摘要:

The empirical response function introduced by Cole and Davidson for the analysis of dielectric relaxation in the frequency domain has been used in an analogous way to reanalyze ionic conductivity relaxation using the electric modulus representation. The fitting of data for ionic relaxation in AgPO3, 0.1AgI‐0.9AgPO3, and 0.4Ca(NO3)2‐0.6KNO3originally fit using a Kohlrausch–Williams–Watts response function has been considerably improved.

ISSN:0021-8979    

DOI:10.1063/1.347052

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The mechanism of atomic transport inside the silicide during thermal oxidation of silicide layers on Si substrates has been analyzed by means of inert gas markers implanted in TiSi2, Mn11Si19, FeSi2, and NbSi2. Oxidation was carried out in dry oxygen. The marker displacement reveals that the growth of metal‐free SiO2over the first three of these compounds occurs via the reverse motion of metal atoms, from the silicide/oxide to the silicon/silicide interface, rather than through the direct diffusion of Si atoms from the substrate to the oxide. Moreover, analysis of the marker position indicates that the total amount of Si between the marker and the free surface decreases during oxidation, as had been previously observed in the oxidation of NiSi2, CoSi2, and CrSi2. Although this could occur via the formation and evaporation of SiO, it is believed that the loss of Si is due to the motion of Si atoms, also in the ‘‘reverse’’ direction as for the metal atoms, across the silicide layer. The experiment conducted with NbSi2shows that this silicide oxidizes via the direct motion of Si from the substrate to the oxide as anticipated. With TiSi2the initial state of oxidation occurs as described, but the experimental observations imply that thick oxide layers grow via the direct motion of Si from the substrate to the oxide.

ISSN:0021-8979    

DOI:10.1063/1.347053

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Defined delamination of thin carbon‐diamond films on Si using a focused electron beam of 0.5 kW/cm2power density is reported. The films were deposited form a CH4/Ar rf plasma and were less than 1 &mgr;m thick with residual compressive stress of 1.0–0.5 GPa. At higher electron beam power densities ablation and crystallization of the films are observed. Analysis of buckling patterns in spontaneously delaminated films give estimates of 128 J m2, 91 GPa and 0.5 for the intrinsic interface toughness, Young’s modulus and Poissons ratio of the films.

ISSN:0021-8979    

DOI:10.1063/1.347054

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The thermal behavior of X/C multilayers (nanometer‐thick layers made of tungsten, nickel, or SiWSi alternating with carbide or pure carbon) was studied. Two types of annealing were performed: the pulsed laser annealing in air and the classical thermal annealing in a vacuum furnace. Depending on the composition and the structure of the layered materials, thermal stability or diffusion mechanisms were observed and further analyzed by small‐angle x‐ray scattering, transmission electron microscopy, and Auger electron spectroscopy. The results show that the period expansion and the reflectivity evolution, that were observed in some cases after treatment, are caused both by structural changes into the layers and by exchange of matter between layers. These changes always induce a partial graphitization of the amorphous carbon and, in the case of W/C multilayers, the formation of a W2C compound.

ISSN:0021-8979    

DOI:10.1063/1.347055

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The change in the chemical surface state of polished Si wafers [p‐type, (100) oriented] during storage in air at room temperature was investigated for storage times up to half a year. Measurements were performed by x‐ray Photoelectron Spectroscopy (XPS) and High Resolution Electron Energy Loss Spectroscopy (HREELS). Immediately after the HF treatment (1 min 5% HF, 2 min water rinse) vibrational spectroscopy (HREELS) shows a predominant coverage of the surface with hydride groups (80%–90% of a ML), which can be inferred from the presence of the stretching (2100 cm−1), scissor (900 cm−1) and bending (640 cm−1) vibrations in the spectra. A slight additional coverage with oxygen is proved by XPS and originates from Si‐OH groups (3670 cm−1) and oxygen‐related hydrocarbon groups (XPS). These Si‐OH groups result from an exchange reaction of Si‐F with water during the two‐minute water rinse. The development of an oxygen coverage during subsequent storage in air occurs extremely slowly and shows a logarithmic behavior. A monolayer coverage of oxygen (7×1014/cm2) is reached after approximately 7 days of storage in air. HREELS spectra exhibit the concurrent development of the asymmetric Si‐O‐Si vibration, which indicates that oxygen penetrates the lattice and breaks Si—Si bonds. During this period the Si‐O‐Si frequency shifts from about 1060 to 1100 cm−1.The penetration of backbonds of Si—H gets evident by broadening of the Si‐H stretching vibration and finally by a shift to higher wavenumbers. Chemically shifted components of the Si 2pline (partially oxidized Si) are present with the SiO2−xcomponent (chemical shift ≳3.4 eV) becoming dominant after roughly a week. Further oxidation proceeds essentially by an increase of the SiO2peak in combination with a steeper slope of the logarithmic growth curve. The SiO2thickness after half a year is about 8 A˚. The frequency of the Si‐O‐Si vibration shifts up to 1120 cm−1, which can be related to a growing angle of the Si‐O‐Si bridge. Si—H groups are still present, the final peak position is about 2220 cm−1. The measurements show an extended induction period until the monolayer range of oxide coverage is attained. We ascribe this to the passivation of the surface by hydrogen and to a HF treatment according to Very‐Large‐Scale‐Integration standards.

ISSN:0021-8979    

DOI:10.1063/1.347056

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The utilization of W/C and W/B4C multilayer structures as Bragg diffractors rests in their reflective efficiency and dependability, both of which rely on the stability of the layered structure. The layers within the vapor deposited multilayers, often amorphous, are typically metastable, hence susceptible to thermally induced structural change. In fact, crystallization and compound formation are known to occur in annealed multilayer systems. In this study, multilayers of W/C and W/B4C were vacuum heat treated, then structurally examined. A comparison between the pre‐ and post‐heat‐treated structures of the two multilayer systems is accomplished using diffraction, depth profiling, and microscopy. Our results indicate structural stability in the W/B4C multilayers, after heat treatment, in comparison with structural degradation noted in the W/C system.

ISSN:0021-8979    

DOI:10.1063/1.347057

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Polycrystalline &agr;‐Al2O3and yttria‐stabilized ZrO2substrates were coimplanted with 175‐keV Mo+and 74‐keV S+at doses of 1×1017and 74‐keV S+and 2×1017cm−2, respectively. An amorphous SiO2substrate was coimplanted with 175‐keV Mo+and 74 keV S+at doses of 4.97×1016and 1.02×1017cm−2, respectively. The energies of Mo+and S+ions were chosen to obtain a nearly overlapping depth profiles in all three substrates. Transmission electron microscopy, Rutherford backscattering, and Auger electron spectroscopy techniques were used to characterize the ion‐implanted materials. The formation of MoS2phase was observed in the as‐implanted condition as well as after annealing at 700 °C in all substrates. Thermodynamic calculations were performed to predict the equilibrium binary phase formed in Al2O3, ZrO2, and SiO2under the present implantation and annealing conditions. The predictions agree with the experimental findings.

ISSN:0021-8979    

DOI:10.1063/1.347058

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The properties of 100‐nm‐thick Ti55N45and Ti45N55films as diffusion barriers between silicon substrates and thin Cu films were studied by sheet resistance measurements, Rutherford backscattering spectrometry, Auger electron spectroscopy, secondary‐ion mass spectrometry, transmission electron microscopy, scanning electron microscopy, energy dispersive x‐ray spectroscopy, x‐ray diffractometry, and diode leakage current measurements. For unpatterned Si/titanium nitride/Cu samples, all the layers were intact and there was no indication of interdiffusion by conventional depth profiling techniques up to 700 °C for Ti55N45and 900 °C for Ti45N55after 30 s rapid thermal anneal in N2, respectively. Leakage current measurements did not show deterioration of diode junction (with junction depth of 0.25 and 0.30 &mgr;m) up to 650 °C for Ti55N45and 800 °C for Ti45N55. The improvement in failure temperature of the N‐rich Ti45N55diffusion barrier is a result of the lower defect density and a more stable feature furnished by nitrogen stuffed at the defects.

ISSN:0021-8979    

DOI:10.1063/1.347059

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Hole mobilities have been measured in tri‐p‐tolylamine‐doped polymers as functions of the polymer composition, temperature, and electric field. Depending on the composition of the polymer, the mobilities vary by over two orders of magnitude. In all cases, the electric field and temperature dependencies can be described as exp(&bgr;E1/2) and exp−(T0/T)2, respectively. The effect of the host polymer on the mobility is largely related to the prefactor &mgr;0. It is suggested that the dependence of &mgr;0on the polymer composition is related to the wave‐function overlap factor, 2&agr;R, and due to differences of the ionization potential of the host polymer.

ISSN:0021-8979    

DOI:10.1063/1.347060

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Measurements of electron lifetime have been carried out on unintentionally doped layers of (111)BHg1−xCdxTe (0.216<x<0.320),p‐type as‐grown by molecular‐beam epitaxy. The temperature dependence of the bulk lifetime is explained in terms of the Shockley–Read recombination mechanism for the extrinsic region. The samples have shown a deep level close to midgap. The surface recombination seen in two of the samples is accounted for. Some samples show clearly Auger‐limited recombination at high temperatures. From the values of &tgr;n0and &tgr;p0of two samples the trap level appears to have a donorlike character.

ISSN:0021-8979    

DOI:10.1063/1.347061

出版商:AIP    

年代:1990

数据来源: AIP