摘要:

Diamond‐like carbon films, prepared by the dual‐ion beam sputtering method on glass substrate, were irradiated by both carbon ions (C+) and hydrogen ions (H+) under the dose of 1×1017ion/cm2and the energy of 114 and 112 keV, respectively. The as‐deposited and the irradiated films were characterized by electrical resistivity, infrared transmittance, and Raman spectroscopy. It showed that the irradiation of both the C+and the H+can lead to the decrease or even the removal of bond‐angle disorder and the increase of thesp2C‐C bond dominated crystallite size and/or number. The irradiation can also break thesp3C‐H bond. But the irradiation of C+can lead to a bigger decrease ofsp3bonds, forming a film containing moresp2bonds, and the induced film was then more graphite‐like. In irradiation of H+, however, the decrease degree ofsp3bonds is smaller and the irradiated film still showed evident diamond‐like characteristics in electrical and optical properties. The different irradiation mechanisms of the two ions on the diamond‐like carbon films are briefly discussed.

ISSN:0021-8979    

DOI:10.1063/1.352148

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Silicidedp+njunctions and contact resistivity test structures were formed by implantation of BF2through TiSi2in crystalline as well as in Si+or Ge+preamorphized silicon. A subsequent rapid thermal annealing at 950 °C in nitrogen atmosphere was performed to activate the dopant, to remove the ion implantation damage, to increase the silicide conductivity, and to improve the electrical characteristics of the junction. Very low leakage currents and low contact resistivities were measured on samples without preamorphization. With Si+or Ge+implantation the channeling of boron was suppressed but residual defects below the original amorphous‐crystalline (a‐c) interface gave rise to an increased leakage current. A Ti‐related defect level was found by deep level transient spectroscopy in the silicon substrate up to a depth of some micrometers.

ISSN:0021-8979    

DOI:10.1063/1.352097

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

1 MeV electron irradiation has been performed in degenerate,n‐type (n&bartil;2×1017cm−3), molecular beam epitaxial GaAs layers, and Hall effect measurements have been carried out during the irradiation in order to get accurate defect production data. The results have been fitted with statistical models, and are most consistent with the usualE1 (EC−0.045 eV) andE2 (EC−0.15 eV) levels being the (−/0) and (0/+) transitions of the As vacancy, respectively. Also, an acceptor well belowEC−0.15 eV is produced at a much higher rate than that ofE1 andE2.

ISSN:0021-8979    

DOI:10.1063/1.352098

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We have demonstrated a stress gettering mechanism in semi‐insulating, copper‐contaminated gallium arsenide (GaAs) using cathodoluminescence (CL), thermally stimulated current spectroscopy (TSC), and low temperature Fourier transform infrared spectroscopy (FTIR). Cathodoluminescence shows a local gettering effect around dislocation cores in bulk semi‐insulating GaAs qualitatively. This gettering result was confirmed by low temperature FTIR data, which show absorption features resulting from the transition of electrons from the valence band to copper levels. The energy level of each absorption shoulder corresponds to the various copper levels in GaAs. After gettering, the absorption depth at each shoulder decreases. Thermally stimulated current measurements show changes after copper doping. The characteristic returns to that of uncontaminated GaAs after gettering. On the basis of these qualitative and quantitative data, we conclude that copper was gettered, and we propose a stress gettering mechanism in semi‐insulating, copper‐contaminated GaAs on the basis of dislocation cores acting as localized gettering sites.

ISSN:0021-8979    

DOI:10.1063/1.352099

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Monolayers of AlAs, in a matrix of GaAs grown by molecular beam epitaxy, were characterized using 1.0 keV O2+secondary ion mass spectrometry (SIMS) employing sample rotation to reduce uneven sputtering and improve depth resolution. Under optimal conditions, a full width at half maximum resolution of 2.6 nm was obtained. This resolution is discussed in terms of surface roughening, the cascade mixing model, and preferential sputtering. Cascade mixing predicts well the mixing estimated from experimental measurements. In addition, using this SIMS characterization procedure, mixing from 280 keV Ar+bombardment was studied as a function of depth. The mixing with depth varied as dictated by cascade mixing. However, quantitative estimates of the mixing were only ∼0.2 of the observed values.

ISSN:0021-8979    

DOI:10.1063/1.352100

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The viscosity of molten Pd82Si18was measured from 1045 to 1210 K by capillary flow method. When the molten specimen was not purified in advance and during the experiment, its viscosity could not be determined for temperatures below the liquidus. On the other hand, in the presence of boron oxide flux, the viscosity could be measured up to an undercooling of 58 K below its liquidus and the entire viscosity can be described very well by the following Vogel–Fulcher equation: ln &eegr;=−3.779+(1102.135/T−684), whereTis in K. No discontinuity is found at the liquidus. The present data were compared with those of other glass forming systems to test the validity of the principle of corresponding states for atomic transport properties.

ISSN:0021-8979    

DOI:10.1063/1.352101

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

An x‐ray diffraction study of the growth of Pb1−xMnxTe/PbTe (x=0.022–0.037) multi‐quantum well (MQW) structures of period lengths 205–950 A˚ is presented. In order to obtain a reliable Mn diffusion coefficient at the growth temperatureT=270 °C, computed diffusion profiles are used as input for the calculation of diffractograms using kinematical diffraction theory. The satellites of the symmetric (222) Bragg reflections are compared to measurements. The analysis is based on a numerical solution of the diffusion equation which considers explicitly the effect that the boundary at the surface of the growing epitaxial layer moves during growth. Thus for the as‐grown MQWs Mn interdiffusion is considered to occur already during the growth process. In addition, the Mn diffusion profiles of one sample which is isothermally annealed 4, 16, and 64 min atT=270 °C, are simulated using fixed boundary conditions. From comparison to both boundary conditions, the Mn diffusion coefficient of 8×10−17cm2/s atT=270 °C is determined within an accuracy of a factor two. The results are well adapted to our special growth conditions, but the numerical model is applicable in generality. It uses only two essential input parameters: the diffusion coefficient and the growth rate.

ISSN:0021-8979    

DOI:10.1063/1.352102

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The thermal diffusivity and thermal conductivity of single crystal (100) lanthanum aluminate (LaAlO3) have been determined in the temperature range 77–353 K. The thermal diffusivity was measured using a transient heat‐pulse technique and the thermal conductivity by a steady state dc technique. The specific heat capacity was calculated from the thermal diffusivity and thermal conductivity data obtained. The temperature dependence of the thermal diffusivity was found to be of the form [T exp(TD/bdT)] and that of the thermal conductivity of the form [T3 exp(TD/bcT)]. Both results are consistent with the expected behavior of the thermal transport, limited by phonon‐phonon collision (‘‘Umklapp’’) processes, in high purity dielectric single crystals. The Debye temperature (TD) was calculated as 720±22 K and the parametersbdandbcwere found to be 1.4±0.1 and 0.7±0.1, respectively. The average sound velocity was calculated to be (5.4±0.6)×105cm/s. The phonon mean‐free‐path at 303 K was found to be (2.2±0.2)×10−7cm.

ISSN:0021-8979    

DOI:10.1063/1.352166

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A fine grain diamond film has been developed by microwave plasma assisted chemical vapor deposition. Various analytical techniques, including Rutherford backscattering, proton recoil analysis, Raman spectroscopy, and X‐ray diffraction, were utilized to characterize the diamond films. The grain size of the film was determined from bright and dark field electron micrographs, and found to be 200–1000 A˚. The films exhibited good optical transmission between 2.5 and 10 &mgr;m, with a calculated absorption coefficient of 490 cm−1. The friction coefficients of this film were found to be 0.035 and 0.030 at dry nitrogen and humid air environments, respectively, and the films had low wear rates.

ISSN:0021-8979    

DOI:10.1063/1.352167

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The photocarrier generation mechanism has been studied in a highly sensitive layered organic photoreceptor for laser beam printers. A series of experiments has been carried out on a layered photoreceptor which has a carrier generation layer (CGL) containing a triphenylamine trisazo pigment as the main component. As a result, we have found that (1) excitons are produced in the bulk of the CGL by photon absorption, (2) the excitons dissociate into free carriers (negative electrons and positive holes) at the interface between the CGL and a carrier transport layer (CTL), and (3) all positive holes are immediately injected into the CTL. The mechanism of photocarrier generation is considered to be based on a photoinduced electron transfer reaction from the ionization potential level of the carrier transport material in the ground state to the ionization potential level of the photoexcited carrier generation material.

ISSN:0021-8979    

DOI:10.1063/1.352171

出版商:AIP    

年代:1992

数据来源: AIP