bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Growth and Optimization of InPSb/InGaAs/InAsSb Strained-Layer Superlattice Emitters by Metal Organic Chemical Vapor Deposition
Authors: Biefeld R. M. , Kurtz S. R. 
Published: April 2011

ABSTRACTWe have prepared InAsSb/InGaAs strained-layer superlattices (SLS's) and InPSb confinement layers using metal-organic chemical vapor deposition (MOCVD) for use as infrared emitters. X-ray diffraction was used to determine lattice matching as well as composition and structure of the SLS's. Photoluminescence linewidth and intensity were used as a measure of the quality of the structures. Typical FWHM were less than 10 meV. The presence of interface layers were indicated by broadened x-ray diffraction peaks for samples grown under non-optimized conditions. Two types of interfacial layers apparently due to a difference in composition at the interfaces were observed with transmission electron microscopy (TEM). The width of the x-ray peaks can be explained by a variation of the interfacial layer thicknesses. Optimized growth resulted in SLS's with narrow x-ray peaks and high radiative efficiency. Room temperature LEDs operating between 4-5 μm have been prepared.
Photoelastic Waveguides Using Strain-Compensated InAsP/InGaP Multi-Quantum-Wells
Authors: Liu Q. Z. , Mei X. B. , Yu L. S. , Tu C. W. , Lau S. S. 
Published: April 2011

ABSTRACTPhotoelastic optical waveguides using strain-compensated InAsP/InGaP multiplequantum-well (MQW) have been fabricated. Lateral light confinement for waveguiding is achieved by introducing stress into semiconductor heterostructures with stable WNi surface stressor stripes. The waveguides have been characterized at both 1.52 μm and 1.32 μm wavelength in term of TE/TM intensity ratio. At 1.52 μm, the waveguides favor the propagation of TE mode, and the TE/TM intensity ratio can be as large as 15 dB. At 1.32 μm, the TE and TM intensity can be comparable. Anisotropy of waveguides fabricated along [110] or [110] directions has also been observed in term of TE/TM intensity ratio, which suggests the presence of anisotropic property of the strain-compensated MQW.
Room Temperature Electron Mobility Enhancement in a Strained Si Channel
Authors: Garchery L. , Warren P. , Sagnes I. , Badoz P. A. 
Published: April 2011

ABSTRACTDuring the last few years, Si/SiGe heterostructures have been used by several groups worldwide in order to achieve high-mobility two-dimensional electron gases.1-3 To confine high-mobility electrons, these heterosystems are grown in such a way that the Si channel, epitaxially grown on a relaxed SixGe1−x buffer, undergoes a tensile strain. As such structures have a significant conduction band offset, the spatial separation of ionized dopant atoms from mobile carriers can be exploited. The confined electrons in the Si channel are then provided by a doped SiGe supply layer. The significant improvement in SiGe buffer quality has led to low temperature mobilities exceeding 100 000 cm2/Vs with best values above 350 000 cm2/Vs.2-5 However, for MOS applications, the most interesting point is the room temperature (RT) mobility of confined electrons in the Si channel. With this aim in view, RT-mobilities between 2000 and 2600 cm2/Vs have been reported.6 These values are more than twice larger than these of commercial MOSFETs and are also higher than the bulk mobility of intrinsic Si. However, these relatively high values are still lower than the predicted ones (3000 cm2/Vs).7 This is partially due to the fact that the RT-mobility measured on modulation doped heterostructures (MDHs) is never exactly that of the confined electrons in the Si channel. The conduction electrons are in fact not completely transferred from the supply layer to the channel. The latter is the primary and desired path for conduction, but the supply layer can become a second, parallel path, with a lower mobility because of donor impurities. Different methods can be used to reduce the contribution of this parallel path. First, the supply layer can be designed with the lowest possible doping level so as to ensure an almost complete electron transfer at room temperature.8 Secondly, gated Hall devices can be fabricated using Schottky or Metal-Insulator-Semiconductor gates.9-11 These devices allow both the electron density and electron mobility in the strained Si channel to be measured for low gate voltage.
Correlation Between Photoluminescence Spectral Features and Crystal Growth Temperature for Sige Single Quantum Wells
Authors: Gerling M. , Nilsson S. , Zeindl H. P. , Jagdhold U. 
Published: April 2011

ABSTRACTSample temperature dependence and excitation power dependence of the photoluminescence intensity were investigated with respect to growth temperature for SiGe single quantum wells grown pseudomorphically to (100)-oriented Si by molecular beam epitaxy. The determined excitation power exponents and thermal activation energies show unambiguously that defect incorporation is effectively reduced at higher growth temperatures. However, at higher growth temperatures the SiGe-related spectral distribution is found to be shifted to higher photon energy which is attributed to intermixing of Ge and Si at the heterointerfaces, governed by diffusion as well as Ge surface segregation during growth. The diffusion process is studied separately by photoluminescence measurements upon thermal annealing at different temperatures and a diffusion model is presented where the diffusion process is assumed to be composed of two different mechanisms, interdiffusion, i.e. lattice-site-exchange diffusion, and point-defectinduced diffusion. The determined activation energies for the two diffusion mechanisms are in good agreement with previous results which confirm that the model gives a realistic picture of the diffusion process.
Solid-Phase Epitaxial Regrowth and Dopant Activation of Arsenic. Implanted Metastable Pseudomorphic Ge0.08Si0.92 AND GeO.16SiO.84 ON Si(100)
Authors: Lie D.Y.C. , Song J.H. , Nicolet M.-A. , Theodore N.D. , Candelaria J. , Thomas S.G. , Tanner M.O. , Wang K.L. 
Published: April 2011

ABSTRACTMetastable pseudomorphic GexSi1−x (x=8%,16%) films were deposited on p-Si(100) substrates by chemical-vapor-deposition and then implanted at room temperature with 90 keV arsenic ions to a dose of 1.5×1015/cm2. The implantation amorphizes approximately the top 125 nm of the 145 nm-thick GeSi layers. The Si-GeSi interfaces remain sharp after implantation. Implanted and non-implanted GeSi samples, together with implanted Si control samples, were subsequently annealed simultaneously by rapid thermal annealing in a nitrogen ambient at 600,700,800 × for 10,20,40s at each temperature. The implanted samples undergo layer-by-layer solid-phase epitaxial regrowth during annealing at or above 600 ×C. The amorphized and regrown GeSi layers are always fully relaxed with a very high density of dislocations (1010-1011/cm2). At a fixed annealing temperature, strain relaxation of an implanted GeSi film is substantially more extensive than that of a non-implanted one. About 50-90% of the implanted arsenic ions become electrically active after the completion of solid-phase epitaxy. The percentages of arsenic ions that are activated in the Si control samples are generally higher than those in GeSi. The room-temperature sheet electron mobility in GeSi is roughly 30% lower than that in Si for a given sheet electron concentration. We conclude that metastable GeSi on Si(100) amorphized by arsenic ions and recrystallized by solid-phase epitaxy cannot recover both its crystallinity and its pseudomorphic strain under rapid thermal annealing.
Formation of Amorphous Interlayers by Solid–State Diffusion in Ti Thin Films on Si–ge Layers on Silicon and Germanium
Authors: Lai J.B. , Liu C.S. , Chen L.J. , Cheng J.Y. 
Published: April 2011

ABSTRACTThe formation of amorphous interlayers (a–interlayers) by solid–state diffusion in ultrahigh vacuum deposited polycrystalline Ti thin film on germanium and Sil-xGex alloys grown on (001)Si has been investigated by transmission electron microscopy and Auger electron spectroscopy.Amorphous interlayers, less than 2 nm in thickness, were observed to form in all as–deposited samples. The growth of a–interlayers was found to vary non–monotonically with the composition of Si–Ge alloys in annealed samples. On the other hand, the formation temperature of crystalline phase was found to decrease with the Ge content. The results are compared with that of the Ti/Si system. The formation mechanism are discussed in terms of thermodynamic and kinetic factors.
Incorporation of Thallium in IN1−xTIxP Grown by Metal Organic Molecular Beam Epitaxy
Authors: Antonell M.J. , Abernathy C.R. 
Published: April 2011

ABSTRACTInxTll−xP has been proposed as a potential narrow bandgap material for the fabrication of IR detectors. 1 It is expected to exist in a zincblende structure with a lattice constant approximately 2% larger than aInP for x=0. In this paper we will discuss attempts to grow this alloy on InP using various combinations of elemental and gaseous sources including In, Tl, trimethylindium (TMI), triethylindium (TEI) and phosphine. The sticking coefficient of Tl was found to decrease rapidly for temperatures above 350°C, mandating the use of low temperatures. Attempts to grow TIP resulted in the formation of Tl droplets which oxidized rapidly upon removal from the vacuum system. Auger analysis of the surface shows the oxide composition to be Tl2O, indicative of a monovalent Tl oxidation state. InTlP grown under similar conditions shows an initial tendency to form structural defects, as observed by cross-sectional TEM, suggesting lattice mismatch due to incorporation of small amounts of Tl. As the Tl concentration at the growth surface is increased, a two-phase material is obtained consisting of Tl-rich droplets and InP. In addition, Auger depth profiling shows clear evidence of Tl segregation.
Spatial Resolution of Small Particles in Silane Discharge
Authors: Spears K. G. , Roth R. M. 
Published: April 2011

AbstractA capacitively coupled, rf glow discharge of silane in argon was studied with laser light scattering to determine the spatial concentration of small particles. Multi-wavelength scattering profiles have been obtained and are being analyzed to obtain size distributions as a function of spatial location. Very sharply defined particle zones can be found under some plasma conditions that are spatially related to the silicon atom profiles. We will report our results and attempt to qualitatively describe how these zones relate to plasma chemistry and film deposition processes.
Studies of the Etching of Si, SiO2 and Mo by Carbon Fluorine Compounds Using Real Time Auger Spectroscopy
Authors: Thomson D. , Helms C. R. 
Published: April 2011

AbstractThe ion etching of Si, SiO2 and Mo by fluorocarbon ions was studied using real time Auger electron spectroscopy. The carbon in the CF3+ ions was found to react rapidly with SiO2 to form volatile products, resulting in a very low carbon concentration on the SiO2 surface. Both Si and Mo formed carbides when bombarded with CF3+ ions. This resulted in a high carbon concentration on these surfaces.
Mechanism of Dry Etching of Silicon Dioxide: a Case of Direct Reactive Ion Etching
Authors: Steinbruchel Ch. , Lehmann H. W. , Frick K. 
Published: April 2011

AbstractReactive sputter etching of SiO2 with CHF3-O2 plasmas has been investigated in a parallel plate reactor by combining etch rate measurements with concurrent determination of ion densities (using a Langmuir probe) and the composition of neutral plasma species (using a mass spectrometer). Etch rates are found to follow the ion density and to be fairly independent of the plasma chemistry under most experimental conditions. Moreover, a comparison of reactive sputter etching and reactive ion beam etching of SiO2 with CHF3 and CF4 shows that etch yields per incoming ion are essentially independent of the flux of neutral radicals to the substrate. This strongly suggests as the dominant etch mechanism for SiO2 direct reactive ion etching, where ions themselves are the main reactants in the etch reaction. Measured values of etch yields are consistent with this picture.
Silicon Etching Mechanisms - Doping Effect
Authors: Lee Young H. , Chen Mao-Min , Bright A. A. 
Published: April 2011

AbstractEtch rates of heavily doped silicon films (n- and p-type) and undoped polysilicon film were studied during plasma etching and also during reactive ion etching in a CF4/O2 plasma. The etch rate of undoped Si was lower than the n+ Si etch rate, but higher than the p+ Si etch rate, when the RF inductive heating by the eddy current was minimized by using thermal backing to the water-cooled electrode. The thermal activation energy for spontaneous chemical etching was measured to be 0.10 eV, independent of the doping characteristics. This doping effect may be explained by the opposite polarity of the space charge present in the depletion layer of n+ Si and p+ Si during reactive plasma etching.
Cluster Model Theoretical Study of the Interaction and Penetration of F on a Si Surface
Authors: Bagus Paul S. 
Published: April 2011

AbstractThe interaction of fluorine with a three-fold open site of the Si(111) surface has been examined using a cluster model. The site considered is taken as representative of one where penetration of the surface may occur. New analyses are used to show that the interaction is ionic with F having essentially a full negative charge for all distances near the surface, both above and below. The bonding is shown to be almost entirely electrostatic between the polarized charges of the positive Si surface and F-. The F-Si binding energy is estimated taking proper account of the electron affinity of F and the ionization potential, work function, of Si. When this is done, it is shown that there is no barrier for the penetration of the Si surface by F; hence, this penetration should not be a rate limiting step in the F-Si etching reaction.
Simulation of Spatially Dependent Excitation Rates and Power Deposition in RF Discharges for Plasma Processing
Authors: Kushner M. J. , Anderson H. N. , Hargis P. J. 
Published: April 2011

AbstractIn low pressure, radio frequency (RF) discharges of the type used in plasma processing of semiconductor materials, the rate of electron impact excitation and energy transfer processes depends upon both the phase of the RF excitation and position in the discharge. Electron impact collisions create radicals that diffuse or drift to the surfaces of interest where they are adsorbed or otherwise react. To the extent that these radicals have a finite lifetime, their transport time from point of creation to surface of interest is an important parameter. The spatial dependence of the rate of the initial electron impact collisions is therefore also an important parameter. The power that sustains the discharge is coupled into the system by two mechanisms: a high energy “e-beam” component of the electron distribution resulting from electrons falling through or being accelerated by the sheaths, and by “joule heating” in the body of the plasma. In this paper, we will discuss the spatial dependence of excitation rates and the method of power deposition in RF discharges of the type used for plasma processing. The basis of that discussion will be results from a Monte-Carlo plasma simulation code for RF discharges. Preliminary results from a model for the etching of silicon in SF6 /O2 plasmas will be presented and evidence for long term changes in the manner of energy deposition will be discussed.
Kinetic Analysis of Chlorofluorocarbon Discharges
Authors: Sawin Herbert H. , Yokozeki Akimichi , Owens Aaron J. , Allen Kenneth D. 
Published: April 2011

AbstractThe fundamental plasma kinetics of chlorofluorocarbon discharges have been studied experimentally and modeled. Electrical impedance analysis of the plasma discharge during the etching process was used to estimate the average electron energy and the electron concentration. Assuming the electron-impact generation of reactant species is the rate limiting step, the etching rate of polysilicon etching was modeled using a simplified expression for the electron-impact rate coefficient for dissociation and the experimentally estimated electron densities and electron energies. Dissociative electron attachment should play a significant role in the production of etchant species at low electron energies. The lower threshold energy and the larger cross-section (σ) for dissociative attachment of chlorofluorocarbons (σmax,∼6×10-18 cm2 at ∼ 3 eV for CF3Cl) in coomprpsanrtison to that of fluorocarbons (σmax ∼0.8×10-18 cm2 at ∼7 eV for CF4 ), increases the significance of this machanism in chlorofluorocarbon discharges. In addition, the production of appreciable concentrations of C1- could influence the transport of positive ions to the electrode surfaces.
Process Characterization of a Load-Locked, Reactive Ion Etching System
Authors: Hendriks Margaret M. , Shanfield S. 
Published: April 2011

AbstractWe report on process characterization of contact hole etching in a load-locked, hexa-gonal reactive ion etching system. Contact holes were etched in silicon dioxide and phos-phosilicate glass (PSG) with emphasis on wall profile control and selectivity to the underlayer of either single crystal silicon, polysilicon, or aluminum.To achieve these requirements, a two stage etch process was developed. In the first stage, controlled wall taper is obtained with a mixture of CHF3 and O2. The second stage utilizes a mixture of CHF3 and a small amount of CO2 to obtain high selectivity to the underlying material. Evaluation of the effects of chamber pressure, RF power, and gas mixture on taper angle, selectivity, resist erosion, and etch rates is presented.In addition, evidence which suggests that the reproducibility of optimum etch condi-tions can be enhanced by the use of a continuously pumped process chamber will be dis-cussed.
Replication Lithography
Authors: Deckman H. W. , Dunsmuir J. H. 
Published: April 2011

AbstractA new method has been developed which allows submicron patterns to be rapidly copied from a master into an inorganic substrate. Physical repli-cation and lithographic pattern transfer are combined to produce a wide variety of surface textures on large area substrates. Physical replication techniques are used to create a polymeric intermediate transfer mask which is then used as an etch mask on the substrate. Both positive and negative copies of the original pattern can be created using this process. Final pattern transfer is accomplished by dry processing, allowing precisely controlled alterations of the aspect ratios in the original pattern. Using this process it is possible to fabricate extremely large area submicron sized surface textures (such as diffraction gratings) which are useful in many areas of science and technology.
Structural Studies of Microcrystalline Silicon Films Produced by Sputtering
Authors: Moustakas T. D. , Weitz D. A. , Prestridge E. B. , Friedman R. 
Published: April 2011

AbstractA number of microcrystalline silicon films have been deposited by RF sputtering and their structure was investigated by Raman spectroscopy, X-ray scattering, SEM, TEM and IR spectroscopy. The interpretation of these results suggests that the film growth proceeds initially via amorphous island formation and that the degree of crystallization of the final film depends on subsequent solid phase crystallization during the time of growth. The size and the preferred orientation of the crystallites correlates with the columnar growth habit of the films while the rest of the amorphous matrix is shown to exhibit a considerable degree of order.
Mechanisms of Plasma Oxidation of Si
Authors: Siejka J. , Perriere J. 
Published: April 2011

AbstractFundamental aspects of the interaction between non equilibrium, low pressure oxygen plasma and Si (silicides) are described. The kinetics of oxide growth in oxygen atmosphere, in plasma at low pressure (p<∼ 1 Torr) and low temperature (T < 1 800°C) regimes are reviewed and the Cabrera-Mott mechanism is postulated i.e. the oxidation process is controlled by ion injection at the plasma/oxide interface. The mechanism of electron injection and conduction during plasma anodization is reviewed and discussed in the frame of theory of high current injection in MIS structure. Enhancement of oxide growth rate due to the irradiation (laser), bombardment by electrons or ions is reviewed and compared to the plasma oxidation. Spectacular enhancement of the anodization rate of Si covered by a thin deposited layer of zirconia or hafnia oxide is analyzed. The anodization rate of Si deposit through ∼’ 0.5 mm YSZ single crystal substrate is evoked as an example of potentiality of plasma anodization process. The mechanism of movement of oxygen ions and of cations deduced from 160/180 experiments is discussed. A few examples of applications of Si plasma oxidation processes are presented.
Formation of Sub-100 NM GE Wires on Si by E-Beam Evaporation/Lithography
Authors: Deng C. , Wu J. C. , Barbero C. J. , Sigmon T. W. , Wybourne M. N. 
Published: April 2011

ABSTRACTA fabrication process for sub-100 nm Ge wires on Si substrates is reported for the first time. Wires with a cross section of 6 × 57 nm2 are demonstrated. The wire structures are analyzed by atomic force (AFM), scanning electron (SEM), and transmission electron microscopy (TEM). Sample preparation for TEM is performed using a novel technique using both pre and in situ deposition of multiple protection layers using a Focused Ion Beam (FIB) micromachining system.
Atomic Diffusion and Strain Measurement on Si Grating Structures by X-Ray Diffraction
Authors: Tanaka So , Umbach Christopher C. , Shen Qun , Blakely Jack M. 
Published: April 2011

ABSTRACTWe have applied high resolution synchrotron X-ray diffraction to two-dimensional (2D) Si gratings with wavelengths of 300 and 400nm. We show that this method is very sensitive to both the geometry (grating wavelength, height, and angle of inclined sidewall) and the state of strain. Morphology changes produced by vacuum annealing can be detected so that the mass transport rates on Si surfaces can be measured. Strain measurements show that grating pillars covered with 1 lnm of thermal oxide were under tension (ε = 3.7 × 10−4). This strain was elastically relaxed by removing the oxide.
TiO2 Nanophases Formed Using the Sol-Gel Technique
Authors: López T. , Gómez R. , Boldú J. L. , Muñoz E. , Bokhimi  , Novaro O. 
Published: April 2011

ABSTRACTWe have prepared nanoparticles of titania using the sol-gel technique. The samples were characterized by FTIR, DTA, TGA, EPR and XRD. The properties observed with these techniques are correlated in the temperature region between 200 and 800°C. The Ti-OH bonds are basic to interpret this correlation.
Surface Structure of A Liquid Perfluoropolyether Examined by Reactive Ion/Surface Scattering
Authors: Pradeep T. , Miller S. A. , Rohrs H. W. , Feng B. , Cooks R. G. 
Published: April 2011

ABSTRACTThis study shows that reactive ion/surface collisions can provide information on the surface structure of molecular systems. The microscopic structures of perfluorinated polyether (PFPE) liquid surfaces are characterized by ion/surface collision experiments in a mass spectrometer and the results are compared to those obtained with a fluorinated self-assembled monolayer (F-SAM) surface. Low energy (< 100 eV) beams of W+ and W(CO)6+ ions are used for surface-induced dissociation (SID) and ion/surface reactive scattering, while Xe+ and Kr+ beams are used for chemical sputtering experiments. Both the PFPE and F-SAM surfaces show similar SID fragments while reactions with W+ and W(CO)6+ lead to the scattered metal ion with multiple fluorine atoms attached. The main peaks in chemical sputtering spectra are similar for both surfaces as well. Both hydrogen probe beams and chemical sputtering confirm that the liquid PFPE surface is nearly free of impurities. Our results on both surfaces also suggest that the CF3 group of the monomer units is most likely projected outward from the bulk of the liquid surface.