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971.
The device degradation under ac and dc stress have been discussed and a relationship between the two has been established,. We have shown that the commonly used lifetime criteria of 10% linear current degradation for 10 years for a transistor under dc stress is overly conservative for representing the circuit operating lifetime. Using experimental and simulated data for inverter chains, we proposed that a meaningful equivalent lifetime based on 10% Idl degradation under dc stress is 1 year lifetime (for a 10 year circuit lifetime based on 54b degradation in ring oscillator frequency). We also compared this criteria to actual circuit degradation for microprocessors and a DRAM. For DSP microprocessors with 0.8 μm LDD transistors, the projected lifetime was more than 200 years at 5.5 V, with a corresponding 10% I dr lifetime of 20 years. For 1 Mb DRAMs with 1 pm LDD transistors, the 5% speed degradation lifetime at 5.5 V was more than 100 years, whereas the individual transistors had 10% Idl lifetime of 4 years. These circuit results support the 10% Idl transistor lifetime. We believe these criterion should be very safe and reasonable for digital IC chips currently in the field, as well as those in future design and development 相似文献
972.
J. C. Sevy 《Calcolo》1993,30(1):41-68
Explicit error estimates are given for the iterated Boolean sum of a sequence of simultaneous approximants; the rate of convergence
is shown to be improved for smooth functions. The general results are applied in the case of the Bernstein, Durrmeyer and
Stancu operators. 相似文献
973.
The thermal stability of interfaces between metals (Ni, Pt, Ti, Mo) and III-V compound semiconductors has been investigated
by the application of Rutherford backscattering spectrometry. Metal diffusion and interfacial lattice disorder of the semiconductors
were analyzed for various metal/semiconductor samples annealed at temperatures up to 500°C. The interfaces of Ni/GaAs and
Ti/GaAs were found to be more stable than those of Ni/In-based semiconductors and Ti/ In-based semiconductors, respectively.
Faster diffusion of Pt atoms was ob-served in In-and As-containing materials than in P-containing materials. Mo/ semiconductor
interfaces were the most stable. 相似文献
974.
Sabate J.A. Jovanovic M.M. Lee F.C. Gean R.T. 《Industrial Electronics, IEEE Transactions on》1995,42(1):63-71
The analysis and design of an LCC resonant inverter for a 20 kHz AC distributed power system are presented. Several resonant converter topologies are assessed to determine their suitability for high efficiency power conversion, under resistive and reactive loads. Two LCC-resonant inverter designs were implemented. One with all switches operating with zero voltage switching (ZVS), and another with two switches operating with ZVS and two switches with zero current switching (ZCS). The experimental results are presented along with a performance comparison of the two versions 相似文献
975.
The pyrolysis of tertiarybutylphosphine (TBP) has been studied in the low pressure conditions used for chemical beam epitaxy
(CBE). The pyrolysis studies were carried out in low pressure reactors of two different configurations, one of which is a
cracker cell designed for use in a CBE system. The reaction products were studied using a quadrupole mass spectrometer. The
products observed are accounted for by a reaction mechanism involving homolysis of the parent TBP molecule to produce PH2 and C4H9 radicals. These undergo subsequent reactions to form the stable products C4H8, PH3 and H2, with smaller amounts of P and P2 being produced. The production of the sub-hydride PH2 using this cracker cell design indicates that the use of partially cracked TBP may be a promising technique for reducing
the amount of carbon incorporated into the growing epitaxial layer. 相似文献
976.
977.
Lightly p-doped (3×1017 cm-3) GaN grown on GaAs substrates by metal organic molecular beam epitaxy (MOMBE) shows deactivation of the residual acceptors on exposure to a microwave (2.45 GHz) hydrogen plasma at 250°C. Subsequent annealing to 350°C produces further dopant passivation, while higher temperatures (450°C) restore the initial conductivity. These results suggest that hydrogen carrier gases should be avoided during vapour phase growth of III-V nitrides 相似文献
978.
Two layer frequency selective surfaces (FSS) comprised of aperture elements on a single dielectric substrate are used to produce extremely narrow and angularly stable passband transmission responses. Experimental results are compared with predictions to verify a computer model which is based on solving a pair of coupled aperture integral equations. Reductions in bandwidth of up to a factor of seven have been achieved 相似文献
979.
C Guimar?es Madeira SA Jorge S Kakehashi I de Oliveira 《Canadian Metallurgical Quarterly》1996,30(2):217-228
The disposition behavior of trientine, a selective copper-chelating drug for Wilson's disease, and its metabolites in normal patients with Wilson's disease and rats were studied. A high concentration of metabolites appeared in blood samples of patients and rats in the early stage after administration of trientine. Furthermore, large amount of trientine metabolites were excreted into the urine of patients. These results suggest that trientine is remarkably subjected to a first-pass effect. The drug concentration area under the curve (AUC) of the unchanged form and the metabolites of trientine in patients was not dependent on the administered dosage. It seems that the absorption process is an important factor for the disposition behavior of trientine, we have also investigated the uptake characteristics of trientine by rat intestinal brush-border membrane vesicles. The uptake characteristics of trientine were similar to the physiological polyamines, spermine and spermidine. The uptake rate of trientine was dose-dependently inhibited by spermine and spermidine. Moreover, spermine competitively inhibited the uptake of trientine with a Ki value of 18.6 muM. This value is very close to the Km value for spermine (30.4 muM). These data suggested that the uptake mechanism of trientine in rat small intestinal brush-border membrane vesicles was almost identical to that of spermine and spermidine, and that the physiological polyamines seem to have the ability to inhibit the absorption of trientine from the gastrointestinal tract. 相似文献
980.
Turmeric curcuminoids are important natural pigments but their instability limits their use in many foods. This study was conducted to examine light-induced degradation of turmeric curcumin as affected by solvent system and oxygen. The rate constants and half-lives were determined for purified curcumin, demethoxycurcumin and bis-demethoxycurcumin exposed to 1450 lux using reversed-phase HPLC. Rates of degradation of each pigment followed first-order kinetics. Differences in rate constants and half-lives between the individual pigments were minor in an acetic acid-NaCl solution; however, in methanol, large differences in stability to light of the individual pigment were observed. Stability of all the pigments to light was several fold greater in methanol than in acid brine. In methanol sparged with air, stability to photooxidation was curcumin > demethoxycurcumin > bis-demethoxycurcumin. In methanol, curcumin was more stable than the other curcuminoids when sparged with air than when sparged with nitrogen. In methanol sparged with nitrogen, demethoxycurcumin was the most stable pigment. All of the pigments were stable in the dark. 相似文献