摘要:

Fluorite CaF2and polyvinyl chloride specimens coated with a grounded thin gold layer have been irradiated with 12 and 30 keV electrons, respectively. The change of the halogen x‐ray signal intensity (FK&agr; and ClK&agr;) has been measured as a function of time and for various incident doses. The experimental results are fully explained by a simple model for the anion migration driven by the electrostatic field. An Auger process is suggested for the initial escape of anions from their lattice site. To our knowledge, the migration of halogen ion is reported for the first time. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361156

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Suppression of dislocation formation and boron transient diffusion by carbon coimplantation is studied by means of transmission electron microscopy, secondary‐ion‐mass spectrometry, photoluminescence spectroscopy, and high‐resolution x‐ray diffraction. It is shown that both the effects are due to the formation of C‐related damage which acts as a trap for Si interstitials. Quantitative simulations indicate that this damage is probably formed by coprecipitation of Si and C atoms in Si1.15C complexes. These complexes also deteriorate the electrical properties of the implanted layer. They dissolve at annealing temperatures higher than 900 °C. When this occurs, the effect of C is reduced and both B transient diffusion and dislocations, as well as the recovery of the electrical properties, are observed. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361157

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Undoped SiC crystals grown by physical vapor transport have been characterized by temperature dependent Hall effect and near infrared optical absorption measurements. Crystals with reduced nitrogen content were found to exhibitp‐type conductivity with carrier concentrations in the 5×1014–1×1016cm−3range at room temperature. The Fermi level position determined from Hall effect measurements at elevated temperatures was 0.35 eV above valence band. The primary acceptor‐type impurity was identified as substitutional boron with total concentration of uncompensated acceptors in the 1×1017–5×1018range. This interpretation was confirmed by near infrared absorption spectra, which were dominated by a broad photoionization band with a threshold at 0.7 eV and a maximum at 1.75 eV. The shape of the band was fitted, and the thermal ionization energy of the defect was found to be in the 0.3–0.4 eV range. A correlation between the photoionization band intensity, and the uncompensated boron content was used to determine the value of maximum optical cross section of boron photoionization band, which was 4.17×10−17cm2. In addition to photoionization band, boron‐containing samples exhibited set of narrow absorption lines near the fundamental absorption edge. Based on correlation with boron content and line position in different SiC polytypes, these lines were identified as due to excitons bound to neutral boron acceptors. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361158

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A comparison of kinematic and dynamic approaches of x‐ray diffraction is made for multiple InGaAs/InGaAlAs quantum wells (MQW), around 002 and 004 reflections, as a function of strain and thickness. A domain of validity of the kinematic approximation is then defined. It turns out that the kinematic approximation is sufficient in the case of typical structures for MQW lasers or modulators. An automatic procedure including kinematic treatment of double‐diffractionXand photoluminescence data is proposed, which allows us to determine precisely the compositions, thicknesses, and even the band offsets of MQW structures. This procedure is applied to a 20 period sample. The results are confirmed by transmission electron microscopy measurement. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361159

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Plasma hydrogenation of Czochralski Si has been performed to investigate the introduction of Si–O stretch modes and their correlation with thermal donor formation. Plasma hydrogenation at 275 °C introduces a well‐resolved vibrational absorption band at 1005 cm−1, while absorption due to electronic excitations for thermal donors remains weak. We attribute this band to a Si–O precursor center for thermal donor formation, and suggest it is the oxygen dimer center discussed in other studies of oxygen in Si. Vibrational modes introduced at 990 and 1000 cm−1during post‐hydrogenation furnace annealing at 400 °C correlate with thermal donors TD2 and TD3, respectively. Stretch frequencies for Si–O in thermal donor centers are compared to those for oxygen aggregates in oxygen‐implanted and electron‐irradiated Si.

ISSN:0021-8979    

DOI:10.1063/1.362658

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report here on the growth and the characterization ofp‐type CdTe grown by molecular beam epitaxy on (001) Cd0.96Zn0.04Te substrates. Nitrogen has been used as a dopant, which is activated in an electron cyclotron resonance plasma source. The carrier concentration was determined using a C/V profiler. Nitrogen has been successfully incorporated substitutionally and hole densities up to 2.6×1017cm−3have been achieved. In addition we present data from x‐ray diffraction and photoluminescence, which demonstrate the effect of self‐compensation on the nitrogen‐doped CdTe layers. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361160

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

In low‐temperature (300–350 °C) silicon epitaxy employing low‐energy inert‐gas ion bombardment on a growing film surface, the effects of ion bombardment energy and ion flux as well as that of ion species on the crystallinity of a grown silicon film have been experimentally investigated. It is shown that the energy dose determined by the product of ion energy and ion flux is a main factor for epitaxy that compensates for the reduction in the substrate temperature. Large‐mass, large‐radius ion bombardment using Xe has been demonstrated to be more effective in promoting epitaxy at low substrate temperatures than Ar ion bombardment. Thus, low‐energy, high‐flux, large‐mass ion bombardment is the direction to pursue for further reducing the processing temperature while preserving high crystallinity of grown films. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361161

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The implant species and dose effects of ion implantation, including crossing the amorphization threshold, on the transient enhanced diffusion (TED) behavior of a boron marker layer in silicon have been studied. It has been found that for lower implant doses, TED is species independent. However, for higher implanted doses, the dependence of TED on species becomes very significant. It has been found that at these higher doses, including amorphizing doses, P implants cause more TED than either Si or As implants. This result is explained based on the fully coupled diffusion mechanism of the impurity dopants where dopants diffuse by temporarily pairing with point defects. Additionally, both point defect clusters and extended defects such as dislocations significantly affect the dopant profile evolution of both the implanted profile and the buried marker layer. By modeling these effects, the experimental results have been simulated and a consistent parameter set has been found to fit the data to a reasonable extent. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361162

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Carbon nitride films were successfully prepared by ion beam synthesis method. 100 keV N+ions at a dosage of 1.2×1018cm−2were implanted into carbon thin films at different temperatures. The samples were evaluated by x‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, cross‐sectional transmission electron microscopy (XTEM), Rutherford backscattering spectroscopy (RBS), x‐ray diffraction analysis (XRD), and Vickers microhardness measurement. XPS results show that most of the implanted nitrogen atoms are free state. Most of the carbon atoms have C–C bonding and a little of them form a C–N bond. It also can be clearly seen that the content of the C–N covalent bonding state in the samples is increased by raising the implanting temperature of the samples. Raman spectrum indicates that there is a Raman band near 2300 cm−1corresponding to carbon‐nitrogen stretching. XTEM and RBS studies show that there is a buried layer of carbon nitride. XRD and TEM analyses reveal that the buried carbon nitride is predominantly amorphous with a small volume fraction of nanocrystallites. The sample has a higher hardness than that of a carbon thin film. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361163

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A model of the basic processes accompanying solid‐phase reactions (SPR) on the Si surface has been developed based on general physical considerations. The model considers these processes in various structures, including M–Si, Si–SiO2, and Si–Si3N4. Analytical expressions have been derived to estimate values of the elastic stresses, steady‐state crystal supersaturation by point defects, and SPR activation energy. Data related to the type of point defect generated during SPR have been obtained. A rule to predict the sequence of phase formation in systems with a polyphase constitution diagram is proposed. In particular it is shown that the steady‐state crystal supersaturation by self‐interstitials during thermal oxidation of Si ranges from 2.4 to 4.4 at 1200 °C. However, the supersaturation by vacancies during the metal silicide formation varies in range from 102to 107depending on the reaction type and temperature. The analytical results have been compared with experimental data on the enhanced diffusion of impurities, growth of oxidation stacking faults, and growth parameters of metal silicide layers, and have shown good agreement. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.361164

出版商:AIP    

年代:1996

数据来源: AIP