摘要:

Angle‐resolved x‐ray photoelectron spectroscopy (ARXPS) has been used to study the Ar incorporation and surface compositional changes in InP(100) after 1–5 keV Ar+bombardment at various ion fluences. The ARXPS measurements showed that the incorporated Ar concentration achieved saturation at ion bombardment fluences of >1016cm−2. The surface Ar concentration decreased with increasing bombardment energy. No Ar bubbles were observed by atomic force microscopy, suggesting that Ar bubble formation was not the main Ar trapping mechanism. The altered layers were, on average, In rich up to the sampling depth of the ARXPS technique. However, the altered layers were inhomogeneous as a function of depth and appeared more In rich at the surface than in the subsurface region. The results are compared with those obtained by other authors and discussed in the context of preferential sputtering, radiation‐enhanced diffusion and segregation, and Ar incorporation. Although the altered layers were In rich, a P‐rich phase induced by Ar+bombardment was identified in the altered layers. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363789

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Octahedral cavities have recently been found in the Czochralski silicon (CZ‐Si) substrate surface layer just under oxide defects. We investigate the effect that adding HCl to oxygen during oxidation has on the oxide defect density. The effect of intentionally introducing impurities onto a Si surface on the oxide defect density is also examined. Our experimental results suggest that impurities are closely related to the generation of oxide defects. A model is presented in which impurities are incorporated into the growing octahedral cavities during Si crystal growth, and then introduced into the growing oxides during thermal oxidation. These impurities in the oxides then act as a conductive path (oxide defects) in the insulator on the CZ‐Si. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363790

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The heat capacity of crystalline zinc tris (thiourea) sulphate, has been measured in the range from 220 to 500 K by differential scanning calorimetry, and was found to obey the relationshipCp(T)=2.76×10−3T+0.366 J g−1 K−1. Thermal expansion data have been measured in the range from 150 to 473 K. From these data, the principal thermal expansion coefficients were found to be &agr;1=6.41×10−5K−1, &agr;2=4.52×10−5K−1, and &agr;3=−4.32×10−6K−1. The thermal conductivity tensor of this orthorhombic crystal was calculated from values of the thermal diffusivity in the directions normal to the (100), (010), and (001) crystal planes by the laser flash method. The thermal conductivity coefficients at 295 K arek1=0.27 W m−1 K−1,k2=0.34 W m−1 K−1, andk3=0.54 W m−1 K−1. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363791

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Advancement of a fine slit along a planar grain boundary in an electric fieldE0, applied parallel to the slit, is investigated by considering electromigration along both the grain boundary and the slit surface. Electrically induced flux in the grain boundaryIgb(+ toward the slit tip) and both electrically and curvature‐induced fluxes on the slit surfaces are considered assuming 2Is>Igb, whereIsis the flux (+ away from the slit tip) on each of the parallel slit surfaces far removed from the tip. Steady‐state solutions of the transport equations are classified according to the value of a parameter &bgr;=tan−1(2Is/Igb) which, under reasonable assumptions, depends on material parameters only. For 5&pgr;/4≥&bgr;≥&bgr;2, unique steady‐state solutions exist; for &bgr;2>&bgr;>&bgr;1, multiple steady‐state solutions occur; below &bgr;1≥&pgr;/4, no steady‐state solution is possible. Since &bgr;1<&pgr;/2,Igb>0 (flux exiting the grain boundary into the slit) for all cases in which no steady‐state solution is possible. In the case of multiple solutions, those corresponding to smallest width (and hence largest velocity) are determined. For all steady‐state solutions, slit width and tip velocity scale asE−1/20andE3/20, respectively. Results also apply to the propagation of a slit within a grain or along a passivation layer. Generally, tip velocities can approach 1 nm/s (3.6 &mgr;m/h), thereby representing a likely failure mechanism in fine‐line (near bamboo structure) interconnects. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363792

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Melting and rapid solidification are induced in amorphous Ge films upon irradiation with 10 ps laser pulses at 583 nm. The role of heat flow during the solidification process was investigated by comparing the behavior of films grown on substrates with different thermal properties. The melting and solidification kinetics are followed in real time by reflectivity measurements in the nanosecond time scale and the induced structural changes are analyzed by means of Raman spectroscopy in micro‐Raman configuration. If the thermal diffusivity of the substrate is high enough, the film reamorphizes via bulk nucleation of the amorphous phase from the melt. When the thermal diffusivity of the substrate is reduced, the initial nucleation of the solid phase leads to an increase in the liquid temperature (recalescence) and in the melt duration, thus promoting the formation of the crystalline phase. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363815

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A new method for unambiguous reconstruction of crystal‐lattice strains in epitaxially grown layers from high‐resolution x‐ray diffraction data is proposed. The technique uses x‐ray diffracted intensity profiles collected for two different radiation wavelengths. We enhance the theory for the previously developed algorithm for model‐independent determination of crystal‐lattice strain profiles in single crystals with epitaxially grown top‐surface layers. The method relies on the retrieval of the scattered x‐ray wave phase from its intensity profile via a logarithmic Hilbert transform. This phase‐retrieval technique is always associated with the problem of complex polynomial root finding. A practical procedure for the mapping of complex polynomial roots is proposed to distinguish true and virtual zeros. This allows the phase of the diffracted x‐ray wave to be retrieved unambiguously. The method was applied to determine physical dimensions and concentration composition of a Si/Si1−xGex/Si alloy multilayer structure typical for SiGe heterobipolar transistor device. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363793

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Ni/Al multilayer films with pair thicknesses of 10 and 20 nm and with overall compositions in the range 48–88 at. % Al were prepared by sputtering. For comparison, Ni‐Al alloy films in the same concentration range were prepared by co‐deposition of the elements. The films were studied by x‐ray diffraction, electron diffraction, and differential scanning calorimetry. It was found that the B2 NiAl phase with a metastable concentration of approximately 63 at. % Al was the first phase to grow upon annealing of the multilayer films. The growth of this phase could be described by Johnson–Mehl–Avrami kinetics with an activation energy of 0.8 eV and an Avrami exponent of 0.5. This low activation energy was consistent with the observation that the phase had formed during deposition and continued to grow upon annealing at low temperatures to thicknesses of a few nanometers. If the reactant phases were not fully consumed by the B2 phase growth, the subsequent reaction was the formation of NiAl3, previously thought to be the first product phase in the Ni‐Al system. The reduction of driving force by the preceding B2 phase growth explains why the formation of NiAl3takes place by a nucleation‐and‐growth process, an observation that has been discussed controversially in the recent literature. The nucleation and growth of NiAl3had an activation energy of 1.5 eV in agreement with previous studies. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363794

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A low‐energy, high‐brightness, broad beam Cu ion source is used to study the effects of self‐ion energyEion the deposition of epitaxial Cu films in ultrahigh vacuum. Atomically flat Ge(001) and Si(001) substrates are verified byinsituscanning tunneling microscopy (STM) prior to deposition of 300 nm Cu films withEiranging from 20 to 100 eV. Film microstructure, texture, and morphology are characterized using x‐ray diffraction &ohgr;‐rocking curves, pole figure analyses, and STM. Primary ion deposition produces significant improvements in both the surface morphology and mosaic spread of the films: AtEi>37 eV the surface roughness decreases by nearly a factor of 2 relative to evaporated Cu films, and atEi&bartil;35 eV the mosaic spread of Cu films grown on Si substrates is only &bartil;2°, nearly a factor of 2 smaller than that of evaporated Cu. During deposition withEi&bartil;25 eV on Ge substrates, the film coherently relaxes the 10% misfit strain by formation of a tilt boundary which is fourfold symmetric toward ⟨111⟩. The films have essentially bulk resistivity with &rgr;=1.9±0.1 &mgr;&OHgr; cm at room temperature but the residual resistance at 10 K, &rgr;0, shows a broad maximum as a function ofEi, e.g., atEi&bartil;30 eV, &rgr;0=0.5 &mgr;&OHgr; cm. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363795

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A scheme is presented for the reduction of threading dislocation densities in InxGa1−xAs/GaAs epitaxial single layers by accurate control of layer thickness. The model developed differs from previous models since the InxGa1−xAs growth is restricted to less than ten times the Matthews and Blakeslee critical thickness (hc) where the asymmetry in the [110] and [1¯10] dislocation densities is the greatest. Beyond this thickness it is shown that the removal or annihilation of threading dislocations in the epilayer is more than offset by the introduction of new threading dislocations from spiral and Frank–Read‐type sources. Maintaining epilayer thickness below this thickness ensures that the majority of misfit dislocations generated lie predominantly in only one of the ⟨110⟩ directions, reducing the likelihood of blocking with orthogonal dislocations, thereby increasing the mean free path from that expected in higher density dislocation arrays. Etch pit densities show that the threading dislocation density can be reduced by up to a factor of 10 below that found in the substrate, with the added benefit of reducing the inhomogenities in the distribution of threading dislocations. Atomic force microscopy shows that the surface quality of these layers remains high with an absence of striations. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363796

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Molecular beam epitaxial growth of Si1−yCyalloys pseudomorphically strained on the (2×1) reconstructed Si(001) has been investigated as a function of growth conditions. An important question concerns the relation between substitutional and interstitial carbon incorporation, which has a large impact on electrical and optical properties of these layers. We show that the interstitial‐to‐substitutional carbon ratio is strongly influenced by the growth conditions, such as growth temperature and Si growth rate. Both reduction in growth temperature and increase of the overall growth rate lead to an increase in the substitutional‐to‐interstitial carbon ratio. However, these changes in growth conditions can also cause some deterioration in crystal quality. The carbon incorporation behavior is well described by first order kinetics. ©1996 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.363797

出版商:AIP    

年代:1996

数据来源: AIP