摘要:

We report on the Seebeck coefficient (S) of Ln1−xCaxBa2Cu2.9Ga0.1O6+z(Ln=Nd,Dy; 0≤x≤0.2) as a function of temperature. For Ln=Dy,Sat 300 K decreased by a factor of 20 asx(Ca) increased from 0 to 0.2. For all the samples, for a restricted range of temperature,Scould be described byS=S0−&agr;TwhereS0, characteristic of each sample, is related toTcbyTc=82.4−0.64S0and &agr; is a constant. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360751

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Optical emission spectroscopy has been employed to study the photolysis and the subsequent reaction processes of the mixture of Si2H6and C2H2irradiated with a 193 nm ArF excimer laser. The emission intensities of SiH*, Si*, and C2*were measured as a function of the laser energy up to 80 mJ (∼0.43 J/cm2). The formation processes of the radicals and atoms were estimated from the dependence of these intensities on the laser energy. The dependence of the SiH* intensity in the low‐energy region up to 10 mJ was quadratic and revealed two‐step processes. The dependence of the intensities of Si* and C2*was the 1.3–1.6 power of the laser energy, which revealed the saturation of the processes. The intensity of C2*increased when Si2H6was added to C2H2. The origin of this increase is the production of the carbon‐based radicals by the collisions of Si* with C2H2and C2H. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359989

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Conductance resonance of tunneling structure with a few Au clusters, deposited on an insulating film, is studied by the generalized Breit–Wigner formula in a tight‐binding approximation. We find that in the conductance resonance the multiple peak structure may come from the interaction between supported Au clusters on an insulating film and the different arrangements of Au clusters may cause difference of the conductance resonance peaks. The experimental observation of multiple peak structure can be explained by generalizing our model to the system of a few quantum dots. Therefore, it is possible to predict the effect of interaction between metal clusters on the conductance resonance and develop some new microelectronic devices by artificially arranging metal clusters onto the surface of the insulating film. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359990

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The possibility of producing nanocrystallites by laser heat treatment of a metallic glass is investigated. Structural and magnetic properties, after various annealing conditions, are reported. Laser annealing is demonstrated to be an effective, alternative technique for control of nanometric crystallization. This technique also shows a number of advantages with respect to conventional heat treatments. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359991

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present investigations on the interdiffusion behavior and thermal stability ofn‐doped and undoped GaInAs/AlGaInAs multiple‐quantum‐well structures, grown lattice matched on InP by molecular‐beam epitaxy. The activation energy of the main interdiffusion process is determined toEan doped=2.5 eV andEaundoped=2.9 eV. The different interdiffusion processes are monitored mainly by photoluminescence spectroscopy atT=8 K after rapid thermal annealing of the samples. The influence of doping is studied by comparing the results ofn‐doped and undoped structures. Additionally photoluminescence excitation spectroscopy atT=2 K was carried out to verify the different interdiffusion processes. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359992

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Measurements of the absolute noise power of highTcmultijunction flux‐flow amplifiers in the frequency range 0.1 Hz–60 kHz are reported. The noise is found to have maxima at the operating points corresponding to optimum transresistance and gain, and is consistent with existing models of critical current fluctuations as found in single grain boundary junctions. The frequency dependence of the noise power is usually close to 1/f, although a Lorentzian term is sometimes observed. The normalized values of measured critical current fluctuations are approximately temperature independent as previously found for single junctions prepared by similar techniques. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359993

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Deposition of diamond on tungsten wires were tried by means of cyclic thermal plasma chemical vapor deposition. Deposition rate, morphology, and uniformity were found to be strongly dependent upon the wire size and its heating history estimated using a simple model based on the heat balance equation. Relatively uniform coatings were obtained on wires with a diameter of 0.2 mm at a rotation speed of 450 rpm. This was not the case with larger wires with a diameter of 0.7 mm at 200 rpm. This effect is attributed to the disturbance of the flow pattern around the large wire. Under the best conditions, 1 &mgr;m uniform highly quality diamond film could be deposited on 0.2‐mm‐diam tungsten wires over a total run time of 75 min. The corresponding depositing duty time is calculated to be about 2 min. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359928

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

cw laser operation has been achieved from a diode‐pumped Nd:LuAlO3crystal for the first time. The tuning characteristics centered about 1083 nm are presented and the laser’s use for3He and4He optical pumping are established. With 1.5 W of output at 1083 nm and a slope efficiency greater than 22%, this crystal represents the first viable alternative to Nd:LMA. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359929

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A very significant Zn evaporation from nongrowing AlxGa1−xAs surface during a post‐&dgr;‐doping purge step was observed in growth of Zn &dgr;‐doped AlxGa1−xAs (x<0.65) by low pressure metal organic vapor phase epitaxy using dimethylzinc as a doping precursor. A &dgr;‐doping sequence different from the normal ‘‘purge‐doping‐purge’’ is therefore proposed to minimize the Zn evaporation. Using this &dgr;‐doping sequence, the dopant memory effect was investigated and the best hole profile of Zn &dgr;‐doped GaAs (Al0.35Ga0.65As) was obtained, having a full width at half‐maximum of 7.0 nm for a peak concentration of 1.1×1020cm−3(13 nm for 4.8×1018cm−3). It was found that the growth temperature significantly influences the hole concentration of Zn &dgr;‐doped GaAs and the hole concentration decreases and the hole profile width increases with increasing Al content of Zn &dgr;‐doped AlxGa1−xAs. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359930

出版商:AIP    

年代:1995

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.360783

出版商:AIP    

年代:1995

数据来源: AIP