摘要:

Heating spinel (MgAl2O4) single crystals in aluminum or magnesium metal vapor at temperatures in excess of 1800 °C results in the introduction of an optical absorption band at 5.3 eV. The same band can be produced by heating in a strongly reducing atmosphere with no metal vapor at 2100 °C. These results strongly support the suggestion of Bunch that the 5.3‐eV band, created by atomic displacement collisions resulting from energetic particle bombardment, is associated with anF‐type center. Isothermal annealing of the 5.3‐eV band in MgAl2O4and the 5.0‐eV band in MgO introduced by thermochemical coloration suggests that the activation energy for oxide‐ion vacancy motion is, respectively, 1.8 and 3.4 eV.

ISSN:0003-6951    

DOI:10.1063/1.90916

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The measurements of the anisotropy of the refractive index have been made for heptyl‐cyanobiphenyl (7CB) at the surface as well as in the bulk by the interferometric method. Using these data, order parameters S¯ at the surface andSin the bulk were calculated. The results show that S¯ is slightly larger thanSin the nematic temperature region.Sbecomes zero in the isotropic region; nevertheless, the order parameter at the surface, S¯, still has a finite value even at temperatures above the clearing point.

ISSN:0003-6951    

DOI:10.1063/1.90926

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Tungsten needles grown from hexacarbonyltungsten vapors in a glow‐discharge condition are described. The needle growth occurs on a tungsten substrate in a temperature range from nearly room temperature to 1500 °K, but needles produced below and above ∼1100 °K are quite different in morphology and crystalline state. The products at lower temperatures are tungsten particles agglomerated in dendritelike shapes while those at higher temperatures possibly are whiskers.

ISSN:0003-6951    

DOI:10.1063/1.90934

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Stress present in thermal SiO2at temperaturesduringgrowthin wet O2has been measured as a function of growth temperature. During growth at 950 °C and below, compressive stress on the order of 7×109dyn/cm2is generated in the SiO2. During growth at 975 and 1000 °C, the SiO2grows in a stress‐free state. The results, which are consistent with a viscous flow point somewhere between 950 and 975 °C, are of value in avoiding mechanical failure effects in integrated‐circuit processing.

ISSN:0003-6951    

DOI:10.1063/1.90905

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The experiments were conducted with a 50‐MW 60‐ns ruby laser to study the variation of plasma temperature with laser flux for a carbon and polyethylene plasma in a purely collisional regime. The plasma temperature showed a &fgr;2/9dependence on laser flux in the intensity regime 2×1010to 5×1011W/cm2. Results are discussed with reference to the scaling laws obtained by different workers in different flux regimes on the basis of collisional and noncollisional absorption.

ISSN:0003-6951    

DOI:10.1063/1.90912

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A magnetically insulated pulsed proton gun is described that provides an extracted parallel beam of annular cross section for microsecond pulse lengths. In initial tests, time‐averaged currents of 5 kA and current densities of 50 A/cm2were achieved with ≲200 kV voltage. The behavior of the gun appears to be determined by instabilities of the cathode electron cloud growing over time scales of the order of 0.5 msec to give ion current‐density enhancements greater than a factor of 50 above the Child‐Langmuir limit.

ISSN:0003-6951    

DOI:10.1063/1.90913

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An integrated Si Schottky‐barrier detector for the output power stabilization of a GaAs/GaAlAs DH laser mounted on a Si heat sink is described. The signal emitted from the rear laser mirror and detected by the integral Schottky diode was used to stabilize the laser output power to within ∼1% over a 32 °C temperature range, thus eliminating the need for mounting fibers to or aligning bulky discrete detectors with the rear laser mirror.

ISSN:0003-6951    

DOI:10.1063/1.90914

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Cr‐MIS solar cells on single‐crystal Si, with a 2‐cm2area and approximately 10% efficiency, have been subjected to 1.0‐ and 1.6‐MeV proton radiation at total dosages of up to 3.3×1013p/cm2. Photovoltaic studies reveal characteristic short‐circuit current and open‐circuit voltage degradation similar to proton‐irradiated junction‐type solar cells. (See H. Y. Tada and J. R. Carter,SolarCellRadiationHandbook, JPL Publication 77‐56, 1977.) Spectral response measurements reveal output decay primarily due to minority‐carrier diffusion‐length decreases of up to 96%.

ISSN:0003-6951    

DOI:10.1063/1.90915

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Polycrystalline silicon layers heavily doped with phosphorus or arsenic were irradiated with a Nd : YAG pulsed laser beam. A 40–50% reduction in sheet resistivity was obtained by laser annealing. However, during subsequent heat treatments the resistivity increased to a value which was higher than the initial value before the laser anneal. The instability of the resistivity is tentatively explained by reprecipitation of dopants both within the grains and at the grain boundaries.

ISSN:0003-6951    

DOI:10.1063/1.90917

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

CuInS2thin films have been made from copper, indium, and hydrogen sulfide gas using a two‐step technique which involves exposing Cu‐In films produced by sputtering pure copper and pure indium to H2S gas diluted with argon. X‐ray diffraction, Auger electron spectroscopy, optical transmission, and electrical measurements were used to identify and characterize the CuInS2. The resulting films were allptype with resistivity in the range 0.1–500 &OHgr; cm and showed a preferred orientation of the (112) plane parallel to the substrate.

ISSN:0003-6951    

DOI:10.1063/1.90918

出版商:AIP    

年代:1979

数据来源: AIP