摘要:

The emission and deposition of molten gold droplets from needle‐tip liquid metal ion sources was investigated. The Taylor cone was identified as the source of droplet emission. An upper limit of 8 &mgr;m for the virtual source size was measured. Gold films were deposited on silicon substrates. The deposited gold spots showed a peaked, axially symmetric, distribution with a half angle for droplet emission of ∼2° which was considerably smaller than the ion emission angle of ∼45°. Typical deposition fluxes were ∼5×105&mgr;m3/s/sr with total deposition rates of ∼3×103&mgr;m3/s and on an average droplet diameter of ∼1 &mgr;m at an emission current of 150 &mgr;A. Smaller diameter droplets are produced with decreasing emission current and angle. Gold films with a fine textured morphology suitable for submicron patterning were obtained at emission currents less than ∼135 &mgr;A.

ISSN:0021-8979    

DOI:10.1063/1.336300

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Inhibition of fluid flow instabilities in the melt by the axial magnetic field in Czochralski silicon crystal growth (AMCZ) is investigated precisely by a high‐sensitivity striation etch in conjunction with temperature measurements. The magnetic field strength (B) was varied up to 4.0 kG, incremented mostly in 0.5‐kG/2.5‐cm crystal length. The convection flow was substantially suppressed atB≥1.0 kG. A low oxygen level of 2–3 ppm and a high resistivity of 400 &OHgr; cm is achieved in the AMCZ silicon crystals atB≥1.0 kG. Random striations atB=0, characteristic of turbulent convection, assumed progressively a periodicity, indicative of oscillatory convection at 0.35<B≤4.0 kG. The striation contrast or ‘‘intensity’’ decreased steadily with the increase inB. AtB=4 kG, most of the crystal was free of striations, although some weak, localized periodic striations persisted near the crystal periphery. Spreading‐resistance measurement shows, however, a uniform dopant distribution in all crystal sections grown at 0.35<B≤4.0 kG within a few percent.

ISSN:0021-8979    

DOI:10.1063/1.335883

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Crack‐propagation rates in vitreous silica were monitored as specimens were heated thermally or irradiated by a laser beam. The laser was tuned to the OH bond vibration to determine the role of OH stretching in the dissociative chemisorption mechanism for stress corrosion of silica in moist environments. Laser radiation heated the silica near the crack tip but did not generate any bond‐specific changes in crack velocity. For samples maintained in moist air, the propagation velocity decreases as temperature increases. The temperature dependence of crack velocity indicates that physisorption is an important step in stress corrosion, and a simple model of the process is proposed.

ISSN:0021-8979    

DOI:10.1063/1.335860

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The absolute x‐ray efficiency of Y2O2S:Tb phosphor screens was measured under fluoroscopy conditions as a function of the x‐ray tube voltage and as a function of the screen’s weight. The experimental results are in very good agreement with the theoretical predictions obtained according to the Hamaker model.

ISSN:0021-8979    

DOI:10.1063/1.335861

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Experimental evidence for light trapping in glass/conductive transparent oxide/p‐i‐n/metal hydrogenated amorphous silicon solar cell structures is presented. A short‐circuit current of 17.8 mA/cm2has previously been reported for a cell made with this structure. The light trapping is treated by a modification of the Yablonovitch–Cody (YC) statistical theory of light trapping in textured layers [E. Yablonovitch and G. D. Cody, IEEE Trans. Electron. DevicesED‐29, 300 (1982)]. Reflection measurements show that 80% of the incident light is trapped. Quantum efficiency measurements made on cells with back electrode metals of different reflectivity are shown to be in agreement with the predictions of the YC theory.

ISSN:0021-8979    

DOI:10.1063/1.335862

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The levitation or suspension forces acting on an arbitrary three‐dimensional dc current source moving over a stratified medium consisting of a track and the underlying earth are determined analytically for arbitrary relativistic velocities. The proposed method also allows the determination of the currents inside the track. As a first step towards the analysis of moving magnets, the obtained results are applied to a moving magnetic dipole.

ISSN:0021-8979    

DOI:10.1063/1.335863

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The rate of nutation of the magnetic moments of2H and1H nuclei in a pulsed NMR experiment is used to measure the skin depth in thin metallic films. This measurement yields values of skin depth which are in good agreement with those calculated from measured electric conductivity data. Also this new method is direct and contactless.

ISSN:0021-8979    

DOI:10.1063/1.335864

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A theoretical paper published in this journal some months ago purported to analyze the performance characteristics of microwave dish antennas. The paper, however, contains three serious errors which totally negate the results described therein. In this communication the nature of these errors is explained and the proper corrections are indicated.

ISSN:0021-8979    

DOI:10.1063/1.335865

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A. W. Love points out three alleged errors in our paper [J. Appl. Phys.54, 3528 (1983)]. We agree that he is correct with regard to the second and third issues, but the first and perhaps most important point is correct. This regards the inequality of transmit and receive patterns of microwave antennas. The standard proof of equality of the patterns, cited by A. W. Love, is shown to be incorrect.

ISSN:0021-8979    

DOI:10.1063/1.335866

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Nuclear magnetic resonance of143Nd and145Nd in Nd2Fe14B and Nd15Fe77B8at 4.2 K by zero‐field spin‐echo nuclear magnetic resonance has been used to determine hyperfine fields, magnetic moments, and relaxation times for the two inequivalent Nd crystal sites. It was found that the Nd spin‐echo spectra of Nd2Fe14B and Nd15Fe77B8are essentially identical, which is consistent with the Nd signal arising from the Nd2Fe14B phase in Nd15Fe77B8. The calculated Nd moments are higher than those obtained by neutron diffraction by 15 to 20%. The relaxation time mechanism appears to arise both from first‐order quadrupolar broadening and from anisotropies in the hyperfine field distribution.

ISSN:0021-8979    

DOI:10.1063/1.336299

出版商:AIP    

年代:1985

数据来源: AIP