摘要:

Large photoinduced Faraday rotations of the polarization direction of a probe beam traveling through a semimagnetic semiconductor are obtained at temperatures higher than that of liquid nitrogen when a pump pulse is sent through the material. These rotations are quasiproportional to the photoinduced free‐carrier density and the applied magnetic field and are strongly resonant with the band‐gap‐probe frequency detuning. A model based on the free‐carrier induced saturation of the refractive indices explains well the experimental observations. The high values obtained for the photoinduced polarization rotations (more than 1° pJ−1 &mgr;m2) make such a process attractive for the design of optical signal processing devices. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113686

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In this letter we report the fabrication and optical‐electrical characterization of violet‐blue GaN homojunction light emitting diodes. Rapid thermal annealing at 1150 °C (for 30 s) was used to activate thep‐dopant species (Mg), which resulted inp‐type GaN whose photoluminescence response centered around 438 nm is much stronger than that obtained from material annealed in the growth chamber at lower temperatures (700–800 °C) and a longer time (20 min). ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113687

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We describe a novel high power semiconductor laser that employs a shaped unstable resonator waveguide to maintain fundamental spatial mode operation at high power levels. We call this device the SHUR (shaped unstable resonator) laser. By photoetching and regrowth we locate a secondary, nonplanar antiguide, beneath the main part of the waveguide. The lasing mode couples to this secondary guide and experiences lateral antiguiding, which is the basis of the unstable resonator action. Prototype versions of the SHUR laser show a maximum pulsed output power of 770 mW per facet. The focused beam is dominated by a single lobe that contains 47% of the output power. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113688

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A low pressure gas discharge switch operating in the 0.1–0.7 Torr range and triggered by electrostatic plasma injection is described. The trigger and cathode electrodes are coaxial cylinders, with the trigger electrode (the inner cylinder) being divided into resistively isolated sections. The anode electrode is collinear with both of these electrodes. Commutation is initiated by the generation of a plasma in the trigger‐cathode region, with subsequent injection into the anode–cathode space. This injection is driven by self‐generated voltage gradients between the sections of the trigger electrode. Results from measurements of the characteristics (plasma injection speed, electron density and temperature, anode and trigger current, and voltage wave forms) of a test device operated at hold‐off voltages of up to 17 kV and currents up to 5 kA are presented. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113689

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The depth profile of a Co (300 A˚)/Ti (50 A˚) bilayer on Si(100) is studied by nondestructive refracted x‐ray fluorescence before and after annealing. Following annealing, the angular distribution of the x‐ray fluorescence indicates an inversion of the Co and Ti layers and the formation of CoSi2. These were confirmed by cross‐section transmission electron microscopy and x‐ray nanoprobe measurements. This success suggests that refracted x‐ray fluorescence, which can be used as aninsituprobe, may be ideally suited for analysis of thin‐film reactions and interdiffusion. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113900

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Scanning tunneling microscopy has been used to investigate the influence of surface boron on silicon growth via chemical vapor deposition (CVD). The presence of boron‐induced reconstructions on the Si(001) surface dramatically changes the surface morphology during subsequent CVD growth of silicon using disilane at 815 K. Boron‐induced reconstructions inhibit the lateral diffusion of silicon atoms from terraces to step edges, leading to greatly enhanced island nucleation, and also reduce the local surface reactivity toward disilane. Strong segregation of boron to the growth surface allows the enhanced island nucleation to persist to subsequent terraces during multilayer CVD growth of silicon, producing a rough but epitaxial surface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113901

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Two surface roughening mechanisms have been distinguished in laser crystallized polycrystalline Si: one is related to rapid release of hydrogen from hydrogen‐rich plasma enhanced chemical vapor deposited amorphous Si and the other is independent of the hydrogen content of the material and is determined by the total number of pulses incident on the surface. At, or beyond, the melt threshold energy there is a positive feedback effect between a beam‐induced periodic surface roughness pattern and enhancement of this pattern by interference effects in subsequent pulses. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113902

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Recently, it was found that electromigration‐induced failure of metallic interconnects in integrated circuits occurs when rounded voids deform into narrow slitlike voids, which are often transgranular. The mechanism of this shape change is now examined by numerical simulation on the basis of electromigration‐driven surface diffusion. As a result, it is found that shape change and motion of voids are competing processes. Large voids with respect to the linewidth are deformed by the electron wind whereas small voids move without any shape changes. Combining diffusional anisotropy with electron wind dynamics allows the experimentally observed faceting of even small voids to be reproduced in the simulation. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113903

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Epitaxial growth of cubic AlN thin films on (100) and (111) silicon substrates by pulsed laser ablation is reported. The epitaxial AlN films can be grown at temperatures above 630 °C in 100–300 mTorr of N2. The epitaxial orientation relationships are (100)AlN//(100)Si and [010]AlN//[010]Si, and (111)AlN//(111)Si and [011¯]AlN//[011¯]Si. The growth of microtwins on (111) planes of AlN was also observed. In the present study, for the AlN thin films grown on (100)Si at around 680 °C in 100 mTorr of N2, the epitaxial growth can cover about 90% of the film region. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113904

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

BaTiO3/YBa2Cu3O7−&dgr;  bilayer structure has been epitaxially grown on a LaAlO3(100) substrate by pulsed laser ablation with sintered YBa2Cu3O7−&dgr; and single crystal BaTiO3targets. The analysis of the BaTiO3/YBCO bilayer structure by x‐ray diffraction (XRD) 2&thgr;/&thgr;,w, and &fgr; scans as well as high resolution electron microscopy indicates that the bilayer thin films have a high degree ofc‐axis‐oriented epitaxial crystalline structure. The surface morphology of the thin film was observed by scanning electron microscopy. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113905

出版商:AIP    

年代:1995

数据来源: AIP