摘要:

We report measurements of the low‐frequency optical response in epitaxial thin films of La0.67Ca0.33MnO3in the temperature range covering both the ferromagnetic metallic state and the paramagnetic insulating state. We observe a bolometric optical response in fully oxygenated films of the above composition as well as in oxygen deficient films. In both types of samples, the optical response is thermal in nature as indicated by its proportionality with the temperature derivative of the resistancedR/dT. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116635

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A new bias‐enhanced nucleation method of forming highly oriented diamond on Si(100) is reported using an alternating current bias source. The percentage of aligned particles via alternating current bias‐enhanced nucleation (ac BEN) was greater than 50%. This is compared to less than 10% highly oriented particles when using a conventional negative dc substrate bias. Based on previous work in this area, the peak negative voltage portion of the ac wave form is believed to be responsible for enhancing diamond nucleation. The positive and moderate negative voltage portion of the ac wave form appears to aid the process of forming the highly oriented diamond. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116636

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The elastic deformations associated with the pulsed laser, photothermal heating of an aluminum alloy surface have been measured within the irradiated region using a Michelson‐type interferometer. The displacements within this region have been measured and have been compared to calculations based on temperature‐rate dependent thermoelasticity theory. The quantitative agreement between calculation and experiment shows the contributions of the local thermal expansion and the propagating acoustic modes on the overall displacements at the epicenter and near the epicenter of the irradiated region. Nonlinear effects on the propagation of the near‐field surface acoustic wave may be present. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116637

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

In this letter we demonstrate an inverse twisted nematic device in which the input polarized light is unaffected in the field‐off state and produces a polarization rotation in the field‐on state. This is done by using a homeotropically aligned sample containing chiral nematic liquid crystal with negative dielectric anisotropy and specially prepared surfaces. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116638

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Deposition of aluminum film from DMEAA in the temperature range of 100–300 °C has been studied. In this temperature range, there is a maximum deposition rate at around 150 °C. The film deposited at 190 °C has elongated blocklike grain shapes, which are ∼600 nm in width and 930 nm in length. Grains in the film deposited at 150 °C showed an equiaxed structure with grain size in the range of 100–300 nm in a film with 600 nm thickness. Aluminum oxide particle inclusion was observed especially at high deposition temperature. Plausible reaction pathways of DMEAA dissociation were suggested to explain the experimental observations. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116639

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An experiment has been performed in which wafers with boron‐doped, buried marker layers were implanted with 100 keV, 2×1015cm−2Si. This is an amorphizing implant. A second implant of B was introduced prior to any post‐implant annealing such that the implanted B was completely contained within the preamorphized region. After the implants, samples were annealed at various temperatures for various times and secondary‐ion mass spectroscopy was used to obtain the dopant profiles. It was found that the buried marker layer exhibited normal transient‐enhanced diffusion behavior. However, the B in the preamorphized region did not experience any significant amount of motion. This suggests that the solid phase regrowth of the amorphous layer did not cause a redistribution of the dopant atoms within that layer, and also the plane of dislocation loops that form at the amorphous/crystalline interface is an effective barrier against the interstitial damage diffusing upwards from the nonamorphized tail of the amorphizing Si implant. The same behavior was observed when As or P implants are used instead of the B implant. This type of behavior has been simulated using a model considering the growth of stacking faults bounded by dislocation loops. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116640

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report a two‐step growth process, using an atomic layer epitaxially grown GaAs predeposition layer for the growth of GaAs/Si layers by metalorganic vapor phase epitaxy technique. Photoluminescence and deep‐level transient spectroscopy techniques are used to show that the quality of the grown material is comparable to that grown by a much complicated procedure involving strained layer superlattice buffers introduced between the active GaAs layer and the Si substrate. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116641

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We demonstrate the performance of a semiconductor photorefractivep‐i‐ndiode operating at 1.55 &mgr;m in the longitudinal quantum‐confined Stark geometry. The device structure consists of a semi‐insulating InP–GaInAs(P) multiple quantum well, sandwiched between two trapping regions, and embedded in ap‐njunction. In this structure, the measured output diffraction efficiency reaches 0.6%. This value is close to the output diffraction efficiency value estimated from electroabsorption measurements. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116642

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Surface segregation processes during the growth of Ga0.5In0.5P/GaAs heterostructures by chemical beam epitaxy have been investigated in real time using reflection high‐energy electron diffraction (RHEED). It is shown that In segregation occurs at both GaInP on GaAs and GaAs on GaInP interfaces. Resulting composition profiles are deduced from the RHEED data. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116643

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Ultrafine (60 nm×10 nm) ZnS:Cu thin film with thickness 200 nm has been prepared by a hydrothermal technique at a relatively low temperature (140 °C). The optical properties of the Cu‐doped ZnS thin film were found to be different from that of the bulk material and normal thin film with large grain size. Compared to the bulk material, the peak position of the blue band shifts to a higher energy (from 445 to 430 nm), and a possible new blue band (peak position at 415 nm) appears as the copper concentration in the ZnS thin film reaches 5×10−3g/g, which is attributed to the equilibrium doping condition and the combination of the Cu+ion with a dangling sulfur bond on the interface of fine grains, respectively. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116644

出版商:AIP    

年代:1996

数据来源: AIP