摘要:

Liquid‐phase epitaxial growth with higher supersaturated InP growth melt could be successfully used in fabricating InGaAsP/InP double heterostructure (DH) lasers emitting in the 1.50–1.55‐&mgr;m wavelength region. InP‐InGaAsP interface characterization has been carried out with scanning electron microscope (SEM), transmission electron microscope, photoluminescence (PL) measurements, and Auger spectroscopy. From the dissolution depth measurements, it was found that there is a slight dissolution on the surface of the InGaAsP layer, even in the 1.3‐&mgr;m wavelength region during an InP layer growth with 16° supersaturated melt. Although the amount of dissolution increases as the composition of the quaternary active layer becomes a longer wavelength, as a result of this dissolution, the transition region does not catastrophically affect the laser performances at a wavelength shorter than 1.55 &mgr;m. It was found that the InP‐InGaAsP interface at 1.59‐&mgr;m wavelength shows rugged configuration under high‐resolution SEM observation and the half‐width of PL spectrum becomes wider than that for DH wafers at a wavelength shorter than 1.55 &mgr;m. This was confirmed by Auger line profile measurements.

ISSN:0021-8979    

DOI:10.1063/1.328550

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Let us consider the surface composition of the binary alloy, where the surface compositionR1is considered to be different from the bulk inside compositionR2and also the segregation region thickness isT. In this model it is possible to count the Auger signals considering the contributions of an attenuating primary beam and the secondary electrons which are backscattered and forwardscattered. Using the theory, we have calculated theseR1for the reported experimental results of the Ag‐Au binary alloy as a function ofT. The calculated Ag compositionR1are compared with the ISS (Ion Scattering Spectroscopy) results that are said to be the most surface sensitive technique. When the bulk Ag content is less than 50 at. %, the Ag segregation region thicknessTis considered to be one monolayer (2.58 A˚ ∼ an average layer spacing,d3=M/6.02×1023&rgr;, whereM= atomic mass and &rgr; = specific mass or density). However, when the bulk content is greater than 50 at. %,Tlies between one and two monolayers (2.58 and 5.16 A˚). The usual method that uses a relative sensitivity factor only estimates the surface average composition in the depth of the mean free path of the Auger electrons. However, this method can estimate the surface compositionR1as well as the segregation region thicknessT.

ISSN:0021-8979    

DOI:10.1063/1.328551

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The structure of vacancies in grain boundaries has been investigated by computer molecular statics employing pairwise potentials. In order to gain an impression of the vacancy structures which may occur generally, a number of variables was investigated, including metal type, boundary type, degree of lattice coincidence, and choice of boundary site. In all cases the vacancies remained as distinguishable point defects in the relatively irregular boundary structures. However, it was found that the vacancy often induced relatively large atomic displacements in the core of the boundary. These displacements often occurred only in the direct vicinity of the vacancy, but in certain cases they were widely distributed in the boundary, sometimes at surprisingly large distances. In certain cases the displacements included a large inward relaxation of one, or more, of the atoms  neighboring the vacancy, and the initial vacant site became effectively″split″. These results were classified and discussed in relation to the variables listed above. Several binding energies to the boundary were also calculated. Finally, the relevance of the results to the mechanism of boundary self‐diffusion was discussed.

ISSN:0021-8979    

DOI:10.1063/1.328508

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Carrier‐concentration profiles of Si in semi‐insulating GaAs have been obtained byC‐Vmeasurement techniques. Si+or Si++ions were implanted at energies ranging from 50 to 600 keV, and annealing was carried out with Si3N4encapsulants. Range parameters such as the projected rangeXpand the projected standard deviation &Dgr;Xpwere experimentally determined by use of depths at the peak carrier concentration and at the 1/&sqrt;evalue of the peak carrier concentration of the profiles. It was found that &Dgr;Xpwas strongly dependent on the Cr contents of substrates whileXpwas not. The measured carrier concentrations could be approximated by the Gaussian distribution, and values ofXpwere in good agreement with the theoretical value of the projected rangeRp. However, &Dgr;Xptended to saturate as the incident energies increased and deviated from the theoretical value of the projected standard deviation &Dgr;Rp.

ISSN:0021-8979    

DOI:10.1063/1.328509

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The feasibility of direct measurement of temperature in shock‐loaded solids was checked in a series of planar impact experiments using commercial nickel gauges embedded in polymethylmethacrylate (PMMA) targets. The technique is based on recording and analyzing the resistance changes of the shocked gauge, which result from heat conduction from the surrounding specimen into the gauge. Results are presented which show good agreement between experimental and calculated values obtained by using a one‐dimensional heat‐conduction program. We also give results of residual temperature measurements, obtained by the same technique, of shocked PMMA samples after release to zero stress.

ISSN:0021-8979    

DOI:10.1063/1.328510

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Incoherent inelastic neutron scattering experiments have been performed in order to establish the longitudinal acoustic modes (LAM) in orthorhombicn‐C32H66crystals by a method different from Raman scattering. Besides the Raman active first order of LAM, the second order of LAM, which is Raman inactive, has been observed. No dispersion of the LAM’s was to be seen. It is masked completely by effects resulting from the absence of optical selection rules. In addition to the LAM’s, the antiparallel translational mode in chain direction, which is optical inactive, was identified. Its assignment was confirmed from theQdependence of the scattering intensity.

ISSN:0021-8979    

DOI:10.1063/1.328511

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The diffusion of aluminum in ion‐implanted noble metal‐aluminum solid solutions has been measured using the ( p,&ggr;)‐resonance broadening technique. The investigated temperature ranges were 375–550, 275–425, and 158–350 °C for copper, silver, and gold and the activation energies obtained were 1.88, 1.28, and 0.72 eV, respectively. Only the activation energy of aluminum in copper corresponds in magnitude to the ’’normal impurity diffusion’’ generally found to be valid for solutes in the noble metals.

ISSN:0021-8979    

DOI:10.1063/1.328512

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The effect of substrate strains upon surface acoustic wave (SAW) velocities were determined for piezoelectric PbTiO3ceramics that were modified by adding Nd2O3, In2O3, and MnO2. SAW velocity variations were measured against uniaxial bending strain in the direction of propagation. It was found that the relationship between fractional SAW velocity change and uniaxial strain reveals strong nonlinearity, which contrasts with the case for single‐crystal substrates. The present ceramics were also found to have an anomalously large SAW velocity strain coefficient (∼10) at a highly strained condition (∼8×10−5).

ISSN:0021-8979    

DOI:10.1063/1.328513

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Diamondlike carbon films produced both by ion‐beam technique and by radio‐frequency (rf) plasma decomposition of hydrocarbon gases (C4H10, C2H6, C3H8, and CH4) have been examined using the technique of transmission electron microscopy. Although these examinations indicate that these films are predominantly amorphous, both single‐crystal and polycrystalline diffraction patterns have been obtained from films of both types that indicate formation of several different phases. Some of these phases appear to be cubic and could be new forms of carbon. The results of secondary ion mass spectrometric analysis of carbon films produced by rf plasma decomposition of hydrocarbon gases are also discussed.

ISSN:0021-8979    

DOI:10.1063/1.328514

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We report a study of bulkn‐InP by deep level transient spectroscopy. Measurements were made onp+njunction diodes and Schottky barriers in which both electron and hole traps were present. The effects of Zn diffusion, phosphorus partial pressure, and relatively low‐temperature heat treatment were studied. Results indicate the presence of uniformly distributed traps as well as nonuniform traps with higher concentration near the junction in the presence of Zn diffusion. Results further indicate significant changes in the thermally induced trap concentration associated with the removal of excess phosphorus. Significant changes in the trap spectra were also seen at temperatures below that typically used for Zn diffusion and may have important consequences in device fabrication.

ISSN:0021-8979    

DOI:10.1063/1.328515

出版商:AIP    

年代:1981

数据来源: AIP