摘要:

Aluminum‐free GaInAs/GaInP strained quantum well (QW) laser diodes grown on GaAs were prepared by molecular beam epitaxy (MBE) employing solid phosphorus and arsenic valved cracking cells for the first time. The separate confinement heterojunction laser structure utilized Ga0.51In0.49P cladding layers, a GaAs waveguide region, and a single 100 A˚ Ga0.18In0.82As QW. Stimulated emission from this structure was observed at &lgr;∼0.98 &mgr;m (1.265 eV). The threshold current density of broad area devices with 100×500 &mgr;m2dimensions were measured as low as 290 A/cm2and had power slope efficiencies between 0.35 and 0.40 W/A. The estimated transparency current density for the structure is 50 A/cm2. The data show all solid source MBE is a growth technology capable of producing laser diode structures of comparable quality to that of the other growth processes requiring hydrides. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114825

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

InAs/AlSb/GaSb/AlSb/InAs interband‐tunneling structures have been analyzed with respect to the composition and structural quality of the AlSb tunneling barriers. The addition of AlAs monolayers at the interfaces between the AlSb barriers and the InAs and GaSb layers was found to result in the expected reduction in the valley current density of the resonant interband‐tunneling diode. Vibrational mode Raman spectroscopy showed that the introduction of AlAs monolayers led to the formation of pseudoternary Al(SbAs) barriers, which cause the observed reduction of the valley current density. Ellipsometric measurements indicate that the structural quality of both types of barrier layers, with and without AlAs monolayers added to the interfaces, is inferior to that of thick bulklike AlSb layers. The observation of Raman scattering from a coupled hole plasmon‐phonon mode indicates the formation of a hole gas in the GaSb quantum well at the center of the tunneling structure. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114826

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Anisotropy of the silicon valence band does not lead to any significant anisotropy in the longitudinal hole transport properties, but we find that the transverse mobility is quite anisotropic. The transverse mobility represents the response of charge carriers to a small transverse electric field in the presence of a strong longitudinal field. A detailed, anisotropic Monte Carlo method has been applied to the calculation of the hole transverse differential mobility in silicon. The transverse differential mobility is studied both with regard to variations in the orientation, with respect to the crystalline axes, of the high longitudinal electric field, and with regard to variations in the transverse direction of the mobility, taken in the plane perpendicular to the high electric field. The anisotropy of the valence band causes the transverse differential mobility to strongly vary with respect to the electric field orientation. Symmetry considerations show that the transverse differential mobility is isotropic in the {100} and {111} planes and has twofold rotational symmetry in the {101} planes. Our calculations bear this out. Furthermore, we show that the transverse mobility can be much different from the chordal mobility, in distinction to the case for isotropic band structures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114827

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Band offsets at the CdS/Cu2In4Se7heterojunction interface were studied by synchrotron radiation soft x‐ray photoemission spectroscopy. CdS overlayers were sequentially grown in steps, at room temperature, on the Cu2In4Se7crystal. Photoemission measurements were acquired after each growth to determine the electronic structure at the heterojunction interface. Results of these measurements indicate that the valence‐band offset &Dgr;Evbmis 1.10(±0.20) eV and that the conduction‐band offset &Dgr;Ecbmis 0.22(±0.20) eV for the CdS/Cu2In4Se7heterojunction. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114828

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We reportp‐type doping of tellurium‐based compounds (CdTe, ZnTe) and alloys (CdMgTe, ZnMgTe, ZnCdTe) in molecular beam epitaxy using nitrogen atoms from a plasma source. The dominant shallow acceptor, as deduced from transport and optical measurements, has an ionization energy close to the effective mass value. A systematic decrease of the doping efficiency is observed as the Zn content decreases. We discuss the key role of the Zn content in the material in the framework of two factors: (i) local strain induced in the lattice by the presence of nitrogen and (ii) formation of compounds involving nitrogen atoms. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114829

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The carrier collection losses in amorphous silicon (a‐Si) and amorphous silicon–germanium (a‐SiGe) alloy single‐junctionnipcells have been experimentally investigated by measuring the biased quantum efficiency and color (blue and red) fill factor values. The study has identified losses near thep/ijunction and the bulk of theilayer. The extent of the losses have been found to be dependent on the quality and thickness of theilayer and the nature of then‐layer surface. The results suggest a broad interrelationship between the initial film properties and deposition conditions and an inhomogeneity in the direction of film growth. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114830

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Quasiequilibrium nonlinear optical absorption spectra are computed for semiconductor superlattices. The theory generalizes the semiconductor Bloch equations to describe anisotropic structures. The equation for the interband polarization is solved numerically and the carrier‐density dependent optical nonlinearities are computed. Starting from excitonic absorption, with increasing density exciton saturation and the development of gain is observed. The dependence of the gain spectra on structural parameters of the superlattice is discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114831

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have used transmission electron microscopy to determine the morphology of InP Stranski–Krastanow islands in GaInP, grown by metalorganic chemical vapor deposition at 580 °C. We investigated both capped and uncapped islands. It was found that the fully developed islands have the principal shape of truncated pyramids with a hexagonal base both before and after overgrowth. The planes defining the islands are of {001}, {110}, and {111} types. The base dimensions are 40–50 nm and 55–65 nm in the [1¯10] and [110] directions, respectively, and the height is 12–18 nm. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114832

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Narrow‐band color filters have been integrated on porous silicon layers. Distributed Bragg reflectors and Fabry–Pe´rot interference filters based on layered porous silicon samples are demonstrated. The effects of narrowing and tuning the porous silicon emission band are shown in structures composed by Fabry–Pe´rot filters integrated on top of thick porous silicon layers. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114833

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The structural properties of low temperature plasma enhanced chemical vapor deposited SiO2films using Si2H6and N 2O have been studied. It is observed that the degree of compaction of as‐deposited SiO2films, upon subsequent annealing, increases up to 4%. The shift of Si‐O‐Si stretching peak wave number of the as‐deposited SiO 2films (&Dgr;&ohgr;=−20 cm−1) compared to the undensified SiO 2films is attributed to 9.4% increase in the film density, resulting in smaller Si‐O‐Si bridging bond angle of 138°. It is also believed that the high temperature annealing results in the reduction of hydroxyl containing species in the film and in turn drives the dielectric constant towards that of thermal SiO2films. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114834

出版商:AIP    

年代:1995

数据来源: AIP