摘要:

Lead titanate (PbTiO3) thin‐film pyroelectric infrared detectors have been fabricated on polycrystalline silicon micromechanical membranes. Pyroelectric PbTiO3thin films of thickness ranging from 0.2 to 0.6 &mgr;m were prepared by sol‐gel spin casting techniques and deposited on 1.0‐&mgr;m‐thick polycrystalline silicon membranes suspended 1.0 &mgr;m above the surface of a silicon wafer. This composite structure offers high sensitivity and low thermal mass. The measured pyroelectric coefficient for 0.36‐&mgr;m‐thick PbTiO3films is 90 nC/cm2 K. The measured blackbody voltage responsivity for a pyroelectric element with an active area of 7×10−4cm2at 297 K and a chopping frequency of 50 Hz is 4.2×104V/W. The measured normalized detectivityD* at 297 K and 50 Hz is 1.0×109cm Hz1/2/W.

ISSN:0003-6951    

DOI:10.1063/1.105650

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have fabricated epitaxial ferroelectric PbZr0.2Ti0.8O3/YBa2Cu3O7−xheterostructures on single crystalline [001] LaAlO3. Only the (00l) peaks of the PbZr0.2Ti0.8O3(PZT) film are observed, indicating that the epitaxial,c‐axis oriented YBCO film is a good structural template for the heteroepitaxial growth of PZT films, in addition to being a metallic bottom electrode. A saturation polarization and remanence as high as 38 and 26.5 &mgr;C/cm2(at 7.5 V, 0.5 kHz), respectively, have been achieved. The coercive field is about 100 kV/cm.

ISSN:0003-6951    

DOI:10.1063/1.105651

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Ni‐P ultrafine amorphous alloy particles have been prepared by reacting nickel chloride and sodium hypophosphite in an aqueous solution. X‐ray diffraction revealed the amorphous structure of the particles and transmission electron microscopy showed that the particles are spherical, with an average diameter of about 150 nm. X‐ray photoelectron spectroscopy confirmed that all nickel and phosphorus atoms are in the elementary state on the surface of the particles, which implied the alloying state of the particles. The dynamic process of the reaction has been studied. It is found that the reaction ended within 65 min at apH value of 10 and 351 K when the sodium hypophosphite was exhausted, and the unreacted solid residue Ni(OH)2should be washed out with ammonia solution to obtain ‘‘pure’’ Ni‐P ultrafine amorphous alloy particles.

ISSN:0003-6951    

DOI:10.1063/1.105652

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

BaTiO3thin films having a perovskite structure were deposited onto stainless steel and fused quartz substrates by sol‐gel processing. Crystalline, transparent, and crack‐free films of 5000 A˚ thickness were fabricated by spinning and post‐deposition annealing at a temperature of 600 °C. Ferroelectric properties were confirmed byP‐Ehysteresis loops. The dielectric constant and optical transmission were also measured.

ISSN:0003-6951    

DOI:10.1063/1.105653

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Crystal face temperatures of single crystals of &agr;‐HgI2growing in transparent ampules by physical vapor transport have been measured,insitu, by a novel, noncontact method which may be called reflectance spectroscopy thermometry. The method is based on the temperature dependence of the energy of the free‐exciton peak as detected with a low‐energy reflected beam. As presently configured, the accuracy is ±1.5 °C for a slowly varying surface temperature. The method has potential for noncontact temperature measurement in some systems for which pyrometry is unsatisfactory.

ISSN:0003-6951    

DOI:10.1063/1.105629

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We develop a new class of three‐dimensional geometrical models of porous media based on the smoothing of random white‐noise images. With the appropriate choice of smoothing parameters, models of this kind are shown to provide reasonable representations of Vycor glass and crystalline dolomites. Transport and structural properties are found to be in accord with experimental data.

ISSN:0003-6951    

DOI:10.1063/1.105630

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The lattice constants of tetragonal PbTiO3grown by organometallic chemical vapor deposition, vary with average crystallite size in the thin film as determined from line broadening in x‐ray diffraction patterns. Thea‐ andc‐lattice constants become equal when the average crystallite size decreases to below ∼5 nm. These data agree with the change in lattice constants as a function of average crystallite size found recently for submicron PbTiO3powder.  

ISSN:0003-6951    

DOI:10.1063/1.105631

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An experimental procedure has been developed which permits accurate short‐time diffusion anneals for diffusion periods as short as a few seconds. This method is applicable to diffusors which are volatile at the diffusion temperature. It will be illustrated for zinc diffusion into silicon which mainly takes place via the kick‐out mechanism. Previous long‐time diffusion studies have yielded the productCeqIDIof equilibrium concentration and diffusivity of Si self‐interstitials(I) involved in the interstitial‐substitutional exchange of Zn. The present short‐time diffusion method enables us to determineCeqIandDIseparately by comparing measured spreading‐resistance profiles with computer simulations based on the kick‐out model.

ISSN:0003-6951    

DOI:10.1063/1.106393

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Using a newly developed femtosecond electro‐optic technique, a built‐in electric field near a semiconductor surface can be measured by a contactless approach. We have observed for the first time equal strength but opposite direction of strain‐induced piezoelectric fields from lattice‐mismatchedAface andBface of GaInSb/InAs strained‐layer superlattices by optically induced microwave radiation.

ISSN:0003-6951    

DOI:10.1063/1.105632

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Single grains of Si crystal are manipulated, for the first time, in solid‐state crystallization of amorphous Si films. The artificial nucleation sites are introduced by employing the self‐ion implantation. The nucleation and growth, during the subsequent thermal annealing strongly depends on the ion dose and energy. Preferential growth of the single nucleus takes place exclusively at each site and continues to propagate over them. Consequently, the location of grains is controlled, and the size distribution is remarkably shrunken in contrast to the films crystallized by random nucleation.

ISSN:0003-6951    

DOI:10.1063/1.105633

出版商:AIP    

年代:1991

数据来源: AIP