摘要:

The thermal emission from a Ni–P disk substrate heated by a pulsed excimer laser is measured with nanosecond time resolution. A fast InGaAs photodetector is employed to capture the thermal emission signal. The spectral surface reflectivity is simultaneously measuredin situ. The transient surface temperature is derived from the spectral thermal emission signal on the basis of Planck’s blackbody radiation intensity distribution. The experimental results and analytical solutions are compared and an important parameter involving the thermal diffusivity and conductivity in the transient temperature response of the material is evaluated. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120286

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A series of intrazeolitic silicon nanoclusters prepared from different Si loadings are investigated by SiKandL2,3x-ray absorption near-edge structure, x-ray photoelectron and photoluminescence spectroscopies. They exhibit strong room-temperature photoluminescence in the yellow-orange region. It is found that the growth of Si clusters within the pores of zeolite Y is limited to an average size of about 75 Si atoms per unit cell. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120287

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We demonstrate a photolithographic technique to fabricate vacuum-deposited organic light emitting devices. Photoresist liftoff combined with vertical deposition of the emissive organic materials and the metal cathode, followed by oblique deposition of a metal cap, avoids the use of high processing temperatures and the exposure of the organic materials to chemical degradation. The unpackaged devices show no sign of deterioration in room ambient when compared with conventional devices fabricated using low-resolution, shadow mask patterning. Furthermore, the devices are resistant to rapid degradation when operated in air for extended periods. This work illustrates a potential foundation for the volume production of very high-resolution, full color, flat panel displays based on small molecular weight organic light emitting devices. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120288

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Fourier analysis of laser emission spectra just above threshold is used to evaluate the impact of structural defects on the emission from optically pumped InGaN lasers. By dry etching a 300-nm-deep groove into the surface of a laser bar, we have modified the emission spectrum of such a device in a controlled manner. The occurrence of sharp features in the Fourier transformed spectrum allowed the identification of the mode spacing corresponding to the full cavity length, as well as to fractions of the full cavity length due to the etched groove. This enables us to identify additional features in the transform spectrum as being due to scattering centers within the waveguide. Identification of the density and strength of such centers is an important capability for the fabrication of blue diode lasers in the gallium–nitride material system. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120289

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The propagation characteristics of the pure SH (horizontal shear) mode piezoelectric surface acoustic wave (SAW) on rotatedY-cuts about theZ-axis of potassium niobate(KNbO3)are theoretically analyzed. The results show that there exists a SH mode SAW which has a velocity lower than the piezoelectrically inactive Rayleigh mode SAW for most of the rotated cuts. Differing from the so-called Bleustein-Gulyaev wave in 6 mm crystals, the particle displacement of the SH mode SAW on the metalized surface ofY-cutKNbO3decays with slow oscillation as a function of depth from the substrate surface, while that on the free surface oscillates with a slight decay. The electromechanical coupling factorK2ranges from a very large value of 0.53 to a relatively small value of 0.026, depending on substrate orientation. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120290

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Recent computer modeling of high-density chlorine plasmas has indicated that the gas is highly dissociated. This important prediction has only been recently confirmed by optical measurements, which require either external or internal calibration. Unfortunately, these optical techniques cannot readily be applied to the more chemically complex multicomponent plasmas commonly used in real processing. Using a new mass spectrometric method capable of detecting the local concentrations of both atomic and molecular atomic species within a plasma, a percent molecular dissociation of>85&percent;has been measured in an electron cyclotron resonance chlorine plasma at low pressures. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120291

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Near-edge x-ray absorption fine structure measurements at the N-Kedge are used to monitor the evolution of defect-related structure in the spectra of buriedSiNxfilms as a function of the implantation dose. The buriedSiNxfilms were fabricated with implantation of 35 keV14N+ions in Si in the dose range2×1017–2×1018 cm−2.The defect-related resonances RL1 and RL2 appear at401.1±0.3and403.3±0.1 eV,respectively. The RL1 is characteristic of a defect structure in the low and intermediate implantation doses and can be annealed out with an activation energy of 0.5 eV. RL2, which is the signature of excess N in N-rich films and is attributed to transitions of1s-electrons to unfilled states withpcomponent at a defect site containing a N dangling bond, can be annealed out only after prolonged annealing at 1150 °C. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120292

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

From the impedance analysis, we report the dielectric constants of lithium triborate single crystals for the three principal axes in the frequency range of 100 Hz–1 MHz and in the temperature range of 303–773 K. The observed highly anisotropic behavior of dielectric dispersions is mainly related to the anisotropy of the activation energy forLi+ion hopping, which is constituted by theB3O7channel framework lain along thecaxis. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120293

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The depth distribution of Ge implanted into thermally grownSiO2films has been studied after annealing using transmission electron microscopy, Rutherford backscattering spectrometry, and x-ray diffraction. At annealing temperatures above 900 °C a significant redistribution of the as-implanted Ge profile was found. Crystalline Ge nanoclusters embedded in theSiO2matrix are formed within a cluster band with well defined boundaries. The evolution of nanoclusters can be explained qualitatively by a model based on nucleation, growth and Ostwald ripening of Ge precipitates. Besides, chemical and interface reactions lead to the formation of additional Ge peaks near the surface and at theSi/SiO2interface. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120294

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Dominant trap energy levels in silicon are extracted from the temperature dependence of minority carrier recombination lifetime, observed through laser microwave photoconductive decay. A small correction is made to the Arrhenius plot by incorporating the weakly temperature-dependent term in the recombination lifetime expression, hitherto ignored. The new extraction technique is simple to implement and the results are in good agreement with published data. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120295

出版商:AIP    

年代:1997

数据来源: AIP