摘要:

We demonstrated a quantum‐confined Stark effect electroabsorption modulator consisting of quantum wells of AlGaAs and GaAs on an epitaxial multilayer dielectric mirror, all grown by molecular beam epitaxy. The resulting reflection modulator avoids problems of substrate absorption, and has relatively high contrast ratio (up to ∼8:1 with peak reflectivity of 25% at 853 nm) because the light passes twice through the quantum wells. Reflection modulators are of interest for bidirectional communication systems, in parallel arrays of optical switching and processing devices and for optical interconnects. For the latter there exists the possibility of this device grown on the same substrate alongside a GaAs integrated circuit or even on Si substrates.

ISSN:0003-6951    

DOI:10.1063/1.97935

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Relaxation oscillation frequencies are reported for short cavity GaAs/AlGaAs multiquantum well lasers with dry‐etched facets. Decreased electron and photon lifetimes combined with the high differential gain constant of short cavity lasers yield very high relaxation oscillation frequencies. A peak value of 24 GHz was achieved with a 40‐&mgr;m‐long laser, and a linear relationship between frequency and the square root of the output power is observed.

ISSN:0003-6951    

DOI:10.1063/1.97936

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The continuous wave electro‐optic probing (CWEOP) technique is for the first time used to probe the GaAs Czochralski liquid encapsulated semi‐insulating surface property. From the second derivative profile of the signal, the space‐charge boundary under different bias is clearly observed. The motion of the detected space‐charge boundary with applied bias shows that the substrate surface evolves from a highly compensated semi‐insulating surface to ap−surface with thermal annealing. The CWEOP experiment also concludes that there is no other level except EL2 possessing enough concentration to compensate the background shallow acceptor. Since this technique is extremely sensitive to the GaAs surface property, it can be used to directly probe the surface potential, field, and charge distribution in GaAs material and device.

ISSN:0003-6951    

DOI:10.1063/1.97937

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Using an empirical pseudopotential method, we have computed the spectrum of two‐photon absorption (2PA) in cubic ZnS. The 2PA coefficients obtained this way agree better with experimental data than 2PA coefficients obtained from simpler band‐structure calculations.

ISSN:0003-6951    

DOI:10.1063/1.97938

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Magnetized argon plasma columns with peak densities of greater than 1018m−3, lengths of 2 m, and full width half‐maximum diameters of 0.3 m have been created at pressures of 40 mPa (3×10−4Torr) with input powers of 1.5 kW of 7 MHz rf.

ISSN:0003-6951    

DOI:10.1063/1.98257

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The use of multilayer target with predrilled holes to inject trace elements into laser‐produced plasma is presented. The tracer plasma obtained shows a smaller source size and reduced opacity compared to a plasma target. The preparation and alignment of the proposed target are extremely simple.

ISSN:0003-6951    

DOI:10.1063/1.97939

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Insitumeasurements of resistance have been used to study the interaction of Pt with a limited amount of Si deposited in adjacent layers on oxidized Si wafers. One observes in sequence the formation of Pt2Si, Pt12Si5, and Pt3Si, as seen previously by others using time‐sequence annealing. The present method has the advantage of being quite rapid and simple. Changing the heating rate provides one with a measure of the activation energies for several reactions, including, for the first time, values of the apparent activation energy for phases whose formation is dominated by nucleation and growth, rather than by diffusion. A phase transformation was observed during the cooling of Pt3Si. The final Pt3Si phase examined by transmission electron microscopy reveals an interesting Widmansta¨tten structure. The resistivities of the different phases have been measured: 29, 32, and 53±10 &mgr;&OHgr; cm, respectively, in order of increasing Pt content.

ISSN:0003-6951    

DOI:10.1063/1.97940

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Deep level transient spectroscopy and resistivity measurements have been used to characterize defects in as‐grown and neutron irradiated epitaxially grown 3C‐SiC on Si(100) substrates. The thick epilayers were free of defects; neutron irradiation induced an electron trap with an activation energy of 0.49 eV. The SiC‐Si interface has a large density of defects and dislocations. Most of the irradiation defects are confined to the lower two‐thirds of the band gap. Ninety percent of these defects can be removed by annealing at 350 °C.

ISSN:0003-6951    

DOI:10.1063/1.97941

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Si(111) surface topography changes during Si molecular beam epitaxial growth were observed by reflection electron microscope images using microprobe reflection high‐energy electron diffraction (RHEED). When RHEED intensity oscillations were observed at low substrate temperature (350 °C), it was found that the shape of atomic steps on the substrate was preserved during the growth and the surface topographies changed repeatedly with the period of the oscillations. When almost no oscillations were observed at higher substrate temperature (500 °C), the shape of the atomic steps changed during the growth. These observations provide direct evidence that RHEED intensity oscillations occur as the result of layer‐by‐layer two‐dimensional nucleation growth.

ISSN:0003-6951    

DOI:10.1063/1.97942

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The technique of cross‐sectional transmission electron microscopy has been used to investigate the defect content of epitaxial CdTe layers grown on {100} and {111}BGaAs and on {111}BCdTe by metalorganic chemical vapor deposition. Growth on {111} oriented substrates invaribly gave rise to layers of {111} orientation and these contained a large number of thin (100–1000 A˚) lamella twins lying parallel to the interface. In contrast, layers grown on {100} GaAs substrates were found to exhibit either {100} or {111} orientation. Epilayers with the former alignment contained arrays of misfit dislocations at the interface, whereas those with the latter orientation exhibited a density and distribution of lamella twins which were comparable with those of layers grown on {111} substrates. The presence of these defects in homoepitaxially grown CdTe, where the effects of lattice mismatch do not arise, clearly indicates that twinning in {111}BCdTe epilayers is a growth phenomenon.

ISSN:0003-6951    

DOI:10.1063/1.97943

出版商:AIP    

年代:1987

数据来源: AIP