bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability and Crystallization of Amorphous Semiconductor Multilayers
Authors: Persans P. D. , Ruppert A. F. , Abeles B.
Published: March 2011

We discuss recent measurements of relaxation, interdiffusion and crystallization in amorphous hydrogenated semiconductors and insulators prepared as periodic multilayers. The stability of multilayer structures depends upon temperature, repeat distance and the nature of the materials. Crystallization of amorphous silicon in amorphous silicon/amorphous silicon dioxide layers is inhibited when the silicon thickness is reduced below 20 nm.
The Effect of Interfacial Disorder on the X-Ray Diffraction of Superlattices
Authors: Locquet J. P. , Neerinck D. , Sevenhans W. , Bruynseraede Y. , Homma H. , Schuller Ivan K.
Published: March 2011

We have generalised our x-ray diffraction results from amorphous/crystalline multilayers, to include random interfacial disorder of a gaussian type. A general relation is obtained which can be applied to both crystalline/crystalline and crystalline/amorphous multilayers. This gaussian fluctuation or “roughness” can strongly reduce the long-range atomic order along the growth direction of the multilayer. Using classical structure factor calculations, we simulate the evolution of x-ray patterns as a function of the fluctuation amplitude, the superlattice wavelength, and the interatomic distances. Applying this model to the crystalline/crystalline case we fit the experimental Nb/Cu data, deduce a fluctuation amplitude of about 0.4 Å, and relate it to the lattice mismatch between Nb and Cu. For crystalline/amorphous systems (Pb/Ge) this amplitude can be significantly larger (2 Å).
Solid-Phase Amorphization in Layered Metal/Silicon thin Films
Authors: Nathan Menachem
Published: March 2011

A general scheme for determining which metal-Si systems undergo solidphase amorphization (SPA) upon rapid thermal annealing is presented and used to investigate Ni-Si, Ti-Si, V-Si, Co-Si and Cr-Si reactions. SPA occurs only in the first three systems. With the glaring exception of Co-Si, the results agree with the thermodynamic predictions of SPA in systems in which the free energy of a glassy phase is significantly lower than the free energy of the separate components. The amorphization may also be influenced by the diffusing species and contamination. Following SPA, the first crystalline compound is determined by nucleation kinetics.
Photon-Controlled Growth of Multilayered Structures
Authors: Lowndes Douglas H. , Geohegan D. B. , Eres D. , Mashburn D. N. , Pennycook S. J.
Published: March 2011

Pulsed ArF excimer laser (193 nm) photolysis has been used to deposit entirely amorphous and mixed amorphous/polycrystalline superlattice structures containing Si, Ge and Si3N4. High resolution in situ optical reflectivity measurements were used to monitor and/or control deposition. Transmission electron microscope cross-section views demonstrate that amorphous superlattice structures having highly reproducible layer thicknesses (from about 50 to several hundred A), and sharp interlayer boundaries, can be deposited at low substrate temperatures under laser photolytic control.
Ellipsometric, Magneto-Optic, and Magnetic Properties of Sputtered Rare Earth-Transition Metal Multilayers
Authors: Tiwald Thomas E. , Woollam John A. , Shan Z. S. , Sellmyer D. J.
Published: March 2011

Ellipsometric and magneto-optical properties of amorphous Dy (3.5 Å) and amorphous Fe (25 Å to 12.5 Å) multilayers were investigated over the spectral range from 3000 Å to 8000 Å in magnetic fields to 0.21 Tesla. In this range of layer thickness the magnetic anisotropy is vertical. Kerr rotations, θk, were weakly spectrally dependent, and as large as 0.1 degrees. The diagonal and off-diagonal elements of the optical dielectric response function were determined over the full spectral range, and were found to be dependent on iron layer thickness.
Hydrogen Bonding in Low-Gap A-Si,Ge:H,F Superlattices
Authors: Conde J. P. , Hager G. , Wagner S.
Published: March 2011

The integrated absorption of the Si-H, Ge-H and Si-H2 IR stretching modes were measured for three series of superlattices where: a) the well to barrier thickness ratio was kept constant while the period was varied; b) the barrier thickness was kept constant while the well thickness was varied and c) the well thickness was kept constant while the barrier thickness was varied. The dark (σd) and photo (σph) conductivities, the photoconductivity exponent γ and the activation energy of the dark conductivity Ea were measured perpendicularly to the plane of the layers for series a) and b). Structural changes induced by sandwiching were documented by IR absorption and correlated with the optoelectronic properties of the thin films.
Atomic Arrangements in Short period MO-GE Multilayers Determined by X-Ray Anomalous Scattering and EXAFS
Authors: Wilson Lane , Bienenstock Arthur
Published: March 2011

Studies of atomic arrangements in amorphous and crystalline, short period Mo-Ge multilayers using synchrotron radiation X-ray diffraction (transmission and reflection), supplemented by EXAFS, are described. Differential anomalous scattering and EXAFS were utilized to determine the environment of each species. Intermixing, as well as a BCC epitaxial Ge structure, are among the observed structural characteristics. A wide range of structural variations is present indicating that specification of the layer thicknesses or composition profile alone is insufficient for characterization of the multilayers.
Transition Metal Excited States in Silicon
Authors: Kleverman M. , Olajos J. , Grossmann G. , Grimmeiss H. G.
Published: March 2011

Recent absorption and photoconductivity studies of deep transition-metal impurities in silicon are discussed, with emphasis on optical transitions from the deep ground state to shallow Coulomb excited states. The P3/2 line spectra of the deep Au and Pt acceptors closely resemble those of group II acceptors in silicon, whereas the P1/2 lines show resonance effects due to interaction with the valence band continuum. Behavior under uniaxial stress is compatible with D2d or C 2y point-group symmetry for the Au and Pt acceptors. A line spectrum in g-dopes Si can be attributed to excitations to shallow donor states since the phononassisted Fano resonances involve characteristic inter-valley phonons. Both the Ag donor spectrum and the corresponding Au spectrum are dominated by excited s-state transitions. Thus, the traditional fingerprint of a donor in silicon, i.e. the effective-mass like p-state series, is missing or at best observed weakly
Interactions of Implanted Carbon with Oxygen and Nitrogen in Silicon
Authors: Stein H. J.
Published: March 2011

Carbon has been implanted into Si to overlap implanted concentrations of oxygen and nitrogen. Impurity incorporation and interactions produced by implantation at 50°C, and upon subsequent annealing to 900°C, were monitored by infrared absorption. Implantation with 0 and C introduces absorption bands for C-0 centers in addition to those for substitutional C, interstitial 0, and 0-vacancy centers. These centers are removed by annealing. The major effect of C in N-implanted layers is a suppression of absorption bands associated previously with N aggregates. There is, apparently, a strong interaction between C and displacement defects which can alter defect reordering and control the loss of C from substitutional sites.
A Study of the Ion Implanted Arsenic Tail in Silicon
Authors: Beck S. E. , Jaccodine R. J. , Filo A. J. , Irwin R.
Published: March 2011

Spreading resistance measurements, Rutherford backscattering spectroscopy, ion channeling, and deep level capacitance transient spectroscopy are used to study ion implanted arsenic in silicon and its tail region. The following comparisons of the furnace annealed samples are made: Electrically active profiles versus total concentration profiles, tail diffusion versus total implant diffusion, and substitutional fractions. These results are compared to currently accepted models for arsenic diffusion in silicon.
Transition Metals in Electrically active Sites after Incoherent Light Annealing of Boron-Doped Czochralski-Grown Silicon
Authors: Barbier D. , Remram M. , Zhu J.
Published: March 2011

Two hole trap levels H(0.45) and H(0.29) with properties close to those of metal-related defect states were found in virgin or implanted CZ silicon substrates submitted to a short duration Rapid Thermal Annealing (RTA) around 1000 °C. These hole trap levels were assigned to the presence of Fe or Cr in interstitial solution after RTA. Control experiments using chromium-diffused samples allowed to verify the quenching mechanism of chromium atoms in electrically active site during the annealing treatment, with a cooling rate-dependent concentration. After a subsequent low temperature annealing, the supersaturated interstitial solution of chromium evolves toward more stable defect configurations.
Hydrogen in Silicon
Authors: Corbett J. W. , Lindström J. L. , Pearton S. J.
Published: March 2011

We summarize the recent results in hydrogen passivation in silicon, including presenting comprehensive diffusion profiles, i.e., profiles in floating zone n-type and p-type silicon vs resistivity. Domination of hydrogen diffusion by impurity trapping is clearly indicated for part of the profile in low resistivity p-type Si. Also mentioned are the current models of hydrogen passivation of dangling bonds, shallow acceptors, shallow donors, and hyper-deep defects.
Hydrogen Neutralization of Chalcogen double donor Centers in Single-Crystal Silicon
Authors: Pensl Gerhard , Roos G. , Stolz P. , Johnson N. M. , Holm C.
Published: March 2011

Chalcogen (S,Se,Te) -doped silicon samples were hydrogen neutralized by different passivation techniques. The electrically active double-donor densities were determined by DLTS measurements. DLTS spectra reveal that both donor levels recover simultaneously. The activation energy for re-activation of neutralized isolated and pure pair sulphur double-donors is Ea(So/+) = 2,13 ± 0,15 eV and Ea(S2o/+) = 2,1 ± 0,15 eV, respectively.
Redistribution of Implanted Hydrogen in p+ GaAs(Zn) and n+ GaAs(Si) Crystais
Authors: Zavada J. M. , Wilson R. G. , Nova S. W. , Von Neida A. R. , Pearton S. J.
Published: March 2011

In order to gain a better understanding of hydrogen in GaAs crystals, a Zn doped p+ GaAs wafer has been implanted with 300 keV protons (H) to a fluence of 1E16/ain and portions of the wafer have been furnace annealed at temperatures up to 600°C. The implanted H and the dopant Zn atomr were then depth profiled using secondary ion mass spectrometry (SIMS). The measurements show that the H redistributes itself in the p+ GaAs(Zn) in much the same manner as it does in n+ GaAs(Si). Movement of the implanted H begins with annealing at 200°C and proceeds rapidly with higher temperatures. However, based on the SIMS profiles, the diffusion coefficient for the H diffusing into the undamaged p+ GaAs(Zn) crystal appears to be considerably higher than that of H into n+ GaAs(Si). Electronic properties of the inplanted and annealed p+ GaAs samples have also been examined and correlated with the SINE profiles.
EL2 and the Electronic Structure of the AsGa—Asi Pair in GaAs: the Role of Jahn-Teller Relaxation
Authors: Baraff G. A. , Lannoo M. , Schluter M.
Published: March 2011

The levels and excitation energies of the weakly interacting AsGa—Asi defect pair have been calculated using the model energy functional introduced by Baraff and Schluter, modified so as to allow Jahn Teller relaxation to distort the Asi away from the symmetry site. The physics underlying this calculation and the results emerging from it are described in this paper. We find that many previously unrelated experimental observations about EL2 are well accounted for by this model. However, there are still some controversial aspects of the fit of the model to the observed properties of EL2 which we cite as requiring further study.
Investigation of Midgap Defects in GaAs Induced By Heat-Treatment (EL2), Electron-Irradiation, and Plastic Deformation
Authors: Haga Toru , Suezawa Masashi , Sumino Koji
Published: March 2011

Thermal behavior of midgap defects generated in GaAs by different procedures has been followed by means of optical absorption measurements at low temperature. EL2 centers existing in as-grown crystals or generated by thermal annealing at temperatures lower than about 1000°C, which are characterized by a perfectly quenchable absorption at a wavelength of 1.0 μm, are found to diminish at temperature higher than 1000°C. The generation kinetics of EL2 centers has been traced during isothermal annealing of a crystal in which grown-in EL2 centers have previously been eliminated by annealing at 1200°C. The result of an analysis with the use of simplified chemical rate equations favors the model that an EL2 center is composed of an As antisite and two Ga vacancies. Both quenchable and unquenchable absorptions are associated with the midgap defects induced by plastic deformation or electron -irradiation. Isochronal annealing reveals that such defects are not identical with EL2 centers that are found in an as-grown crystal even if they accompany the quenchable absorption.
Annealing of Grown-in Defects in Gaas
Authors: Dannefaer S. , Mascher P. , Kerr D.
Published: March 2011

Detailed analyses of positron lifetimes in GaAs have shown that an omnipresent type of defect acts as a shallow positron trap. This trap modifies the experimentally determined bulk lifetime to higher values and also influences the trapping rate into deep traps such as vacancies. It is suggested that the shallow trap likely is associated with boron. An annealing stage around 450°C is found.
Quantitative Raman Scattering from Acceptors in GaAs
Authors: Harrisz T. D. , Lamont M. G. , Seibles L.
Published: March 2011

Recent reports have demonstrated the possibility of probing acceptor concentrations in bulk semi-insulating GaAs by electronic Raman scattering using 1.06 μm radiation.1 The inefficiency of detectors in this spectral region severely limits sensitivity, precluding extension to epitaxial layers. We will discuss an approach using both 1.06 μm radiation to photo-neutralize acceptors, and a tunable dye laser to excite Raman scattering. Using a cooled CCD detector, an improvement in detection limit of 104 is realized. Comparison of Raman signals with infrared local mode measurements for samples with carbon concentrations from 1×1014 to 4×1015 cm-3 will be reported. The effect of 1.06 μm power density, dye laser wavelength, dye laser power, and sample fluorescence are included.
Effects of Surface and Bulk Defects in InP
Authors: Warren C. , Reinhardt K. , Singh A. , Lee Y. S. , Anderson W. A.
Published: March 2011

Undoped, n-type InP has been studied utilizing Au-oxide- InP metal-insulator-semiconductor (MIS) structures. Processing variations have included oxide growth techniques, and annealing of grown oxides. Annealing of the devices in N2 or N2 :H2 after oxide formation has reduced reverse saturation current density by up to a factor of 10 and increased barrier height from 0.45 to 0.65 eV. Annealing of the oxide increases refractive index due possibly to a densification or changed chemical structure. ESCA data reveals thin native oxides to be InP04 whereas thermally grown ones also contain P2 05 and In2 03. DLTS data reveals a dominant defect 597 meV below the conduction band.
X-Ray and Raman Studies of MeV Ion Implanted GaInAs/GaAs
Authors: Wie C. R. , Xie K. , Burns G. , Dacol F. H. , Pettit D. , Woodall J. M.
Published: March 2011

The elastic strain in 2 MeV He ion-bombarded pseudomorphic or lattice-relaxd GaInAs is found to vary by 13% over tlhe beam dose range, 5x1012 - 5×1015 cm-2, with a minimum at 5×1013 cm-2. The data suggest a beam-induced annealing effect at lower doses and the build-up of radiation damage at higher doses, which are also indicated by the phonon line shift data. The phonon shift and the elastic strain in lattice-relaxed GaInAs, bombarded with 15 MeV Cl ions, are approximately the same as in an ion-bombarded bulk GaAs. The lattice mismatch in parallel constant decreases for a sample with a lower misfit and increases for a sample with higher misfit with increasing beam dose. The phonon shift in a pseudomorphic GaInAs bombarded with 15 MeV Cl ions is smaller than in the relaxed samples by a factor of two.
Study of DX Centers in GaAs1−xPx :Te
Authors: Kaniewski J. , Kaniewska M.
Published: March 2011

A capacitance study of GaAs1−xPx : Te. x > 0.2, obtained by vapor phase epitaxy, has revealed two DX centers, characterized by thermal activation energies ΔEA = 0.18 eV and ΔEB = 0.39 eV. and photoionization energies 0.6 eV and 1.1 eV, respectively. Both traps show strong non-exponential behavior in thermal emission and capture processes. It is shown that correct parameter values for DX centers can be determined from measurements of the transition region width. This method, which allows us to circumvent alloy effects, has been used to study DX center parameters as a function of the phosphorus content. It is demonstrated that the level B is linked to the X minimum, and that the barrier height for electron capture at this trap, with respect to the indirect minimum, is independent of alloy composition.
Interface Defects in GaAs and GaAs-AlxGa1−xAs Grown on Ge
Authors: Cho N.-H. , McKernan S. , Carter C. B. , Wagner D. K.
Published: March 2011

Σ=3 lateral twin boundaries and a Σ=19 boundary have been investigated by highresolution electron microscopy. The lateral twin boundary was produced by growth on single crystal (110) Ge substrate and was observed to facet parallel to the common (112) plane and the (111)/{115} planes. The Σ=19 boundary was grown on a bicrystal substrate and faceted parallel to the common {331} plane. In this case, convergent-beam electron diffraction was used to determine the polarity of the adjoining grains. A possible model for the atomic configuration is proposed for each of the observed boundaries. GaAs-AlxGa1−xAs heterolayers were grown on a (001) Ge substrates to examine the interaction of antiphase boundaries with heterojunctions.
The Nucleation and Propagation of Misfit Dislocations aear the Critical Thickness in Ge-Si Strained Epilayers
Authors: Kvam E. P. , Eaglesham D. J. , Maher D. M. , Humphreys C. J. , Bean J. C. , Green G. S. , Tanner B. K.
Published: March 2011

The nucleation and propagation of misfit dislocations in Ge-Si strained epilayers on (100) Si have been investigated using transmission electron microscopy and X-ray diffraction topography at low lattice parameter mismatch (˜ 0.8%). Misfit dislocations nucleate as half loops which are predominantly unfaulted (> 90%) at the advancing growth interface. Under the driving force of the epilayer strain, unfaulted half loops glide and expand on inclined { 111 }planes toward the heterointerface (i.e. substrate/epilayer interface). These unfaulted half loops consist of a 60°-dislocation segment which lies along < 011> in a plane parallel to the heterointerface (i.e. (100)) and this segment is connected to the growth interface by two screw dislocation segments which both lie on the same inclined {111} glide plane. As 60° dislocations reach the heterointerface on each of the four inclined {111} variants, they form an orthogonal array of misfit dislocations which lie along [011] and [011]. At higher lattice parameter mismatch (˜ 2%), there appear to be some important changes in the dislocation behavior and these changes result in orthogonal arrays of heterointerface dislocations which are predominantly edge type (i.e. 90°dislocations).
The Formation and Cathodoluminescence Activity of Buffer Layer Edge Dislocations in In0.12Ga0.88As/GaAs Heterostructures
Authors: Fitzgerald E. A. , Kirchner P. D. , Petit G. D. , Woodall J. M. , Ast D. G.
Published: March 2011

The defect structure of lattice-mismatched one micron In0.12 Ga0.88As epilayers on (001) GaAs was studied with scanning cathodoluminescence (CL) and transmission electron microscopy (TEM). CL examination of the GaAs buffer layer revealed the formation of a segmented network of defects below the interface. Cross-sectional TEM analysis shows that these defects are dislocation half-loops extending from the interface, and the vast majority of these loops lie on the GaAs side of the interface. The dislocations in the GaAs buffer layer were determined to be edge dislocations. Thus, CL images show that edge dislocations in this system are centers for non-radiative recombination. We propose that two 60° dislocations with opposite screw and interface tilt components can glide into the buffer layer to form edge dislocations. Potential energy plots for 60° dislocations near the interface and interacting with interface dislocations supports this model.
Defect and Dopant Control During Silicon Epitaxy Using B and Ge
Authors: Kola R. R. , Posthill J. B. , Salih A. S. M. , Rozgonyi G. A. , Bean K. E. , Lindberg K.
Published: March 2011

The control of dopants, impurities and defects for VLSI of silicon integrated circuits requires a complex set of crystal and processing conditions to be satisfied simultaneously. In order to achieve the maximum yield and highest level of electrical performance for a given device design, we have manipulated the lattice constant and boron doping levels in CVD epitaxial silicon layers co-doped with germanium. By adjusting the ratios of germane and diborane in a dichlorosilane/hydrogen CVD reactor we have obtained buried high conducting layers which are strain-free and lattice matched to the Si substrate. Degenerate boron and boron and germanium codoped epitaxial layers on (100) p-type silicon substrates were investigated. Solubility, electrical activity limits and defect structure of boron in strained and strain-free silicon epitaxial layers were investigated by spreading resistance, SIMS profiling, X-ray and transmission electron microscopy techniques. Bright field and weak-beam dark field imaging of cross-sectional and plan-view specimens were used to confirm the presence or absence of precipitates and threading dislocations. A model has been proposed to describe the mechanism of threading dislocation formation in heavily boron-doped layers. We are now in a position to strategically locate co-doped Si(B, Ge) p++ layers as recombination zones or buried field plates to suit the needs of MOS latchup control, high speed and radiation hard devices, as well as the needs of defect free p++ etch stops for thin membranes and three-dimensional silicon structures.
Identification of An Interstitial Carbon – Interstitial oxygen Complex in Silicon
Authors: Trombetta J. M. , Watkins G. D.
Published: March 2011

The Si-G15 EPR spectrum and the 0.79eV “C-line” luminescence spectra in silicon are shown to arise from an interstitial carbon - interstitial oxygen complex. The g-tensor and 13C hyperfine interaction tensor indicate the structure in the vicinity of the carbon atom while stress alignment studies reveal the configuration near the oxygen atom. The pairing of the two impurities leads to a lattice relaxation which serves to stabilize the complex against dissociation.
The Effect of Growth Ambients on the Local Atomic Structure of Thermally Grown Silicon Dioxide Thin Films
Authors: Fitch J. T. , Lucovsky G.
Published: March 2011

This paper represents a study of the local atomic structure of SiO2 films formed by thermal oxidation in dry oxygen, pyrolytic steam, and a variety of different sequences of these ambients. All oxidations were carried out at 850 °C. Local atomic structure was studied via infrared spectroscopy (IR). The growth ambient dependence of the frequency v, and half-width Δv, of the bond stretching feature, and the refractive index, n, was investigated. Consistent with previous work [1,2] it was found that.when the majority of the sample thickness was grown in steam the oxides were generally less dense than dry oxides. Also, the last ambient in a sequential oxidation process was found to have the most influence on the oxide properties. The observed variations in v, Δv, and n could be readily explained in terms of systematic changes in the bond angle at the oxygen bonding site between corner connected tetrahedra.
The Effects of Overlying Layers On The Ftir Spectra of Thin Thermal Oxides On Silicon
Authors: Cox J. Neal , Rastogi R.
Published: March 2011

The most intense feature in the infrared spectrum of SiO2 is the “νas band” near 1070 cm-1. Assigned to the asymmetric stretching mode, this peak exhibits a shoulder on the high frequency side of the band. In this study, Fourier transform infrared (FTIR) spectrophotometry is used to examine the effects of overlying, unpatterned layers of undoped polysilicon (poly) and of tungsten silicide (WSi) upon 0.08 μm of themal oxide grown on silicon. For the poly studies, the oxide is grown on both sides of double-side-polished wafers. 0.11 μm of poly is then deposited on each side of half of the set; 0.25 μm, on the remainder. For the WSi studies, 0.21 μm of undoped poly is deposited onto oxide grown on single-side-polished, low-oxygen wafers. WSi is then deposited on one side.

For the poly set, the peak position (PP) of the “νas band” shifts from 1074 to 1071 to 1066 cm-1 when comparing the uncoated oxide, 0.11 μm poly/oxide, and 0.21 μm poly/oxide samples, respectively. As a result of the observed shifts, the high frequency shoulder becomes resolved as a broad, weak band centered near 1168 cm-1. Thus, the “νas band” appears to be a doublet, consisting of a weak high-frequency component that is insensitive to, and an intense low-frequency component that is sensitive to. overlying films. For the WSi set, the PP of the “νas band” shifts from 1068 to 1076 to 1083 cm-1 for the poly/oxide, WSi/poly/oxide, and annealed-WSi/poly/oxide samples, respectively. Possible causes for the doublet character of the “νas band” and mechanisms for the film-film interactions, such as hydrostatic pressure, are discussed.
Thermal Oxidation of Amorphous Silicon-Boron Alloy
Authors: Lau W. M. , Yang R. , Tong B. Y. , Wong S. K.
Published: March 2011

The thermal oxidation of amorphous silicon-boron alloy (prepared by low pressure chemical vapor deposition) with boron contents ranged from 0–40% at a temperature range of 25- 700 °C has been carried out. Crystalline silicon and polycrystalline boron have also been studied for comparison purposes. The resultant thin oxide overlayers were characterized by X-ray photoelectron spectroscopy. It was found that both the oxidation of Si and of B are enhanced by mixing of the two elements. The oxidation of boron is significantly slower than silicon. During oxidation of silicon-boron alloy, preferential oxidation of silicon occurs at the oxide/bulk interface and the silicon oxide overlayer advances into the bulk faster than the boron oxide.
Total Energy Calculation in α-SiO2 and β-Si3N4
Authors: Xu Yongnian , Ching W. Y.
Published: March 2011

The self-consistent electronic structures and total energies for the crystalline α-SiO2 and β-Si3N4 are studied by means of the first-principles orthogonalized linear combination of atomic orbitals method. The calculated band structures are compared with the earlier non-self consistent results. The total energies in the local density approximation are evaluated as a function of lattice parameters. Reasonable values of equilibrium lattice constants and cohesive energies are obtained but the bulk modulus for α-SiO2 is overestimated.
The Role of Electron and Hole Traps in the Degradation and Breakdown of thermally grown SiO2 Layers
Authors: Heyns M. M. , De Keersmaecker R. F.
Published: March 2011

The degradation and charge build-up of thermally grown silicon diozide layers (with thicknesses varying between 20 and 40 nm) during various stress experiments was investigated. The slow trapping instability generated during charge injection was demonstrated to originate from initially present hole traps. The generation of electron traps in the oxide layer close to the non-injecting interface during high-field stressing was established both for Al-gate and poly-Si gate structures. No evidence could be found for the generation of hole traps during high-field stressing. No bulk oxide charges were detected after a high-field stress, but only unstable near-interface charge trapping was evidenced.
Study of Spatial and Energetical Behavior of Slow Si-SiO2 Interface States By Tunnel-Dlts Under Fowler-Nordheim Stress
Authors: Vuillaume D. , Lakhdari H. , Bourgoin J. C. , Bouchakour R. , Jourdain M.
Published: March 2011

We study the behavior of the spatial and energetical distribution of the slow Si-SiO2 interface states ( i.e. the defects located in the strained SiO2 layer near the interface) when the Metal-oxide-semiconductor (MOS) structure is submitted to a high field electrons injection from the Si substrate. We have analysed the creation kinetics of these slow states in order to compare with the behavior of the fast interface states which are better studied. We demonstrate that the fast interface states are more rapidly generated than the slow states and that the creation kinetics of fast states reach a saturation at lower injected charge. We also find that the fast interface states generation is independent from the energetical location of the states in the Si bandgap. For the generation of slow states, we observe a weak dependence on the energetical location of the defects in the SiO2 bandgap, and a strong dependence on the depth location from the Si-SiO2 interface.
The SiO2/Si Interface Probed With Positrons
Authors: Nielsen Bent , Lynn K. G. , Leung T. C. , Welch D. O. , Rubloff G.
Published: March 2011

The effects of the heat treatment of Si covered with a thermally-grown ˜50 nm overlayer of SiO2 were probed by means of measurements of positron annihilation characteristics obtained with a variable-energy positron beam. From measurements at elevated temperature (˜500°C) it was observed that positrons implanted overlapping the SiO2/Si interface decay from a state with properties distinctively different from the state in Si and in SiO2. The nature of the annihilation characteristics indicates the presence of open volume defects.
Tem Studies of Silicon-Silicon Oxide Interface Roughness
Authors: Park Kyung-Ho , Sasaki T. , Matsuoka S. , Yoshida M. , Nakano M.
Published: March 2011

Interfaces between two kind of substrate, a bulk silicon wafer and a laser-recrystallized Silicon-On-Insulator (SOI), and its thermally grown oxide have been studied. High resolution transmission electron microscopy (HRTEM) of cross sectional specimen shows that the roughness at the interface is atomically flat and nearly uniform for the bulk single crystal silicon and silicon oxide, while being nonuniform and rough as much as 20 nm height for the recrystallized silicon and silicon oxide interface. Consideration of interface between recrystallized silicon and silicon oxide, and the oxide surface above, the observed roughness at the interface is due to original grain boundaries of polycrystalline silicon which was used as the material for the laser recrystallized silicon formation. It is also discussed HRTEM of the interface between polycrystalline silicon and silicon oxide.
The Effects of Interface Roughness on Ellipsometric Measurements of Thin Oxides
Authors: Dunham Scott T. , Agrawal Bhawana
Published: March 2011

Measurements of film thickness using ellipsometry assume all interfaces to be ideally planar. This approximation works well for films much thicker than the roughness of the interfaces. For very thin films. the interface roughness can cause significant errors in thickness measurements. In this paper, we calculate the effect of interface roughness on oxide thickness measurements and use those calculations to account for some of the observed differences between film thickness measurements of thin oxides (< 200 A) as measured by ellipsometry and transmission electron microscopy.
Arsenic in SiO2 - Phase Segregation, Drift, and Diffusion Phenomena
Authors: Celler G. K. , Trimble L. E. , Sheng T. T. , West K. W. , Kosinski S. G. , Pfeiffer L.
Published: March 2011

We have recently determined that anomalously low diffusion of high dose As implants in SiO2 is caused by phase separation. In an inert ambient, As segregates into spherical As-rich droplets of 50 to 500Å in diameter, which are essentially immobile when heated isothermally, even at 1405 °C. In a temperature gradient the droplets move toward the heat source.

The dependence of the segregation rate, drift, and diffusion on-the ambient and arsenic concentration is discussed here, and a new interpretation of the published arsenic diffusion data is provided.
Structure of Perturbed Twin Boundaries in Silicon
Authors: Garg Anita , Clark W. A. T. , Hirth J. P.
Published: March 2011

Silicon bicrystals containing Σ =3(60°/[111]1,2) twin boundaries have been fabricated by sintering together single crystal (IMi) :vafers (which deviated from the exact (111) by upto ±4′). Transmission electron microscopic investigation revealed the boundaries to be near-twin boundaries having a superposed tilt component. The grain boundary dislocation structure of these boundaries has been studied in a transmission electron microscope (TEM) and interpreted as arising from the interaction of a large tilt component with a smaller twist component, to give the observed low energy configuration.
Redistribution of Boron Implanted into TaSi2/Poly-Si Gates
Authors: Schwalke U. , Mazure C. , Neppl F.
Published: March 2011

The redistribution of boron implanted into TaSi2/poly-Si gates after high temperature anneals has been studied as a function of the implantation dose and energy as well as implantation scheme, i.e. boron implantation either into the silicide or into the poly-Si prior to TaSi2 deposition. SIMS measurements indicate that boron can easily diffuse from TaSi2 into poly-Si and vice versa at 900 °C. Independent of the implantation scheme, the boron concentration within poly-Si was found to saturate at approximately 1 × 1019 at/cm3 for boron doses greater than 5 × 1014 at/cm2. The excess of boron always accumulates within the silicide. The observed boron redistribution behavior within polycrystalline TaSi2/poly-Si layers is discussed in terms of combined lattice and grain boundary diffusion as well as grain boundary segregation.
Control of Grain Boundary Location By Selective Nucleation Over Amorphous Substrates
Authors: Yonehara T. , Nishigaki Y. , Mizutani H. , Kondoh S. , Yamagata K. , Ichikawa T.
Published: March 2011

A selective nucleation based crystal-growth-technique over amorphous substrates is originated. The method manipulates nucleation sites and periods and hence, controls the grain boundary location by modifing the substrate surface. In Si, small Si3 N4 nucleation sites are formed, 1–2 pm in diameter, 100 μm in period, over Sio2. One Si nucleus is formed exclusively in the small area of Si3 N4 by CVD. The highly faceted and periodically located nuclei grow over SiO2 up to 100 μm in diameter before impingement. A MOS-FET fabricated inside the island operates comparably to the bulk Si control
Rapid Thermal Annealed Undoped LPCVD Si/Single Crystal Si Substrate Structures with an Implant of Si Near Interfaces
Authors: Ogawa S. , Okuda S. , Kouzaki T. , Yoshida T. , Yoshioka Y.
Published: March 2011

The breaking up of a native oxide layer of a LPCVD amorphous Si/single crystal n+Si substrate interface by a rapid-thermal annealing was studied from the point of view of oxygen movement and morphological change. Oxygen atoms began to move at 1025 °C. After annealing at 1115 °C for 30sec, the quantity of oxygen atoms near the interface decreased dramatically and a silicon implant near the interface could enhance the decrease. More detailed observation was carried out by cross-section high-resolution transmission electron microscopy. After annealing at 940 °C for 30sec, the native oxide layer was continuous. On the qther hand, with a silicon implant near the interface, it changed into small oxide balls and an epitaxial growth occurred in the LPCVD layer with twins caused by these oxide balls. After annealing at 1115°C for 30sec, even without the silicon implant, a complete epitaxial growth occurred but it seemed that some SiOx particles dissolved into a single crystal Si layer near the interface.
Fabrication and Properties of Single, Double, and Triple Gate Polycrystalline-Silicon Thin Film Transistors
Authors: Proano R. E. , Soave R. J.
Published: March 2011

Polysilicon based Thin Film Transistors (poly-Si TFT's) with superior electrical performance can be achieved by maximizing the number of intrinsic point defect injected into the material during high temperature processing. These point defects will migrate to grain boundaries (GB's), enhance their mobility by facilitating climb, and allow the boundary to achieve a low energy configuration with a minimum of electrically active broken bonds. Proper processing of poly-Si TFT's therefore requires a redesign of the conventional processing cycle where, working with single crystal silicon, one minimizes the concentration of intrinsic point defects which otherwise precipitate out as Oxidation induced Stacking Faults (OSF's).

TFT's were fabricated under nine different processing cycles to study the relationship between device performance and fabrication conditions. Device performance increased with higher gate oxidation temperature, elimination of HCI flow during gate oxidation, post hydrogenation, and multiple gates. Using conventional MOS processing steps only, n-type (p-type) devices were fabricated, which were capable of handling 40 volts VDS with a leakage current of 2×10−11 (6×10−12) A/μm and effective electron (hole) channel mobilities of 130 (50) cm2/Vs.
Hydrogen Passivation of Grain Boundaries in Polycrystalline Silicon Deposited by Molecular Beams
Authors: Jousse D. , Delage S. L. , Iyer S. S. , Crowder M.
Published: March 2011

Grain boundary properties of polysilicon deposited by molecular beams have been investigated by electron spin resonance and conductivity measurements. The variations of the conductivity activation energy with doping can be explained by a density of states model consisting mainly of two exponential bandtails, implying that dangling bonds play a minor role. A hydrogen plasma treatment at 500 °C reduces the spin density by a factor of three but also passivates weak Si-Si bonds thus leading to steeper bandtails. The possibility of hydrogen-related intra-grain gap states is also discussed.
Grain Boundary Characterization in Polysilicon by Light Beam Induced Current Topography and Image Processing
Authors: Masri K. , Boyeaux J. P. , Kumar S. N. , Mayet L. , Laugier A.
Published: March 2011

A high performance light-beam-induced-current (LBIC) analyser has been used to determine the recombination velocity at the grain boundary (S) and the minority-carrier diffusion length (L). For this purpose a Schottky diode (Cr/Si) was fabricated using a p-type silicon bicrystal (1Ω cm, Σ13 grain boundary). The contacts were obtained by a “cold” technology. The diffusion length, determined by the method proposed by Ioannou, was subsequently fitted into the model proposed by Marek to evaluate the recombination velocity by the curve-fitting of the experimental and theoretical photocurrent profiles. A value of S = 2.104 cm/s was thus obtained. The influence of the thin oxide layer at the Cr/Si interface is also discussed.
Photoluminescence Characterization of Thin Silicon-On-Insulator Films Produced by Oxygen Implantation
Authors: Weber J. , Baumgart H. , Petruzzello J. , Celler G.K.
Published: March 2011

Single crystal silicon films on top of a buried SiO2 layer were produced by implanting 1.7x10180+ions/cm2 at 150keV into (100) Czochralski silicon, followed by annealing at higher temperatures. The defect properties of the layers are studied after each processing step by low temperature photoluminescence measurements and transmission electron micrography (TEM). Dislocation-related photoluminescence signals correlate with their TEM observations in the same samples. The photoluminescence method proves to be a very versatile and convenient method for characterizing the quality of silicon-on-insulat or structures.
HVEM and Electrical Characterisation of SIMOX Structures
Authors: De Veirman A. , Yallup K. , Van Landuyt J. , Maes H.E. , De Meyer K. , Dupas L.
Published: March 2011

This paper reports on a study of the Silicon-On-Insulator (SOI) structures obtained by oxygen ion implantation (SIMOX) and subsequent thermal annealing. With Transmission Electron Microscopy (TEM) a novel defect structure is revealed in the case of low temperature annealings. Electrical measurements of test devices are performed and a correlation with impurity decoration of defects is investigated.
Monitoring SIMOX Layer Properties and Implantation Temperature by Optical Measurements
Authors: Harbeke Guenther , Steigmeier E.F. , Hemment Peter L.F. , Reeson Karen J. , Jastrzebski Lubek
Published: March 2011

Infrared absorption and Raman scattering measurements of SIMOX structures implanted at various temperatures yield information on the structure and the strain in both the top silicon and the buried oxide layers. Both techniques can also be used to monitor the implant temperature after the implantation.
Contamination Control in SIMOX Implanters
Authors: Cordts Bernhard , Guerra Michael
Published: March 2011

The Semiconductor Equipment Division of Eaton has, for the past year, supplied Simox wafers to various companies and laboratories throughout the world. A review will be presented of the operation in a production mode of the NV-200 Oxygen Implanter. Improvements in the production version will be related to both particulate counts and elemental contamination on the wafers. The addition of a polysilicon liner in the beamline has greatly reduced the heavy metal and carbon contamination levels in the machine. Historical Sims and Auger data will be presented to show these effects. The most recent production machine is operating on the manufacturing floor. Sims data from wafers implanted in October 1987 will be presented.
Liquid-Solid Interface Morphologies and Defect Structures in Zone-Melting-Recrystallized Silicon-On-Insulator Films
Authors: Im J. S. , Chen C. K. , Thompson C. V. , Geis M. W. , Tomita H.
Published: March 2011

In-situ optical microscopy has been used to observe liquid-solid interface morphologies during zone-melting recrystallization of silicon-on-insulator films. These morphologies have been correlated with the defect morphologies of the recrystallized films. Stable cellular solidification fronts, which are obtained at low zone velocities if the radiation intensity gradient in the interfacial region is small, yield subboundary free films. We suggest that under these experimental conditions the interface morphology is primarily the result of radiative heating rather than constitutional supercooling.
Improvements in Zone Melt Recrystallized Soi Layers by the Use of Selective Epitaxial Growth in the Seed Windows.
Authors: Williams D.A. , McMahon R.A. , Ahmed H. , Karapiperis L. , Garry G. , Dieumegard D. , Barfoot K.M. , Godfrey D.J.
Published: March 2011

The effect of selective epitaxial growth (SEG) of silicon in the seed windows of silicon on insulator structures prior to recrystallization has been investigated. Subsequent zone melt recrystallization of these structures was performed in a dual electron beam system, and it was found that the full planarisation of the deposited silicon layer results in uniform film thickness after recrystallization. Cross sectional scanning and transmission electron microscopy, optical microscopy after defect etching, and bevelling are used to analyse the material. The SEG method improves the uniformity of the film for device island etching, and so is useful for all silicon on insulator applications, although the one of most interest for these investigations is the production of three dimensional circuitry. This is achieved by stacking layers of devices, and so planarity is particularly important.
Cold Cathode Electron Beam Recrystallization of Soi Films
Authors: Thompson L. R. , Knapp J. A. , Moore C. A. , Collins G. J.
Published: March 2011

A cold cathode line source electron beam system for forming SOI films by zone melt recrystallization is described. Possible advantages gained from using a cold cathode electron beam include the controllability of the beam profile and power level, as well as straight-forward scaling to recrystallization of 6 or 8 inch wafers. A computer-based melt width control procedure incorporating feedback to the line intensity from optical observation of the molten zone is also described. This technique allows direct control and adjustment of the melt zone over widths typically from 1 to 3 mm.
Selective Epitaxial Growth Followed by in Situ Deposition of a- or Poly-Si for Seeded Soi.
Authors: Karapiperis L. , Garry G. , Dieumegard D.
Published: March 2011

Selective Epitaxial Growth (SEG) techniques find a growing number of applications in the field of Si IC's, such as, lateral isolation, vertical interconnects, seeded recrystallisation etc. In the present work, the use of Si SEG by CVD combined with in-situ deposition of a- or poly-Si for the improvement of SOI obtained by Zone Melting Recrystallisation (ZMR) or by Lateral Solid Phase Epitaxy (SPE) is described. The principle application for which the present work is intended is Three Dimentional (3D) Integration. One of the main constraints imposed on process is thermal compatibility with previously executed process steps. Hence the need to reduce the thermal budget for the Selective Epitaxial Growth as much as possible.
Buried Silicide Synthesis and Strain in Cobalt-Implanted Silicon
Authors: Barbour J.C. , Picraux S.T. , Doyle B.L.
Published: March 2011

Silicon (001) substrates were implanted with 350 keV co at room temperature and 450°C with fluence of from 1x1017 Co/cm2 to 6x10 Co/cm2. All samples were annealed at 1000°C in order to form the CoSi2 phase. Concentration profiles were determined with Rutherford backscattering spectrometry (RBS), and the associated strain profiles were analyzed with double-crystal X-ray rocking curve measurements. Ion channeling was also used to characterize.the suicide formation and crystal quality. An implantation of 6x1017 Co/cm2 at 450°C forms a single-crystal CoSi2 layer while lower fluences do not. A continuous, buried CoSi2 single-crystal layer is formed for the 3x1017 Co/cm2 sample implanted at 450°C and annealed at 1000°C. The continous CoSi2 layer is thicker than the critical layer thickness for a fully coherent film, and therefore the layer partially relaxes. A relaxation of 50% of the fully coherent value is observed for this buried suicide system.
Nisi2-Formation By 6 Mev High Dose Nickel Implantation Into Silicon
Authors: Lindner J.K.N. , Kaat E.H.Te
Published: March 2011

Deep buried metallic layers are formed by 6 MeV high dose Ni implantation into Si at 450 K. The layers have been characterized by optical reflectivity and spreading resistance depth profiling as well as TEM and XTEM. They consist of epitaxially grown NiSi2 crystallites of both type-A and type-B orientations and thin NiSi2-platelets on {111} lattice planes. Investigations indicate the suppression of amorphization by Ni as well as damage gettering of Ni atoms.
Trade-Offs For RAD-Hard Soi Structures
Authors: Davis G. E.
Published: March 2011

Total dose, dose rate, transient, single event upset and neutron radiation effects for dielectrically isolated MOS devices on S01(silicon-on-insulator) substrates are discussed. For large-scale, high-speed circuits, material, layout and process characteristics optimized for high circuit yield and reliability may conflict with improvements required to extend radiation thresholds. Some radiation hardening techniques applicable to silicon-on-insulator high speed thin film MOS devices are presented.