摘要:

Tungsten contacts to Zn‐doped In0.53Ga0.47As have been formed by rapid thermal processing. Contacts to layers with a Zn doping concentration of 5×1018cm−3were rectifying as sputter deposited as well as after heat treatments at temperatures lower than 450 °C. Higher processing temperatures caused a linear decrease of the contact resistivity values from 0.6 as deposited to 0.15 &OHgr; mm after heating at 550 °C. Rapid thermal processing at these higher temperatures stimulated the Schottky‐to‐ohmic contact conversion with a minimum contact resistance value of 8.5×10−5&OHgr; cm2and a sheet resistance value of 150 &OHgr;/&laplac; as a result of heating at 600 °C for 30 s. By increasing thep‐InGaAs doping level to 1×1019cm−3, the specific resistance of this contact was dropped to the minimum of 7.5×10−6&OHgr; cm2as a result of heating at 600 °C for 30 s. The W/p‐In0.53Ga0.47As contact showed excellent thermal stability over the temperature range of 300–750 °C, with an abrupt and almost unreacted metal‐semiconductor interface. Heating at temperatures of 800 °C or higher caused degradation of the contact. This was reflected by a distinct increase in the heterostructure sheet resistance as a result of the intensive interfacial reaction which took place at the contact, accompanied by outdiffusion of both In and As.

ISSN:0003-6951    

DOI:10.1063/1.102066

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A high‐resistivity layer formed beneath the silicon surface layer by using proton implantation and two‐step annealing is described. Rapid thermal annealing with tungsten halogen lamps was carried out during the first annealing step and the time of the high‐temperature treatment in the second annealing step was comparatively long. Experiments show that the quality of the top layer has been improved with the increase in surface Hall mobility of ∼25%. This novel semiconductor will likely be a new material for the manufacture of very high speed integrated circuits.

ISSN:0003-6951    

DOI:10.1063/1.102067

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The reflectivity of thin‐film platinum silicide was measured by means of a helium‐neon (He‐Ne) laser when samples of platinum films deposited on top of silicon wafers were annealed in a rapid thermal processor. This processor consists of two rows of tungsten‐halogen quartz lamps placed above and below a quartz processing chamber. The thermal cycles consisted of a fast heating (about 200 °C/s), followed by an isothermal plateau at temperatures ranging between 410 and 600 °C. Film reflectivities dropped in two stages, as a result of the reaction between platinum and silicon. This two‐stage drop was identified as due to the transformation of the platinum film, first into Pt2Si, and then into PtSi. The amounts of time required to complete the transformations were found to be in good agreement with the Arrhenius laws derived from the work of J. T. Pan and I. A. Blech [Thin Solid Films113, 129 (1984)] on isothermal low‐temperature (220–330 °C) sintering of platinum films on silicon, who unambiguously established the correlation between reflectivity changes and silicide formation.

ISSN:0003-6951    

DOI:10.1063/1.102068

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Bi‐Pb‐Sr‐Ca‐Cu‐Ag alloy coatings were made by vacuum induction melting followed by melt dipping on substrates of MgO, SrTiO3, and Al2O3. The metallic precursor layers were then subjected to a controlled atmosphere oxidation and annealing to produce oxide superconductors. Superconducting coatings with onset temperatures of 112 K and zero resistance temperatures of 80 K were obtained in this way. The addition of Ag aided in the alloy melting and dipping processes, and produced a superconducting oxide/noble metal composite after oxidation. The resulting superconducting phases were analyzed by x‐ray powder diffraction. The influence of the substrate, dipping processes, oxidation, and annealing conditions on the superconducting properties are discussed.

ISSN:0003-6951    

DOI:10.1063/1.102353

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A ferroelastic‐like transition at ∼140 °C in a single‐crystal LaGaO3substrate was directly observed with an optical microscope at elevated temperatures. In addition, it was found for the first time that a polished surface morphology of a pseudocubic (001) LaGaO3substrate degraded after a heat cycle up to only 200 °C. This surface degradation, i.e., surface roughening, is associated with the transition at ∼140 °C, and it may possibly be the major origin of relatively low critical current density reported for a superconducting YBa2Cu3Oxfilm grown on a LaGaO3substrate.

ISSN:0003-6951    

DOI:10.1063/1.102354

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report on electrical noise measurements made on YBCO (Y1Ba2Cu3O7−x) films on SrTiO3, on bulk silicon with a ZrO2buffer layer, and on thin dielectric membranes. We have found that 1/fnoise predominates in the unoriented films and that thermal fluctuation noise is the chief source of noise in good films on SrTiO3.

ISSN:0003-6951    

DOI:10.1063/1.102355

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A melt‐annealing method has been developed to deposit highly textured superconducting thick films on different substrates in the Bi‐Sr‐Ca‐Cu‐O system. As opposed to previous techniques, this method uses powder made from an extremely dense glass sample to yield very uniform and dense thick films. The x‐ray diffraction and scanning electron microscopy results indicate that the superconducting phase is strongly oriented along thecaxis perpendicular to the substrate and the films are chemically uniform. Electrical transport measurements consistently show aTcnear 80 K for all samples.

ISSN:0003-6951    

DOI:10.1063/1.102356

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

It is shown that high quality Ag/Fe superlattices can be grown on (001) GaAs by molecular beam epitaxy, provided that adequate intermediate layers are interposed between the GaAs substrate and the superlattice structure. In addition to the growth of a GaAs buffer layer, a sufficiently thick Fe nucleation layer is necessary for the further growth of a high quality Ag buffer layer showing clear reflection high‐energy electron diffraction intensity oscillations. This growth sequence ensures the obtention of single‐crystal Ag/Fe superlattices with well‐defined interfaces.

ISSN:0003-6951    

DOI:10.1063/1.102069

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Guided‐wave magneto‐optic Bragg cells atX‐band microwave frequencies using magnetostatic forward volume waves (MSFVWs) in bismuth‐doped yttrium iron garnet‐gadolinium gallium garnet (Bi‐doped YIG‐GGG) waveguides are reported for the first time. Performance figures that have been obtained at an optical wavelength of 1.303 &mgr;m include a center frequency tuning range of 3.7–12.0 GHz, a diffraction efficiency of 12% at the magnetostatic wave power of 56 mW, a linear dynamic range >40 dB, and a −3 dB magneto‐optic bandwidth of 150 MHz. These results represent a significant improvement over those obtained previously with the Bragg cells using pure YIG‐GGG waveguides. Maximum scan angle of 6° and 5.3° were also measured, respectively, by tuning the rf frequency ∼10.0 GHz at a fixed dc magnetic field of 3660 Oe and by varying the dc magnetic field ∼3660 Oe at a fixed rf frequency of 10.0 GHz. A frequency resolution of 30 MHz was measured with rf spectral analysis experiments carried out at 12 GHz. Finally, a Faraday rotation coefficient as large as −2313°/cm was measured for the Bi‐doped YIG‐GGG waveguides.

ISSN:0003-6951    

DOI:10.1063/1.102070

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A novel, solid‐state electrochromic device is described which utilizes a single film of Prussian blue as the only electrochemically active element. The device can be reversibly bleached by the application of a voltage across the film. Removal of the voltage results in immediate recoloration.

ISSN:0003-6951    

DOI:10.1063/1.102071

出版商:AIP    

年代:1989

数据来源: AIP