bluuebunny/crossref_metadata_2025 huggingface dataset:
Tensile and Creep Rupture Properties of Co + Co3AIC0.5 Two-Phase Alloys
Authors: Ishibashi R. , Nakamura S. , Aono Y. , Miura S. , Mishima Y.
Published: April 2011

It is expected that the κ-phase of the intermetallic compound Co3A1C0.5 would strengthen Cobase alloys used at high temperatures like the γ' -phase of Ni-base superalloys. Tensile and creep rupture properties of Co+κ two-phase alloys with κ-phase volume fractions up to 0.75 were investigated. Alloy samples made by directional solidification casting were annealed at 1573 K for 3.6 ks and at 1373 K for 28.8 ks in vacuum, followed by Ar gas cooling. Tensile tests at RT and 1073 K and creep rupture tests at 1089 K under a stress of 172 MPa were conducted with the tensile axis parallel to the solidification direction. In alloys with low κ-phase volume fraction, cuboidal K-precipitates with average particle diameters of 0.4 to 1.0 μm were observed. They were coherent with the Co(fcc) matrix with misfits of about 3%. As the κ-phase volume fraction increased, tensile strength also increased. The alloy with κ-phase volume fraction of 0.4 had a 0.2% proof stress of 817MPa, tensile strength of 1047 MPa at RT, creep rupture life of 1.43 Ms, and tensile strain higher than 10%. These strengths are better than those of the conventional Co-base alloys. However, ductility of alloys with κ-phase volume fraction larger than 0.4 decreased due to large eutectic and primary κ-phase particles.
Dislocation Dynamics Studied by Mechanical Loss in a Ni3(AI, Ta) Single Crystal at Intermediate Temperatures
Authors: Cheng B. L. , Carreño-Morelli E. , Baluc N. , Bonneville J. , Schaller R.
Published: April 2011

Dislocation dynamics in Ni3AI intermetallic single crystals has been studied by mechanical spectroscopy between 300 and 700 K. It has been found that in the anomaly domain of the flow stress, which is characteristic of this material, the mechanical loss of predeformed specimens is strongly dependent on strain amplitude, predeformation level, annealing temperature and time. The results can be interpreted as a combination of two phenomena which simultaneously occur as temperature is increased from 300 K to about 500 K: exhaustion of the mobile dislocation segments (superkinks) and pinning of the screw dislocation segments via cross-slip from the (111) onto the (010) planes.
Continuous Solid Solution of -K-phase in the Third Period Transition Metals-Aluminum-Carbon Pseudo-Ternary Systems
Authors: Hosoda Hideki , Suzuki Kensyo , Hanada Shuji
Published: April 2011

Phase stability of κ-phases (perovskite-type phases) was studied in the third-period transitionmetals (M: Mn to Cu) - aluminum (Al) - carbon (C) systems. The concentrations of transition metals (CM) were systematically changed from 60mol%Mn to 20mol%Ni+40mol%Cu along the periodic table under the constant nominal alloy compositions of CMl+CM2=60mol%, CA1=60mol% and Cc=20mol%. Alloys were prepared using mechanical alloying and hot pressing. Constituent phases were investigated by X-ray diffraction analysis, scanning electron microscopy and electron probe microanalysis. It is confirmed that Mn3Al(C,O)0,95, Fe3Al(C,O)0.87, Co3AI(C,O)0. 6 and Ni3Al(CO)0.26 exist in their ternary systems where oxygen is introduced during the process. Also, only one κ-phase is recognized in an alloy having an intermediate composition in every system. This suggests that continuous solid solutions between these κ-phases are formed in the pseudo-ternary systems. Composition dependence of lattice parameter is discussed.
Mechanical Properties of E21 (Mn, Fe)3AIC-Base Alloys
Authors: Suzuki Kensyo , Hosoda Hideki , Hanada Shuji
Published: April 2011

Mechanical properties of E21 (Mn, Fe)3AlC-base alloys were investigated. The E21 crystal structure is closely related to L12, and thereby E21 compounds are expected to exhibit superior properties similar to those of the L12 Ni3AL. Nominal compositions are fixed to be 60mol%(Mn, Fe)-20mol%A1–20mol%C. Alloys were prepared by mechanical alloying and hot pressing. ICP chemical analysis, X-ray diffraction analysis, scanning electron microscopy and electron probe microanalysis were carried out for alloy characterization. Mechanical properties were evaluated by Vickers hardness tests at room temperature (RT) and compression tests from RT to 1273K. Strain rate dip tests were also carried out. It is found that most alloys are composed of two phases of E21 as the primary phase and graphite as the precipitates, and that the volume fraction of graphite increases with increasing Fe content. Hardness and 0.2% flow stress at RT are raised with increasing Fe content. At RT, 0.2% flow stress and fracture strength of Fe3A1C alloy used are 2.9GPa and 3.4GPa, respectively. An alloy containing 40%Mn-20%Fe shows weak positive temperature dependence of strength at 700–800K, similar to the observation in some Co3AIC alloys. Moreover, work-hardening coefficient of all alloys shows strong positive temperature dependence below 700K. These results suggest the occurrence of K-W related mechanism for plastic deformation in these alloys.
Thermal Fatigue of NiAl Single Crystals
Authors: Kush M. T. , Holmes J. W. , Gibala R.
Published: April 2011

Single crystals of [001]-oriented NiAI single crystals were subjected to thermal fatigue by a method which employs induction heating of disk-shaped specimens heated in an argon atmosphere. Several time-temperature heating and cooling profiles were used to produce different thermal strain histories in specimens cycled between 973 K and 1473 K. After thermal cycling, pronounced shape changes in the form of diametrical elongations along <100> directions with accompanying increases in thickness at and near the <100> specimen axes were observed. The deformations were analyzed in terms of operative slip systems in tension and compression, ratchetting (cyclic strain accumulation), and the elastic properties of NiAl. The experimental results correlate best with thermal stresses associated with the large elastic anisotropy of NiAl.
Fabrication Of High Quality Qc Films Via The Route Of The Amorphous Phase
Authors: Haberkern R. , Roth C. , Knöfler R. , Schulze L. , Häussler P.
Published: April 2011

We discuss the preparation of thin icosahedral films (Al-Cu-Fe and Al-Pd-Re) via the route of the amorphous (a-)phase which in some aspects is a precursor to the icosahedral phase. A direct transition from the a- to the i-phase occurs for Al-Cu-Fe films at 430°C on the time scale of minutes. The resulting films are of good quality as shown by diffraction and electronic transport properties. The surface of the resulting films is very smooth.
Structural Studies Of Decagonal Quasicrystals And Approximants Using The High-Angle Annular Dark-Field Method
Authors: Saitoh Koh , Tsuda Kenji , Tanaka Michiyoshi , Tsai An Pang
Published: April 2011

High-angle annular dark-field (HAADF) images of an A172Ni20Co8 decagonal quasicrystal and monoclinic Al13Fe4 and τ2-inflated Al13C04 approximants have been presented. We found that a 2 nm atom cluster of Al72Ni20Co8, which have been believed to be tenfold so far, has no tenfold symmetry. A new structural model of Al72Ni20Co8 has been constructed on the basis of the HAADF images and the structure of monoclinic Al13Fe4 approximant. We have found that the monoclinic Al13Fe4 and τ-inflated Al13Co4 approximants are composed of the same basic structure of a pentagonal atom cluster with an edge length of 0.47 nm. We have also found that a fivefold atom-cluster with a 2 nm diameter exists in τ-Al13Co4, which was observed in decagonal quasicrystals of Al-Ni-Fe, Al-Ni-Co, Al-Cu-Co and Al-Co by highresolution electron microscopy. A structural model of τ-inflated Al13Co4 is constructed on the basis of the convergent-beam electron diffraction symmetry, HAADF images and the structure of monoclinic Al13Fe4.
Characterization And Properties Of The AIPdMn 5 Surface
Authors: Cappello G. , Dechelette A. , Schmithusen F. , Chevrier J. , Comin F. , Stierle A. , Formoso V. , De Boissieu M. , Lograsso T. , Jenks C. , Delaney D
Published: April 2011

The surface of the AlPdMn quasicrystal perpendicular to a fivefold axis has been probed by LEED, XPS, Auger spectroscopy and surface EXAFS.
Oxidation Of AI-Cu-Fe Quasicrystals
Authors: Wehner B. I. , Köster U.
Published: April 2011

The oxidation behavior of i-A163Cu25Fe12 at 800°C in air was investigated by means of TGA, XRD, SEM and TEM. In the beginning a homogeneous oxide layer is formed by the subsequent growth of metastable γ-Al2O3 and Θ-Al2O3. Nucleation of the thermodynamical stable α-Al2O3 occurs at the interface oxide/quasicrystal. The following growth of α-Al2O3 through the oxide layer leads to the formation of oxide nodules. The high growth rate of the α-Al2O3 can be explained by the incorporation of copper ions. The oxidation resistance of the quasicrystal is insufficient at high temperatures, because no protective oxide layer is formed. The high temperature oxidation behavior of Al-Cu-Fe quasicrystal and the aluminides β-FeAl and β-NiAl is compared regarding the oxidation rate, the oxide phases and the concentration changes in the material due to selective oxidation of aluminum.
Effect of Processing Variables on The Magnetic Field Orientation of Liquid Crystalline Thermosets
Authors: Lincoln Derek M. , Douglas Elliot P.
Published: April 2011

We have investigated the effect of various processing variables on the magnetic field orientation of a liquid crystalline epoxy. By using a modified fractional factorial design, we created an empirical model which can be used to predict the degree of orientation as a function of these variables. The model predicts the correct qualitative trends, namely that orientation increases with increasing magnetic field strength, increases with increasing time in the field, and decreases with increasing B-staging. The model also reveals some surprising effects of B-staging on the degree of orientation.
The Dynamic Properites of Confined Antiferroelectric Liquid Crystal Investigated By Photon Correlation Spectroscopy
Authors: Panarin Yu.P. , Rosenblatr C. , Aliev F.M.
Published: April 2011

Dynamic light scattering was used to examine ferrielectric liquid crystalline phases in porous media. Whereas in larger pores (200 Å) ferrielectric phases were observed, they were not found in the smallest pores (200 Å). Additionally, the temperatures of SmC - SmA phase transition were found to be suppressed in the pores relative to bulk, while SmCA - SmCγ phase transition is not affected by the confinement. These observations have been explained by the structural aspects of antiferroelectric liquid crystalline materials in a confined geometry and show the importance of long range electrostatic interaction for existence of ferrielectric phases.
Polymer Dispersed Liquid Crystals as Optical Storage Materials
Authors: Simoni F. , Bella S. Di , Lucchetti L. , Cipparrone G. , Mazzulla A.
Published: April 2011

Among the different methods used to prepare Polymer Dispersed Liquid Crystals (PDLC), the Polymerisation Induced Phase Separation technique (PIPS) can be exploited to obtain optical recording in these materials. The possibility of performing optical storage of binary images in PDLC during the curing process and post curing holographic recording, will be described and discussed.
Grazing Incidence X-Ray Scattering Studies of the Structure and Morphology of the Ni/Mgo(001), Co/Nio(111) and Nife/Nio(111) Interfaces During their in Situ Growth
Authors: Renaud G. , Barbier A. , Mocuta C.
Published: April 2011

Combined in situ structural and ex situ magnetic studies of the Co/NiO(111) and Ni81Fe19/NiO(111) interfaces are presented. The Co and Permalloy films were grown on NiO(111) single crystals. Structural studies were performed by Grazing Incidence X-ray Scattering during growth. The effect of the temperature of the substrate during deposition was investigated. Under specific growth conditions, almost pure FCC Co and NiFe films can be obtained, with small quantities of twins. Magnetic measurements were performed ex situ by Magneto-Optical Kerr Effect (MOKE). A strong correlation between the magnetic properties and the crystallographic structure of the Co film is evidenced. High coercive fields are measured for all samples. High temperature annealing of the NiFe film leads to an improved crystalline quality, but the interface becomes reactive and diffuse: part of the Fe diffuses into the NiO substrate and forms an interface compound, likely to be the spinel NiFe2O4. We also report an in situ grazing incidence X-ray scattering study of the Ni/MgO(001) interface during its formation at room temperature. In-plane measurements reveal that the interface is sharp and that the epitaxial relationship is complex. Two distinct lattices are found to exist: expanded Ni(001) and Ni(110). The latter exhibits several orientations with respect to the substrate depending on the thickness. The Ni(110) orientations disappear by annealing at high temperature, leaving only the Ni cube/cube orientation. The layer was also almost fully transformed into NiO(001) by high temperature oxidation.
Growth and Structure of Metallic Barrier Layer and Interconnect Films I: Exeriments
Authors: Windt D. L. , Tortre J. Dalla , Gilmer G. H. , Sapjeta J. , Kalyanaraman R. , Baumann F. H. , O'Sullivan P. L. , Dunn D. , Hull R
Published: April 2011

We present experimental results directed at understanding the growth and structure of metallic barrier layer and interconnect films. Numerical simulation results associated with this experimental work are presented in an accompanying paper in these proceedings. Here, thin films of Al, Ti, Cu and Ta have been grown by magnetron sputtering onto oxidized Si substrates. Using a specially-constructed substrate holder, the orientation of the substrate with respect to the growth direction was varied from horizontal to vertical. Films were grown at both low and high argon pressure; in the case of Ta, the cathode power was varied as well. The film structure and in particular the surface roughness was measured by X-ray reflectance and also by atomic force microscopy. We find that the surface roughness increases markedly with orientation angle in the case of Ta and Cu films, and in Ti films grown at high argon pressure. At low pressure, however, the Ti film surface roughness remains constant for all substrate orientations. No variation in roughness with either orientation angle or argon pressure was observed in the Al films. These results suggest that, under certain circumstances, shadowing effects and/or grain orientation (i.e., texture) competition during growth can give rise to lower density, more porous (and thus more rough) films, particularly at large orientation angles, as on sidewalls in sub-micron trenches.
Crystalline Texture of CoCrPt Films on CrMn/NiAl and Cr/NiAl Underlayer Structures
Authors: Zou J. , Lu B. , Bayer A. E. , Laughlin D. E. , Lambeth D. N.
Published: April 2011

In this study, we examine the effects of CrMn/NiAl and Cr/NiA1 underlayer structures on the crystalline texture and microstructure of CoCrPt magnetic films using x-ray and electron diffraction. The former underlayer structure was found to induce better CoCrPt (image1) texture. The stress in the CoCrPt layer was measured. The effective in-plane anisotropy energy densities of the CoCrPt films on the above two underlayers were also measured by using out-of-plane torque and Miyajima methods and the result was consistent with the texture analysis.
Microstructural Characterization Methods for Magnetic Thin Films
Authors: Wittig J. E. , Bentley J. , Nolan T. P.
Published: April 2011

Microstructural characterization is key to determining the structure-property-processing relationships required to optimize the performance of magnetic thin films for longitudinal magnetic recording. Since the grain size of modem recording media is on the order of 10 to 20 nm, only high-resolution characterization methods such as transmission electron microscopy (TEM) can accurately describe the microstructure. Complete analysis requires a combination of conventional and high-resolution TEM imaging with analytical methods such as energy dispersivespectroscopy and energy-filtered TEM imaging. This paper provides examples from CoCr(Pt,Ta) alloys that reveal the strengths and limitations of these characterization methods as they apply to microstructural characterization of magnetic thin films.
Mechanism of Cu removal during CMP in H2O2-glycine based slurries
Authors: Hariharaputhiran M. , Ramarajan S. , Li Y , Babu S.V. , Babu S.V.
Published: April 2011

Hydroxyl radical generation has been observed during Cu CMP using hydrogen peroxide-glycine based slurries. While the Cu dissolution/polish rates increased with increasing glycine concentration, the copper dissolution rate decreased with increasing peroxide concentration indicating the occurrence of both dissolution and passive film formation during CMP. This is further confirmed by both in situ and ex situ electrochemical experiments.
Interfacial Pressure Measurements at Chemical Mechanical Polishing Interfaces
Authors: Shan Lei , Danyluk Steven , Levert Joseph
Published: April 2011

We have found that the entrainment of a slurry between a silicon surface and a polyurethane pad will cause the generation of subambient pressure at that interface. These pressures cause the silicon to be further impressed into the pad. We have measured these pressures and this paper reports on the pressure distribution maps over an area beneath a 100mm diameter silicon wafer. The pressures are generally not uniform. The leading 2/3 of the wafer has subambient pressures of the order of 50kPa and the trailing 1/3 of the wafer has positive pressures of approximately 10kPa. The reasons for the subambient pressures is related to the dynamics of the compression of pad asperities, the boundary effects of the silicon edge, the rebound of the asperities, and re-infiltration of the slurry.
Directions in the Chemical Mechanical Planarization Research
Authors: Murarka Shyam P.
Published: April 2011

Planarized surfaces have become key to the success of advanced semiconductor devises/circuits/chips. The planarization, achieved by the use of chemical mechanical means, has enabled the interconnection of ever increasing number of devices and also the use of lower resistivity copper as the interconnect material for such devices. Chemical mechanical planarization (CMIP) has now found application at several different stages of semiconductor chip fabrication and many other microelectronic applications. However, there remain a large number of nuances and effects e.g. pattern, chemical, and pad dependencies and scratching, that need to be carefully studied, evaluated and eliminated if we want to continue to progress in sub 0.1 µm (minimum feature size) regime, where the amounts of material to be removed will be small, surfaces will dominate the performance, and margin of error extremely small and unforgiving. This presentation will discuss the future needs, the CMP variables, the relationship of these variables to CMP behavior and planarity, scratch-free CMP, and size-impact on CMP outcome. A new set of goals will be presented and discussed.
A Novel Retaining Ring in Advanced Polishing Head Design for Significantly Improved CMP Performance
Authors: Osterheld Thomas H. , Zuniga Steve , Huey Sidney , McKeever Peter , Garretson Chad , Bonner Ben , Bennett Doyle , Jin Raymond R.
Published: April 2011

This paper reports a technological advancement in developing and implementing a novel retaining ring of advanced edge performance (AEPTM ring) for an advanced polishing head design. The AEP ring has been successfully used for significantly improved CMP performance in different CMP applications: oxide (PMD and ILD), shallow trench isolation (STI), polysilicon, metal (W and Cu), silicon-on-insulator (SOI), and silicon CMP. Robust processes have been developed using AEP ring along with many hardware upgrades for each application with extended runs to meet requirements of advanced IC device fabrication.
N2O Oxidation Kinetics of Ultra Thin Thermally Grown Silicon Nitride: An Angle Resolved X-Ray Photoelectron Spectroscopy Study
Authors: Mao A. Y. , Lozano J. , White J. M. , Kwong D. L.
Published: April 2011

The oxidation kinetics of ultra thin thermally NH3-nitrided Si3N4 films in N2O ambient has been extensively studied using angle resolved x-ray photoelectron spectroscopy (ARXPS). Ultra thin (7Å) Si3N4 films formed by RTP nitridation of Si in NH3 were annealed in N2O at various temperatures (700 °C - 1000 °C) for 30 sec. ARXPS showed that Si substrate at the Si-Si3N4 interface was oxidized when annealed at 1000 °C for 30 sec, and was accompanied by the oxidation of the top Si3N4 surface. The total film thickness increases 4–5 times of that of the original Si3N4 layer. However, the oxide formed on the top Si3N4 surface is twice as thick as that formed at the Si3N4/Si interface. No interfacial oxide was found when annealing below 900°C, although the formation of the silicon oxide and oxynitride above the Si3N4 layer was still observed.
Nitridation by NO Or N2O of Si-SiO2 Interfaces
Authors: Caricato A. P. , Cazzaniga F. , Cerofolini G. F. , Crivelli B. , Polignano M. L. , Tallarida G. , Valeri S. , Zonca R.
Published: April 2011

X-ray photoelectron spectroscopy (XPS) and photocurrent measurements for the determination of surface recombination velocity provide complementary information on the structure of the Si-SiO2 interface, being sensitive to the chemical nature of foreign species at the interface the former, and to intrinsic defects the latter. The comparison of the XPS N(1s) peaks determined for the Si-Si0 2 interfaces nitrided in NO or N2O ambients is useful to identify the species responsible for the broadening of the peak. In fact, nitridation by NO is mainly responsible for the formation of Si3N moieties at the silicon surface in which silicon atoms are partially oxidized; while nitridation by N2O proceeds with the oxidation of Si – Si backbonds to Si – N bonds, thus resulting in the formation of N(Si(O-)3)3 groups embedded in the oxide. Surface recombination velocity by photocurrent measurements gives evidence that nitridation in N2O is associated with an appreciable co-oxidation, while nitridation in NO is mainly associated with the passivation of interface states. Furthermore N2O and NO nitridation are responsible for different morphologies of the nitrided layers.
Nitrogen Profile Engineering for Tunnel Oxynitrides
Authors: Sugizaki Taro , Tada Yoko , Hikazutani Ken-Ichi , Nakanishi Toshiro , Takasaki Kanetake
Published: April 2011

We consider nitrogen profiling in oxynitrides to be the key technology for next generation Flash Memories, because of its ability to suppress the generation of traps in tunnel oxides. We are trying to develop an oxynitriding technique for tunnel oxides that uses nitric monooxide. This time, we tried to control nitrogen profile in oxynitrides by using reoxidized oxynitride process. By using a three- step oxidationoxynitridation-reoxidation process, we attempted to systematically tune oxidation conditions, to obtain a satisfactory tunnel oxide/Si interface and SILC characteristics. Highly reliable tunnel oxide for flash memory has been achieved using recently developed reoxidized oxynitrides processing, which is characterized by wet oxidationoxynitridation-dry oxidation. This process yields excellent characteristics, such as low oxide trap formation, low leakage current, and high charge to breakdown (Qbd). This three-step oxynitride process is best suited for flash memories having superior Program/Erase (P/E) cycling endurance and data retention characteristics. In addition, I will propose the optimum conditions for the reoxidation process.
Ultrathin oxide film formation using radical oxygen in a UHV system
Authors: Watanabe K. , Kimura S. , Tatsumi T.
Published: April 2011

Radical oxidation at thickness of under 2.0 nm in an ultrahigh vacuum (UHV) system with an electron cyclotron resonance (ECR) plasma has been studied. The interface roughness and oxide density were evaluated by atomic force microscopy (AFM) and grazing incidence xray reflectrometry, respectively. We found the oxide thickness could be easily controlled at Tsub = 750°C when using radical oxygen at 5.0×10−3Torr. The interface roughness at a thickness of 1.8 nm, measured by the root mean square (RMS), was 0.11 nm. The density of the radical oxide fell as the oxide thickness decreased, especially at less than 2.0 nm. However, the density of the radical oxide annealed in molecular oxygen at 5×10−3Torr and Tsub = 750°C increased, without the oxide thickness increasing. We think that the first insertion of an oxygen atom into the first Si layer has a much higher energy barrier than that into a SiOx layer. The radical oxygen can pass through this higher energy barrier, and thus oxygen molecules fill the oxide layers. This mechanism means that we can control the oxide thickness and density separately at thickness of less than 2.0 nm through the radical oxidation time and the annealing time in molecular oxygen. We expect low-pressure radical oxidation to be the most suitable process for future ultrathin gate oxidation.
Tantalum Pentoxide Gate Dielectrics Formed by Tantalum Oxidation
Authors: Hobbs C. , Hegde R. , Maiti B. , Nagabushnam R. , La L. , Reid K. , Dip A. , Grove L. , Conner J. , Kaushik V. , Prabhu L. , Anderson A. , Bagchi S. , Mendonca J. , Tobin P.
Published: April 2011

Tantalum pentoxide (Ta2O5) films were formed by oxidizing thin tantalum (Ta) films on bare and NO-nitrided silicon substrates. The 43-400 Å thick Ta films were deposited using physical vapor deposition (PVD) and oxidized using O2 for 2-60 min at 550-800 C in a furnace or single wafer tool. Uniform and stoichiometric Ta2O5 films were successfully produced as determined from XRD, AES depth profiling, XTEM, and ellipsometric analysis. The nitridation pretreatment was found to minimize the interfacial Ta-Si reactions which occur during the oxidation. Well-behaved CV and IV curves were obtained from mercury probe measurements. No CV hysteresis was observed. An equivalent oxide thickness of 38 Å and a leakage current of 7×10−9 A/cm2 at +1V were obtained for a 120 Å thick Ta2O5 film on a 15 Å interfacial SiO2 layer.
Properties of Epitaxial SrTiO3 Thin Films Grown on Silicon by Molecular Beam Epitaxy
Authors: Yu Z. , Droopad R. , Ramdani J. , Curless J.A. , Overgaard C.D. , Finder J.M. , Eisenbeiser K.W. , Wang J. , Hallmark J.A. , Ooms W.J.
Published: April 2011

Single crystalline perovskite oxides such as SrTiO3 (STO) are highly desirable for future generation ULSI applications. Over the past three decades, development of crystalline oxides on silicon has been a great technological challenge as an amorphous silicon oxide layer forms readily on the Si surface when exposed to oxygen preventing the intended oxide heteroepitaxy on Si substrate. Recently, we have successfully grown epitaxial STO thin films on Si(001) surface by using molecular beam epitaxy (MBE) method. Properties of the STO films on Si have been characterized using a variety of techniques including in-situ reflection high energy electron diffraction (RHEED), ex-situ X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Auger electron spectroscopy (AES) and atomic force microscopy (AFM). The STO films grown on Si(001) substrate show bright and streaky RHEED patterns indicating coherent two-dimensional epitaxial oxide film growth with its unit cell rotated 450 with respect to the underlying Si unit cell. RHEED and XRD data confirm the single crystalline nature and (001) orientation of the STO films. An X-ray pole figure indicates the in-plane orientation relationship as STO[100]//Si[110] and STO(001)// Si(001). The STO surface is atomically smooth with AFM rms roughness of 1.2 AÅ. The leakage current density is measured to be in the low 10−9 A/cm2 range at 1 V, after a brief post-growth anneal in O2. An interface state density Dit = 4.6 × 1011 eV−1 cm−2 is inferred from the high-frequency and quasi-static C-V characteristics. The effective oxide thickness for a 200 Å STO film is around 30 Å and is not sensitive to post-growth anneal in O2 at 500-700°C. These STO films are also robust against forming gas anneal. Finally, STO MOSFET structures have been fabricated and tested. An extrinsic carrier mobility value of 66 cm2 V−11 s−1 is obtained for an STO PMOS device with a 2 μm effective gate length.
Electrical Characterization of Al2O3 - SiO2 Mos Structures
Authors: Ragnarsson L-Å , Aderstedt E. , Lundgren P.
Published: April 2011

A comparative capacitance voltage method is used to investigate the equivalent thickness reduction during post metallization annealing of thermally grown ultrathin (∼15-27 Å) oxides. It is found that a double layered dielectric consisting of a thin Al2O3—SiO2 sandwich is appropriate to describe both the increased capacitance and the nearly unaltered current after anneal. It is further shown that the impact of initial thickness and method of growth — in a conventional furnace or by rapid thermal oxidation — on the equivalent thickness reduction is negligible.
Sub-Nanometric Resolution Depth Profiling of Ultrathin Ono Structures
Authors: Radtke C. , Salgado T.D.M. , Krug C. , Andrade J. de , Baumvol I.J.R.
Published: April 2011

Ultrathin silicon oxide/nitride/oxide films on silicon prepared by the usual route -thermal growth of an oxide followed by deposition of a nitride layer by chemical vapor deposition, and finally a reoxidation step - were characterized using isotopic substitution of N and O and depth profiling with sub-nanometric resolution. The redistribution of N and O during the oxide/nitride/oxide film processing was investigated by: i) 15N and 18O depth profiling by means of narrow nuclear resonance, and ii) 16O profiling using step-by-step chemical dissolution associated with areal densities determinations by nuclear reaction analysis. It was observed that the reoxidation step, here performed varying temperature and time, induces atomic transport of O and N thus resulting in oxide/nitride/oxide structures which are not stacked layered ones, but rather silicon oxynitride ultrathin films, in which the N concentration presents a maximum in the bulk and is moderate in the near-surface and near-interface regions.
Process Definition for Obtaining Ultra-Thin Silicon Oxides Using Full-Wafer Electrical and Optical Measurements
Authors: Oberhofer A. , Chen J. , Koh K. , Schrader M. , Shah S. , Venables R. , Young C. , Xu M. , Kuehn R. , Maher D. , Venables D.
Published: April 2011

The objective of this research was to establish a new baseline process for obtaining ultra-thin silicon-oxide gate material in a prototype vertical furnace. Of particular concern was the optimization of a process sequence whereby unpatterned 150 mm diameter wafers ‘see’ the same processing steps prior to gate oxidation as patterned device wafers ‘see’. The figures-of-merit for evaluating process optimization include: i) full-wafer current-voltage (I-V) maps using Hg-gate capacitors; ii) the variation in the current or current density at a given bias voltage, extracted from an I-V map; iii) the variation in electrical oxide thickness that is extracted from full-wafer capacitance-voltage measurements using Hg-gate capacitors; and iv) the variation in optical oxide thickness that is extracted from full-wafer spectroscopic ellipsometry measurements. The results from this research demonstrate that: i) the addition of 1% O2 to the usual N2 gas during the ramp-up cycle in the vertical furnace is necessary to achieve acceptable across-the-wafer oxide-thickness uniformity as determined from both electrical and optical figures-of-merit; and ii) a full-wafer response surface of the current at a given bias voltage is a powerful finger print for process development when the question of variation in as-grown silicon-oxide thickness is at issue.
Modeling of {311} Defects
Authors: Hobler G. , Rafferty C.S.
Published: April 2011

An improved model of {311} defect evolution is developed based on the rate equations approach. A new expression for the reaction rate constant is presented that is based on the assumption that interstitials may react with the {311} defects along their whole surface. The energetics of {311} defects is treated by calculating the strain energy within the framework of the theory of dislocations in isotropic continua. Using the core energy of the atoms in the defects as the only fit parameter, we explain a wide range of experimental data. Furthermore, we apply the model to investigate closure assumptions used in moments models and propose a new two-moments model that uses the rate equations solver as a pre-processor.
Transient Enhanced Diffusion and Dose Loss of Indium in Silicon
Authors: Dokumaci Omer , Ronsheim Paul , D'emic Christopher , Domenicucci Anthony G. , Hegde Suri , Kozlowski Paul , Wong H.-S. Philip
Published: April 2011

The dose loss and transient enhanced diffusion of indium in silicon were studied as a function of dose. Indium was implanted into silicon through a 90 A oxide at 50 keV for doses ranging from 3x 1012 to 2x14 cm−2. These conditions provide peak concentrations that approximately range from 1x1018-1x1020 cm−3. After an RTA anneal at 1000°C for 5s, indium exhibits substantial motion at both the tail and peak regions for high doses. The enhanced diffusion is mostly over within 5s. There was not any observable enhanced diffusion in the tail region at the lowest dose although there was significant movement at the peak region. The dose loss correlates very well with the enhancement in the diffusivity. TEM images show that the amorphization dose lies between 3x1013 and 8x1013 cm−2. In spite of the amorphization, diffusion enhancement in the tail region still keeps increasing with dose, which is contrary to a model of “+1” interstitials and complete removal of interstitials in the regrown layer. The 550°C lh anneals show that the dose loss can partially be attributed to the sweeping of the dopant by the growing a/c interface. Previously, the solubility of indium has been estimated to be around 1–2×1018 cm−3. At high doses, significant movement is observed at the peak of the indium profile although the peak concentration exceeds the solubility level by at least an order of magnitude. This shows that indium is not precipitating into an immobile phase like antimony or boron.
Relative Stability of Perfect and Faulted Dislocation Loops in Silicon
Authors: Omri M. , de Mauduit B. , Claverie A.
Published: April 2011

We have studied by TEM the thermal evolution of a population of extrinsic defects composed of a mixture of both perfect and faulted dislocation loops (PDL's and FDL's respectively). It is shown that, when isolated from an external sink, the FDL's trap the Si interstitial atoms emitted by PDL's. When a highly recombining surface is located close to the defects, it preferably « pumps » the PDL's. On the contrary, injecting Si(int)'s from the surface helps stabilizing the PDL's while the FDL's grow. These experiments clearly show that FDL's are more stable, i.e. have higher binding energies than PDL's.
Two-dimensional Dopant Diffusion Study using Scanning Capacitance Microscopy
Authors: Yu Guanyuan M. , Griffin Peter B. , Plummer James D.
Published: April 2011

The results of a two-dimensional dopant diffusion study using two new sample preparation techniques and a database-driven deconvolution technique are presented. These techniques are applied to real devices to justify complex implantation and diffusion models. It will be shown that the dose loss behavior is not uniform along the silicon/oxide interface from the source/drain region to the channel region. A new non-uniform dose loss model is proposed and used to explain the experimental results.
Practical Aspects of Forming Ultra-Shallow Junctions by Sub-keV Boron Implants
Authors: Foad M. A. , Murrell A. J. , Collart E. J. H. , de Cock G. , Jennings D. , Current M. I.
Published: April 2011

As the drive towards the production of 100 nm CMOS devices pick up speed, the practical aspect of transistor shallow junction formation, including a large menu of process integration issues, must now be solved in a short order. The most direct path to 50 nm junction depths is through the sub-keV boron implantation and rapid thermal annealing.

The material aspects of the process integration centers on: (1) CMOS devices for shallow, highly-activated and abrupt junctions (involving the choice of ion species [B, BF, B10H14, BSi2, etc.], substrate materials [ Cz, Epi, SOI], anneal conditions [ramp rate, soak time, ambient gas], etc.) and (2) Defect-dopant interactions during annealing (including surface reactions of high concentration species [B, F], diffusion and carrier trapping by background and co-implanted species [C, 0, F, etc.].

Process data for atomic and electrical activity profiles as well as defect and interface structures will be presented to illustrate progress towards understanding these complex process interactions. A particular focus will be the effects of anneal ambient and rapid temperature rise times approaching the “pike” anneal ideal.
Polytope Models of Metallic Glasses: S-Band Electronic Properties
Authors: Selinger Jonathan V. , Nelson David R.
Published: April 2011

Inspired by the experiments of Turnbull (1952) on undercooled liquid mercury, many investigators have argued that polytetrahedral short-range order is an important ingredient in the structure of undercooled liquids and metallic glasses. A paradigm for such order is “polytope {3,3,5},” which is a regular lattice of 600 perfect tetrahedra with an icosahedral point symmetry embedded on the surface of a four-dimensional sphere. We present results for the band structure of polytope {3,3,5} in the presence of disclinations, and compare them with band structures obtained from dense random packing models of metallic glasses.
Metal Alkoxide Synthesis of Glasses and Glass-Ceramics
Authors: Drummond Charles H.
Published: April 2011

Metal alkoxide syntheses of the general form or can be used to form soluble alkoxides of most metals. Mutual solution of these alkoxides followed by acid or base hydrolysis, drying and calcining results in the formation of fine-grained (<10Å) amorphous powders at low temperatures. Subsequent hot-pressing or calcining leads to densification and/or crystallization. Compositions in the MgO-Al2O3-SiO2 system with ZrO2 contents to 30 mol% are discussed. Also glass formation of transition oxides derived from metal alkoxides of Hf, Zr, Y and Nb in various combinations are presented.
Density and Packing in Uranium Based Metallic Glasses
Authors: Drehman A. J.
Published: April 2011

Density and x-ray diffraction measurements were performed over a wide compositional range of U-Fe and U-Co metallic glass ribbons. The compositional dependence of both the density and the average nearest neighbor distance exhibits a change in slope at approximately 28 at.% transition metal. This suggests an “ideal” glass composition possessing a minimum excess volume. A qualitative model of atomic packing is proposed, which is based on the compositional dependence of the atomic volume and nearest neighbor distance.
Diffusion in Crystalline and Amorphous Solids
Authors: Lazarus David
Published: April 2011

Decades of work by a wide variety of techniques were required to establish unambiguously the essential role of simple – and sometimes not so simple – “point” defects in mediating bulk diffusion in crystalline solids. Amorphous solids present new problems for establishing basic diffusion mechanisms. Most experimental techniques which work well for study of diffusion in crystalline solids are useless for study of amorphous materials because of their inherent nonequilibrium structures. A survey of some current results also gives a strong impression that more complex basic mechanisms than simple point defects may be required to account for volume diffusion in these materials.
Application of Nucleation and Growth Theory to the Development of Industrial Products
Authors: May John E.
Published: April 2011

In this paper we discuss some features of the microstructure of large-grainsized very low voltage varistors and the effects of heat treatments on the pre-breakover electrical characteristics. It is shown that a second phase precipitates in the bismuth-rich segregation phase and is thought responsible for the reduced device leakage properties.
MBE Growth and Characterization of Composite InAlAs/In(Ga)As Vertically Aligned Quantum Dots
Authors: Kovsh A. R. , Zhukov A. E. , Egorov A.Yu. , Maleev N. N. , Mikhrin S. S. , Ustinov V. M. , Odnoblyudov V. A. , Musikhin Yu. G. , Livshits D. A. , Tsatsul'nikov A. F. , Maximov M. V. , Shernyakov Yu. M. , Volovik B. V. , Bedarev D. A. , Ledentsov N. N. , Kop'ev P. S. , Alferov Zh. I. , Suvorova A. A. , Werner P. , Bimberg D.
Published: April 2011

In the present work we study the effect of vertical alignment in the quantum dot array formed by successive deposition of several rows of InAlAs and InGaAs quantum dots separated by thin AIGaAs spacer layers. Transmission electron microscopy and photoluminescence studies revealed that the InAlAs QDs characterized by high areal density force InGaAs to be transformed into the denser array as compared to the case of spontaneous transformation. Using denser array of composite quantum dots in the active region of a diode laser leads to the increase in modal gain, decrease in internal loss, and decrease in the threshold current density for short cavity diodes. Room temperature continuous wave output power as high as 3.3 W at 0.87 µm is achieved.
Theory of Addition Spectra in Double Quantum Dots: Single-Particle Tunneling vs Coulomb Interactions
Authors: Rontani M. , Rossi F. , Manghi F. , Molinari E.
Published: April 2011

We study coupled semiconductor quantum dots theoretically using a generalized Hubbard approach, where intra- and inter-dot Coulomb correlation, as well as tunneling effects are described on the basis of realistic electron wavefunctions. We find that the ground-state configuration of vertically coupled double dots undergoes non-trivial quantum transitions as the inter-dot distance d changes; at intermediate values of d we predict a new phase that should be observable in the addition spectra and in the magnetization changes.
New Self-Organized Nanostructure: Chain of Crystalline-Silicon Nanospheres
Authors: Kohno H. , Takeda S. , Iwasaki T.
Published: April 2011

We have grown chains of crystalline-Si nanospheres: the crystalline-Si nanospheres of about 10 nm in diameter are supported in amorphous silica and carbon at a nearly equal spacing by a self-organized process. The self-organized phenomenon was attributed to the periodic instability of catalyst on the top of growing wire and oxidization during the growth of nanowires.
Optical Near-Field Properties of Lithographically Designed Metallic Nanoparticles
Authors: Weeber J.C. , Krenn J.R. , Dereux A. , Bourillot E. , Goudonnet J.P. , Schider B. , Aussenegg F.R. , Girard Ch.
Published: April 2011

We report on the experimental observation of localized surface plasmons sustained by small metallic particles using a photon scanning tunneling microscope (PSTM). The surface plasmons are excited in gold nanostructures tailored by electron beam lithography. The constant height operation of the PSTM allowed a direct comparison with theoretical computations of the distribution of the optical near-field intensity. Plasmon coupling above a chain of Au particles and electromagnetic energy transfer from a resonantly excited nanoparticle to a nanowire are demonstrated. Our experimental results appear to be in good agreement with theoretical computations based on the Green's Dyadic Technique.
Thermal Annealing Effects in Vanadium Pentoxide Films Intercalated with Eu3+
Authors: Oliveira H. P. , Rosolen J. M. , Calefi P. S. , Brunello C. A. , Graeff C. F. O.
Published: April 2011

This work reports on the spectroscopic properties of europium ions intercalated in a vanadium pentoxide matrix, as well as the effects of thermal treatment on its structural and electronic properties. X-ray diffraction, TG/DTA, ESR, luminescence as well as XANES were used in order to characterize the intercalation compound. For the as grown samples, the intercalation of Eu3+ is observed to have little effect in the V2O5 lamellar structure, however the inter-planar spacing grows from 1.19 nm to 1.33nm for a 10% Eu3+ content. The luminescence for the as grown samples are dominated by the host, the same happening with the ESR spectra. However ESR data show that the presence of Eu3+ in the host induces the partial reduction of vanadium to V4+ For samples treated above 873K the luminescence excitation spectra presents a new shoulder at 300 nm, which when excited shows emissions bands typical of the Eu3+ In ESR the same thermal treatments are marked by the appearance of a new broad line assigned to ferromagnetic EuO, as well as the partial oxidation of V4+ to V5+ This result may be correlated to suppression of Eu3+ luminescence due to the presence of water in the neighborhood of Eu3+.
Epitaxial Growth of BaZn1/3Ta2/3O3 Thin-Films for Microwave Applications
Authors: Rong G. , Tsakalakos L. , Browning J. , Newman N.
Published: April 2011

BaZn1/3Ta2/3O3 (BZT) ceramics are widely used in current microwave communication applications due to the material's large-dielectric constant (εr > 25), ultra-low loss tangent (tan δ < 2×10−5 at 2 GHz) and a near-zero temperature-coefficient of resonant frequency (τf∼0). In this paper, we report the first growth of epitaxial BZT thin films. The films are grown on MgO substrates using pulsed laser deposition. X-ray diffraction data indicate the films have a disordered pseudocubic perovskite structure with a small tetragonal distortion (i.e. a = b = 4.100 Å; c = 4.088 Å). An optimized substrate temperature of 575°C results in films which are over 98% oriented in the (001) direction and are relatively smooth (rms roughness of 5.2 Å). X-ray diffraction Φ scans of off-axis (202) reflection show four-fold symmetry, indicating a high degree of in-plane epitaxy, albeit with small angle grain boundaries. The refractive index of epitaxial BZT films is inferred to be 5 from Fabry- Perot fringes in optical transmission spectra. Substrate temperatures during growth are limited to ∼600°C as a result of Zn loss.
Influence of Cation Stoichiometry of la1-xSrxCoO3 Bottom Electrodes on the Orientation and Ferroelectric Properties of Pb(Ta0.05ZrO0.48Ti0.47)O3 Films
Authors: Yin J. , Liu Z. G.
Published: April 2011

The Ta-doped PZT films (PTZT) were deposited on Pt/TiO2/SiO2/Si(001) substrates by pulsed laser deposition using La1-xSrxCoO3 buffer layers. The grain orientation of PTZT films is strongly influenced by the cation ratio of La1-xSrxCoO3. The PTZT films deposited using La0.75Sr0.25CoO3 with rhombohedral structure prefer (110)-orientaion, and those deposited using La0.25Sr0.75CoO3 with psuedo-cubic structure prefer (001)-orientation. It is found that the fatigue property of the PTZT capacitors can be improved enormously by using (001)-oriented La0.25Sr0.75CoO3 bottom electrodes. SEM morphology pattern for the surface of PTZT films and for the cross-section show that no obvious interdiffusion occurs across the interfaces. The ferroelectric capacitor La0.25Sr0.75CoO3/PTZT/La0.25Sr0.75CoO3/Pt/TiO2/SiO2/Si(001) shows almost no degradation in its polarization after 1.5×1010 switching cycles at an applied voltage 5 V and a frequency 1MHz.