Search

Provides information on a study which discussed cross-sectional transmission electron microscope study of residual defects in BF[sup+sub2] implanted (111) silicon. Origin of the residual defects; Factors prepared for transmission electron microscope examinations; Motive for using the weak-beam dark-field technique; Considerations taken in the density of defects distributed in a band.

Presents a cross-sectional transmission electron microscope (XTM) study of solid phase epitaxial growth in boron-fluorine-implanted silicon. Usefulness of XTEM in providing data on the regrowth of implantation-amorphous layer; Activation energy for the regrowth; Uncertainties in the XTEM measurements of solid phase regrowth rate.

Presents a combined cross-sectional and plan-view transmission electron microscope study of residual defects in boron fluoride-implanted (001)silicon. Discussion on the origins of residual defects; Possible influences of residual defects on device applications; Results of the amorphization of the surface layer.

Examines some aspects of thermal reactions in aluminum/titanium bilayers in which the interface is contaminated with oxygen. Diffusion of aluminum following thermal annealing; Nucleation and lateral growth of Al[sub3]Ti at the interface; Competition between the lateral growth of Al[sub3]Ti at the interface and the diffusion of aluminum to the free surface.

Examines the effects of backsputtering and amorphous silicon capping layer on the formation of TiSi[sub2] in sputtered titanium films on silicon by rapid thermal annealing using scanning and transmission electron microscopy. Characteristics of TiSi[sub2] layer; Experimental details; Results and discussion; Conclusions.

Studies the intrinsic solid-phase epitaxial growth in self-ion-implanted silicon using a cross-sectional transmission electron microscope. Importance of the study on the kinetics of solid-phase epitaxial growth of implantation-amorphous layers in silicon; Methodology of the study; Discussion on the results of the study.

Demonstrates the feasibility of studying dynamical changes in metal/silicon and ion-implanted silicon thin films by cross-sectional transmission electron microscopy (XTEM) with intermittent annealings in N[sub2] ambient. Deposition of nickel thin films onto silicon substrates; Method used to examine XTEM specimens; Dislocations originally located in the region near the silicon surface that was consumed during NiSi[sub2] growth.

Presents a study which examined the partial epitaxial growth of hafnium silicon (HfSi)[sub 2] grown on silicon. Characteristics of refractory metal silicides; Effectiveness of two-step annealing in promoting the epitaxial growth of HfSi.

Reports on an in situ transmission electron microscopy study on the epitaxial growth of CoSi[sub2] on silicon(111) formed by codeposition of cobalt and silicon near room temperature. Preparation of the amorphous cobalt/silicon mixture; Description of the microstructure of an as-deposited film; Observations on the epitaxial growth of CoSi[sub2] from a codeposited cobalt/silicon amorphous mixture.

Presents a study that analyzed lattice distortions and their correlations to characteristics of the superconducting transitions in 123 thin films grown in situ by sequential ion beam sputtering. Methods and procedures used in the preparation of the films; Analysis of transition temperatures as a function of the c-axis lattice parameter; Expression for the line broadening due to inhomogeneous lattice distortions along the c-direction.

Provides information on the epitaxial growth of vanadium silicide on (111) silicon. Electron gun deposition of vanadium thin films; Interfacial dislocation network at epi-vanadium silicide and silicon interfaces; Difference in thermal expansion coefficients between vanadium silicide and silicon.

This study investigates the formation of Ni suicides on Si1-yCy(0 ⩽ y ⩽ 0.02) epilayers grown on Si(001). The presence of C atoms retards the growth kinetics of NiSi and significantly enhances the thermal stability of NiSi thin films. In particular, an abnormal redistribution of C atoms in the NiSi thin films was observed during Ni silicidation. The NiSi layer was split into two sublayers by an obvious pileup of C atoms. This study proposes a mechanism to elucidate this phenomenon in terms of the C solubility. C atoms accumulated at the NiSi/Si1-yCy interfaces and NiSi grain boundaries may act as diffusion barriers, effectively hindering the grain growth and agglomeration of NiSi and extending the process window of low resistivity NiSi silicides [ABSTRACT FROM AUTHOR]

High-quality single-crystal nanothick Y2O3 films have been grown epitaxially on Si (111) despite a lattice mismatch of 2.4%. The films were electron beam evaporated from pure compacted powder Y2O3 target in ultrahigh vacuum. Y2O3 3 nm thick exhibited a bright, sharp, streaky reconstructed (4×4) reflection high energy electron diffraction pattern. Structural studies carried out by x-ray diffraction with synchrotron radiation and high-resolution transmission electron microscopy show that the films have the cubic bixbyite phase with a remarkably uniform thickness and high structural perfection. Two Y2O3 domains of B-type Y2O3 [211]∥Si[112] and A-type Y2O3 [211]∥Si[211] coexist in the initial film growth with B type predominating over A type in thicker films as studied using x-ray diffraction. The narrow full width at half maximum of 0.014° in the ω-rocking curve is the characteristic of excellent crystalline films. High-resolution transmission electron microscopy and fast Fourier transform analysis show atomically sharp interface and strain relaxation in thicker films. [ABSTRACT FROM AUTHOR]

Cubic phase Y2O3 films 1.6–10 nm thick of excellent quality have been epitaxially grown on Si (111) with Y2O3(111)∥Si(111) using electron beam evaporation of Y2O3 in ultrahigh vacuum. Structural and morphological studies were carried out by x-ray scattering and reflectivity and high-resolution transmission electron microscopy, with the growth being in situ monitored by reflection high energy electron diffraction. There are two Y2O3 domains in the initial stage of the oxide growth with equal population, and the B-type domain of Y2O3[211]∥Si[112] becomes predominating over the A-type domain of Y2O3[211]∥Si[211] with increasing film thickness. Besides the excellent crystallinity of the films as derived from the small ω-rocking curve width of 0.014°, our results also show atomically sharp smooth surface and interfaces. [ABSTRACT FROM AUTHOR]

Striking effects of dopant atoms on the formation of Ni silicides were observed. Epitaxial NiSi2 was found to grow on both BF+2- and B+-implanted (001) and (111)Si at 250–280 °C. The formation of Ni2Si was suppressed. It is conjectured that the presence of dopant atoms may lower the activation energy substantially to promote the formation of epitaxial NiSi2 at low temperatures. The effects may be exploited to grow other epitaxial silicides on silicon at low temperatures. [ABSTRACT FROM AUTHOR]

Fluorine bubbles were observed in 5×1015/cm2 BF+2 -implanted (001) and (111) Si annealed at 1000–1100 °C. Bubbles were found to form in samples annealed at 1100 °C for a time as short as 10 s. The bubbles were distributed mostly near the original amorphous/crystalline interface and silicon surface. The growth of bubbles was seen to be intimately related to the presence of residual defects. Possible ramifications of bubble formation in device applications are discussed. [ABSTRACT FROM AUTHOR]

We have studied the correlations between deposition parameters and structural and electrical properties of YBa2Cu3O7-δ thin films grown in situ by sequential ion beam sputtering. Epitaxial, c-axis oriented YBa2Cu3O7-δ films were grown both on (100) SrTiO3 and on (100) MgO substrates following the stacking sequence of the ‘‘123’’ compound, with deposited layer thicknesses nominally equal to 1 monolayer. The c-axis lattice parameters obtained were larger than the corresponding lattice parameter in bulk samples, even after low-temperature anneals in O2. The transition temperatures were found to decrease with the enlargement of the c-axis lattice parameter. A clear correlation between growth temperature and the value of the c-axis lattice parameter was observed. The c-axis lattice parameter and the x-ray linewidth of Bragg reflections with the G vector along the c-axis were also found to be correlated. This suggests a relationship between the c-axis lattice parameter and the structural coherence of the epitaxial films. [ABSTRACT FROM AUTHOR]

We have investigated the microstructure of epitaxial YBa2Cu3O7-x thin films on SrTiO3(100), LaGaO3(100), and LaAlO3 (100) with particular emphasis on how the final microstructure is developed. Cross-sectional transmission electron microscopy as well as plan-view transmission electron microscopy combined with sputter depth profiling were used to study the change in microstructure with the increase in film thickness. For a thin film or near the substrate/film interface of a thick film, the YBa2Cu3O7-x film is composed primarily of grains oriented with c axis normal to the substrate surface and a small volume fraction of grains with c axis parallel to the substrate surface. As the film grows thicker, the c-axis parallel grains increase in size and grow over the top of the c-axis normal grains. The volume fraction of c-axis parallel grains increases rapidly as the film thickness increases and eventually the entire film surface is covered by c-axis parallel grains. However, the number density of the c-axis parallel grains remains constant throughout the whole film thickness. A growth model is proposed to explain the observed microstructure. Based on this model, a computer simulation is carried out. The simulated microstructure agrees well with the experimental result. [ABSTRACT FROM AUTHOR]

We report the first observation of a lateral junction formed in an alloy due to an abrupt transition from segregated to random AlGaAs alloy compositions. Al0.25Ga0.75As epilayers were grown by molecular beam epitaxy on [011] oriented grooves in a nonplanar (100) GaAs substrate. A quasi-periodic modulation of the aluminum concentration occurs spontaneously in material grown on the (111) facets of the groove, with a period of 50–70 Å along the [111] direction. The compositional modulation is associated with a reduction of the band gap by 130 meV, with respect to the random alloy. While segregation of the AlGaAs alloy has been seen previously, this is the first observation of segregation of AlGaAs grown on a (111) surface. The compositional modulation terminates abruptly at the boundaries of the (111) facet, forming abrupt lateral junctions in the AlGaAs layers grown on a groove. [ABSTRACT FROM AUTHOR]

We have studied transmission electron microscopy (TEM) cross sections and plan views of YBaCuO films on SrTiO3 single-crystal substrates at various stages of post-deposition anneal. These TEM studies reveal in extraordinary detail the process of nucleation of epitaxial crystal structure characteristic of the films. In partially annealed samples sputtered from separate Cu, Y, and BaF2 sources, we see the 2-4-8 phase nucleates at the substrate interface, with the c axis parallel to the [001] substrate direction (surface normal). Upon further annealing, the 1-2-3 phase nucleates on this layer with the c axis parallel to each of the [100], [010], and [001] substrate directions. Rapid growth in the a- and b-axis directions results in an uneven ‘‘basket weave’’ surface texture. This information is crucial to the successful control and optimization of crystal orientation and surface morphology of superconducting thin films necessary for the application of this material to multilayer structures for electronic devices. [ABSTRACT FROM AUTHOR]

Formation of the equilibrium intermetallic compound NiZr in sputter deposited Ni/Zr diffusion couples is suppressed by the formation of a metastable amorphous NiZr alloy until a critical thickness of the amorphous NiZr interlayer is reached. The temperature dependence of this critical thickness is studied experimentally. A phenomenological model based on the premise of interfacial heterogeneous nucleation is proposed to understand the evolution of Ni/Zr diffusion couples. [ABSTRACT FROM AUTHOR]

Epitaxial NiSi2 of single orientation was grown on (111) Si inside miniature size oxide openings. Striking oxide opening size effects on the growth of NiSi2 epitaxy were observed. The formation temperature of NiSi2 on (111) Si was found to be as low as 550 °C inside oxide openings 1.8 μm or smaller in size. Epitaxial NiSi2 of single orientation which is identical to that of (111) Si substrate was formed inside oxide openings of or smaller than 1.8, 1, and 0.8 μm in size in samples annealed at 550–750, 800, and 850–900 °C, respectively. The results are discussed in terms of the variation in tensile stress exerted by oxide near the silicon surface and small free-energy difference between type A and type B NiSi2 epitaxy inside small size oxide openings. [ABSTRACT FROM AUTHOR]