摘要:

A turn‐on delay, during which the output voltage of a Josephson logic circuit is very small, is of prime interest for the design of high‐speed Josephson digital integrated circuits. We have derived an analytical formula for the turn‐on delay of the current‐injection logic circuits, which is in good agreement with computer simulations. Analysis of the circuit equations shows that the nonlinear inductance of a current‐summing Josephson junction plays an important role for the turn‐on delay. Dependences of the turn‐on delay on circuit parameters and operating conditions are calculated. For parameter values typical of 5‐&mgr;m current‐injection circuits, the turn‐on delay is on the order of 10 ps. The turn‐on delay and operating margin are compared in various types of current‐injection logic circuits. The higher sensitivity of the threshold gate current to the input current is found to be desirable not only to reduce the turn‐on delay but to operate in a wide margin.

ISSN:0021-8979    

DOI:10.1063/1.335279

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Copolymers of vinylidene fluoride–trifluoroethylene P(VDF‐TrFE) exhibit large piezoelectric and pyroelectric effects. In addition to the most common application of the pyroelectric effect (radiant detection) it is possible to convert heat directly into electrical energy by pyroelectric conversion. This study reports the first pyroelectric conversion cycle to be measured for the copolymer P(VDF‐TrFE). It is found that standard isothermalD‐Ehysteresis loop measurements are not necessarily accurate predictors of pyroelectric conversion performance for this material. Conduction effects are found to obscure the observation of conversion cycles in most cases for the presently available materials. In spite of these difficulties, a conversion cycle was measured whose output electric energy density was 30 mJ/cm3. The output density is 15 times larger than any other polymer previously measured .

ISSN:0021-8979    

DOI:10.1063/1.335280

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The influence of the optical absorption coefficient, the particle size, the chopping frequency, and the length of the gas phase on the recently observed enhancement of photoacoustic signals in the presence of saturated vapors of ether has been investigated. Amorphous selenium has been used as the standard. The particle size plays a crucial role in understanding the enhancement as a function of optical absorption coefficient or chopping frequency. The enhancement is more when the optical absorption length is greater than particle size. The frequency dependence of the photoacoustic signal in the presence of ether is different from that in air when the thermal diffusion length of the solid is greater than the particle size. A qualitative interpretation of the results based on the ‘‘adsorbed’’ piston effect has been made.

ISSN:0021-8979    

DOI:10.1063/1.335281

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The emission of electrons, photons, and positive ions was monitored during three‐point bending, compression, and fast compression (impact loading) of single‐crystal pentaerythritol tetranitrate (PETN). The emission appears to be fracture mode dependent with negligible emission from cleavage‐type fracture and very intense electron emission accompanying impact. Possible causes of this enhanced emission are discussed in terms of shear effects and frictional grinding of the crystal fragments. Evidence of a microdischarge (electrical breakdown between fracture surfaces) during impact loading of the crystals is presented.

ISSN:0021-8979    

DOI:10.1063/1.335282

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

X‐ray photoelectron spectroscopy spectra measured on copper sulfide (CuxS) films showed that a thin surface reaction product containing Cu in the +2 valence state was formed on CuxS films exposed to air for 46 h at 40 °C and 90% relative humidity. An entirely different CuxS surface reaction product layer was formed in dry air at 170 °C for 30 min and it contained sulfur in the +6 valence state. The copper (Cu) valence state in CuxS was not found to be +2 even when thexvalue was less than 1.9. When the argon sputter‐cleaned surface of CuxS or CuxS/CdS films was exposed to room‐temperature air for 10 min, cadmium (Cd) atoms appeared on the CuxS surface. X‐ray powder diffraction patterns showed that CuO and CdS reacted at 500 °C in flowing nitrogen to form Cu2S and CdO. This cation exchange between CdS and copper oxide may explain the surface Cd on the CuxS films. The standard free energy of reaction between CuO and CdS is positive while that between Cu2O and CdS is negative. These results indicate a method for stabilizing CuxS/CdS solar cells against degradation.

ISSN:0021-8979    

DOI:10.1063/1.335283

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Near surface properties are reported for ZnO varistors irradiated with high‐intensity pulses from both KrF excimer and CO2lasers. Electrical, optical, and Rutherford backscattering measurements reveal that a thin conducting film is formed by pulsed‐laser heating of a varistor surface. The conductive film is evaluated as a varistor electrode.

ISSN:0021-8979    

DOI:10.1063/1.335284

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We respond to the recent claim that in face‐centered‐cubic Fe‐Ni alloys the two cubic elastic‐shear coefficients,C44and (C11−C12)/2, vary linearly with composition. Both theory and measurement support a nonlinear variation.

ISSN:0021-8979    

DOI:10.1063/1.335285

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Ledbetter’s critical discussion on our work on the elastic stiffness coeffficients of nickel‐iron single‐crystal alloys at room temperature clearly shows that our conclusion regarding the linear dependence of the shear constants of this alloy crystal on the composition is, in general, not valid throughout the whole range of composition. The linearity is destroyed by the onset of instability of the fcc phase of the alloy crystal at about 45% Ni. However, so long as the alloy crystal remains in the stable fcc phase (from 100% to 45% Ni) shear constants do follow a linear dependence on composition.

ISSN:0021-8979    

DOI:10.1063/1.335286

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Optical emission spectra are studied from the vapor produced by irradiation of polycrystalline CuCl, under vacuum, by pulsed excimer laser radiation at 248 and 308 nm. For fluences &fgr;≲0.4 J/cm2(intensityI≲20 MW/cm2), well‐resolved molecular CuCl emission bands and weak atomic Cu lines are observed. At higher fluences, the CuCl emission increases and develops into a broad continuum due to the broadening and overlap of the bands, whereas the Cu atomic line emission increases more rapidly. At even higher fluences (&fgr;≳1 J/cm2,I≳50 MW/cm2), the Cu atomic emission dominates the entire spectrum. A thermal equilibrium model is used to calculate the vibrational‐rotational temperature of the emitting CuCl molecules as a function of fluence by fitting the experimentally observed emission bands. Temperatures in the range 500<T<2000 K for fluences in the range 0.27<&fgr;<0.4 J/cm2were obtained.

ISSN:0021-8979    

DOI:10.1063/1.335287

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The phase of the photoacoustic signal is measured as a function of chopping frequency for different thicknesses of Pb resting on a water backing. Analysis of the results is in agreement with the theory of Rosencwaig and Gersho [J. Appl. Phys.47, 64 (1976)] and leads to a simultaneous determination of thermal conductivity and specific heat of the sample.

ISSN:0021-8979    

DOI:10.1063/1.335288

出版商:AIP    

年代:1985

数据来源: AIP