bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of the Hydrogen/Deuterium (H/D) Isotope Effect of Hot-Electron Degradation of MOS Devices
Authors: Chen Zhi , Guo Jun , Ong Pangleen 
Published: April 2011

ABSTRACTIn order to verify Van de Walle and Jackson's theory on the isotope effect of the Si-H/D bonds resistant to hot-electron excitation [Appl. Phys. Lett., 69, 2441 (1996)], we measured the Si-H, Si-D, and other vibrational modes in oxidized silicon wafers annealed in hydrogen and deuterium using Fourier Transform Infrared (FTIR) spectrometry. Our FTIR data suggest that the frequency for the Si-D bending mode at the SiO2/Si interface is 490 cm−1. Our experimental data support Van de Walle and Jackson's theory with some modification. Their theory is correct for the experiments of breaking Si-H/D bonds using scanning tunneling microscope (STM) where no oxide is involved. In the SiO2/Si case, the de-excitation of the Si-D bond may be due to the energy coupling from the Si-D bending mode to two vibrational modes; i.e., the Si-O TO mode and the Si-Si TO phonon mode. Van de Walle and Jackson only pointed out coupling to the Si-Si TO phonon mode. The strongest coupling might happen between the Si-D mode and the Si-O TO mode. Therefore, the oxide may play a crucial role in energy dissipation of the Si-D bond in metal-oxide-semiconductor (MOS) devices.
Development of SiC-based Gas Sensors for Aerospace Applications
Authors: Hunter G. W. , Neudeck P. G. , Xu J. , Lukco D. , Trunek A. , Artale M. , Lampard P. , Androjna D. , Makel D. , Ward B. , Liu C. C. 
Published: April 2011

AbstractSilicon carbide (SiC) based gas sensors have the ability to meet the needs of a range of aerospace applications including leak detection, environmental control, emission monitoring, and fire detection. While each of these applications require that the sensor and associated packaging be tailored for that individual application, they all require sensitive detection. The sensing approach taken to meet these needs is the use of SiC as a semiconductor in a Schottky diode configuration due to the demonstrated high sensitivity of Schottky diode-based sensors. However, Schottky diode structures require good control of the interface between the gas sensitive metal and SiC in order to meet required levels of sensitivity and stability. Two examples of effort to better control the SiC gas sensitive Schottky diode interface will be discussed. First, the use of chrome carbide as a barrier layer between the metal and SiC is discussed. Second, we report the first use of atomically flat SiC to provide an improved SiC semiconductor surface for gas sensor deposition. An example of the demonstration of a SiC gas sensor in an aerospace applications is given. It is concluded that, while significant progress has been made, the development of SiC gas sensor systems is still at a relatively early level of maturity for a number of applications.
Epitaxial Growth of 2 inch 3C-SiC on Si Substrates by Atmospheric Hot Wall CVD
Authors: Zhu Jiliang , Chen Yi , Mukai Yusuke , Shoji Akira , Nishiguchi Taro , Ohshima Satoru , Nishino S. 
Published: April 2011

AbstractAs a high mobility, wide bandgap semiconductor, 3C-SiC has great promise. In this paper, we examined to obtain 3C-SiC epilayer on Si substrates using hot-wall CVD furnace and report the use of hexamethyledisilane (HMDS) and propane as reaction gases to grow uniform thickness on 2 inch (100), (111), (110) and (211) orientation of Si substrates. A horizontal atmospheric pressure CVD reactor was used. A reaction zone was specially designed. To obtain uniform thickness of the epilayer, inside of the suscceptor hole was intentionally tapered along flow direction as follows; inlet of the square hole is 13 mm × 60 mm and outlet of the hole is 7 mm × 60 mm, and laminar channel for changing the gas flow profile was managed. The susceptor was surrounded by graphite foam. Temperature of the suscepotor was measured at inside wall of the susceptor by optical pyrometer. H2 flow rate for etching was 3 slm. An initial carbonization procedure was performed using 0.9 sccm propane at 1250 oC for 2-3 minutes. During the growth of SiC at 1300 °C, the flow rate of HMDS was 0.75-1.2 sccm and the flow rate of propane was 0.1 – 0.5 sccm. The hydrogen carrier gas flow rate was 3-10 slm. Typical growth rate was 4.5 micron /h. Uniform thick 3C-SiC was obtained. The samples were examined using ultra violet light spectrometer and RHEED.
Photoluminescence Characterization of Defects Introduced in 4H-SiC During High Energy Proton Irradiation and Their Annealing Behavior
Authors: Ahoujja M. , Crocket H. C. , Scott M. B. , Yeo Y.K. , Hengehold R. L. 
Published: April 2011

AbstractWe report on the optical properties of defects introduced in epitaxial 4H-SiC by 2 MeV protons using photoluminescence spectroscopy. The near band edge characteristics of nitrogen-doped n-type 4H-SiC are present in the optical spectrum of the as-grown samples. Following a proton irradiation, the material is altered and the luminescence of the shallow centers is attenuated almost entirely with the emergence of deeper shallow traps at energies greater than 300 meV below the conduction band. Subsequent hightemperature thermal annealing of the material results in an increase in the emission spectrum at both the near band edge region (Eg = 3.25 eV) and between 2.65 and 2.95 eV. Recovery of the characteristic nitrogen-related peaks at the near band edge following high-temperature annealing is identified, but is not complete even at 1500 °C. In the deep trap region below 2.95 eV, activation of trap centers with annealing results in a sharp increase in the signal intensity of an irradiation-induced defect trap (2.90 eV) as well as the associated phonon replicas. Based on previous ion-implantation and other radiation studies in 4H-SiC, the emergence of the 2.90 eV defect complex and associated phonon replicas after high temperature anneal is the well known D1 photoluminescence. The observed lines in the D1 spectrum are due to exciton recombination at isoelectronic defect centers.
Saturation and Flow Rate Effects on the Response of a Pd/AIN/SiC Hydrogen Sensor
Authors: Rahman M.H. , Ng K.Y.S. , McCullen E.F. , Naik R. , Newaz G. , Danylyuk Y. , Rimai L. , Baird R.J. , Auner G.W. 
Published: April 2011

AbstractA Pd/AlN/SiC device was fabricated with a 550 Å thick AlN layer in between the SiC substrate and Pd gate. At fixed flow rate, the response to Hydrogen initially increases roughly linearly with concentration, but eventually becomes saturated. The magnitude of the response as well as the saturating concentration increase with temperature. At 120° C the response saturates around 60 ppm of H2 whereas at 250° C, the onset of saturation occurs at higher ppm. The magnitude of the response also increases with the total flow rate, up to a flow rate of 250 sccm beyond which it remains constant. In the linear region, the magnitude of the response increases by a factor of 4 between 120° and 250° C, at a flow rate of 250 sccm.
The Electrical Behavior of Pd/AIN/Semiconductor Thin Film Hydrogen Sensing Structures
Authors: Rimai L. , Rahman M.H. , McCullen E.F. , Zhang L. , Thakur J.S. , Naik R. , Newaz G. M. , Ng K.Y.S. , Baird R.J. , Auner G.W. 
Published: April 2011

AbstractThe device on Si substrates behaves as an MIS capacitor and the response to hydrogen is given by a shift of the capacitance vs. bias profile along the bias voltage axis, whereas the device on SiC behaves as a rectifying diode and the presence of hydrogen causes a shift of the forward current vs. voltage plot. The relatively large forward current, in both cases, indicates that there is measurable electrical transport across the AlN layer, but at the same temperature the turn on bias is different. Either structure contains two rectifying contacts in series, namely a Schottky contact between Pd and AlN and a heterojunction between AlN and the substrate.
MOS Interface Properties and MOSFET Performance on 4H-SiC{0001} and Non-Basal Faces Processed by N2O Oxidation
Authors: Kimoto T. , Kanzaki Y. , Noborio M. , Kawano H. , Matsunami H. 
Published: April 2011

Abstract4H-SiC(0001), (000-1), and (11-20) have been directly oxidized by N2O at 1300°C, and the MOS interfaces have been characterized. The interface state density has been significantly reduced by N2O oxidation on any face, compared to conventional wet O2 oxidation at 1150°C. Planar n-channel MOSFETs fabricated on lightly-doped 4H-SiC(0001), (000-1) and (11-20) faces have shown an effective channel mobility of 26, 43, and 78 cm2/Vs, respectively. The mobility decreased with increasing the doping concentration of p-body. SIMS analyses have revealed a clear pile-up of nitrogen atoms near the MOS interface. The thickness of interfacial SiCxOy layer can be decreased by utilizing N2O oxidation. The crystal face dependence of interface structure is discussed.
Copper CMP Formulation for 65 nm Device Planarization
Authors: Stauf Gregory T. , Boggs Karl , Wrschka Peter , Ragaglia Craig , Darsillo Michael , Roeder Jeffrey F. , King Mackenzie , Liu Jun , Baum Thomas 
Published: April 2011

AbstractTo achieve 65 nm technology node requirements, CMP processes must provide improved control of selectivity, topography, wire cross section, and process robustness. Slurries and processes must also be compatible with fragile low k materials by providing low erosion and shear forces. We present data on a unique step 1 bulk Cu removal slurry with high selectivity, removal rates over 8000 Å/min, and extremely low liner removal/erosion in high (90%) density structures. This is achieved through a combination of surface modified abrasives and alternative inhibitors which provide superior performance and reduced electrochemical activity compared to benzotriazole, a commonly used inhibitor. The step 1 slurry was used with a step 2 liner removal slurry that can be chemically tuned to adjust relative selectivities of Cu:Ta:oxide from the nominal ratio of 1:0.9:1.6, allowing its use with a variety of integration schemes. Results of CMP planarization experiments on 200 mm blanket and patterned single damascene test wafers are described, including electrical data which demonstrates low overpolish sensitivity.
A Study on the Self-Stopping CMP Process for the Planarization of the High Step Height(@step height>1.5um) Pattern
Authors: Kim Kwang-Bok , Lee Hyo-Jin , Jang Ki-Hoon , Ko Joung-Duk , Kim Kyung-Hyun , Hwang In-Seac , Ko Yong-Sun , Song Chang-Lyong 
Published: April 2011

AbstractCMP(Chemical Mechanical Planarization) process is widely used to reduce step height in semiconductor fabrication processes. As a design rule shrinks, a highly planar surface becomes inevitable within wafer scales. In order to get a high degree of a planarization, self-stopping characteristics of a ceria-based slurry should be studied and used in semiconductor process. In this study, threshold polishing pressure for a self-stopping characteristics was obtained by optimizing down pressure, pad conditioning, and mixing ratio of ceria abrasive and additive. A series of experiments were made to optimize the threshold polishing pressure in variable line & space patterns that consist of 0.8um step height and unit oxide film. As a result, self-stopping cmp process is twice batter than conventional silica-based process with respect to planarity and WIWNU. In addition, WIWNU and step height was dramatically decreased to less than 1000Å when applying to real fabrication devices over 2um step height.
CMP Modeling and Characterization for Polysilicon MEMS Structures
Authors: Tang Brian , Boning Duane 
Published: April 2011

AbstractThe current bedrock technology for integrated circuit (IC) planarization, chemical-mechanical polishing is beginning to play an important role in microelectromechnical systems (MEMS). However, MEMS devices operate with bigger feature sizes in comparison to ICs, in order to fulfill mechanical functions. We present an experiment to characterize and model a polysilicon CMP process with the specific goal of examining MEMS-sized test structures. We utilize previously discussed CMP models and examine whether assumptions from IC CMP can be applied to MEMS CMP. An analysis of the data collected points to a polishing dependence on not only pattern density, but also partly on feature size or feature configuration. The existing pattern density and step height CMP models are able to capture the major trends in up and down area polishing. However, certain layout features relevant to MEMS are difficult to predict, motivating the need for further model development and application.
Cerium Oxide Abrasives – Observations and Analysis
Authors: Evans David R. 
Published: April 2011

AbstractThe use of cerium oxide (ceria) as an abrasive for dielectric chemical mechanical polishing has a “checkered” history to say the least. Nevertheless, its use remains attractive for this purpose because of favorable polishing characteristics that are generally not obtainable using conventional fumed or colloidal silica abrasives. To be specific, large differences are commonly observed between removal rates of thin film silicon oxide, silicon nitride, and/or polysilicon. Moreover, such rate selectivity invariably favors removal of oxide films, which of course, is precisely what is desirable for fabrication of modern shallow trench isolation schemes. Even so, CMP using ceria abrasive often exhibits unusual characteristics that cannot be explained adequately by conventional polishing models based on pad/asperity elasticity or pressure distribution over features. Most notably, non-conventional, observed behaviors can be collected under the rubric of “slow start phenomena”. In this work, it is asserted that specific polishing characteristics of ceria slurry are largely due to the detailed surface chemistry of ceria particles and their interaction with silica. In any case, it is further shown that modification of slurry lubrication can alleviate slow-start and shift CMP process characteristics back toward more conventional behavior.
Rare-earth doped microlasers for microphotonic applications
Authors: Yang Lan , Min Bumki , Vahala K. J. 
Published: April 2011

AbstractSol gels provide a highly flexible technique for preparation of both planar and non-planar oxide thin films. They also enable the incorporation of various dopants into the films. In this work we describe the application of erbium-doped solgel films to surface functionalize optical microresonators. The resulting microlaser devices are especially interesting because their emission band falls in the important 1.5 μm window used for optical fiber communications. Both microsphere and ultra-high-Q microtoroid resonators-on-a-chip were functionalized into lasers and then characterized [1]. The erbium-doped sol-gel films were applied to the resonator surface and subsequently a CO2 laser was used to induce flow and densification of the sol-gel film on the surface. Optical quality thin films were obtained after the CO2 laser induced anneal. By varying the doping concentration and thickness of the applied sol-gel layers in microsphere resonators, we can vary the laser dynamics so that both continuous-wave and pulsation operation are possible. Single mode performance with high differential quantum efficiency was also obtained using the ultra-high-Q microtoroid resonator. These chip-based microlasers enable integration with other optical or electronic functions [2-3].
In-situ Control of Nitrogen Content and the Effect on PL Properties of SiNx Films Grown by Ion Beam Sputter Deposition
Authors: Kim Kyung Joong , Moon Dae Won , Yang Moon-Seung , Shin Jung H. 
Published: April 2011

AbstractStrong visible luminescence was observed in silicon nitride (SiNx) thin films grown by ion beam sputter deposition (IBSD) using nitrogen ion as a sputtering source. Nitrogen content (x) of the films was controlled by variation of the sputtering N2 ion flux and analysed by in-situ x-ray photoelectron spectroscopy (XPS). Relative sensitivity factors of Si and N peaks could be calculated by Rutherford backscattering spectroscopy. The photoluminescence (PL) spectra of the post-annealed samples showed visible luminescence at blue-green region. PL energy showed a blue-shift due to quantum confinement with decreased excess Si and intensity showed a maximum value near x = 1.1. These PL properties are well correlated with the formation of Si nanocrystals (nc-Si). We found that there is a great increase of PL energy of SiNx thin films compared with SiOx thin films, which indicate that the surface state of Si nanocrystals plays an important role to increase PL energy and intensity.
Optical and Nanomechanical Characterization of an Omnidirectional Reflector Encompassing 850 nm Wavelength
Authors: Deopura Manish , Fink Yoel , Schuh Christopher A. 
Published: April 2011

AbstractWe demonstrate that multilayers composed of nineteen alternating layers of tin sulfide and silica can function as omnidirectional reflectors. These materials exhibit omnidirectional reflectivity for a range of frequencies in the near infra-red (NIR) encompassing the 850 nm wavelength. A refractive index contrast of 2.7/1.46 is achieved, one of the highest values demonstrated until now in NIR photonic bad gaps. In addition, new nanoindentation procedures have been developed to measure mechanical properties of these fine laminate materials, and demonstrate that tin sulfide-silica multilayers are mechanically stable for practical applications.
Structural Characterization of Molecular Beam Epitaxy Grown GaInNAs and GaInNAsSb Quantum Wells by Transmission Electron Microscopy
Authors: Gugov Tihomir , Wistey Mark , Yuen Homan , Bank Seth , Harris James S. 
Published: April 2011

AbstractIn the past decade, the quaternary GaInNAs alloy has emerged as a very promising material for lasers in the 1.2-1.6 μm range with application in telecommunication fiber-optic networks. While most of the challenges in growing high quality laser material with emission wavelength out to 1.3 μm have been successfully resolved, extending the emission beyond 1.3 μm has proven to be quite difficult. Achieving emission out to 1.5 μm requires higher In (up to 40%) and N (up to 2%) compositions. This makes the growth of this thermodynamically unstable alloy quite difficult with phase segregation occurring even at lower growth temperatures. Recently, adding small amounts of antimony has dramatically improved the quality of the material and high luminescence has been demonstrated at wavelengths beyond 1.5 μm. In this study, high-resolution transmission electron microscopy (HRTEM) was used in a novel way in conjunction with dark-field (DF) TEM to elucidate the role of antimony in improving the material quality. The results show that antimony improves the material uniformity via reduction of the local compositional fluctuations of indium.
Multilevel Nonvolatile Memories Based on Nanowire / Molecular Wire Heterostructures
Authors: Li Chao , Fan Wendy , Lei Bo , Zhang Daihua , Han Jie , Meyyapan M. 
Published: April 2011

AbstractNonvolatile nanoscale memories with ultra-long retention times have been demonstrated for both binary and multilevel applications. These devices were based on nanowires functionalized with a self- assembled monolayer of redox active molecular wires, where the bit was represented by the charge stored in the redox molecules and the nanowire conductance was used as the readout. Our devices exhibited reliable operation, on/off ratios ∼ 104 and retention times ∼ one month, one of the longest retention times ever achieved with nanoscale devices. These devices were further tailored for multilevel data storage with appreciable noise margins, representing a new concept for functional devices. Our work clearly demonstrates the potential of combining nanowires and molecular wires for superior performance.
Characterization and Manipulation of Exposed Ge Nanocrystals
Authors: Sharp I.D. , Xu Q. , Liao C.Y. , Yi D.O. , Ager J.W. , Beeman J.W. , Yu K.M. , Zakharov D.N. , Liliental-Weber Z. , Chrzan D. C. , Haller E.E. 
Published: April 2011

AbstractIsotopically pure 70Ge and 74Ge nanocrystals embedded in SiO2 thin films on Si substrates have been fabricated through ion implantation and thermal annealing. Nanocrystals were subsequently exposed using a hydrofluoric acid etching procedure to selectively remove the oxide matrix while retaining up to 69% of the implanted Ge. Comparison of transmission electron micrographs (TEM) of as-grown crystals to atomic force microscope (AFM) data of exposed crystals reveals that the nanocrystal size distribution is very nearly preserved during etching. Therefore, this process provides a new means to use AFM for rapid and straightforward determination of size distributions of nanocrystals formed in a silica matrix. Once exposed, nanocrystals may be transferred to a variety of substrates, such as conducting metal films and optically transparent insulators for further characterization.
Laser-Grown Silicon Nanoparticles and Photoluminescence Properties
Authors: Herlin-Boime N. , Jursikova K. , Trave E. , Borsella E. , Guillois O. , Fabbri F. , Vicens J. , Reynaud C. 
Published: April 2011

AbstractLight-emitting silicon nanocrystals (Si nc) have attracted much interest due to their possible application as optoelectronic devices. The interest for Si nanopowders is enhanced by their photoluminescence (PL) emission intensity that can be very strong at room temperature. Due to the intrinsic biocompatibility of Si nanoparticles, this strong optical emission intensity as well as the long decay time (mean life time around hundred microseconds) make these powders potential candidates as tracers for in-vivo applications.Si nanopowders were obtained in gram quantities by CO2 laser pyrolysis of silane. The particles in the produced powders are in the size range 10-15 nm. These nanoparticles exhibit strong red photoluminescence after heat treatment. The appearance of intense PL emission is clearly related to the surface oxidation of the powders which must be carefully controlled. Several steps have been identified in the oxidation process. This paper presents a detailed study of the evolution of both the photoluminescence intensity and spectral dependence and of the crystalline structure as a function of the heat treatment. We also show that the nanopowders can be dispersed in liquids and incorporated in gel samples while keeping their intense photoluminescence. This result opens a route towards the fabrication of novel devices
Silicon Nanoparticle Synthesis Using Constricted Mode Capacitive Silane Plasma
Authors: Bapat A. , Dong Ying , Perrey C. R. , Carter C. B. , Campbell S.A. , Kortshagen U. 
Published: April 2011

AbstractCrystalline semiconductor nanoparticles are of interest for a variety of electronic and opto-electronic applications. We report experimental studies of the synthesis and characterization of crystalline silicon nanoparticles using a constricted-mode capacitive RF plasma in continua- tion of results reported earlier from an RF inductively coupled plasma [1]. The constricted-mode discharge is based on a thermal plasma instability yielding a high-density plasma filament, which rotates at a high frequency. Silane is dissociated, leading to particle nucleation and growth. Particles are extracted by passing the particle-laden gas through an orifice to form a beam and col- lected by inertial impaction.We are able to reproducibly synthesize highly oriented freestanding single-crystal silicon nanoparticles. Monodisperse particle size distributions centered at a 35nm particle diameter with a geometric standard deviation of 1.3 are obtained. Transmission electron microscope (TEM) studies show uniformly shaped cubic particles. Selected-area electron diffraction patterns indi- cate the particles have the diamond-cubic silicon structure. To study the electrical properties of these particles, metal-semiconductor-metal structures were fabricated and analyzed.