bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Resolution Spectroscopy of Point Defects in Silicon
Authors: Grimmeiss H.G. , Kleverman M. , Olajos J.
Published: March 2011

The paper briefly outlines recent developments in high resolution spectroscopy of point defects in silicon. One of the methods, namely photothermal ionization spectroscopy (PTIS) is discussed in detail. Impurities induced by selenium and several transition metals are used as examples m order to illustrate the powerful scope of both transmission and PTIS measurements. These measurements are capable of providing unique information on the electronic properties of point defects, even when the defects exhibit complex excitation spectra.
Electronic Structure of Two Sulphur-Related Bound Excitions in Silicon Studied by Optical Detection of Magnetic Resonance
Authors: Chen W.M. , Henry A. , Janzén E. , Monemar B. , Thewalt M.L.W.
Published: March 2011

We report an investigation on the electronic structure of two bound exciton (BE) systems from a complex defect in S-doped Si, by optical detection of magnetic resonance (ODMR). A spin-triplet (S=1) is identified to be the lowest electronic state of the BE's, which gives rise to deep photoluminescence (PL) emissions when recombining. A weak anisotropy of the magnetic interaction of the BE’s (not possible to resolve in Zeeman data) is revealed, which leads directly to the determination of the symmetry for the excited state of the defect. A S-related complex model is suggested as the identity of the defect. A critical test of two possible metastable configurations of the constituents of a single defect is undertaken.
An Electron Paramagnetic Resonance Investigation of Iron-Indium Pairs in Silicon
Authors: Emanuelsson P. , Gehlhoff W. , Omling P. , Grimmeiss H. G.
Published: March 2011

Three different Electron Paramagnetic Resonance (EPR) signals, one trigonal and two orthorhombic, which originates from iron-indium pairs in silicon are investigated. It is shown that the two orthorhombic spectra can be explained as transitions within the two doublets of a S=3/2 system with a large zero-field splitting. The temperature dependence of-the intensities reveals that the newly discovered spectrum corresponds to the lower doublet and that the zero-field splitting is 9.8 ± 2.0 cm-1.
Effects of Confinement on the Optical Properties of a Shallow Acceptor and its Bound Exciton in Narrow GaAs/AIGaAs Quantum Wells
Authors: Holtzv P.O. , Sundaram M. , Rune G.C. , Monemar B. , Merz J.L. , Gossard A.C.
Published: March 2011

Transitions from the 1s ground state to 2s excited states of the Be-acceptor confined in GaAs/AIGaAs quantum wells (QWs) have been observed via two independent spectroscopic techniques: Two-hole transitions of the bound exciton (BE) measured in selective photoluminescence and Resonant Raman Scattering. The dependence of the 1s - 2s transition energy on the QW thickness (50 Å < Lz < 140 Å) has been studied for the case of acceptors in the center of the QW. The experimentally determined 1s - 2s transition energies have then been added to recently calculated binding energies for the 2s excited state in order to obtain the total binding energies for the acceptor at different confinements. The derived binding energies are finally compared with theoretical predictions. The same kind of measurements have been performed for a QW with a given thickness, but in which the position of the acceptor has been varied from the center to the edge of the QW.

The dependencies of the binding energies of the exciton bound to the investigated acceptor on the QW thickness and the position of the acceptor in the QW have also been studied. For the case of varying QW thickness, an almost linear relationship between the binding energies of the BE and the acceptor binding the exciton is found. This fact implies that a correspondence to Haynes' rule in bulk material could be applied to these QW systems, but in this case for the same acceptor at different binding energies due to the effect of varying confinement.
Intrinsic Luminescence of GaAs/AIGaAs Heterojunctions in a Transverse Electric Field
Authors: Zhao Q.X. , Bergman J.P. , Holtz P.O. , Monemar B. , Hallin C. , Sundaram M. , Merz J.L. , Gossard A.C.
Published: March 2011

Radiative recombination of the two dimensional electron gas (2DEG) in a modulation doped GaAs/AIGaAs heterojunction (the so called H-band luminescence) has been studied under transverse electric field perturbation (i.e. perpendicular to the layers) in special structures prepared by molecular beam epitaxy. Both positive and negative gate voltages have been applied to the GaAs/AIGaAs interface, and shifts of the H-band energy position depending on the gate voltage are induced by the corresponding changes in the notch potential and the potential across the GaAs layer. It is demonstrated that a transverse electric field allows a simple way to modify the width and shape of the potential, so that detailed spectroscopy can be done on the recombination of carriers localized in a interface potential.
Qualitative Physics of Defects in Quantum Wells: Interface Roughness
Authors: Hjalmarson Harold P.
Published: March 2011

The electronic properties of interface roughness in a quantum well are described. Interface roughness is shown to always produce localized bound states. Thus intrinsic roughness can explain the giant oscillator strength observed for “free” excitons in quantum wells.
Optically Detected Magnetic Resonance of a Hydrogen-Related Complex Defect in Silicon
Authors: Chen W.M. , Awadelkarim O.O. , Monemar B. , Lindström J.L. , Oehrlein G.S.
Published: March 2011

We present for the first time an optically detected magnetic resonance (ODMR) study of a hydrogen-related defect in silicon. The defect is present in hydrogenated boron-doped silicon single crystals, after room-temperature electron-irradiation. A spin-triplet (S=1) is shown to be the electronic state responsible for the observed ODMR spectrum. An angular dependence study of the ODMR spectrum reveals a C2v defect symmetry. The defect model is discussed in terms of a di-hydrogen-vacancy complex. The role of this defect as an efficient recombination channel (presumably non-radiative) for the non-equilibrium free carriers is also demonstrated.
Complex Defects in Semiconductors
Authors: Monemar B.
Published: March 2011

Complex defects in semiconductors are briefly reviewed, with emphasis on the electronic structure. Classes of such defects with a varying degree of complexity are discussed, with reference to recent optical data for neutral defects in GaP and silicon. These include PGa-antisite related substitutional complexes in GaP, Gai-acceptor complexes in GaP, substitu-tional chalcogen complex defects in silicon and vacancy-impurity complexes in silicon.
Modeling of the Diffusion of Hydrogen in Silicon
Authors: Mathiot D. , Ballutaud D. , De Mierry P. , Aucouturier M.
Published: March 2011

A model is proposed to describe hydrogen motion in silicon near 150°C. This model leads to a consistent view of H° behaviour in low doped n and p-type Si, with a diffusivity in agreement with the high temperature data. On the other hand, a systematic variation of DH+ with the boron concentration forces us to conclude that some still unknown interactions take place and contribute to hydrogen trapping in highly doped p-Si.
Electronic Structure and Hyperfine Parameters for Hydrogen and Muonium in Silicon
Authors: Van De Walle Chris G.
Published: March 2011

First-principles spin-density-functional calculations are used to evaluate hyperfine and superhyperfine parameters for hydrogen and muonium at various sites in the Si lattice. The results can be directly compared with values from muon-spin-rotation experiments, leading to an unambiguous identification of “anomalous muonium” with the bond-center site. The agreement found in this case instills confidence in the general use of spin-density-functional calculations for predicting hyperfine parameters of defects.
Hydrogen in Crystalline Silicon under Compression and Tension
Authors: Nichols C.S. , Clarke D.R.
Published: March 2011

The behavior of hydrogen in crystalline silicon (c-Si) containing regions of compressive or tensile stress is important for understanding the solute’s interaction with dislocations, grain boundaries, and crack tips. A series of first-principles total-energy calculations probing the stable site for hydrogen as a function of its charge state, the Fermi level position, and the crystalline lattice constant has been performed. We find that the stable site for hydrogen depends critically on both pressure and on the hydrogen charge state. Furthermore, hydrogen is predicted to undergo a transition from an interstitial site to the bond-center site as a function of pressure.
Hydrogen Induced Defects at Silicon Surfaces and Buried Epitaxial Misfit Dislocation Interfaces
Authors: Zhou Tian-Qun , Radzimski Zbigniew , Xiao Zhigang , Sopori Bhushan , Rozgonyi George A.
Published: March 2011

A silicon epitaxial structure containing spatially confined arrays of misfit dislocations has been used in order to investigate the interaction between hydrogen and individual extended defects. Hydrogen was introduced using a Kaufman plasma ion beam source. A characteristic Si-H peak at 2100 cm-1 was obtained using multiple internal reflection infrared spectrophotometry. Microdefects such as gas bubbles and {111} planar defects were found near the surface, as well as at the misfit dislocation interfaces, using transmission electron microscopy. A heavily damaged region was obtained on the top Si surface and an extended area SEM/EBIC contrast was obtained due to a surface electrical field.
Hydrogen Complexes in III-V Semiconductors
Authors: Pajot Bernard
Published: March 2011

A review of the occurence, nature, structure and stability of the H complexes in III-V compounds is presented, mainly based on electrical and spectroscopical data. The importance of the problem of formation and dissociation of the complexes is pointed out and the use of H complexes in actual III-V devices is described.
Sn-H Complex in Hydrogen Pass Ivated GaAs
Authors: Kozuch D. M. , Stavola Michael , Pearton S. J. , Abernathy C. R. , Lopata J.
Published: March 2011

It is confirmed that Sn donors in GaAs are passivated by exposure to a hydrogen plasma. The Sn-H complexes give rise to vibrational absorption bands at 1327.8 cm-1 and 967.7 cm-1 that are assigned to H-stretching and H-wagging modes respectively. A study of the thermal stability of the Sn-H complexes shows that they dissociate for annealing temperatures above ~150°C. The properties of the Sn-H complexes are compared to those of other donor-H complexes. Our results suggest a configuration for the complex with H at the antibonding site adjacent to the Sn.
Reassessment of Acceptor Passivation Models in p-Type Hydrogenated GaAs
Authors: Szafranek I. , Stillman G.E.
Published: March 2011

The existing microscopic models of acceptor passivation in p-type hydrogenated GaAs are reviewed in light of new experimental results concerning the relative thermodynamic stability of the passivating complexes. In particular, the present model for neutralization of Group II acceptors, Be, Mg and Zn, on Ga sites is shown to be inadequate to account for the observed trends, which imply existence of a strong interaction between the hydrogen and acceptor. It is proposed that a direct acceptor-hydrogen bond is formed due to attractive Coulomb interaction between the ionized species. The relative stability of the pair complex can be then explained based on electronegativity of the acceptor species. Passivation at intermediate pair separations up to about twice the Bohr radius of the nearest acceptor, is also discussed.
Hydrogen Passivation of Interfacial Defects in MOCVD grown GaAs/InP
Authors: Swaminatan V. , Chakrabarthi U. K. , Hobson W. S. , Caruso R. , Lopata J. , Pearton S. J.
Published: March 2011

The results of a low temperature (5K) photoluminescence study of hydrogenation of GaAs on InP grown by metal organic chemical vapor deposition are presented. An emission band at ~ 1.4 eV originating from the GaAs/InP interracial region shows a 30 fold increase in intensity relative to the GaAs band edge emission after exposure to hydrogen plasma for 30 min at 250°C. This improvement in intensity is attributed to hydrogen passivation of defects at the heterointerface caused by the large (≈4%) lattice mismatch between GaAs and InP. The passivation effect recovers on annealing the hydrogenated sample at 350°C. Excitation dependence of the ~1.4 eV band suggests that the interfacial region consists of a compositionally graded layer. Further, this band shifts to higher energy on annealing the sample in the temperature range 150-450°C with the hydrogenated sample exhibiting a larger shift than the untreated sample. It is suggested that the annealing induced peak shift arises due to intermixing of the compositionally graded interface and that the degree of intermixing is greater in the hydrogenated sample compared to the untreated sample.
A Steady-State Model for Coupled Defect Impurity Diffusion in Silicon
Authors: Morehead F. F. , Lever R. F.
Published: March 2011

We extend our earlier model which was proposed to explain tails in the diffusion profiles of high concentration boron and phosphorus in silicon. Our quasi-steady-state approach is generalized here to include both vacancies (V) and interstitials (I) at equivalent levels. I-V recombination is regarded as near local equilibrium, occurring through reactions of the defects with defect-impurity pairs. This approach leads to the well-known plateau, kink and tail in high surface concentration P diffusions in Si and to the less well recognized tails in B as well. Our extended model, in its simplest form, allows a more complete and less restrictive treatment of Au diffusion in Si. An important advantage is the direct inclusion of these defect-impurity interactions and the resulting gradients in the defect concentrations.
Extreme Supersaturation of Oxygen in Low Temperature Epitaxial Silicon and Silicon-Germanium Alloys
Authors: Schwartz P.V. , Sturm J.C. , Garone P.M. , Schwarz S.A.
Published: March 2011

We report the low temperature growth (625 - 700 °C) of epitaxial silicon and silicon-germanium alloy films by vapor phase techniques with oxygen concentrations approximately 1020 cm-3. These concentrations are well above the accepted solid solubility for oxygen in silicon. The films, however, have excellent structural and electrical properties with virtually no stacking faults or “haze”. Infrared transmission analysis suggests the possible presence of OH, but the exact nature of the oxygen is not known.
An Anomalous Vacancy Diffusion in Silicon during the Antimony Drive-in Diffusion
Authors: Wijaranakula W. , Matlock J.H.
Published: March 2011

In the substrate region underneath the antimony buried layer, an enhanced oxygen donor generation and a retardation of the oxygen precipitation were observed. Both phenomena can be explained by the vacancy mechanism in which the charged vacancies dominate at high temperatures. Based upon this hypothetical model, it is suggested that the intrinsic vacancy concentration could play a significant role in both oxygen thermal donor generation and oxygen precipitation in silicon.
Diffusion of Point Defects in a Stressed Simple Cubic Lattice
Authors: Maroudas Dimitrios , Brown Robert A.
Published: March 2011

A systematic theoretical and computational study is presented for the diffusion of point defects in a stressed cubic lattice. The study combines an atomistic description of point defect migration with a continuum model for point defect transport. Moment analysis of the macroscale transport equation gives expressions for the drift velocity and the diffusivity tensor of the point defects, which are calculated by a dynamic Monte Carlo simulation of the defect migration process. Results are presented for the case of diffusion under a constant force of interaction between the applied stress on the crystal and the defects. The continuum model gives the general constitutive model for stress-assisted point defect diffusion.
The Enhancement of the Interdiffusion in Si/Ge Amorphous Artificial Multilayers by Additions of B and Au
Authors: Park B. , Spaepen F. , Poate J.M. , Jacobson D.C.
Published: March 2011

Amorphous Si/ amorphous Ge artificial multilayers were prepared by ion beam sputtering. Boron or gold impurities were introduced into the Si/Ge multilayers by ion implantation or during the sputtering deposition. Diffusion coefficients were determined by measuring the decrease in the intensity of the first order X-ray diffraction peak resulting from the composition modulation. It was found that the interdiflusion of Si and Ge in their amorphous phase can be enhanced by doping. The enhancement factor is independent of the degree of structural relaxation, as observed by the decrease of diffusivity with annealing time, of the amorphous phase. A model is proposed that describes this behavior in terms of electronic effects, introduced by the dopants, on the pre-existing structural defects governing diffusion.
Hydrogen Diffusion and Complex Formation in Silicon
Authors: Borenstein J.T. , Tulchinski D. , Corbett J.W.
Published: March 2011

The kinetics of hydrogen diffusion and complex formation in crystalline silicon are investigated using a model previously developed to explain the influence of dopant type and concentration on observed deuterium profiles in silicon. The predictions of the model have been shown to be in close agreement with recent SIMS profiles of deuterated FZ-Si crystals, with the in-diffusion process dominated by trapping at impurity sites and by the formation of immobile hydrogen molecules.

Previous studies have treated the surface concentration of hydrogen and the capture radii of hydrogen at complexes as free kinetic parameters. We present an analytic relationship between the diffusion coefficient D of neutral hydrogen and both the hydrogen surface concentration and the capture radius for molecule formation. The consequences of fixing D at the known high-temperature value for the diffusion coefficient in the model are determined. The existence of this analytic relation reduces the number of free parameters in the kinetic model and leads to an improved understanding of hydrogen reactions in silicon.
Room-Temperature Diffusion of Mn in CdTe and the Formation of Cd1-xMnxTe
Authors: Wall A. , Raisanen A. , Haugstad G. , Franciosi A.
Published: March 2011

Deposition of Mn at room temperature onto atomically clean CdTe(110) surfaces yields atomic interdiffusion for metal coverages <3 angstroms with Mn atoms occupying cation sites within the surface and near-surface layers of the semiconductor. Synchrotron radiation photoemission studies with variable photoelectron escape depth indicate the formation of a relatively homogeneous semiconductor surface alloy. The highest Mn concentration observed in the alloy exceeds those obtainable with bulk crystal growth methods.
The Role of Charged Point Defects on the Diffusion Behavior of Silicon in GaAs
Authors: Murray Jeffrey J. , Deal Michael D. , Stevenson David A.
Published: March 2011

A multilayered Si doped MBE structure was used to study the effective diffusivity of Si and the results are modeled with an (n/ni)2 dependence over the temperature range of 750°C – 950°C. An activation energy, Ea′, of 4.0 eV is obtained which is higher than normally reported in the literature. This higher Ea′ value results from appropriate accounting of the temperature dependence of ni, which is often neglected in the expression for Deff. Si diffusion at a buried n+/n++junction of a MOCVD grown structure also follows an (n/ni)2 dependence. These results support a Fermi-level model of Si diffusion in GaAs and suggest that the local point defect chemistry of the GaAs, through Si doping, is responsible for this diffusion behavior, regardless of the proximity to the surface.
Electric Field Enhancement of Electron Emission from DX Centers and Consequences
Authors: Bourgoin J.C. , Zazooi M. , Feng S.L. , von Bardeleben H.J. , Alaya S. , Maaref H.
Published: March 2011

We present data which show that electron emission from the DX center is sensitive to the Poole-Frenkel effect. We demonstrate that this result implies that the DX center is an L effective-mass state of the donor impurity accompanied by a small lattice relaxation. We show that all the observations so far obtained on this center are in agreement with this model.
Characterization of Deep-Level Defects in Semi-Insulating GaAs and InP by Photoinduced Transient Spectroscopy (PITS)
Authors: Kaminski Pawel
Published: March 2011

Deep states in semi-insulating (SI) materials :GaAs:Cr ,un-doped GaAs and InP:Fe are investigated by Photoinduced Transient Spectroscopy (PITS) .The relationship between the Hall mobility in undoped SI GaAs and occurrence of the EL2-related peak in the PITS spectrum is shown.
Optically Detected Magnetic Resonance of Group IV and Group VI Donors in Al0.6Ga0.4As/GaAs Heterostructures
Authors: Glaser E. , Kennedy T.A. , Molnar B. , Mizuta M.
Published: March 2011

The influence of chemically different donor species on the nature of shallow donor states in Al0.6Ga0.4As/GaAs heterostructures has been investigated by optically detected magnetic resonance (ODMR). Previous theoretical work by Morgan predicts a triplet state for group IV donors and a singlet state for group VI donors. ODMR experiments were performed on as-grown and implanted Si-, Se-, and S-doped epitaxial layers of Al0.6Ga0.4As grown on (001) GaAs substrates. The effective-mass states are modified by the heter-oepitaxial strain in these layers. The Si donors are characterized as quasi-independent valley states. The Se and S donors have valley-orbit splitting energies (i.e. chemical shifts) of 19-20 meV . The results indicate that Si, Se, and S donors are on the lattice sites in the metastable state of DX.
Photoluminescence and Bandgap Narrowing in Heavily Doped n-GaAs
Authors: Yao H.D. , Compaan A.
Published: March 2011

Extremely heavily doped n-GaAs was produced by pulsed-laser annealing of Si implanted GaAs, achieving carrier concentrations exceeding 3.2×1019/cm3. Our photoluminescence (PL) spectra indicate a bandgap narrowing due to heavy n-type doping with a functional form of Δεg(eV) = - 6.3 × 10cm-8[(cm-2)]1/3 . At the highest carrier concentration, the bandgap shrinkage reaches -200 meV and the electron Fermi energy is -410 meV. These large values indicate that there exists a considerable conduction band “stretch” between the Γ and L-valley of GaAs for very high n-type concentrations.
Electronic Structure of Li-Impurities in ZnSe.
Authors: Oguchi T. , Sasaki T. , Katayama-Yoshida H.
Published: March 2011

Electronic properties of ZnSe with a Li impurity are investigated with use of the local-density-functional approach. The electronic structures are calculated for different impurity sites by taking the neighboring lattice relaxation into account. By comparing their total energies, the stability of the Li impurity in ZnSe is discussed. It is proposed that the Li impurity at the substitutional Zn site might be unstable to the tetrahedral interstitial site with an ionization of Li and a vacancy at the Zn site.
The Symmetry of the EL2 Defect in GaAs
Authors: Trautman P. , Baranowski J.M.
Published: March 2011

Linear dichroism has been measured in the broad absorption band of the EL2 defect in GaAs under uniaxial stress. In addition, the splittings of the EL2 zero phonon line (ZPL) at 8378 cm-1 under uniaxial stress applied along [100], [111], and [110] directions have been measured. Splitting of the ZPL under [100] stress is over one order of magnitude smaller than under [111] stress, on the other hand, the linear dichroism in the broad absorption band is roughly equal for these two directions of stress. This is an evidence for the quenching of the coupling to tetragonal strains due to interaction with trigonal modes of the lattice (the Ham effect). Therefore, it is established, that the excited T2 state of EL2 is a localized state subject to dynamical Jahn-Teller coupling to trigonal modes of the lattice. The possibility that the excited T2 state has hydrogenic nature associated with the L minima is ruled out by the present results. The observed splittings of the ZPL together with polarization selection rules clearly indicate the tetrahedral Td symmetry of the EL2 defect ruling out any other point group in particular trigonal C3v In view of the presented experimental results, their interpretation, and recent theoretical investigations, the isolated arsenic antisite AsGa most successfully accounts for the properties of the neutral charge state of the EL2 defect.
Recovery from the Metastable EL2 Defect in GaAs Under Monochromatic Light Illumination.
Authors: Manasreh M. O. , Fischer D. W.
Published: March 2011

The infrared absorption technique is used to study the recovery of the EL2 metastable state in semi-insulating GaAs under monochromatic light illumination. The induced optical recovery is monitored after low intensity (≤ 2mW/cm2) irradiation in the energy range 0.7 ≤ hv ≤ 1.5 eV. The data exhibit a complex structure consisting of a broad band around 0.9 eV and a set of multiple sharp peaks between 1.44 and 1.5 eV. This recovery is strongly dependent on the sample, temperature and illumination time. The present results suggest that a) the existing data and theoretical predictions for the isolated AsGa antisite structure are not compatable with the optical recovery data, b) EL2 is affected dramatically by other defects (traps) present in the sample and c) the peaks observed in the optical recovery data are coincident with the arsenic vacancy energy levels and therefore the present results support the proposed complex models involving an arsenic vacancy.
Acceptor Delta-Doping in GaAs
Authors: Hobson W. S. , Pearton S. J. , Abernathy C. R. , Cabaniss G.
Published: March 2011

We have investigated the formation and diffusion of delta-doped layers in GaAs employing the acceptors Zn, Cd, and C. Organometallic Vapor Phase Epitaxy was used for the growth of the Zn and Cd δ-doped layers while Metalorganic Molecular Beam Epitaxy was utilized to achieve C δ-doping. The narrowest atomic profiles for Zn had full width at half maxima of 80 Å for peak Zn concentrations of ≤ 3 × 1018 cm-3, as measured by SIMS. An effective diffusion coefficient of ≤ 7 × 1017 cm2/s is estimated for a growth temperature of 625°C, based on multiple Zn δ-doped layers. For carbon, a doping spike of 7 × 1019cm-3 with a full width at half maximum of 50Å, as measured by electrochemical capacitance voltage profiling, was achieved and represents the highest doping level yet reported for planar doping. By contrast, it was difficult to achieve doping levels ≥ 4 × 1017 cm-3 for Cd due to its high vapor pressure.
Precipitation Phenomena Associated with Ultra-High Be Doping in Ga0.47In0.53P Layers grown by MBE
Authors: Cotell C.M. , Panish M.B. , Hamm R.A. , Hopkins L.C. , Gibson J.M.
Published: March 2011

Ultra-high Be doping of Ga0.47In0.53 As layers grown by gas source molecular beam epitaxy has shown that for each growth temperature, there exists a maximum hole concentration (≥1×1020cm-3). Increasing the Be flux above that which produces the maximum hole concentration results in a degradation of the crystalline quality of the films. The degradation of film quality results from precipitation of a Be-rich phase on the surface during growth and nucleation of dislocations at each precipitate. Below that concentration, some of the Be segregates and floats on the growing surface.
Carbon Doping in InGaAs grown by MBE
Authors: Ito Hiroshi , Ishibashi Tadao
Published: March 2011

Carbon doping in InxGa1-xAs is investigated using solid source MBE. InAs mole fractions, x, from 0 to 1 are tested. Under a constant doping level, hole concentration decreases with increasing x. When x is higher than 0.6, the conduction type is n and electron concentration increases with x. The conduction-type inversion and the behavior of carrier mobilities are explained by a self-compensation mechanism.
Comparison of Ordered and Modulated Structures in InGaP Alloy Semiconductors grown by MOCVD, Chloride-Vpe and LPE Methods
Authors: Ueda O , Kato T. , Matsumoto T. , Hoshino M. , Takechi M. , Ozeki M.
Published: March 2011

Ordered and modulated structures in InGaP alloy semiconductors grown on (001) GaAs substrates by metalorganic chemical vapor deposition, chloride-vapor phase epitaxy, and liquid phase epitaxy have been systematically studied by transmission electron microscopy. In InGaP grown by metalorganic chemical vapor deposition at 630°C, strong ordering of CuPt-type has been observed, which is associated with an abnormality in the photoluminescence peak energy. For crystals grown by chloride-vapor phase epitaxy, CuPt-type ordered structures have also been observed. However, the degree of ordering is weaker in the latter case and crystals grown at 576-740°C exhibit normal photoluminescence peak energies. On the other hand, in crystals grown by liquid phase epitaxy, no superstructure spots are found in the electron diffraction patterns and the crystals exhibit normal photoluminescence peak energies. Modulated structures do not depend on the growth method since they are observed in all crystals. From these results, it has been concluded that the ordered structures are not generated under thermal equilibrium conditions but rather by the diffusion and reconstruction of deposited atoms on the growth surface.
Oxygen and Iron Redistribution upon Thermal Treatment in Iron Implanted Silicon
Authors: Pivac B. , Borghesi A. , Ottolini L. , Geddo M. , Piaggi A. , Stella A.
Published: March 2011

In order to study the iron-oxygen interaction and their redistribution in silicon, different doses of 100 keV iron ions have been implanted into CZ silicon substrates, and subsequently annealed. The redistribution of iron and oxygen upon thermal treatment in nitrogen atmosphere was monitored with SIMS and FTIR measurements. A significant gettering of iron as well as of oxygen into the layer close to the implanted surface has been found only for doses exceeding the critical fluence, therefore indicating that the structural disorder and associated lattice strain field are the main driving forces for gettering mechanism. It has been found, however, that for doses above the critical fluence not all iron ions have been trapped into the damaged region, but a significant part of them have diffused into the bulk of the material, unaffected by gettered oxygen.
Molecular Dynamics studies of Dislocations in SI
Authors: Duesbery M.S. , Michel D.J. , Joos B.
Published: March 2011

The mobility of dislocations in a model Silicon lattice is examined at an atomistic level using molecular dynamics. Straight and double-kinked 30° and 90° partial dislocation glide-set dipoles are modelled in a strain-free environment: reconstruction and antiphase defects are found to be present for 30° partial dislocations. The effects of applied shear strains and of temperatures up to the melting point are considered.
A Tem Investigation of Secondary Dislocations in Grain Boundaries in Germanium
Authors: Griss M. , Seibt M. , Möller H.J.
Published: March 2011

Germanium bicrystals containing dissociated low energy grain boundaries with a common [011] tilt axis were studied. The dislocation structure of a grain boundary with a misorientation of about 28° has been investigated in detail and could be interpreted as a near-coincidence Σ 27 - tilt grain boundary. Both conventional and high-resolution techniques were applied to analyze the Burgers vectors of the secondary dislocation network. In all cases non - primitive Burgers vectors were observed. The comparison with previous results indicates that the Burgers vectors of the dislocation network may depend on the degree of misorientation of the bicrystal.
AC Photovoltaic Inspection of P-N Junctions having High Leakage Current
Authors: Honma N. , Shimizu H. , Munakata C. , Ogasawara M.
Published: March 2011

A focused photon beam chopped at 2 kHz scans p-n junctions in a p-type Si wafer and ac photovoltages are capacitively measured in order to inspect homogeneities of the junctions. It is found that the ac photovoltages are high not only in the junction areas but also in the field oxide regions around the junctions when the junctions are leaky. This indicates that dense positively charged traps exist at the interface between the heavily boron implanted Si substrate and the field oxide layer around the high leakage junction, and that the traps cause the increase in both the junction leakage current and the ac photovoltage.
Defect Levels in the Near-Surface Region of 2.0 MeV 16O+ Ion Implanted n-GaAs.
Authors: Tin C.C. , Barnes P.A. , Bardin T.T. , Pronko J.G.
Published: March 2011

MeV ion implantation in GaAs is known to cause amorphization of the region at the end of the ion range. The near-surface region, however, is still crystalline albeit heavily compensated. We have carried out deep level transient spectroscopy (DLTS) studies of the defect levels in the near—surface region of n—GaAs samples implanted with different doses of 2.0 MeV 16O+ ions.

A comparison between the defect structures in the original and the implanted samples shows that implantation produced a broad range of defect levels ranging from 0.58 to 0.3 eV from the conduction band edge. This broad range of defects has an unusually large capture cross—section. The intensities of the DLTS peaks increase with the dose of 160+ ions. The presence of EL2, which was present in the original samples, was not observed in the implanted samples.

Results from measurements made on samples that have been implanted at 200°C and on implanted samples subjected to rapid thermal annealing will also be discussed.
Correlation of Void Formation with the Reduction of Carrier Activation and Anomalous Dopant Diffusion in Si-Implanted GaAs
Authors: Ko Kei-Yu , Chen Samuel , Lee S. -Tong , Zheng Longru , Tan T.Y.
Published: March 2011

We report the study of high-dose Si-implanted GaAs containing doses ranging from 1×1014 to 1×1015 cm-2 and with subsequent anneals at 850°C for 1 hour. At doses ≥ 3×1014 cm-2, a severe reduction of carrier concentration and anomalous Si diffusion are observed in the near-surface region. In the same region, small, near-spherical voids are found by transmission electron microscopy. In contrast, for samples implanted with doses ≤ 1×1014 cm-2, voids are not found, and both normal carrier activation and Si diffusion profiles are observed. The concurrent onset of these three phenomena in the same region in high-dose samples leads us to conclude that the severe reduction of carrier concentration and anomalous Si diffusion are attributable to the formation of voids.
Improved Hole Diffusion Lengths in Bulk n-Type GaAs for High Efficiency Solar Cells
Authors: Wong D. , Schlesinger T. E. , Milnes A. G.
Published: March 2011

A method for wafer annealing which is effective in suppressing defects and raising minority carrier diffusion lengths in n-type bulk GaAs is described. The beneficial effect of the annealing is shown to be associated with the proximity surface with measurements of photoresponse as a function of depth. The concentration of the hole trap HCX (Ev+0.29eV) varies as a function of depth from the surface, qualitatively, as might be expected of the concentration of the dominant recombination center in the material. The impact of improving the material in this manner on the performance of Zn diffused solar cells is demonstrated.
New Photosensitive Polyimide (SIM2000XL-RTS) for Packaging Applications
Authors: Jeng S. , Xu M. , Liu P. L. , Kwok H. S. , Lee C. J.
Published: March 2011

Polyimides are finding increased use as dielectric materials in multi-level metallization technology, which is the key to high-density packaging applications for microelectronics.

Newly developed photosensitive polyimidesiloxane (SIM2000XL-RTS) has been evaluated in terms of thermal stability, photosensitivity and lithography as well as dielectric breakdown properties. The sensitivity to N2 laser exposure has been measured under optimized process conditions. We also find that SIM2000XL-RTS can be processed up to 350°C without significant decomposition. Micron-scale contact images can be successfully patterned by both N2 laser and conventional UV lamp exposure. The dielectrical breakdown field strength of SIM2000XL-RTS is about 4 MV/cm by sandwich measurements.
A New Polyimide for Multi-Chip Modules Applications
Authors: Satou Hidetaka , Makino Daisuke , Kikuchi Toru , Saito Takayuki
Published: March 2011

Currently polyimides are used for a multitude of applications in the electronics field. No where else is it's use growing faster than in the multi-chip module market. It's inherent features in process ability, planarity, heat resistance, and patternability make it ideal for production use in multi chip modules.
Adhesion, Reaction and Stability of Metal/Polyimide Interfaces
Authors: Kim J. , Kowalczyk S. P. , Kim Y. H. , Chou N. J. , Oh T. S.
Published: March 2011

Interfacial reactions of polyimide with several metals have been investigated by XPS and TEM to determine their effects on adhesion and long term stability. It has been found that the polyimide-on-metal interface and the metal-on-polyimide interface are intrinsically different; in the case of PI-on-metal interface, the precursor of polyimide, polyamic acid, reacts with the metal resulting in a strong chemical bond and therefore, higher adhesion strength than the corresponding metal-on-PI interface. Both interfaces are found susceptible to T/H environment, resulting in significant adhesion loss. The mechanical and electrical properties of polyimide may be altered as a result of the interaction with metals and therefore, great care is necessary to insure a stable interface and the reliability of devices.
Solvent-Induced Damage in Polyimide Thin Films
Authors: Hu M. S.
Published: March 2011

Solvent induced damage bands formed in residually strained polyimide thin films on different substrates have been studied. Microscopy studies have shown that these bands resemble crazes. A mechanics approach Is taken to understand the band formation phenomenon.

The critical strain for damage formation has been identified. This strain decreases with increase in exposure time, but always exhibits a threshold value. In contrast to the cracking of brittle films, the critical strain has only a weak dependence on the film thickness over a wide range. This behavior obtains because the crazing of the polyimide films is nucleation controlled. Strain-enhanced diffusion of solvent into the films is considered to be responsible for the property degradation that leads to damage formation.
Ion Exchange Reaction in a Thin Film of Polyimide
Authors: Akagi Yoshiro , Ishino Mariko , Okamoto Yasunari , Taniguchi Hiroshi , Ohoka Kohji , Nakajima Yoshiharu
Published: March 2011

Relationship between the degree of imide-ring-condensation and the absorbed quantity of sodium ion was studied in a polyimide film of 100nm thick immersed in an alcoholic solvent containing sodium ion in order to elucidate a mechanism of incorporation of ionic species. Absorption and depth-profile of sodium ion in a film were quantitatively determined by chemical analysis and secondary ion mass spectroscopy. Concentration of sodium ion in a thin film by two orders of magnitude was observed, and distribution of sodium ion in a thin film was found to be uniform, which cannot be accounted for by any kinds of previous models based on diffusion, permeation, or solvation. Instead, chemical ion-exchange model is proposed and is found to satisfactorily explain the experimental results.
New Multilayered Materials with Low Dielectric Permittivity for VLSI Applications
Authors: Mehrotra V. , Kwon T. , Giannelis E. P.
Published: March 2011

A new generation of substrate materials with low dielectric permittivity have been developed. These new ceramic-based nanocomposites consist of a quasi two-dimensional, multilayered structure realized by the intercalation of molecular species into the galleries of a host lattice. The materials have been characterized by x-ray diffraction, electronic and infrared spectroscopy. The relative permittivities vary between 2.5 and 4 at 1 MHz. The new hybrids can be processed at relatively low temperatures (below 350°C) and allow for step coverage of submicron structures.
Dielectric Properties of Sintered AIN
Authors: Harris R. D. , Enck R. C. , Fields J. L.
Published: March 2011

We have initiated a study of the ac electrical properties (dielectric constant and dielectric loss) and the dc resistivity of sintered AIN. For this study, we have used samples purchased commercially as well as samples made by the Carborundum Company, a member of the BP Group. Variations are observed in the room temperature dielectric constant for AIN substrates obtained from different sources. The source-to-source range is from 8.5 to 8.7. This range is lower than the 8.8 to 9.2 that is generally reported in the product literature. Similar source-tosource variations in the room temperature dielectric loss are observed. All of the samples show thermally activated behavior in the dc resistivity. The activation energy observed for all of the samples is similar, EA ∼0.47 eV; however, different pre-exponential factors are apparent. As a result, there are large variations in the measured room temperature resistivities for samples from different sources.
Influence of Firing Gas Pressure on the Microstructure and Thermal Conductivity of ALN Ceramics
Authors: Tsukada M. , Makihara H. , Kamehara N. , Niwa K.
Published: March 2011

The thermal conductivity of aluminum nitride is significantly affected by its purity. We used CaCO3 as an additive to decrease the oxygen content. Calcium-aluminate is formed by the reaction of the aluminum nitride powder oxide layers and CaO during firing. We investigated the influence of firing gas pressure on the microstructure and thermal conductivity of aluminum nitride. The thermal conductivity reached 270 W/m°K when 4 wt% CaO was added and firing gas pressure was 700 kPa. Under these conditions, the amount of remaining oxygen was at its minimum and the grain size of the aluminum nitride was at its maximum.
Planar and Curved Defects in Aluminum Nitride: Their Microstructure and Microchemistry
Authors: Westwood Alistair D. , Notis Michael R.
Published: March 2011

The microstructure and microchemistry of planar and curved defects in Aluminum Nitride (AIN) has been investigated using Conventional Transmission Electron Microscopy (CTEM), Convergent Beam Electron Diffraction (CBED), and Analytical Electron Microscopy (AEM) techniques. Both defect morphologies were identified as Inversion Domain Boundaries (IDB). Microchemical analysis revealed oxygen segregation to the planar faults; when present on the curved defects, oxygen was at a lower concentration than in the planar defect case. Annealing experiments on defect containing AIN support our microchemical analysis of oxygen segregation. A proposed model for the formation of these two types of boundaries is presented.
Inversion Domain Boundaries and Oxygen Accommodation in Aluminum Nitride
Authors: Youngman R. A. , Harris J. H. , Labun P. A. , Graham R. J. , Weiss J. K.
Published: March 2011

Aluminum nitride is known to have a large affinity for oxygen as an impurity. At high levels (>∼4 wt/o) the oxygen is incorporated in the form of planar stacking faults where “pure” 2H AIN is regularly interspersed with a layer of oxygen at the faults. At oxygen levels lower than ∼ 4 wt/o the structure shows an expanded c-axis. The present authors have not observed this effect, rather a random distribution of stacking faults is observed along with another, more prevalent, extended defect identified as an inversion domain boundary (IDB). The IDBs are significantly aplanar (indicating a low interface energy), and often have precipitates and other, faceted defects associated with them. The role of these defects in oxygen accommodation in AIN has been investigated both structurally and chemically by electron optical methods (SEM, TEM, STEM, HREM, CBED, EDS, EELS, and CL-TEM). The structural nature of the boundaries, in the absence of oxygen, requires Al-Al or N-N bonding to occur with some frequency across the boundary. Such bonding is unlikely due to the excess energy required. Chemical analysis (EELS) and luminescence studies (CL-TEM) reveal that oxygen is often associated with the boundaries and may mediate the bonding at the boundary. A model is proposed for the IDB which includes structural aspects combined with considerations of stoichiometry in an effort to understand the origin and energetics of this defect.
Future Packaging Directions in the 1990's and their Materials Challenges
Authors: Eastman Dean E.
Published: March 2011

In the 1990's, silicon integrated circuit technology will continue to rapidly advance from VLSI towards ULSI. For example, 64 × 106 circuit microprocessor chips, 106 gate CMOS logic chips, and 105 circuit bipolar logic chips, and beyond, will make up the electronics systems of the 1990's. To support these silicon technology advances in density, performance, and cost reduction, packaging technology will also have to advance rapidly to meet packaged electronics systems requirements. Packaging solutions will be required for machines ranging from supercomputers and mainframes to minis and workstations, and for consumer electronics. Silicon technology advances will continue to enable the unique rates of change in performance, function, and cost per function that characterize the information technology industry, including the computer, communications, and consumer electronics industries.
X-Ray Diffraction and TEM Studies of the Delamination of Copper Thin Films from Glass and Silica Substrates
Authors: Fox Alan G. , Cannon Rowland M.
Published: March 2011

The events associated with fractures along interfaces between copper thin films and glass substrates were investigated by X-ray diffraction and transmission electron microscopy (TEM). In the as-bonded films the Bragg diffraction lines were shifted and broadened (relative to pure strain-free copper) due to residual in-plane tensile strains arising from the differences in thermal contraction between the copper and the substrates; TEM studies of these films in cross-section showed that the residual stresses had been relieved somewhat by dislocation densities as high as 1010 lines/cm2 in Cu/SiO2 films.

The passage of a crack along the Cu/glass interfaces led to a significant reduction in the line shift and a slight reduction in the line broadening. Thus dislocations generated by the fracture events ‘plastically relaxed’ the residual stresses present in the as-bonded Cu by superposing a compressive component onto the pre-existing in-plane tensile strains. This dislocation generation was confirmed by TEM studies. In addition, it was found that the greater the strength of an interface, the greater was the reduction in mean strain due to the fracture; this is consistent with a larger crack-tip plastic zone and the generation of greater numbers of dislocations in the Cu films by fracture along interfaces of higher toughness (i.e. bond strength).
Oxidation of PB-SN and PB-SN-in Alloys: Bulk VS. Grain boundary regions
Authors: Sluzewski D. A. , Chang Y. A. , Marcotte V. C.
Published: March 2011

Air oxidized Pb-Sn and Pb-Sn-In single phase alloys have been studied with scanning Auger microscopy. Line scans across grain boundaries combined with argon ion sputter etching revealed grain boundary oxidation. In the Pb-Sn samples, tin is preferentially oxidized with the grain boundary regions having a much higher percentage of tin oxide than the bulk surface oxide. In the Pb-Sn-In alloys, both tin and indium are preferentially oxidized with the grain boundary regions being enriched with tin and indium oxides.