摘要:

An all‐optical logic gate consisting of a GaAs‐GaAlAs multiple quantum well structure inserted in a 1.3‐&mgr;m‐thick Fabry–Perot cavity is demonstrated to perform with subpicosecondonandoffswitching time. The use of a purely optical field effect allows for a recovery time as rapid as the switch‐on time.

ISSN:0003-6951    

DOI:10.1063/1.97535

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The analytical solution is given for the nonlinear propagation in a linearly mismatched directional coupler taking into account an arbitrary nonuniform nonlinearity. The effect of mismatching which causes nonreciprocal nonlinear switching of the device is analyzed in detail.

ISSN:0003-6951    

DOI:10.1063/1.97536

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A nonlinear guided‐wave concept and nonlinear coupled‐wave equations are used to study numerically the coupling characteristics of two planar waveguides in a GaAs/GaAlAs multiple quantum well structure with self‐defocusing nonlinearities. Both the mode‐intensity‐dependent critical power and the coupling length are calculated for the first time using the nonlinear field distributions. An optically controlled modulation/switching behavior is predicted.

ISSN:0003-6951    

DOI:10.1063/1.97537

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Efficient collection of photoexcited electrons and holes by thin, strained quantum wells is demonstrated in an In0.16Ga0.84As‐GaAs pseudomorphic quantum well heterostructure laser. The undoped laser structure, which was grown by molecular beam epitaxy, consists of five 50 A˚ pseudomorphic In0.16Ga0.84As quantum wells separated by thick (700 A˚), unstrained GaAs confining layers. Despite the fact that the quantum wells are undoped, decoupled, and of dimensions which are known to be too small to provide efficient carrier collection in unstrained AlxGa1−xAs‐GaAs structures, 77 K photopumped laser operation is achieved on quantum well transitions (&lgr;∼870 nm) at a threshold excitation intensity of 9.3×103W/cm2. At photoexcitation intensities even as high as five times the threshold value, spontaneous emission from the quantum well is more than 700 times as intense as the confining layer luminescence. Based upon these photoluminescence results and some simple physical arguments, we suggest that carrier collection is enhanced in pseudomorphic quantum wells.

ISSN:0003-6951    

DOI:10.1063/1.97538

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A new method for time‐resolved luminescence spectroscopy with subpicosecond resolution is proposed in the 1–1.6 &mgr;m spectral range, using parametric amplification in a highly nonlinear organic crystal. This technique is used to characterize the luminescence of an infrared dye and of an InGaAs‐InAlAs multiple quantum well structure.

ISSN:0003-6951    

DOI:10.1063/1.97539

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Low voltage scanning electron microscopy is an important part of microelectronic inspection technique. This makes it possible to examine devices without changing the electrical properties, and to examine nonconducting samples such as photoresist without the use of a surface metal layer. The secondary electron imaging method suffers, however, from the difficulty that the image can be spoiled by slight charging of the specimen by the incident electron beam. This problem can be solved by the use of the low‐loss electron image.

ISSN:0003-6951    

DOI:10.1063/1.97540

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A class of electrostatic lenses with extremely low spherical aberration is proposed. The axial potential distribution of these lenses has an asymmetric bell‐shaped form with a lower potential on the image side. A lens withCso∞/fo=0.51 is presented as an example. The maximum required electrode voltage is only five times larger than the initial accelerating voltage. At 5 mrad acceptance half‐angle, 51 mm focal length, and magnificationM=−3.3 the radius of the spherical aberration disk is 6 nm.

ISSN:0003-6951    

DOI:10.1063/1.97541

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Using blue tunable pulse laser radiation of low fluence, we have investigated laser‐induced sputtering from cleaved BaF2(111) surfaces under ultrahigh vacuum conditions. Time correlated with the laser pulses the positive ions Ba+, Ba++, (BaF)+and F+were observed. Practically no negative ions were found. Neutral atomic fluorine (F 0) was desorbed abundantly. A pulse correlation of F 0as well as the relative amount of F 0and F+could not be established at this stage. The emission yield of all positive ions as well as of F 0was strongly wavelength dependent and showed a broad resonance around 2.9 eV.

ISSN:0003-6951    

DOI:10.1063/1.97542

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The time evolution of the silicon concentration profiles in ion‐implanted polycrystalline &agr;‐Ti has been studied in the temperature range 650–800 °C. Diffusion couples were created by ion implantation. The time‐dependent concentration profiles were monitored by the use of the nuclear resonance broadening technique through the30Si(p,&ggr;)31P reaction. The values of 1.09±0.18 eV for the activation energy and (4.4±404.0)×10−7cm2/s for the frequency factor were obtained. The solubilities of Si in Ti are reported. The present result is discussed in the framework of the Ti silicide formation.

ISSN:0003-6951    

DOI:10.1063/1.97543

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The Ge0.1Si0.9surface and the Ge0.1Si0.9/Si interface on the Si(111) 4° off substrate were observed by a cross‐sectional transmission electron microscope. The Ge0.1Si0.9surface grown at 750 °C was composed of alternate planes of (111) terraces and step bands, whose widths in the ⟨112⟩ direction were about 450 and 150 A˚, respectively. A step band was formed by steps several monolayers high. On the other hand, the Ge0.1Si0.9/Si interface was very flat and the step bands were not formed in the Si on Si homoepitaxy process at 750 °C.

ISSN:0003-6951    

DOI:10.1063/1.97544

出版商:AIP    

年代:1986

数据来源: AIP