摘要:

Continuous operation of 2.1 &mgr;m wavelength Ga0.84In0.16As0.15Sb0.85/Al0.27Ga0.73As0.04Sb0.96double heterostructure injection lasers has been achieved up to a temperature of 190 K for the first time. The laser wafers were grown by liquid phase epitaxy. In pulsed operation, broad area devices with active layer thicknesses of 0.8–1.0 &mgr;m exhibited room‐temperature threshold current densities as low as 7 kA/cm2.

ISSN:0003-6951    

DOI:10.1063/1.97350

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

An analysis of a new type of high power semiconductor laser array is presented. The array consists of parallel, uncoupled waveguides linked atYjunctions in one region. We show that for the lowest threshold array mode all the waveguides oscillate in phase and all (except possibly the outermost) have equal amplitudes. The array mode should be stable above threshold and it radiates in a single‐lobe far‐field pattern if the individual waveguide mode width is comparable to the guide separation.

ISSN:0003-6951    

DOI:10.1063/1.97351

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The nonlinear coupling of energy between the polarization eigenmodes is shown to affect both the relative phase and amplitude ratio of a light beam propagating in a birefringent fiber. These two quantities determine the polarization state at the output. The general formalism and some specific numerical examples are presented.

ISSN:0003-6951    

DOI:10.1063/1.97352

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Epitaxial insulator (CaF2) layers have been grown on epitaxial metal (CoSi2and NiSi2) layers on Si(111) by molecular beam epitaxy. The surface morphology and bulk crystallinity are much better for growth on NiSi2, with scanning electron microscopy revealing only small triangular hillocks, and channeling minimum yields as low as 3% measured in the CaF2using 2.5 MeV4He+ions. CaF2layers grown at 650 °C on CoSi2consist of a mixture of regions either aligned or rotated 180° with respect to the CoSi2lattice, while CaF2layers grown at 550 °C on NiSi2are of a single orientation, regardless of the orientation of the NiSi2with respect to the Si substrate.

ISSN:0003-6951    

DOI:10.1063/1.97353

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

It is demonstrated, using two very different techniques (viz., CF4reactive ion etching and Ar ion beam etching), that dry etching exposure causes extensive boron acceptor neutralization in silicon. This boron neutralization is observed to occur as far as microns below the etched surface with etching exposures of only &bartil;1 min. Neutralization occurs if the temperature does not exceed about 180 °C during etching; it may be annealed out by subsequent exposure to such temperatures. Adsorbed water vapor or, alternatively, hydrogen inherent in the silicon is proposed to provide hydrogen‐related species which cause this neutralization. Protons created in the plasma from these sources, or hydrogen‐related species directly liberated from their sources on or in the solid, may be injected into the silicon during the energetic ion impact constantly present in dry etching. This observation of boron neutralization deep below the etched surface demonstrates that dry etching exposure causes extensive permeation of foreign species into the etched material.

ISSN:0003-6951    

DOI:10.1063/1.97354

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We have observed a negative differential resistance (NDR) in a single‐barrier tunneling structure in which electrons tunnel from a doped semiconductor emitter layer into a quantum well (QW) layer and subsequently drift laterally to a specially designed contact. Pronounced NDR is seen already at room temperature and at 77 K the peak to valley (PTV) ratio in current is more than 2:1. Our results lend support to a recent hypothesis by Luryi [Appl. Phys. Lett.47, 490 (1985)] that the NDR in double‐barrier tunneling structures is not related to a resonant enhancement of the tunneling probability at selected electron energies, but rather originates from tunneling into a system of electron states of reduced dimensionality. For comparison we have also fabricated a QW structure with two tunneling barriers, in which the parameters of the emitter barrier and the QW are identical to those in the single‐barrier structure. In the double‐barrier structure we have obtained current densities as high as 4×104A/cm2and a NDR with PTV ratios of 3:1 at 300 K and 9:1 at 77 K.

ISSN:0003-6951    

DOI:10.1063/1.97355

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Resonant tunneling and accompanying negative differential resistance are observed at 85 K in Al0.4Ga0.6As/GaAs triple barrier diodes, where two GaAs wells are separated by three AlGaAs barriers. Five resonance peaks, one small peak for one bias polarity, one medium and one large peak for each bias polarity, are observed. These are the resonance current peaks from the ground level of a populated well to the ground, the first excited or the second excited level of an adjoining unpopulated well. These are the direct electrical observations of the resonant tunneling between confined electron states in two potential wells of a semiconductor multiheterostructure.

ISSN:0003-6951    

DOI:10.1063/1.97356

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A comparative study is presented of the room‐temperature decay of laser excited microwave photoconductivity and of cathodoluminescence of high quality GaAs multiple quantum wells grown by molecular beam expitaxy and of high quality GaAs liquid phase epitaxial layers. The results from both experiments are inquantitativeagreement and prove that carrier recombination in multiple quantum wells occurs via excitonic decay channels at excess carrier densities less than 1017cm−3. In contrast, band‐band recombination prevails in three‐dimensional material.

ISSN:0003-6951    

DOI:10.1063/1.97357

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A novel Si epitaxial growth technique using mercury‐sensitized photochemical vapor deposition has been developed. Epitaxial thin films (300–8000 A˚) were grown on (100)Si substrates at 100–300 °C from a gas mixture of Si2H6+SiH2F2+H2by irradiation of a low pressure mercury lamp (1849,2537 A˚). The growth rate, plotted as a function of the reciprocal substrate temperature, represented an activation energy which was found to be a small value of 0.18 eV. Observation of the surface structure by reflective high‐energy electron diffraction showed fine (100) streak patterns for films grown at 200 °C as well as at 250 and 300 °C.

ISSN:0003-6951    

DOI:10.1063/1.97626

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Powder synthesis by thermally induced vapor phase reactions is described. The powder generated by this technique consists of spherical, nonagglomerated particles of high purity. The particles are uniform in size, in the 0.1–0.2 &mgr;m size range. Most of the particles are crystalline spheres. A small fraction of the spheres are amorphous. Chain agglomerates account for less than 1% of the spherules.

ISSN:0003-6951    

DOI:10.1063/1.97358

出版商:AIP    

年代:1986

数据来源: AIP