carrier concentrations of approximately 10¹⁷ cm³. Transmission electron diffraction studies indicate that the Ga_0.5In_0.5 Sb layers are ordered. Two variants of the Cu-Pt structure are observed with nearly the same diffracted intensities. This is the first report of ordering in GalnSb alloys.     

Analysis of culture fluorescence by a fiber-optic sensor inNicotiana tabacum plant cell culture

The on-line sensing of viable cell weight in plant cell culture process is applied to analysis and control of process. The fiber-optic fluorescence sensor was constructed to measure the NADH-dependent fluorescence inNicotiana tabacum plant cell culture and the analysis of fluorescence signal was done to be correlated with the viable cell weight. The structured kinetic model for cell growth was proposed to estimate the theoretical viable cell weight. The dimensional analysis was proposed for the interpretation of fluorescence signal, in which the path length, the inner filter effect and the hydrodynamic conditions were considered as the key factors on fluorescence signal. The dimensional analysis and empirical correlation of fluorescence signal to viable cell weight was applied to the interpretation of the detected fluorescence signal during cultivation. The proposed interpretation of fluorescence signal using dimensional analysis was well correlated with the viable cell weight estimated by the structured kinetic model as well as by empirical correlation.     

Development of the Base Station Controller and Manager in the CDMA Mobile System

The base station (BS) in the CDMA Mobile System (CMS) connects calls through the radio interface and is designed to provide mobile subscribers with high quality service in spite of mobile subscribers’ motions. The BS consists of multiple base station transceiver subsystems (BTSs), a base station controller (BSC) and a base station manager (BSM). This paper is concerned with the BSC and the BSM. The BSC is located between the BTSs and the mobile switching center (MSC) connected with the public network, and is responsible for controlling mobile calls from and to mobile subscribers via the BTSs. The BSM provides operator-interfaces per the BS and takes responsibility of operation and maintenance (OAM) of the BS. Design of the BSC is based on two module types: functional module and unit module. The functional module is used to support new services easily and the unit module to increase the system capacity economically. Both modular types are easily achieved by inserting the corresponding modules to the system. Particularly, in order to efficiently support the soft handover which is one of CDMA superior advantages, the BSC adopts a large high-speed packet switch connecting up to 512 BTSs, and thus mobile subscribers can be provided with soft handover in high probability. The BSM is based on a commercial workstation to support OAM functions efficiently and guarantee high reliability of the functions. The BSM uses graphical user interface (GUI) for efficient OAM functions of the BS.     

Insight into the chemical reaction of CH2OH with NO: Formation of N-hydroxy formamide as an isocyanic acid precursor

This study has explored the potential energy surface on the chemical reaction of CH₂OH with NO by using ab initio calculation. We have found the new reaction pathway producing N-hydroxy formamide, which can further decompose to generate isocyanic acid as a reducing agent of hydrocarbons selective catalytic reduction.