摘要:

This study focused on the performance of commercial AlGaN/InGaN/GaN blue light emitting diodes (LEDs) under high current pulse conditions. The results of deep level transient spectroscopy (DLTS), thermally stimulated capacitance, and admittance spectroscopy measurements performed on stressed devices, showed no evidence of any deep‐level defects that may have developed as a result of high current pulses. Physical analysis of stressed LEDs indicated a strong connection between the high intrinsic defect density in these devices and the resulting mode of degradation. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116936

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An improved version of the commonly employed C. C. Teng and H. I. Man (Appl. Phys. Lett.56, 1734 [1990]) measurement technique is illustrated by the characterization of films of a new high glass transition temperature polyurea. Measurements taken in the transmission mode are shown to be free from non‐negligible errors introduced by interference effects present in standard reflection geometry measurements. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116937

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Microscopic dust particles may be formed by accretion of neutral or positively charged precursors in laboratory plasmas. When the concentration of neutral precursors is large, as when a mixture of He and CO is discharged, the radius of grains increases linearly with time andexsituelectron microscopy shows polydisperse particle sizes. By contrast, when the particle acquires multiple negative charges to satisfy the floating potential and the grain size is less than the plasma’s linearized Debye length, ionic growth increases the radii of the particles ast1/3. Monodisperse particle size distributions consistent with ionic growth kinetics are observed in low pressure He plasmas excited by graphite electrodes.

ISSN:0003-6951    

DOI:10.1063/1.116938

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The processes leading to permanent deformation when two bodies make contact are important in adhesion, wear, and tribology. We present nanoindentation results for GaAs showing that impact kinetic energies of only a few eV can lead to a dramatic reduction in the load required to cause permanent deformation when compared to the load required for impact energies of less than 1 eV. We explain this extreme sensitivity to the initial contact in terms of atomic size asperities which must be deformed if defects are to be generated on impact. Lower kinetic energies do not destroy the asperities, and dislocations must be nucleated later in the indentation cycle. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116939

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report the synthesis of nanocomposites of Bi in an aluminum based metallic glass matrix by rapid solidification. It is shown that constrained melting and solidification of nanometer sized embedded Bi particles lead to the formation of symmetry related multidomained particles. The Bi particles exhibit a significantly large depression of bulk melting point (over 100 K) requiring a free energy gain of greater than 0.7×108J m−3. This cannot be explained by the size dependence of melting points or other pressure effects and represents an intrinsic characteristic of the multidomained particles. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116940

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Gold particles embedded in a polymer are studied using high resolution electron microscopy, nanodiffraction, and image processing. These particles have interesting properties such as nonlinear optical susceptibility. It is found that most of the nanoparticles are single crystals, and twins and planar defects are scarcely observed. On the other hand, it is found that nanoparticles do not show smooth facets but they are instead very rough. The effects of this extended roughness in the optical properties are discussed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116941

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Localized epitaxial growth of hexagonal (6H) and cubic (3C) SiC films on Si by annealing the Si substrates at 700–850 °C in a vacuum of 1–2×10−6Torr is presented. The orientation relationships of epitaxial SiC films grown on (111)Si and (100)Si were (0001)6H‐SiC//(111)Si and [112¯0]6H‐SiC//[011¯]Si, (111)3C‐SiC//(111)Si and [1¯10]3C‐SiC//[1¯10]Si, and (100)3C‐SiC//(100)Si and [011]3C‐SiC//[011]Si, respectively. The amount of 6H‐SiC epitaxy was less than that of 3C‐SiC epitaxy. For the films grown at 750–850 °C for 0.5 h, the area fraction of SiC epitaxy ranged from 60% to 80% and the film thickness ranged from 0.02 to 0.15 &mgr;m. The main carbon source for the growth of SiC on Si during vacuum annealing was the carbon‐containing residue present at the chamber walls. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116942

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Theinsitux‐ray reflectivity measurements during linear and isothermal annealings of a W/Si multilayer (ML) were performed, and successive disappearance and reappearance of the second and third ML Bragg maxima between 400 and 500 °C were observed. Such behavior is direct evidence of a long‐range interface shift, and was found to be connected with a substantial decrease of the electronic density of the expanding originally W layers and the ML period. Surprisingly, the changes take place without smearing‐out the interfaces. The results are explained by the Si diffusion into the W layers. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116943

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have measured the effect of pressure on As diffusion in Ge. Diffusion anneals on ion‐implanted samples were carried out in a high‐temperature diamond anvil cell using fluid argon as a clean, hydrostatic pressure medium. At 575 °C over the pressure range 0.1–4 GPa, pressure slightly enhances the diffusivity, characterized by an activation volume of −1.7±1.4 cm3/mole or −0.12±0.10 times the atomic volume. The results call into question the prevailing view that diffusion of groups III, IV, and V elements are mediated entirely by vacancies. If diffusion of As is mediated entirely by vacancies then either the vacancy formation volume must be unexpectedly low or the energy of vacancy migration must be unexpectedly high. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116944

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The kinetics of solid phase epitaxy have been measured in buried amorphous Si layers produced by ion implantation. Crystallization occurs simultaneously at both amorphous/crystalline interfaces of the buried layer. By collecting time resolved reflectivity data simultaneously at &lgr;=1152 nm and &lgr;=632.8 nm it is possible to accurately determine the crystallization rates at both interfaces. Both interfaces crystallize at a constant rate that is comparable to the intrinsic rate found for thick amorphous surface layers before rate retardation due to H infiltration has occurred. Thus, buried amorphous Si layers provide a suitable environment for studies of the intrinsic growth kinetics of amorphous Si. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116945

出版商:AIP    

年代:1996

数据来源: AIP