摘要:

We report the observation of two photon absorption which is strongly dependent on the applied electric field and the optical polarization. At 1.55 &mgr;m wavelength, the two‐photon absorption coefficient of the GaAs/AlGaAs multiquantum well (MQW) waveguides for transverse‐magnetic light is about seven times lower than for transverse‐electric polarized light and changes by a factor of approximately 4 for a change in applied direct‐current electric field of ∼140 kV/cm. Ultrafast nonlinear refraction causing phase changes of over &pgr; radians without appreciable excess loss is observed. These measurements demonstrate that GaAs/AlGaAs MQW waveguides could be successfully used for subpicosecond all‐optical switching near half‐band gap, at wavelengths corresponding to the 1.55 &mgr;m optical communications band.

ISSN:0003-6951    

DOI:10.1063/1.105700

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We determine types and concentrations of free carriers in GaAs layers under organometallic chemical vapor deposition growth conditions from the linear electro‐optic structure observed near 3 eV in reflectance‐difference spectroscopy. The sensitivity is about 1017cm−3at 400 °C and 1018cm−3at 600 °C, sufficient to measure common doping levels at or near growth temperatures. We observed the transition betweenn‐ andp‐type doping during atomic layer epitaxy of a carbon‐dopedp‐type layer on ann‐type substrate at 470 °C.

ISSN:0003-6951    

DOI:10.1063/1.105672

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Rapid thermal diffusion of phosphorus intop‐type silicon from a spin‐coated film containing the dopant has been studied as a function of process temperature and time duration. The electron diffusion length measurements performed by the surface photovoltage method present evidence for a gettering phenomena since the diffusion length values of the diffused silicon samples are found to exceed the initial value reported for the virgin material.

ISSN:0003-6951    

DOI:10.1063/1.105673

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A scheme for selective electroless copper patterning of Si wafers has been developed with palladium silicide as the catalytic layer initiating copper deposition. Thermal conversion of a palladium layer to silicides on a SiO2patterned silicon substrate, followed by an acid etching of the unreacted palladium on the SiO2surfaces, leaves only the silicided regions at the base of the windows for electroless copper deposition. Excellent via‐filling down to 0.5‐&mgr;m dimensions and an aspect ratio of 6 has been demonstrated. The thin copper deposited on the Pd2Si has a resistivity of ∼2.0 &mgr;&OHgr; cm. Contactless photocarrier decay measurements indicate virtually no degradation of Si lifetimes by these processing steps.

ISSN:0003-6951    

DOI:10.1063/1.105674

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We show that extremely high quality InGaAsP/InP superlattices grown by chemical beam epitaxy meet the stringent requirements for optical modulator application in the wavelength range from 1 to 1.6 &mgr;m. Double crystal x‐ray diffraction from multiple quantum well samples of 20 to 100 periods show that the satellite peaks have widths comparable to or narrower than the substrate peak width, which indicates very reproducible thickness and composition control along the growth direction. For optical modulation, ap–i–nwaveguide structure consisting of 20 periods 90/90 A˚ InGaAsP/InP exhibits very sharp excitonic feature and large quantum confined Stark effect near 1.5 &mgr;m. A room temperature exciton shift of about 25 meV has been measured for a bias voltage of 100 kV/cm in the photocurrent spectra.

ISSN:0003-6951    

DOI:10.1063/1.105675

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The epitaxial quality of GexSi1−xfilms grown on Si⟨100⟩ by a novel laser‐assisted technique has been investigated for compositions in the rangex≤0.37 and thicknesses between 50 and 500 nm. Epitaxy is induced during electron beam deposition of GexSi1−xfilms on Si substrates by pulses of an excimer laser operating at 308 nm with 30 ns pulse duration. Good epitaxial growth is obtained for 50 nm films forx≤0.04 on chemically cleaned Si(100) surfaces even in the presence of substantial fluorine coverage. Using a predeposition/crystallization of a 50 nm pure‐Si buffer layer, good epitaxy is then obtained in 50 nm films forx=0.05–0.13. Atx=0.07, defect‐free alloys have been grown up to thicknesses of 0.5 &mgr;m. However, for films with compositions above 19 at.% Ge, dislocations at a nearly constant density of ≊10 &mgr;m/&mgr;m2are observed. This uniform density suggests a breakdown mechanism other than simple strain relaxation.

ISSN:0003-6951    

DOI:10.1063/1.105676

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The effect of AsH3preflow on initial stages of GaAs grown on Si was studied by transmission electron microscopy. As the temperature of AsH3preflow was increased, the surface of the Si substrate became rougher: At 1000 °C, many threading dislocations originating at the rough surface were observed in the GaAs layer. In contrast, at low temperature, 450 °C, the Si surface became smooth and the dislocations were reduced. Furthermore, the Si surface was still smooth after long AsH3preflow at 450 °C. The roughness of the Si surface is attributed to the supply of As atoms to the Si surface at high temperature.

ISSN:0003-6951    

DOI:10.1063/1.105677

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A unique method for nucleating diamond films on surfaces using C clusters is described. The process substitutes the need for diamond polish pretreatment of substrates prior to diamond film growth, as currently practiced in low‐pressure (<1 atm) chemical vapor deposition methods. As an example, the use of C clusters C60and C70as nucleating layers on single‐crystal Si surfaces is presented. It is shown that a thin layer (approximately 1000 A˚) of pure carbon C70is sufficient for the nucleation and growth of fine grain polycrystalline diamond films. The enhancement of nucleation by the C70layer is nearly ten orders of magnitude over an untreated Si surface. It also follows that C clusters can be used as a one‐step lithographic template for growing diamond on selected regions of the substrate. In addition, insight into the mechanism for diamond nucleation from C clusters is given.

ISSN:0003-6951    

DOI:10.1063/1.105678

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A high‐efficiency, resonant‐cavity, bipolar inversion channel field‐effect transistor detector is demonstrated with a triple‐strained InGaAs quantum‐well absorbing region. A quantum efficiency of 80% is obtained at a resonant wavelength of 0.94 &mgr;m, and a bandwidth of 20 A˚, giving a 26‐fold enhancement in absorption due to resonance. The transistor detector operates in the FET mode with an independent gate electrode to control its sensitivity, and in a bipolar mode with a photogain of 25. The structure is identical to that used in other inversion channel laser structures, and hence provides an optimum configuration for optoelectronic integration. This is the first demonstration of a three‐terminal quantum‐well resonant‐cavity photodetector.

ISSN:0003-6951    

DOI:10.1063/1.105654

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We show how analysis of the stacking sequences at CoSi2/Si interfaces formed by 100 kV Co+implantation into Si (001) or (111) predicts the formation of partial dislocations or stacking faults at precipitate corners. The presence and nature of the stacking fault can uniquely identify the bonding coordination at the CoSi2/Si(111) interface. Consideration of the interfacial structure for twinned (B) and untwinned (A) {111} interfaces helps explain the competitive nucleation and growth ofAvsBprecipitates.

ISSN:0003-6951    

DOI:10.1063/1.105655

出版商:AIP    

年代:1991

数据来源: AIP