摘要:

The effects of individual bistable defects on the dark counting rate of avalanche photodiodes have been monitored and their temperature dependence studied. The presence of a bistable defect in the diode is indicated by the repeated random switching of the counting rate between two well‐defined rates. Four of the defects studied were produced via reaction with a single neutron from a Be–Am source, while two were found to exist without irradiation. Results were analyzed in terms of the activation energies of the electron generating capabilities of the defects, and the effective potential barriers between the two structural configurations of the bistable states. Among the six defects studied, two of them could be of the same type. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113985

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Radioactive isotopes are produced by nuclear reactions in a thin target foil. The recoiling products are directly implanted into samples mounted off‐axis to the primary beam. Using proton or &agr; beams and appropriate target foils, radioactive isotopes of Ti, V, Cr, Mn, and Co were implanted. The implantation parameters are presented and compared with other implantation techniques for radioactive isotopes. To demonstrate an application, a deep‐level transient spectroscopy measurement on48V in silicon is presented. Ti and V correlated band‐gap levels were observed during the48V decay. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113986

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Crystalline quality and residual strain in GaAs films epitaxially grown on Si substrates have been investigated after annealing them under ultrahigh pressures up to 2.1 GPa. The strain in the films decreased linearly with increase of pressure and it became zero at a pressure around 1.9 GPa. The strain depended weakly on the annealing temperature in the range from 300 to 500 °C. A slight increase in the channeling minimum yield in Rutherford backscattering spectrometry was observed in the samples with broad‐area GaAs films. However, the degradation in the crystalline quality was avoided by etching the GaAs films in a stripe pattern with 10 &mgr;m width. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113987

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Intermixing timetiand interdiffusion coefficientsDof nanometer periods Si/Ge strained layer superlattices (SLSs) were measured by Raman scattering technique. Si12Ge12and Si19Ge9SLSs have been annealed in the temperature range 760–900 °C during various time intervals. The observedDandtifollow the Arrhenius‐like behavior with different activation energies &Dgr;E=1.78±0.15 eV and 3.94±0.15 eV and pre‐exponential factorsD=2×10−10cm2 s−1and 0.7 cm2s−1, respectively, for the Si12Ge12and Si19Ge9SLSs.D,ti, &Dgr;E, andD0are strongly affected by the changes of the SLS layer thickness, and strain. An explanation of the experimental observations is proposed in terms of the kinetic electron‐related theory of atomic diffusion in solids. The observed variations of &Dgr;EandD0are related to the material parameters, which are characterized by picosecond atomic and electronic phenomena in nanometer regions, in good agreement with the observations. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113988

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Photoluminescence of erbium‐implanted porous silicon is investigated. Room temperature 1.54 &mgr;m Er3+luminescence is observed after annealing. The luminescence spectrum, annealing characteristics, temperature quenching, and the luminescence lifetime suggest that the Er3+luminescence is mediated by photocarriers in the amorphous silicon matrix in porous silicon, and not related to the presence of the crystal nanograins. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113989

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Carbon ions were implanted into crystal silicon wafers at an energy of 50 keV and with a dose of 1017cm−2followed by thermal annealing. A layer of polycrystalline &bgr;‐SiC was formed beneath the sample surface. Porous nanometer structures were prepared by conventional anodization. At room temperature, the samples exhibit a blue luminescence peak at 2.79 eV (445 nm), which is higher than the energy gap of bulk &bgr;‐SiC (2.2 eV), and its intensity is stronger than that of the reference porous silicon. The results could be explained by the quantum confinement effect. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113990

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Hall bars with widths down to about 250 nm were prepared by overgrowth on patterned GaAs(001) substrates using molecular beam epitaxy. This fabrication method generates a lateral confinement potential determined by AlGaAs barriers. The four‐terminal magnetoresistance of a single wire, measured at 1.3 K after illumination, displays the well‐known features of quasi‐one‐dimensional electron systems. We estimate the electron mobility in a ∼250 nm wide wire to be larger than 51 000 cm2/V s at a carrier concentration of 3.3×1011cm−2.This mobility is comparable to the one measured in a wide reference sample fabricated under identical conditions. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113991

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the observation of cavity‐induced modifications of the three‐dimensional bulk exciton emission in a planar GaAs microcavity, in which the entire cavity layer is an active material. We have performed standard photoluminescence measurements at various emission angles, obtaining evidence of coupling between the exciton and the cavity mode. The modified density of photon states available for the exciton decay shows up in the angle dependence of the emission lineshape, as well as of the photoluminescence peak intensity. The experimental results are qualitatively clarified with theoretical calculations performed with an adapted transfer‐matrix approach. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113949

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The appearance of quantum wirelike morphology on InGaAs single quantum well structures grown by molecular beam epitaxy on (100)InP vicinal surfaces is reported. The results of transmission electron microscopy reveal that the misorientation of the substrate drives the development of a lateral contrast modulation related to In‐rich or Al‐rich regions oriented along {133} or {122} planes that initiate on the InAlAs tensile buffer layer and propagate across the structure, giving rise to an anisotropic rippling of the InGaAs well. Conversely, a misfit dislocation network at the InAlAs/InP interface was observed for the same layers grown on exact (100) surface. A comparison of the two structures suggest that the development of such modulated configuration is apparently a strain relieving mechanism. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113950

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effects on minority carrier diffusion length and surface recombination velocity of the oxidation ofp‐type silicon in a copper contaminated ambient have been analyzed using electron beam induced current. The experiments were carried out on Czochralski and float‐zone silicon in order to obtain two different microstructures of defects and copper precipitation modes at the interface, and to study the influence, respectively, on the diffusion length and surface recombination velocity. The diffusion length was drastically decreased in regions free of extended defects, showing the existence of pointlike recombinant defects in the matrix. In each case, it has been evidenced by electron beam induced current measurements and imaging that these pointlike defects were passivated by hydrogen radio‐frequency plasma annealing, while no effect was observed on extended recombinant defects. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113951

出版商:AIP    

年代:1995

数据来源: AIP