摘要:

A space‐resolved soft x‐ray (SXR) transmission grating spectrometer and a SXR streak camera are used to investigate the evolution of spectrally discriminated spatial uniformity of line‐shaped plasmas produced by uniform laser illumination in line focus. It is found that the spatial nonuniformity of SXR emissions and ion turbulence occur during optical laser’s heating. Various instabilities can be excited due to the long scale length in line‐shaped plasmas to produce the phenomenon.

ISSN:0003-6951    

DOI:10.1063/1.104716

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Interdiffusion and interface compound formation has been observed at the system Ni/In by using thin‐film couples as well as thin In films on low index Ni single‐crystal substrates. The method applied was the perturbed &ggr;&ggr;‐angular correlation technique, which is very sensitive to local structures and their changes around probe atoms. The successive occurrence of different Ni/In compounds could be observed on isochronal annealing above 230 K. A correlation between the appearance of compounds and In film thickness has been found.

ISSN:0003-6951    

DOI:10.1063/1.104717

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We present an electrically controlled bistable surface switching for nematic liquid crystals, in cells with the usual display geometry. The surface bistability is controlled by means of an electrochiral effect, by doping a nematic with chiral ions. The alternate transient commutation between the two surface states is related to the sign of an applied pulsed electric field. The threshold behavior allows a writing surface time of 32 &mgr;s for a field of 21 V/1.3 &mgr;m. In the birefringence mode, the optical texture response time is 0.3 ms. The effect, comparable with the one used with ferroelectric smectic liquid crystals, could be used to realize high definition video passive matrix displays.

ISSN:0003-6951    

DOI:10.1063/1.104718

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Ferroelectric lead‐zirconate‐titanate (PZT) thin films have been deposited by excimer laser ablation on sapphire substrates with and without an electrode. In preparation for the films, O2gas pressure has greatly influenced the film structure and morphology. For the first time, we have confirmed the ferroelectric properties of PZT films prepared by laser ablation without post‐annealing. It appears to be possible to use these films for nonvolatile random access memories with some additional improvements in the film properties.

ISSN:0003-6951    

DOI:10.1063/1.104719

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The metallizations of AuGeNi/GaAs(001) and Au/GaAs(001) contacts at 4×10−3Pa and 7×108Pa pressure have been analyzed by using x‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. Our observations show that the high‐pressure ambient inhibits the As sublimation loss and that only interdiffusion takes place without any formation of compounds in those contacts annealed in argon at 7×108Pa. The experimental results are also discussed on the basis of phase diagrams.

ISSN:0003-6951    

DOI:10.1063/1.104720

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Palladium atoms have been gettered from the bulk of an amorphous Si (a‐Si) layer to an ion‐implanted surface region. The 2.2‐&mgr;m‐thicka‐Si layers, formed by MeV Si implantation, were implanted with 500 keV Pd and then annealed at 500 °C. This produces a complete redistribution of Pd within the layer and relaxation or substantial defect annihilation in thea‐Si. Subsequently, defects were introduced into the surface region (∼4000 A˚) by 200 keV Si implantation at various doses. After low‐temperature diffusion at 250 °C, Pd atoms are gettered in the Si‐implanted region. At low Si fluences, Pd decorates the Gaussian depth distribution of the ion‐induced damage, while at higher a saturation is reached in the gettering profile. The ion damage is calculated to saturate when 2% of the target Si atoms are displaced by atomic recoils. Below saturation, the displacement of two Si atoms is calculated to produce one Pd trapping site.

ISSN:0003-6951    

DOI:10.1063/1.104721

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

20‐&mgr;m‐thick diamond films deposited on Si single‐crystal substrates by microwave plasma‐enhanced chemical vapor deposition showed significant curvature. The internal stress distribution was estimated using the model of an elastic bimetallic strip. The results indicate that the films are under a mean tensile stress of 1.1 GPa, and are discussed using information from x‐ray diffraction and Raman spectra.

ISSN:0003-6951    

DOI:10.1063/1.104722

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Measurements of the contact potential difference between different materials have been performed for the first time using scanning force microscopy. The instrument has a high resolution for both the contact potential difference (better than 0.1 mV) and the lateral dimension (<50 nm) and allows the simultaneous imaging of topography and contact potential difference. Images of gold, platinum, and palladium surfaces, taken in air, show a large contrast in the contact potential difference and demonstrate the basic concept.

ISSN:0003-6951    

DOI:10.1063/1.105227

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The application of a simple three‐parameter fit to the temperature dependence of semiconductor band gaps is justified on both practical and theoretical grounds. In all trials the fit is numerically better than that obtained using the widely quoted Varshni equation. The formula is shown to be compatible with reasonable assumptions about the influence of phonons on the band‐gap energy. Approximate analytical expressions are derived for the entropy and enthalpy of formation of electron‐hole pairs in semiconductors.

ISSN:0003-6951    

DOI:10.1063/1.104723

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The crystalline quality of 0.3‐&mgr;m‐thick silicon on sapphire structures has been improved by double solid phase epitaxy of germanium‐implanted material. This regrowth technique increased the mobility with 70–100% in phosphorus‐ and boron‐doped films, respectively. The depth distribution of germanium induced donors was measured by capacitance‐voltage profiling on diodes made in preamorphized bulk silicon and the energy distribution in the band gap was investigated with deep level transient spectroscopy. It was shown that the main part of the germanium implantation induced defects could be removed by a high‐temperature annealing treatment.

ISSN:0003-6951    

DOI:10.1063/1.104724

出版商:AIP    

年代:1991

数据来源: AIP