bluuebunny/crossref_metadata_2025 huggingface dataset:
DEPTH-DEPENDENT MIXING OF AN AlAs-GaAs SUPERLATTICE BY ION IMPLANTATION
Authors: SCHWARZ S.A. , VENKATESAN T. , BHAT R. , KOZA M. , YOON H.W. , ARAKAWA Y. , MEI P.
Published: March 2011

The effects of implantation and annealing on an AlAs-GaAs superlattice grown by OMCVD is examined with SIMS (secondary ion mass spectrometry). Several 180 keV 28Si+ implants, with doses ranging from 3 × 1013 to 3 × 1015 cm−2, are examined before and after a three hour 850 C anneal. While the implantation by itself causes some intermixing in the vicinity of the projected range, the 850 C thermal anneal induces significant mixing at depths well beyond the implant range. In the region of maximum implant damage, however, the post-thermal mixing effect is inhibited. Depth dependent diffusion lengths of Al and Si are derived from the SIMS data. The diffusion coefficient of Si is markedly enhanced in the mixed regions.
INTERMIXING OF ION-IMLANTED AlGaAs/GaAs SUPERLATTICES
Authors: Ralston J. , Wicks G.W. , Eastman L.F. , Rathbun L. , DeCooman B.C. , Carter C.B.
Published: March 2011

Cross-sectional Transmission Electron Microscopy, Sputter-Auger spectroscopy, and Raman spectroscopy have been used to study intermixing and residual damage in annealed ion-implanted Al0.3Ga0.7As/GaAs superlattices. Several implant species were studied Nse, Si, Mg, Be). Three different regions can be distinguished in the annealed ionimplanted superlattice samples. The topmost region contains a dense network of stacking faults and microtwins, residual damage from an implantation-amorphized region which has recrystallized during annealing. In the second region, which is relatively defect-free, either total, or at least appreciable intermixing of the GaAs and Al0.3Ga0.7As layers occurs. For fixed annealing conditions, the degree of intermixing varies with the mass of the implanted species. The third region contains many small dislocation loops which form by the agglomeration of point defects during implantation or the subsequent annealing process. Raman spectroscopy is used to compare the degree of intermixing and residual damage between AlGaAs alloys generated by superlattice disordering and uniform “as-grown” alloys of the same composition which have undergone identical implant and anneal treatments.
MULTILAYER X-RAY MIRRORS, A FIRST STEP TOWARDS THE CUSTOM DESIGN OF NEW MATERIAL PROPERTIES
Authors: SPILLER EBERHARD
Published: March 2011

Soft x-ray reflectivities up to a factor 104larger than those of the best homogeneous materials have been obtained with multilayers coatings. Thickness control and boundary definition has been achieved on an atomic scale with amorphous films. We will review design, fabrication, performance and characterization of the coatings and discuss possibilities to extent these methods to the improvement of other material properties.
MULTILAYER X-RAY REFLECTORS: EFFECTS OF LAYER IMPERFECTIONS
Authors: Wood J. , Grupido N. , Hart K. , Flessa S. , Kadin A. , Keem J. , Ferris D.
Published: March 2011

Periodic multilayer structures, consisting of largely amorphous alternating layers of heavy and light elements, have been fabricated by sputtering techniques. Investigations have been carried out into the effects of various types of layer imperfections on the x-ray optical properties of these multilayers. These have included extensive numerical modeling of real multilayers (using a computational scheme based on the complete dynamical theory) with simulations of diffused interfaces and deviations from constant d-spacing. Results are presented for examples of W–C and Hf–Si multilayers, with comparison of measurements at Cu–K to the theoretical model.
THERMAL, STABILITY OF W/C MULTILAYER FILMS
Authors: Takagi Yasuo , Pawlik David A. , Kadin Alan M. , Flessa Steven A. , Hart Keith L. , Keem John E. , Tyler John E.
Published: March 2011

Arstract:

W(15 Å)/C(15 Å), W(50 Å)/C(50 Å) and W(100 Å)/C(100 Å) periodic multilaver films were prepared by magnetron sputtering and suhsequently annealed at 980, 730 and 500°C. The changes of layered and crystal structures were studied by x-ray diffraction. The results depended largely on the thickness of W layers and their initial crystal struictures of W. The kinds of transformations are classified into two types: one is the non-reacting type in the case of multilayers having the thinner W layers like W(15 Å)/C(15 Å), in which the crystallization of W layers prevails over the reactions between W and C layers; the other, the reacting type in the multilayers having thicker W layers like W(50 Å)/C(50 Å) and W(100 Å)/C(100 Å), in which reactions Prevail over crystallization. A tentative model in which the effective reaction rate between amorphous–W and amornhous–C is much smaller than that of crystalline-W(beta phase) and amorphous-C is proposed to explain the origin of the phenomena.
SUPERCONDUCTING PROPERTIES OF TERNARY GRAPHITE INTERCALATION COMPOUNDS
Authors: Chaiken A. , Roth G. , Enoki T. , Yeh N. C. , Dresselhaus M. S. , Tedrow P.
Published: March 2011

Graphite intercalation compounds (GIC's) are metal-semimetal superlattices which exhibit crystalline order, and have atomically perfect interfaces between the layers of the constituent species. From the standpoint of superconductivity, the KHg-GIC's are particularly interesting. The preparation and properties of these compounds are described, along with a series of recent experiments with hydrogen doping which have helped to elucidate their electronic properties. A density of states model suggested by the results of the hydrogen–doping experiments is presented and used to explain the variation of the superconducting transition temperature in these materials.
MULTILAYER ANODIZATION PROFILE (MAP) A NOVEL DEPTH PROFILE TECHNIQUE FOR METALLIC–BASED LAYERED STRUCTURES
Authors: KADIN A.M. , BURKHARDT R.W. , KEEM J.E.
Published: March 2011

A simple and inexpensive technique is described, which makes novel use of electrolytic anodization to obtain an effective depth profile of artificial nultilayered structures based on a number of refractory metals. Successful MAPs (Multilayer Anodization Profiles) have been obtained for multilayer structures of Nb/Si, W/Ti, and a variety of other material pairs, with individual layer spacings ranging from less than 10 Å to greater than 50 Å. The spatial resolution of these MAPs annears to be less than about 10 Å, and may in some cases be comparable to the interface sharpness of the sputtered films. Comparison with conventional techniques such as Auger depth profiling and low–angle x-ray diffraction is discussed. Examples of semiquantitative analysis, using the MAP technique, of changes in interface structure brought about by thermal annealing, are also presented.
HEAVILY Si-DOPED AlAs FILMS GROWN BY MOLECULAR BEAM EPITAXY
Authors: KOBAYASHI K. , KAMATA N. , SUZUKI T.
Published: March 2011

Heavily Si-doped aluminium arsenide films on GaAs substrate by MBE have been investigated. It is found that the Si activation energy ED for AlAs films decreases with increasing Si donor concentration, approaching a few meV for n≧3×l018. The maximum free electron concentration of n=7×l018 cm−3 and electron mobility of 200 cm2/V.sec for n=5×l017 were obtained. It is also shown that the replacement of the ternary AlxGal−xAs with a superlattice having heavily Si-doped binary AlAs in the barrier layers is effective to increase free carrier concentration.
DEFECTS IN GaAs GROWN ON Ge SUBSTRATES
Authors: CARTER C. B. , COOMAN B.C. DE , CHO N.H. , FLETCHER R.M. , WAGNER D.K. , BALLANTYNE J.
Published: March 2011

The growth of polar semiconducting materials on non-polar semiconducting substrates is illustrated by experimental observations of GaAs grown on Ge substrates and on Ge epilayers which had been grown on Si substrates. The GaAs epilayers are grown in each case by metal-organic, vapor-phase deposition. The GaAs/Ge heterophase junction, the grain boundaries in GaAs grown on {110} Ge and on {001} Ge/Si composit substrates and the anti-phase boundaries in GaAs grown on {001} Ge substrates are eat.h illustated. The interfaces have been studied by transmission electron microscopy and reveal the pronounced faceting of the anti-phase boundaries in GaAs. Also demonstrated experimentally is the strong interaction between dislocations/grain boundaries and these anti-phase boundaries.
TWO DEFECT-RELATED PHOTOLUMINESCENCE SPECTRA AND CROSS-SECTION TEM OF MBE GROWN CdTe ON (100) InSb
Authors: FENG Z.C. , MASCARENHAS A. , CHOYKE W.J. , FARROW R.F.C. , GREGGI J. , SHIRLAND F.A.
Published: March 2011

A series of MBE grown CdTe films were grown on (100) InSb substrates. The substrate temperature, Ts, was varied from 170° to 285°C in eleven steps. Low temperature (∿2K) photoluminescence measurements and TEM have been combined to show a strong correlation between defect density and the details of the luminescence spectra. A natural division is obtained for samples grown with substrate temperatures from 285°C to 250°C (Region I) and from 225°C to 170°C (Region II).
Infrared Absorption Studies of Thermal Donors in Silicon
Authors: Wagner Peter
Published: March 2011

Infrared absorption investigations of oxygen containing silicon reveal that the thermal donors generated by annealing around 450 °C consist of a series of shallow double donors with slightly differing ground state energies. The kinetics of formation and decay of these donors in samples with varying oxygen content annealed at temperatures between 460 and 600 °C support the relation of the thermal donors to aggregates of oxygen atoms. A preferential orientation of thermal donors induced by uniaxial stress during their growth demonstrates their low symmetry and extended defect-like nature. Optical cross sections evaluated by comparing IR-absorption spectra with resistivity measurements allow to estimate the concentrations of the different donors.
On the Kinetics of Oxygen Clustering and Thermal Donor Formation in Czochralski Silicon
Authors: Tan T. Y. , Kleinhenz R. , Schneider C. P.
Published: March 2011

We report the results of an experiment of annealing Czochralski silicon at 450°C for up to 500 hrs. Concentrations of oxygen atoms (Ci) and thermal donors (TD) have both been monitored. Analyses of the oxygen concentration data yielded the apparent interpretation that the overall kinetics is dominated by the formation of small clusters (dimers and trimers). This cannot account for TD formation, since they are supposed to be larger clusters. On the other hand, analyses of existing TD kinetic models did not yield calculated Ci values to satisfactorily account for the present Ci data. We believe that a satisfactory TD model is not yet available.
Oxygen Precipitation and Thermal Donors in Silicon
Authors: Newman Ronald C.
Published: March 2011

Oxygen in silicon precipitates with second order kinetics at the normal diffusion rate at 450° C and there Is evidence for self-Interstitial generation. These findings are discussed In relation to thermal donors.
Cluster Computations Related to Silicon Thermal Donors
Authors: Snyder Lawrence C. , Corbett James W.
Published: March 2011

Ab-initio quantum chemical computations have been applied to a set of molecular clusters derived from Si5 H12 to model defects in crystalline silicon involving boron, carbon, nitrogen, oxygen, and hydrogen. In computations of defect structure, hydrogen atoms terminating silicon valencies are fixed at their computed positions in Si5H12, to represent forces from the lattice, while the position of other atoms are varied.

We have computed the stable bonding structures of boron, carbon, nitrogen and oxygen atoms to a vacancy, as well as interstitial oxygen, the silicon-oxygen ylid and two oxygen atoms bound to a vacancy. The structures of the dipositive ions of the oxygen bearing clusters have been computed as part of a search for candidates for the core of the 450° C oxygen thermal donor in silicon crystal. The computed cluster energies are employed to give an account of defect thermochemistry; the addition of the free atoms to a vacancy, the addition of interstitial oxygen atoms to a vacancy, the reaction of interstitial oxygen atoms to form a vacancy-oxygen complex with the emission of silicon monoxide, and the reaction of interstitial oxygen with the dipositive ion of substitutional oxygen to form the dipositive ion of two oxygen atoms bound to a vacancy.
Transmission Electron Microscope Studies of O, C, N Precipitation in Crystalline Silicon
Authors: Bourret A.
Published: March 2011

The understanding of the precipitation phenomena of light non dopant Impurities has been recently improved thanks to high resolution electron microscopy and microanalysis. After a one-step annealing in Czochralski silicon long coesite (SIO2) ribbons are formed between 485° and 750°C; amorphous platelets (SIOxwith x =1. 2 to 2) are formed between 650°C -1050°C. Silicon Interstitlals generated during the precipitation partly relax the strain energy associated with the volume change. These Interstltlals are also able to precipitate In various forms. After a two-step annealing both platelets and/or octahedra containing amorphous SIOxare formed. The role of carbon on oxygen precipitation Is important: It changes the nucleation parameters and gives a retardation phenomena In a two-step annealing treatment. Similar phenomena are observed in oxygen implanted silicon. The nucleation and growth process able to explain these observations is far from being well understood. The SIO2polymorphism, the Important role of SI Interstitials and the mutual attraction between oxygen and carbon are some of the ingredients which explain this complexity.
Electron Energy Loss Microspectroscopy: Small Particles in Silicon
Authors: Skiff W. M. , Tsai H. L. , Carpenter R. W.
Published: March 2011

The method of electron energy loss spectroscopy in a transmission electron microscope is applied to the analysis of small particles in silicon. Elemental and chemical microanalysis is demonstrated on nitrogen and oxygen-associated defects in silicon, using silicon-based standards.
Oxygen Precipitation in Silicon
Authors: Hu S. M.
Published: March 2011

The precipitation of oxygen in silicon exhibits many interesting phenomena: the precipitates are often distributed in striated zones; the morphology of precipitates changes with annealing temperatures; the kinetics of precipitation in the bulk is affected by annealing ambients and other surface treatments. These phenomena are briefly reviewed. A model consistent with all these phenomena is presented. Then, the energetics and the kinetics of nucleation and precipitation are discussed. Finally, a growth law is derived in general for disc precipitates, and applied in particular to oxygen precipitates in silicon.
Roles for A Precursor Oxide Phase in The Siting, Shaping, and Shrinking of Oxygen Precipitates
Authors: Fraundorf P.
Published: March 2011

Three separate “anomalous” effects in the precipitation of oxygen in silicon may be explained if typical poorly-crystallized platelet oxygen precipitates begin as tiny crystalline clusters. The first anomaly, sometimes referred to as the induction effect, may be explained if one postulates the existence of kinetically stable precipitate embryos (seeds) containing no more than one or two oxygen atoms. We show here that such a postulate, coupled with observations, places rather specific constraints on binding energy as a function of size for such tiny clusters. The second and third anomalies, arising in precipitate shape and retrogrowth behavior dependences, respectively, may be explained if one postulates the existence of a relatively dense precursor phase which undergoes first order phase transition, following otherwise classical rules, to the final-stage amorphous oxide normally found. In this case, both precipitate shape and strain field can be interpreted as a barometer of the interstitial ambient during key periods in a precipitate's history.
Oxygen Precipitation in N+ Silicon
Authors: Dyson W. , Makovsky J.
Published: March 2011

The advantages of oxygen precipitation in terms of intrinsic gettering to reduce oxidation induced surface defect densities and improve minority carrier generation lifetimes (τ) are well documented in the literature (1–3). Various gettering cycles to establish oxygen precipitation in n type and p type nondegenerate substrates have been developed (4–6), based on homogeneous nucleation theory. For nondegenerate silicon no differences in oxygen precipitation kinetics related to the dopant type have been reported. However, with the increasing interest in both p/p+ and n/n+ epitaxial layers for CMOS devices (7), work on the precipitation of oxygen in both p+ and n+ degenerate silicon substrates has revealed a dependence of oxygen precipitation kinetics on dopant type (8–11). In the case of p+ silicon the differences in precipitation kinetics are small when compared to p- silicon (10,11). For n+ silicon it has been reported (8–11) that the dopant concentration plays a major role and that a significant retardation of oxygen precipitation is observed. There are currently two different explanations for the difficulty encountered in producing sufficient oxygen precipitation in n+ Si. These are the failure to incorporate sufficient oxygen into the crystal during crystal growth (12) and an interaction between intrinsic point defects and the n type dopant, which influences the oxygen precipitation kinetics (8,13).
An Overview of Oxygen in Silicon
Authors: Mikkelsen J. C.
Published: March 2011

Oxygen in silicon has been an important scientific and technological subject for over 30 years. It derives its technological importance from the fact that silicon crystals pulled from silica crucibles have been the standard substrates for fabrication of integrated circuits. The scientific interest originates both from support of this technology and the wide variety of phenomena that occur when cooled Czochralski (CZ) Si crystals become supersaturated with oxygen. Furthermore, the semiconducting nature of Si permits the use of very sensitive electrical and optical probes to complement the structural and chemical characterization of these varied solid state phenomena.
Diffusivity and Diffusion Mechanism of Oxygen in Silicon
Authors: Lee S.-Tong , Nichols D.
Published: March 2011

The diffusivities of oxygen in Czochralski Si (CZ-Si) and float-zone Si (FZ-Si) have been measured by using secondary ion mass spectrometry. The diffusivity at 700–1160°C deduced from the outdiffused profiles of oxygen incorporated in CZ-Si shows little or no dependence on processing conditions and can be expressed as D = 0.14 exp(−2.53 eV/kT) cm2/s. Diffusivity at 700–1100°C of oxygen implanted in FZ-Si is insensitive to doses and follows D = 0.13 exp(−2.50 eV/kT) cm2/s, which agrees remarkably well with CZ-Si data. Since large variations in point-defect concentrations existed under the conditions studied, the excellent agreement among the diffusivities leads to the conclusion that point defects in Si have little effect on oxygen diffusion. This demonstrates that oxygen diffuses primarily via an interstitial mechanism in the temperature range studied.
Interaction Between Deposited Film Extrinsic Gettering and Intrinsic Gettering in CZ Silicon During Simulated CMOS Process Cycles
Authors: Hahn S. , Wong C.-C. D. , Ponce F. A. , Rek Z. U.
Published: March 2011

The gettering effectiveness of various thin film structures on n-type CZ silicon wafers has been investigated using electron microscopy, synchrotron radiation topography and optical techniques. Polysilicon, silicon nitride, and poly/nitride films were deposited on etched wafer backsurfaces. The various materials characteristics were correlated with gate oxide breakdown voltage, minority carrier lifetime and yield of MOS capacitors. These studies show that the poly/nitride configuration is superior as a gettering technique.
The Effects of Carbon on Czochralski Silicon Used for Dynamic Random Access Memory Production
Authors: Craven R. A. , Bailey W. E. , Moody J. W. , Falster R. J. , Shive L. W.
Published: March 2011

Czochralski silicon with constant controlled oxygen level of 15+/-0.5 ppma (ASTM F121–80) and varying carbon content intentionally doped at five different levels from 0.1 ppma to 4.1 ppma (ASTM F123–81) was used to fabricate 16K dynamic random access memories, MOS test capacitors with guard rings, and pn junctions. The results of the experiment have been analyzed for relative yield to functional and refresh characteristics, MOS generation and bulk recombination lifetime, pn junction leakage, and both surface and bulk defect densities. Peak performance of the silicon did not occur at the lowest carbon level, but was dominated by the oxygen precipitate defect density and depth of the denuded zone near the active device regions. The results of the capacitor measurements, the DRAM yield measurements, the junction leakage measurements and the bulk and surface lifetime measurements are self-consistent and emphasize the need for control of the oxygen precipitation whether it is nucleated by carbon or other homogeneous and heterogeneous processes. There is no evidence that carbon has any impact on the device performance other than its impact on the precipitation kinetics of the interstitial oxygen.
Infrared Spectroscopy of Intersitial Oxygen in Silicon
Authors: Pajot Bernard , Cales Bernard
Published: March 2011

A discussion of the isotope shift of the low temperature spectrum of the stretching mode of interstitial oxygen (Oi) in silicon introduces IR results showing the interaction of Oi with the silicon lattice. Evidence is given that the temperature dependence of a combination band observed at liquid helium temperature (LHT) at 1205.7 cm−1 is responsible for the room temperature (RT) band at 1227 cm−1 and that a weak band near 1013 cm−1 is an overtone of the 518 cm−1 band.
Carbon in Crystalline Silicon
Authors: Newman Ronald C.
Published: March 2011

Early measurements are reviewed relating to the solubility. the segregation coefficient, diffusion. Internal precipitation, the infrared absorption and the effect on the lattice parameter of silicon due to substitutional carbon. Interactions with oxygen and group III Impurities are mentioned. A survey is given of the effects of high energy irradiation and heat treatments on both FZ and CZ silicon containing carbon. A rich variety of defects can form, but in general atomic structures have not been determined. The process of site switching from substitutional to interstitial locations which occurs by the selective trapping of self-Interstitials is proving to be invaluable in elucidating the mechanisms of various defect reactions, particularly those Involving oxygen Impurities.
Oxygen and Carbon Defect Characterization In Silicon by Sims
Authors: Hockett R. S. , Fraundorf P. B. , Reed D. A. , Wayne D. H. , Fraundorf G. K.
Published: March 2011

Oxygen and carbon aggregation in silicon after thermal processing can be characterized using SIMS profiles and SIMS imaging. Fluctuations in the oxygen SIMS signal during the profile have been correlated with the change in interstitial oxygen after thermal processing as measured by FTIR and the precipitate size as measured by TEM. In cases where precipitation is known to be the cause of impurity clustering, a computer program for simulating the profiling process allows semi-quantitative characterization of precipitates as a function of depth. The use of a Resistive Anode Encoder on a CAMECA IMS-3f coupled with image enhancement can be used to image oxygen and carbon related defects. Examples of this technique are given by imaging oxygen aggregation and the co-aggregation of oxygen and carbon in thermally-processed Czochralski-silicon.
Carbon Precipitation in Cz and Efg Silicon
Authors: Feng S. Q. , Kalejs J. P. , Ast D. G.
Published: March 2011

The defects formed in carbon rich CZ and EFG silicon after a 900°C, 160 or 560 min long, phosphorous diffusion were studied with TEM. Besides misfit dislocations, numerous precipitates were observed in the junction region in both materials. However, no precipitates were found in the bulk. The precipitates in CZ had a larger strain field than those in EFG material. The difference in the extent of the strain field of precipitates in CZ and EFG silicon can be ascribed to the higher oxygen content in CZ silicon. It appears that oxygen is involved in the Si-self interstitial promoted precipitation of carbon.
Self-Interstitial Injection Effects on Carbon Diffusion in Silicon At High Temperatures
Authors: Ladd L. A. , Kalejs J. P.
Published: March 2011

Carbon diffusivity is reported for different ambient conditions imposed during annealing of silicon in the temperature range from 800 to 100°C, which produce varying levels of silicon self-interstitial supersaturation. The diffusivities are deduced from SIMS analysis of carbon out-diffusion profiles. Carbon diffusivity is increased by up to a factor of 70 in annealing with phosphorus in-diffusion, and by a factor of as much as seven in an oxidizing ambient, when compared to anneals in a nitrogen ambient. The enhancements tend to decrease above 11000C. This behavior can be explained by attributing the increase in carbon diffusivity to self-interstitial supersaturation which increases the concentration of highly mobile carbon selfinterstitial pairs. Significant time dependent effects were also observed for 800 and 9000C phosphorus in-diffusion conditions.
Oxygen-Related Defects in Silicon
Authors: Lindström J. Lennart , Svensson Bengt G.
Published: March 2011

In this review we focus on oxygen-related defects created by electron irradiation (vacancy-oxygen defects) and subsequent thermal treatments. The annealing of the vacancy-oxygen pair (VO-center) at 300–350 °C is discussed as well as results from the formation and annealing of the successors to VO, the VO2 and VO3-centers. It -s found that VO2 is formed by diffusion of a vacancy-oxygen pair to an interstitial oxygen atom. It is suggested that VO3 is formed by the diffusion of interstitial oxygen to a VO2-center (in the temperature range 450–485 °C). At continued annealing at these temperatures VO3 is transferred to a new defect VO4 by attaching one more oxygen. Simultaneously thermal donors are developing in a normal way i.e. as in an unirradiated sample. It is therefore concluded that VO2 is not an important core for thermal donors but a possible nucleus for oxygen precipitation.
Characterization of Polycrystalline Silicon Grown by Gas-Assisted-Solidification
Authors: Hwang H. L. , Yang M. H. , Hseu T. H. , Chu C. H.
Published: March 2011

Polycrystalline Si crystals grown by gas-assistedsolidification have been characterized by chemical and physical techniques with particular emphasis on carbon determination. The life time of this material appears to be not correlated with [0] or [C].
Electrical Transport Studies of the Hydrogen-Related Compensating Donor in B-Doped Silicon Diodes
Authors: Tavendale A. J. , Williams A. A. , Alexiev D. , Pearton S. J.
Published: March 2011

Transport of the hydrogen-related, acceptor-compensating defect has been observed in reverse-bias annealed Al-gate Schottky and n+-P diodes from hydrogenated, B-doped p-Si. Secondary ion mass spectroscopy (SIMS) profiling (deuterium substitution) confirmed field-aided migration. Significant differences in field transport (and thermal diffusion) between diodes from Hand D-treated p-Si(B) qualitatively indicates a monatomic species. The effect is interpreted as field drift of a positively charged species, possibly H+, with a donor charge state in the upper-half band gap, in conflict with long-held theory predicting very deep level activity. Acceptor compensation is unstable under minority (electron) carrier injection by forward bias or illumination at 25°C, supporting the acceptor-protonic trap pair model (A-H+) of Sah, Pan and Hsu [J. Appl. Phys. 57, 5148 (1985)].
Hydrogen Passivation of Oxygen Donors in Si
Authors: Pearton S. J. , Chantre A. M. , Kimerling L. C. , Cummings K. D. , Dautremont-Smith W. C.
Published: March 2011

The electrical activity of the oxygen-related thermal donors in heat-treated, P-doped, Czochralski grown Si is passivated by reaction with atomic hydrogen. Secondary ion mass spectrometry and spreading resistance profiles on deuterium plasma treated samples show a direct correlation between the deuterium incorporation depth and the distance over which the thermal donors are passivated. The donor activity is restored by annealing above 400°C, and comparison with other defect dehydrogenation data suggests that the thermal donors may contain Si dangling bonds. Results obtained from deep level transient spectroscopy measurements are used to illustrate the observed donor passivation and reactivation kinetics.
Channeling Measurements on Deuterium Implanted Silicon
Authors: Nielsen B. Bech
Published: March 2011

The channeling technique has been used to study the lattice location of deuterium ion-implanted into silicon. Compared to earlier measurements by Picraux and Vook, the temperature range has been extended from 30 to 500 K, and the dose has been decreased down to ≃ 8 × 1014 D/cm2. The implantation was performed at 30 K gnd at an energy of 10 keV. The channeling analysis was done using the d(3 He,p)4 He nuclear reaction. Angular scans were measured along the <100>, <110>, <111> axis and the {100}, {110}, {111} planes, Experiments were carried out on the implanted sample (30K) and after annealing to 200 and 500 K. In the as-implanted sample, 80% of the deuterium is located close to the bond center, whereas the remaining 20% is placed at the tetrahedral site. The deuterium sites change after annealing to 200 and 50OK, and the nature of these annealings stages will be discussed.
Redistribution of Ion Implanted Hydrogen in Polycrystalline Silicon Thin Films
Authors: Legge Ronald N. , Brown James F.
Published: March 2011

The effect of implanted hydrogen on the resistivity of polycrystalline silicon films has been investigated. The observed reduction in resistivity due to hydrogen is most pronounced for lightly doped films, and is accentuated by a 450°C anneal. An increase in Hall mobility is also observed. The pre-implant resistivity is completely recovered by annealling at 600°C. Diffusion of hydrogen at low temperatures is monitored by local resistivity changes detected with spreading resistance measurements.
Variations in the Refractive Index of the Near-Surface Region of Low Energy Hydrogen Ion Bombarded Silicon
Authors: Pettit R. B. , Panitz J. K. G.
Published: March 2011

Using ellipsometric analysis, the complex index of refraction of lowenergy, hydrogen ion bombarded, [100] single-crystal silicon was measured as a function of distance from the bombarded surface. The bombardment conditions were a 1600 eV hydrogen beam produced by a Kaufman ion source, 1.4 mA/cm2 flux, 2 × 1018 ions/cm2 fluence and 275°C bulk silicon temperature. These conditions are comparable to the conditions generally reported to result in a substantial increase in the electrical conductivity of polycrystalline silicon solar cell material. The results of this study indicate that the real and imaginary parts of the refractive index of the ion bombarded surface region approach that of the unbombarded substrate at a depth of 50 nm. The refractive index of about the first 10 nm of ion bombarded material is strongly dependent on the bombardment conditions. Variations in the imaginary part of the refractive index indicate that approximately 10% of incident radiation is absorbed by the first 50 nm of modified material.
Nitridation Induced-Reactions in Si and SiO2
Authors: Jaccodine Ralph J.
Published: March 2011

Current IC technology uses SiO2 almost exclusively; however, several technological and reliability problems warrant the search for an alternative dielectric. Proposed alternatives are silicon nitride and nitrided SiO2. This paper reviews the work on thermal nitridation of Si and SiO2. Several of the experimental thermal nitridation processes used to achieve good thin dielectrics are discussed. At this time a clear mechanism for the nitridation of Si is not available. The two theoretical attempts to model this process are reviewed. Innovative processes to accomplish the nitridation, such as plasma growth, etc., are presented. Finally, the influence of nitridation on stacking faults and diffusions is also reviewed.
The Role of Vacancies in Enhancing Oxygen Diffusion in Silicon
Authors: Oates A. S. , Newman R. C. , Tucker J. M. , Davies G. , Lightowlers E. C.
Published: March 2011

Measurements of optical bands in irradiated Si are combined with numerical modelling of the radiation induced reactions. No evidence is found for appreciable interaction of self-interstitials with O atoms for irradiations carried out at temperatures between 25 and 500°C. The reduction during electron irradiation of stress-induced dichroism in the 9μm oxygen band is shown to occur by sequential capture of a vacancy and a self-interstitial at the oxygen for irradiations carried out between 25 and 280°C. At higher temperatures repetitive capture and release of vacancies at oxygen atoms appears to dominate in the oxygen migration process.
Direct Comparison of FTIR and SIMS Calibrations for [O] in Silicon
Authors: Chu P. K. , Hockett R. S. , Wilson R. G.
Published: March 2011

Fourier Transform Infra-Red spectroscopy (FTIR) is commonly used to measure interstitial oxygen concentrations in silicon. The absorption coefficient αOX derived from the IR transmittance curve is converted to a concentration value through a multiplicative calibration factor γOX. Presently used calibration factors include 2.45 × 1017 cm−2 (ASTM F121−80), 3.03 × 1017cm−2 (JEIDA), and 4.81 × 1017 cm−2 (ASTM F121−76). These have been obtained from different analytical methods, including charged particle activation, helium carrier gas fusion-gas chromatography, vacuum fusion gas analysis, and photon activation combined with inert gas fusion. An alternative analytical method by secondary ion mass spectrometry (SIMS) is reported here. Oxygen ions of a known fluence are implanted into silicon samples of which oxygen content has been measured by FTIR. SIMS profiles of oxygen are performed using a cesium primary ion beam on a CAMECA IMS-3f. The result is a profile of the superposition of the implanted oxygen and the constant, bulk CZ oxygen. Integration of the implant signal followed by subtraction of the bulk signal can be used to calibrate the implant concentration from the implanted oxygen fluence, so that, in the same sample and during the same measurement, the SIMS calibration and FTIR calibration at the CZ bulk level can be directly compared. The γOX obtained from this method is 3.45 × 1017cm−2 and is closest to the JEIDA value of 3. 03 × 1017 cm−2.
SIMS Measurements of Oxygen in Heavily-Doped Silicon
Authors: Bleiler R. J. , Hockett R. S. , Chu P. , Strathman E.
Published: March 2011

Oxygen precipitation in CZ silicon is known to provide beneficial yield improvements in integrated circuit processing if the location and amount of precipitation can be properly controlled. The concentration of oxygen in the unprocessed silicon substrate is one of the most important variables to control for achieving these improvements. Fourier Transform Infrared Spectroscopy (FTIR) has successfully been used to measure [0] in silicon when the silicon resistivity is greater than about 0.1 Ω-cm. At lower resistivities typical of p+ and n+ substrates used for epi-wafers as free carrier absorption interferes with the FTIR measurement of bulk [0].

This work will focus on how to quantitatively measure oxygen in heavily-doped silicon by Secondary Ion Mass Spectrometry (SIMS) with a high sample thruput, low background signal, and tight σ/x distribution. SIMS calibration is performed against FTIR-calibrated substrates with resistivity higher than 0.1Ωcm. Typical background signals as measured in FZ are a factor of 20 below signals in CZ, and the 160− signal in CZ is over 105 count/sec. resulting in an excellent signal-to-noise ratio for each single measurement. Typical thruput is 18 samples per day where each sample is analyzed four to five times to obtain a σ/x of 3% for an oxygen level of 15 ppma (ASTM F121−80).
Structure and Properties of The Oxygen Donor
Authors: Kimerling L. C.
Published: March 2011

During aggregation, an assembly of oxygen atoms in silicon produces an electrically active site. The center is an effective mass, helium-like center (double donor) with a wave function of C2v symmetry. The formation reactions of the assembly reveal details of the invisible early stages of aggregation. The donor character of the center controls the aggregation process in heavily doped material. The atomic structure and the source of the electrical activity of the center remain unresolved.
Design Principles for Microwave Heating and Sintering
Authors: Tinga W.R.
Published: March 2011

Microwave heating equations are shown to have a complex functional dependence on material and process parameters such as composition, density, temperature, frequency and geometry. Power flow and its deposition in the presence of simple material shapes are used to illustrate relevant electromagnetic boundary conditions. Various types of applicator design using standing wave and travelling wave structures are discussed with respect to the results on power density, process efficiency and controllability. The problem of measuring and controlling the temperature inside a microwave system is addressed with emphasis on the use of thermocouples and infrared thermometry. Some of the problems peculiar to high temperature processing are considered. A review of the dielectric and magnetic property variation with temperature and frequency is given in order to understand the complexity and difficulty of uniformity of heating even with microwaves. The use of combination processing, for example, microwaves and infrared heating, is discussed. A short bibliography is presented listing some important publications in the field.
Compositional Control of Ceramic Microstructures: An Overview
Authors: Harmer M. P. , Chan H. M. , Smyth D. M.
Published: March 2011

A review is given of the controlled use of compositional variation in the sintering of ceramics. The difficulties in determining the mechanisms of operation of sintering additives are outlined and the mechanistic approaches for studying the subject are described. Important remaining issues, new developments and opportunities for developing unique ceramic microstructures through the controlled use of compositional variation are described. Attention is focused on lattice defects and grain growth inhibition, particle pinning, multiple doping, anion effects, anisotropy effects, scavenging, surface diffusion and the formation of wavy grain boundaries.
Fabrication Reliability of Ceramics: Controlling Flaw Populations
Authors: Lange F.F.
Published: March 2011

The major hindrance in using structural ceramics in well defined engineering applications is their lack of reliability caused by uncontrolled flaw populations introduced during fabrication. Mechanical reliability is thus a matter of fabrication reliability. The strengthening that can be achieved by either eliminating or reducing the size of flaw populations through changing either processing or microstructure will be reviewed.
Computer Simulation of Defect Properties and Processes at High Temperature
Authors: Harding J. H.
Published: March 2011

We show how the entropies of formation and migration of point defects may be calculated accurately. The approximations inherent within static lattice calculations are assessed, in particular the Vineyard reaction rate theory.
New and Old Ceramic Processes: Manufacturing Costs
Authors: Rothman E.P. , Bowen H.K.
Published: March 2011

Recent advances in the property and performance requirements of ceramics have stimulated new approaches to ceramics processing. One approach being studied in numerous laboratories around the world involves the introduction of specialty chemicals to the sequential processing steps. Because many of these new approaches involve changes in equipment, raw materials, and processing variables, this paper focuses on an examination of the process economics. In some instances we can project the costs for these new technologies by considering the costs of similar commercial processes.
Atomic Resolution Studies of Tilt Grain Boundaries in NiO
Authors: Merkle K. L. , Reddy J. F. , Wiley C. L. , Smith David J. , Wood G. J.
Published: March 2011

The atomic structures of a number of <001> high-angle tilt grain boundaries in NiO have been studied by high-resolution electron microscopy (HREM). Crystal 1inity is always maintained right up to the grain boundary (GB). Grain boundary planes bounded by a (100)-plane are preferred, however symmetrical facets are also found at each misorientation. A tendency to match atomic planes across the GB is not only observed in symmetrical, but also in asymmetrical GBs. Structural units can be clearly recognized in symmetrical GBs. Contrast differences suggest that a multiplicity of structural units exists for some GB configurations. Frequently symmetric GBs also show deviations from mirror symmetry. Multislice simultations indicate that the image contrast associated with HREM GB images is not particularly sensitive to GB relaxation.
Electrical Conductivity and Seebeck Coefficient of Divalent-Metal-Doped YCrO3
Authors: Weber W. J. , Bates J. L. , Griffin C. W. , Olsen L. C.
Published: March 2011

The substitution of divalent metal ions for γ(+3) in γCrO3 results in a charge compensating transition of Cr(+3) to Cr(+4) and the formation of small polarons as charge carriers. The experimentally measured electrical conductivity, σ, and Seebeck coefficient, S, exhibit behavior consistent with a theoretical model developed for small polaron transport in these narrow-band semiconductors. The small polaron transport is a thermally-activated process with a measured activation energy, E, of about 0.18 to 0.25 eV in these materials. Both σ and S increase with temperature and show a near linear dependence on dopant concentration and a strong dependence on dopant (ionic) size. Analysis of the results in terms of the model indicates that Ca is much more effective in polaron formation than any of the other dopants in γCrO3; this is due to the similar ionic size of Ca(+2) and γ(+3) which minimizes the lattice distortion from substitution.
The Study of the Formation and Growth of Ni-Al Spinel Using a New, Thin-Film, Specimen Geometry
Authors: Simpson Y. Kouh , Carter C. B.
Published: March 2011

The formation of nickel-aluminate spinel during the reaction between nickel oxide and alumina has been studied by a new approach which utilizes a thin-film substrate of alumina. It is found that the spinel grows in either near- or exact-topotactic alignment along the edges of the thin-film substrate. It also grows on and into the surface of the substrate, but the deviation from exact topotaxy then tends to be larger. The topotactic relationship is such that the (0001) of the alumina is parallel or nearly parallel to the {111} planes of the spinel with <1100> parallel to <110>. A second orientation relatioship is found where the {1120} of the alumina is parallel or nearly parallel to the {111} planes of the spinel; <1100> is again parallel to <110>. First order twin boundaries are found to be common in the spinel particles which have grown on the edge of the thin alumina substrate. Direct observation of the change in the orientation of the spinel twins with respect to the alumina substrate after reannealing is reported. The morphology of the various types of spinel particles is discussed briefly.
Probability of Detection of Internal Voids in Structural Ceramics Using Microfocus Radiography
Authors: Baaklini George Y. , Roth Don J.
Published: March 2011

The reliability of mlcrofocus x-rad1ogrphy for detecting Internal voids 1n structural ceramic test specimens was statistically evaluated. The micro-focus system was operated in the projection mode using low x-ray photon energies (≤;20 keV) and a 10 μm focal spot. The statistics were developed for Implanted Internal voids 1n green and sintered silicon carbide and silicon nitride test specimens. These statistics were compared with previously-obtained statistics for implanted surface voids in similar specimens. Statistical results are given as probability-of-detection curves at a 95 percent confidence level for voids ranging in size from 20 to 528 μm in diameter.
Calculated Impurity Segregation at the Surfaces of α-Al2O3
Authors: MacKrodt W. C. , Tasker P. W.
Published: March 2011

Atomistic lattice simulations are reported of the segregation of yttrium at the {0001}, {1010} and {0112} surfaces and magnesium at the {0001} surface of α-Al2O3. Equilibrium coverages are deduced from the calculated enthalpies of segregation on the basis of a non-Arrhenius isotherm. For magnesium the calculated enthalpy of segregation at low coverage, ∼158 kJ mole−1, is in good agreement with a measured value of ∼146 kJ mole−1 reported recently.
Ceramics and Ceramic Composites: Opportunities and Cooperative Research Modes
Authors: Wachtman John B.
Published: March 2011

Ceramics and ceramic composites are a rapidly evolving category of materials capable of being tailored to have unique combinations of electrical, optical, mechanical, and chemical properties that make them essential and irreplacable in many engineering applications. Conventional ceramics have both enabled and enhanced many important aspects of our modern technological society; the next generation of ceramics will play a further enabling role for still higher performance devices.

A briefing panel of the National Academies of Science and Engineering recently identified four areas into which promising research areas for advanced ceramics can be grouped:

1.

New thin films and layer structures with improved properties.

2.

Exploration of completely new, multicomponent ceramic crystal structures and composites.

3.

The mechanical behavior of ceramics and tough composites.

4.

Ceramic processing of large parts and assemblies.

Three mechanisms for achieving critical mass in ceramics research were recommended:

1.

University/industry programs.

2.

A summer institute.

3.

A large interdisciplinary center.
Interaction of Copper With Single Crystal Sapphire
Authors: Schrott A. G. , Thompson R. D. , Tu K. N.
Published: March 2011

The effect of small coverages of Cu evaporated in ultra-high vacuum (UHV) on A12O3 (0001) surfaces has been investigated by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). These surfaces were cleaned either by annealing at 1000°C in O2 or by Ar sputtering. They differ both in their initial state and their interaction with Cu. The XPS spectra from as-deposited Cu on sputtered samples exhibit small shifts in the energy location of the various peaks as compared to those from a Cu standard. Annealing the Cu/sputtered A12O3 structure at 500°C produces a shoulder on the Cu 3d peak as well as a new Cu (L3 M4.5 M4.5) Auger feature. Neither of these effects are observed after similar treatment of the Cu/annealed A12O3 structure. An influence of this different bonding situation on the Cu-sapphire interfacial energy is observed.