摘要:

An electric probe was used for measurements of the normal cathode fall in a glow discharge in flowing CO2laser mixtures (CO2:N2:He=4.5:13.5:82 and 5:20:75) for uncooled copper, stainless‐steel and tungsten cathodes. The results imply that the cathode fall value in the mixture is governed mainly by the presence of carbon dioxide.

ISSN:0021-8979    

DOI:10.1063/1.350584

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A hypervelocity accelerator has been developed utilizing the extreme condition produced by the collapse of the cylindrical imploding shock wave. The cylindrical shell of the explosive is detonated by the explosion of rows of copper wires bound around it. The wire explosion is caused by the application of an impulsive electric current. The energy concentrated at the implosion center is imparted to the projectile accelerating it. The launch velocity of 1.2 km/s has been attained for a 2 g launched weight with a 60 g explosive (PETN: pentaerythritoltetranitrate). A further increase of the launch velocity is expected by increasing either the explosive thickness or the height of the cylindrical shell within practical limit.

ISSN:0021-8979    

DOI:10.1063/1.350585

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Based on the study on chemical reactivity of Si2H6and CH4toward two different excitation modes (photo and plasma‐photo hybrid), it was suggested that generating pulsed plasma under constant photo irradiation to a mixture of Si2H6and CH4could deposit continuously amorphous superlattices composed of hydrogenated amorphous silicon (a‐Si:H) and hydrogenated amorphous silicon carbide (a‐SiC:H) layers. The periodical structure in the deposited film by the pulsed plasma and photo chemical vapor deposition was verified by the small angle x‐ray diffraction pattern and high resolution scanning electron microscope image. The optical band gap ofa‐Si:H(0.5–25 nm)/a‐SiC:H(5 nm) superlattices deposited by this method showed a blue shift as the well layer (a‐Si:H) thickness decreased.

ISSN:0021-8979    

DOI:10.1063/1.350586

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Measuring with a spectroscopic ellipsometer (SE) in the 1.8–4.5 eV photon energy region we determined the complex dielectric function (&egr; = &egr;1+i&egr;2) of different kinds of amorphous silicon prepared by self‐implantation and thermal relaxation (500 °C, 3 h). These measurements show that the complex dielectric function (and thus the complex refractive index) of implanteda‐Si (i‐a‐Si) differs from that of relaxed (annealed)a‐Si (r‐a‐Si). Moreover, its &egr; differs from the &egr; of evaporateda‐Si (e‐a‐Si) found in the handbooks as &egr; fora‐Si. If we use this &egr; to evaluate SE measurements of ion implanted silicon then the fit is very poor. We deduced the optical band gap of these materials using the Davis–Mott plot based on the relation: (&egr;2E2)1/3∼ (E−Eg). The results are: 0.85 eV (i‐a‐Si), 1.12 eV (e‐a‐Si), 1.30 eV (r‐a‐Si). We attribute the optical change to annihilation of point defects.

ISSN:0021-8979    

DOI:10.1063/1.350587

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A regime for growing high‐quality GaAs/AlGaAs single‐quantum‐well structures by molecular‐beam epitaxy with interruption only at the AlGaAs‐on‐GaAs heterointerface is reported. For 15‐ and 20‐nm‐wide wells the luminescence linewidth is found to be 0.44 and 0.29 meV, respectively. The data are among the lowest values reported to date. Photoluminescence line splitting due to the formation of extended growth islands was not observed.

ISSN:0021-8979    

DOI:10.1063/1.350588

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Whispering gallery modes (WGMs) that propagate along a bent dielectric waveguide with two‐dimensional field confinement are analyzed with a self consistent field approximation (weighted index theory). WGMs are quasi‐modes (leaky modes) with their field shape distorted toward the outermost boundary of a bend. Numerical results are shown for the modes in an optical embedded channel waveguide whose center of curvature is on an arbitrary location. Calculation of the leakage loss is included as well.

ISSN:0021-8979    

DOI:10.1063/1.350589

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

To investigate the possibility that deep levels are associated with dislocations in narrow band gap HgCdTe, deep level transient spectroscopy has been used to studyn+‐pdiodes fabricated onp‐type bulk Hg0.78Cd0.22Te samples with either a ‘‘normal’’ dislocation density of about 105cm−2or a high dislocation density of about 106cm−2. These samples which are gold doped with a hole concentration of 1.2×1015cm−3, have a band gap of about 0.12 eV at 77 K. In samples with a ‘‘normal’’ dislocation density, a deep level of about 80 meV above the valence band was found. However, a midgap level of about 60 meV above the valence band with larger peak amplitude and broader line shapes was found in the sample with a high dislocation density.

ISSN:0021-8979    

DOI:10.1063/1.350590

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The coefficient of performance of the refrigeration cycles of ferromagnetic material is derived. It is shown that the Ericsson cycle, using the composite working substance, cannot only possess the condition of perfect regeneration, but also attain to or approach the Carnot coefficient of performance.

ISSN:0021-8979    

DOI:10.1063/1.350591

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Aitaetal. [J. Appl. Phys.66, 4360 (1989)] studied the ultraviolet optical behavior of rf sputter‐deposited AlN thin films. The same optical behavior is found for reactively dc magnetron sputter‐deposited AlN thin films at different total gas flows for constant Ar/N2ratios. The microcrystallites of these films exhibit diameters between 5 and 20 nm.

ISSN:0021-8979    

DOI:10.1063/1.350592

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Oxidation of silicon in a radio frequency discharge oxygen plasma was studied usinginsituduring process rapid ellipsometry (1 s resolution and interval). Plasma characteristics were also determined by the Langmuir probe method and emission spectroscopy. From the measurement ofinsituduring process rapid ellipsometry, oxidized film thickness of silicon increased steeply right after starting rf discharge and slowly after ≊3000 s. It was found that thickness change rate measured byinsituduring process rapid ellipsometry immediately after starting the rf discharge was strongly proportional to O2+ions density.

ISSN:0021-8979    

DOI:10.1063/1.350541

出版商:AIP    

年代:1992

数据来源: AIP