摘要:

High‐resolution, rapid synchrotron x‐ray topography is used to study oxygen‐induced microdefects and their spatial distribution in a large number of (100)n‐type silicon wafers, which had undergone different two‐stage thermal anneals. Section topographs reveal a 40–60‐&mgr;m‐thick defect‐free zone on the surface of a wafer annealed first at 800 °C for 20 h and then at 1150 °C for 4 h.

ISSN:0021-8979    

DOI:10.1063/1.335470

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

In this paper we report the observation of a new luminescence band at ∼1.4 eV in the low temperature (10 K) spectrum from bulk GaAs crystals when they are subjected to surface damage by saw cutting, mechanical polishing, and scribing. The band is observed in all crystals, independent of the growth method, dopant, and conductivity type. The peak position of the 1.4‐eV band shifts to lower energy with decreasing excitation intensity by as much as 7 meV per decade change in excitation power. The luminescence quenches thermally above ∼30 K with an activation energy of 33±7 meV. We suggest that this new luminescence is a donor‐acceptor pair transition involving defects introduced by the surface damage. The mechanical damage, as monitored by the intensity of the luminescence band, is found to extend into the crystal by 10–20 &mgr;m depending on the severity of the damage, and it anneals out at ≳400 °C.

ISSN:0021-8979    

DOI:10.1063/1.334492

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Extrinsic photoconductivity spatial and spectral distribution characteristics in undoped, semi‐insulating GaAs crystal wafers have been investigated and the results are compared with those for optical absorption. The photoconductivity spatial distribution in a single wafer has been shown generally in reverse relation with that for optical absorption.

ISSN:0021-8979    

DOI:10.1063/1.334493

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Magnetization and nuclear magnetic resonance spin‐echo studies were carried out on an amorphous Co‐Fe‐Mn‐B‐Si alloy ribbon. The high‐field susceptibility is negligible and saturation is attained atH∼1.6 MA/m. This would indicate that the alloy is a strong ferromagnet. At 4.2 K, the magnetic moment of the alloy corresponds to 1.13 &mgr;Bper atom. From the usual values of Co and Fe moments, and based on the charge transfer model, the Mn moment is estimated to be 3.7 &mgr;B. Nuclear magnetic resonance studies also give a hyperfine field for Mn corresponding to a moment of about 3.5&mgr;B, in agreement with the magnetization values. Such a moment for Mn is indeed high and is reported for the first time in amorphous alloys. The effects of annealing and crystallization on the nuclear magnetic resonance spectra are also reported. For instance, the crystalline phase Co3B contains Mn as an impurity, a fact which is indicated by the still high value of the Mn moment. Finally, the Co‐Mn coupling is shown to be ferromagnetic in both the amorphous and crystalline states.

ISSN:0021-8979    

DOI:10.1063/1.334494

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Effects of a uniaxial tensile plastic deformation on magnetically induced velocity changes for 10‐MHz ultrasonic longitudinal waves in a specimen of SAE 4340 steel were investigated. The velocity change as a function of the applied magnetic field, measured after plastic deformation under uniaxial tension, was found to be similar to that obtained under uniaxial compression before deformation, suggesting the presence of a residual compressive stress in the plastically deformed specimen. This finding agrees with other reported results.

ISSN:0021-8979    

DOI:10.1063/1.334495

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Backscattering spectrometry with channeling and x‐ray rocking curves have been employed to analyze metalorganic chemical‐vapor‐deposition‐grown AlxGa1−xAs/GaAs strained superlattice structures in significant detail. Both techniques complement each other in the precise determination of composition, thickness, and strain in the individual layers of the superlattices. In addition, the sensitivity of the two techniques allows quantitative measurements of transition regions at the interfaces of various layers. Such fine probing into thin layered superlattice structures provides essential feedback in controlling their growth.

ISSN:0021-8979    

DOI:10.1063/1.334496

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We present calculations of the band gap and of the corresponding cutoff wavelength of HgTe‐CdTe superlattices. These calculations are done for different temperatures as a function of the thickness of the layers, showing in particular that interesting cutoff wavelengths for infrared detectors (∼10 &mgr;m) can be obtained with reasonable thickness between 4 and 300 K.

ISSN:0021-8979    

DOI:10.1063/1.334497

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Donor‐acceptor twins in silicon can exist only in zones where the electric field exceeds a critical value. This hypothesis removes some anomalies in the description of current‐voltage characteristics of almost ideal siliconp‐njunctions. The critical field seems to depend upon the final anneal temperature—about 2×104V/cm for an anneal at 950 °C and of the order of 4×103V/cm for anneals at 800 and 650 °C.

ISSN:0021-8979    

DOI:10.1063/1.334498

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The grain boundary passivation effect in polycrystalline silicon (polysilicon) thin films by hydrogen implantation has been studied. Boron‐doped polysilicon was implanted with low‐energy ions followed by low‐temperature annealing. Resistivity measurements show that the change in resistivity after implantation depends on the boron concentration in polysilicon. At low boron concentration (<1×1019cm−3), three orders of magnitude decrease in resistivity has been achieved. However, at higher boron concentration (>1×1019cm−3), the resistivity increased after hydrogen implantation. This increase is ascribed to implant‐induced damage which cannot be totally recovered by low‐temperature annealing.

ISSN:0021-8979    

DOI:10.1063/1.334499

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Photoconductive detectors have emerged to beome an important technology for lightwave communication since the recent demonstration of a Ga0.47In0.53As detector having a receiver sensitivity better than that of a Ga0.47In0.53Asp‐i‐nphotodiode. This study shows that the receiver sensitivity of a photoconductive detector compares fairly well with that of ap‐i‐nphotodiode (CT=1.0 pF) in the multigigabit rate regime. The calculated result is within 1.4 dB of our measurement data at 1 Gb/s, &lgr;=1.3 &mgr;m for a bit error rate of 10−9. This study further illustrates that noise in an undoped GaInAs photoconductive detector/field effect transistor front end system is dominated by the detector for bit rates less than 3 Gb/s.

ISSN:0021-8979    

DOI:10.1063/1.334500

出版商:AIP    

年代:1985

数据来源: AIP