bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical Vapor Deposition of Beta Silicon Carbide Epilayers Using the Single Source Precursor 1,2-Disilylethane
Authors: Parsons J. D. , Roberts D. A. , Wu J. G. , Chadda A. K. , Chen H-S. , Hockenhull H. 
Published: March 2011

ABSTRACTA β-SiC epitaxial growth process, using 1,2-disilylethane (DES), was developed. DSE was selected because it contains an equal number of C and Si atoms and its reported decomposition characteristics suggest that C and Si could be obtained from it at approximately equal rates. Repeatable nucleation and epitaxial growth conditions, giving complete substrate coverage and controlled growth, were established by atmospheric pressure CVD, in an inverted-vertical reactor. A substrate temperature of 1290± 10°C was found to be optimum for β-SiC epilayer nucleation and growth. The maximum β-SiC epitaxial growth rate obtained was 10μms/hr. Undoped β-SiC epilayers were n-type (n≈1016 cm−3 ). DSE synthesis, CVD growth parameters, SiC deposition characteristics and β-SiC epitaxial film properties are described.
Chemical and Electrical Mechanisms in Titanium, Platinum, and Hafnium Contacts to Alpha (6H) Silicon Carbide
Authors: Porter L. M. , Glass R. C. , Davis R. F. , Bow J. S. , Kim M. J. , Carpenter R. W. 
Published: March 2011

ABSTRACTThin films (2 Å - 1000 Å) of titanium, platinum, and hafnium were deposited via UHV electron beam evaporation at room temperature on n-type, (0001) alpha (6H)-SiC and compared in terms of interfacial chemistry, energy barriers to electrical conduction, and macroscopic electrical behavior. Current-voltage measurements have shown that these contacts are rectifying, all with ideality factors between 1.01 and 1.09. The lowest leakage currents (∼5 × 10−8 A/cm2 at -10 V) were determined for unannealed Pt contacts and for Hf contacts annealed at 700°C for 20 minutes. Current-voltage (I-V), capacitance-voltage (C-V), and x-ray photoelectron spectro-scopy (XPS) were among the techniques used to determine barrier heights, all of which were within a few tenths of an electron volt of 1.0 eV. The narrow range of calculated barrier heights along with the XPS valence spectrum of the chemically prepared SiC surface give evidence that the Fermi level is pinned at the semiconductor surface.
Oxygen Atom Induced Deposition of Silicon Dioxide
Authors: Levedakis Dimitri A. , Raupp Gregory B. 
Published: March 2011

ABSTRACTSilicon dioxide was deposited from tetraethylorthosilicate (TEOS) and remote microwave oxygen plasma on a heated silicon substrate in a cold-wall reactor. The deposition rate and film quality were examined as functions of substrate temperature, total pressure, absorbed plasma power and O2:TEOS flow ratio. The deposition reaction exhibited an activation energy of approximately 10 kJ/mol for substrate temperatures in the range of 323–623 K. The deposition rate reached a maximum with increasing total pressure. The rate was found to be a near-linear function of the absorbed microwave power. At fixedabsorbed power the rate reached a maximum with increasing O2:TEOS flow ratio. A one-dimensional mathematical model was developed to predict the oxygen radical concentration at the exit of the afterglow region of the oxygen discharge. Comparisons of the predicted oxygen radical concentrations with the deposition rates at corresponding deposition conditions supports the view that the overall SiO2 deposition reaction is largely controlled by the concentration of oxygen radicals. The average refractive index ofthe deposited films was 1.466 ± 0.011. Fourier transform infra-red (FTIR) transmission spectra showed significant concentrations of hydroxyls in the deposited films.
Reactive Scattering of Si2 H6 from the Si(100) Surface
Authors: Hansen D. A. , Furjanic M. J. , Xia L.-Q. , Engstrom J. R. 
Published: March 2011

ABSTRACTThe reaction of Si2H6 with the Si(100) surface has been examined via supersonic molecular beam scattering techniques. The effects of incident translational energy, incident angle, mean vibrational energy and surface temperature have been considered explicitly. It is found that the reaction probability is most sensitive tothe incident translational energy, varying nearly linearly with increasing energy. The effect of incident angle θi can be accounted for by an energy scaling law that is given approximately by <Etr>cosnθi, where n ∼ 1.
Growth of GaN, AlN and InN by Electron Cyclotron Resonance-Metal Organic Molecular Beam Epitaxy
Authors: Wisk P. W. , Abernathy C. R. , Pearton S. J. , Ren F. , Lothian J. R. , Katz A. , Jones K. 
Published: March 2011

ABSTRACTWe have investigated the feasibility of depositing GaN, AIN and InN from nitrogen plasmas by electron cyclotron resonance-metal organic molecular beam epitaxy (ECR-MOMBE). Growth rate, morphology, and resistivity were evaluated as function of growth temperature and group IB flux. It was found that stoichiometric materials could be deposited at reasonable growth rates on either GaAs or sapphire substrates. Low contact resistance, ∼5 × 10−7 Ω-cm2, can be obtained on In due to the high carrier concentrations, 1020 cm−3 obtained in this material.
The Decomposition Chemistry of an AlN Precursor Bis-Dimethylaluminum Deutero-Amide, [(CH3)2AlND2]3, as Revealed by Time-of-Flight Molecular beam mass Spectrometry
Authors: Amato Carmela C. , Hudson John B. , Interrante Leonard V. 
Published: March 2011

ABSTRACTA molecular beam mass spectrometer coupled to the inlet portion of a hot-wall CVD reactor has been used to measure the time-of-flight (TOF) distribution of molecules sampled from the reactor. The molecular weights of the species in the reactor can be determined from test TOF distributions. This technique has been used to identify the gas phasespecies present in a hot-wall reactor during the CVD of A1N using bis-dimethylaluminum deutero-amide,[(CH3)2AlND2]3 (I), as the precursor. Evidence has been found for: deuterated methane, CH3D, trimeric form of the precursor I, and its dimeric form. TOF evidence also supports the presence of an oligomer of I with a pentameric structure, as well as a number of substituted versions of trimer and dimer. Mechanisms have been formulated that explain methane elimination from the precursor as well as the formation of all species observed.
Strained Quantum Dots in Porous Silicon
Authors: Zhao Xue-Shu , Persans Peter D. , Schroeder John , Wu Yeun-Jung 
Published: March 2011

ABSTRACTOn the basis of Raman, photoluminescence, and absorption studies of porous and nanoparticle silicon we propose that the strong luminescence in porous silicon results from strained silicon quantum dots. A silicon nanoparticle is a special Jahn-Teller system induced by extended electron states rather than localized state. Thus Raman scattering and photoluminescence in porous silicon are multi-phonon assisted free electronic transition processes, all observed anomalous properties of porous silicon can be clearly explained by using this strained quantum dot model.
Picosecond Decay Dynamics in Porous Silicon
Authors: Matsumoto T. , Futagi T. , Mimura H. , Kanemitsu Y. 
Published: March 2011

ABSTRACTPicosecond decay dynamics of luminescent porous silicon has been studied using the second harmonics (SH) of a cw modelocked YLF laser and a synchroscan streak camera. Picosecond luminescence decay shows nonexponential behavior that becomes large with decreasing emission energy. When increasing hydrogen termination on the surface of a Si microcrystal occurs, this picosecond luminescence decay becomes faster. Our experimental results indicate that there are two luminescent states in porous Si : a weak luminescent quantum confinement state and a strong luminescent surface localized state.
Study of Photoluminescent thin film Porous Silicon on Sapphire
Authors: Dubbelday W. B. , Szaflarskf D. M. , Shimabukuro R. L. , Russell S. D. 
Published: March 2011

ABSTRACTPhotoluminescence in porous silicon on sapphire (SOS) prepared through chemical staining and photo-initiated chemical etch is demonstrated. SOS consists of single crystal quality material on a transparent substrate through which photoluminescence can be excited and observed. Porous silicon films as thin as 270 nm are shown to photoluminesce. This study explores the effect of varying film thickness and crystal quality on the photoluminescent emission from porous silicon. Introduction of crystal defects by ion implantation is used to create controlled damaged layers prior to fabricating porous silicon. No photoluminescence is observed from chemically stained or electrochemically etched amorphized layers. Corroborative results are obtained using LPCVD deposited amorphous silicon layers.
Fast Photoluminescence from Porous Silicon
Authors: Petrova-Koch V. , Muschik T. , Kovalev D. I. , Koch F. , Lehmann V. 
Published: March 2011

ABSTRACTTime-resolved studies of the visible photoluminescence in porous silicon with three different coverages of the internal surface are reported. We use aged, naturally oxidized porous Si (oxihydride), rapid thermal processed material (oxide) and samples stored in HF (pure hydride). A new, fast luminescence band in the blue-green spectral range and with response time less than 100 ns is observed at room temperature in each of the samples, although with different intensities. The observations prove that this is not an oxide-defect luminescence. We speculate on mechanisms for the origin of the fast luminescence in nanometer-size crystallites of Si.
Structural Investigation of Electrochemically Etched Silicon
Authors: Heuser B. J. , Spooner S. , Glinka C. J. , Gilliam D. L. , Winslow N. A. , Boley M. S. 
Published: March 2011

ABSTRACTSmall-angle neutron scattering (SANS) measurements of four electrochemically etched, porous silicon (PS) samples have been performed over a wide wavevector transfer (Q) range. The intermediate to high Q results can be modeled with a non-particulate, random phase model. Correlation length scales on the order of 1 to 2 nm thought to characterize the PS skeleton have been deduced from the SANS data. The microstructural anisotropy was studied tilting two of the samples with respect to the neutron beam. These samples exhibited an asymmetric scattering pattern at intermediate Q (0.1 ≤ Q ≥ 0.6 nm-1) in this condition. Photoluminescence spectra from all four samples have been recorded as well. A correlation appears to exist between the SANS and photoluminescence measurements. An x-ray diffraction measurement of one sample demonstrates that the PS layer retains the silicon lattice structure. Significant peak broadening is observed that we interpreted as a quasi-particle size effect The PS particle size calculated from the x-ray diffraction measurement is equal to the correlation length obtained in the SANS measurement.
Photochemical Etching Effects on Optical Properties of Porous Silicon
Authors: Kanemitsu Y. , Uto H. , Masumoto Y. , Matsumoto T. , Futagi T. , Mimura H. 
Published: March 2011

ABSTRACTWe have studied effects of hydrogen-termination on optical properties of porous Si. The hydrogen concentration in the samples was controlled by photochemical etching after the electrochemical anodization. Transmission electron microscopy examination shows that the size of Si crystallites in porous silicon ranges from 3 to 10 nm and no significant size changes occur by the photochemical etching process. The PL spectra, the PL excitation spectra, and the picosecond PL decay rate were sensitive to the photochemical etching process. Spectroscopic analysis suggests that the radiative recombination occurs at the near-surface region of the Si crystallites.
Investigation of Porous Silicon Films Structure by Optical Methods
Authors: Basmaji P. , Grivickas V. , Surdutovich G. I. , Vitlina R. , Bagnato V. S. 
Published: March 2011

ABSTRACTThe structure of aged porous silicon (PS) has been investigated using reflectivity, photoluminescence (PL), optical absorption and photoconductivity decay. An optical anisotropy in a perpendicular to surface direction is observed for PS samples below a critical porosity of 70%. The photostability of the PL spectra imply three different structures of PS, these should be attributed to quantum size structures, polymeric type structures and fluor-related structures. The absorption edge is deconvoluted into a band-to-band absorption with energy ranging between Eg = 1.6–2 eV and an absorption shoulder at hu ≤ Eg. The high energy PL band around 2.3 eV resembles that of fluoroindate glass. The observed rapid lifetime at high injection level is attributed to excitonic Auger-type recombination.
Rapid Photoluminescence Intensity Degradation in Porous Silicon
Authors: Basmaji P. , Bernussi A. A. , Rossi J. C. , Matvienko B. 
Published: March 2011

ABSTRACTRapid photoluminescence intensity degradation are observed in porous silicon layers formed at different preparation conditions. The decay rate, ranging from 0.5 to tens of seconds, is found to be a function of illumination intensity, sample temperature and emission wavelength. We attributed the degradation effect to photochemical reactions on the surface.
Light Emission from Porous Silicon Subjected to Rapid Thermal Oxidation
Authors: Cullis A. G. , Canham L. T. , Williams G. M. , Smith P. W. , Dosser O. D. 
Published: March 2011

ABSTRACTLuminescent oxidised porous Si is produced by rapid thermal annealing of the anodised material in a dry oxygen ambient. Its light-emitting properties are studied by both photoluminescence and cathodoluminescence methods. The structure of the oxidised material is examined by transmission electron microscopy, while its oxygen content is determined by X-ray microanalysis. These investigations show that crystalline Si nanostructures remain in the oxidised porous material and account for its luminescence properties. The work demonstrates that the speculated importance of either Si-based amorphous phases or the interesting material, siloxene, in this regard is unrealistic.
The Effect of Lewis Base Chemisorption on the Luminscence of Porous Silicon
Authors: Coffer Jeffery L. , Lilley Sean C. , Martin Rebecca A. , Files-Sesler Leigh Ann 
Published: March 2011

ABSTRACTWe report here studies on the effects of Lewis base addition on the observed luminescence of porous silicon generated non-anodically from a stain etch of <100> p-type wafers and whose surface morphology has been characterized by atomic force microscopy (AFM). Addition of dilute heptane solutions of alkyl amines such as n-butyl amine (C4H7NH2) results in dramatic quenching of the steady-state photoluminescence (PL) near 625 nm. The observed fractional changes in integrated PL intensity as a function of amine concentration have been fit to a simple equilibrium model demonstrating Langmuir-type behavior from which adduct formation constants have been calculated. These steady-state PL measurements are complemented by Fourier Transform Infrared (FT IR) spectroscopic measurements monitoring the effect of amine adsorption on the silicon hydride stretching modes [v(Si-Hx)] near 2100 cm-1. Based on these results, a physical model for the amine interactions with the porous silicon surface is presented.
New Results on Electroluminescence from Porous Silicon
Authors: Steiner Peter , Kozlowski Frank , Sandmaier Hermann , Lang Walter 
Published: March 2011

ABSTRACTFirst results on light emitting diodes in porous silicon were reported in 1991. They showed a quantum efficiency of 10-7 to 10-5 and an orange spectrum. Over the last year some progress was achieved:- By applying UV-light during the etching blue and green light emitting diodes in porous silicon are fabricated.- When a p/n junction is realized within the porous region, a quantum efficiency of 10-4 is obtained.
Porous Silicon-Based Optoelectronic Devices: Processing and Characterization
Authors: Kalkhoran Nader M. 
Published: March 2011

ABSTRACTA patterning process compatible with conventional Si electronics technology, which has resolution better than 5 μm, has been developed in order to perform selected-area anodic etching for producing luminescent porous Si layers (PSL). Correlations between the anodic etching and photolithographic parameters have been identified, and their effects on the resolution and luminescence of porous Si layers have been studied. Finally, the first monolithic processing, i.e., true wafer-scale integration, of a Si-based visible light-emitting diode (LED) and a photodetector using conventional Si technology has been demonstrated.
Quantum Confinement Effects on the Dielectric Constant of Porous Silicon
Authors: Tsu R. , Ioriatti L. , Harvey J. F. , Shen H. , Lux R. A. 
Published: March 2011

ABSTRACTThe reduction of the dielectric constant due to quantum confinement is studied both experimentally and theoretically. Angle resolved ellipsometry measurements with Ar- and He-Ne-lasers give values for the index of refraction far below what can be accounted for from porosity alone. A modified Penn model to include quantum size effects has been used to calculate the reduction in the static dielectric constant (ε) with extreme confinement. Since the binding energy of shallow impurities depends inversely on ε2, the drastic decrease in the carrier concentration as a result of the decrease in ε leads to a self-limiting process for the electrochemical etching of porous silicon.
Composition and Structure of Spark Eroded Porous Silicon
Authors: Hummel R. E. , Chang S.-S. , Ludwig M. , Morrone A. 
Published: March 2011

ABSTRACTPorous silicon which has been prepared by a “dry” technique, that is, by spark erosion, yields similar photoluminescence spectra as anodically etched porous silicon which has been prepared in aqueous solutions. Fourier transform infrared spectra reveal that the dominant features in spark eroded silicon are the Si-O-Si stretching mode and the Si-O-Si bending mode. No infrared vibrational modes characteristic for siloxene have been found in spark eroded Si. Results from X-ray and electron diffraction studies suggest that spark eroded Si involves minute polycrystalline silicon particles which are imbedded in an amorphous matrix.
Carrier Transport Through Grain Boundaries in Hydrogenated Microcrystalline Silicon
Authors: Grebner S. , Wang F. , Schwarz R. 
Published: March 2011

ABSTRACTTo analyse the influence of the grain boundaries (gb) on the transport of carriers in hydrogenated microcrystalline silicon (μC-Si:H) the ambipolar diffusion length (LLMB) was measured by SSPG. In addition, the films were characterised by photo-conductivity, dark conductivity activation energy, Urbach energy (determined by CPM), hydrogen effusion, Raman spectroscopy, X-ray scattering and optical transmission.The sample series was prepared by PECVD of SiH4 diluted with increasing H2 content. Taking the structural information by Raman spectra and X-ray into account, we explain our optical and activation energy measurements within a three-phase-model (amorphous phase, crystalline phase, gb) and a Fermi level pinning in μc-Si:H.
Spectroscopic Ellipsometry and Interference Reflectometry Measurements of CVD Silicon Grown on Oxidized Silicon
Authors: Jellison G. E. , Keefer M. , Thornquist L. 
Published: March 2011

ABSTRACTSeveral samples of thin-film silicon grown on oxidized Si, both oxidized and unoxidized, have been examined using spectroscopie ellipsometry (SE) and constant angle reflection interference spectroscopy (CARIS). The SE data was fit to 5- or 6- layer models of the sample near-surface region, using the optical functions of thin-film silicon determined from a previous work. Reasonable fits were obtained from samples containing amorphous Si (a-Si) or large-grain poly-crystalline Si (p-Si), but fits to samples containing small-grain, undoped p-Si were poor unless a 8–15 nm surface roughness layer is included. Furthermore, the optical functions of p-Si:ud are not consistent from sample to sample. The optical functions determined from SE measurements were then used to interpret CARIS measurements, extracting the thicknesses of the films, which are then compared with the thicknesses obtained from SE.
A Particular Structure of B-doped μc-Si/a-Si:H Layers on Insulator
Authors: Le Berre M. , Lemiti M. , Pinard P. , Bustarret E. , Grieshaber W. , Bruyère J.-C. , Brunei M. 
Published: March 2011

ABSTRACTMicrocrystalline films of thicknesses ranging from 0.3 to 1.1 μm have been deposited on oxidized silicon wafers by PECVD in a 50KHz capacitive discharge reactor at 450°C. Two series of films have been elaborated over a wide range of boron concentrations at the same H2:SiH4 ratio of 9:1. Cross section TEM micrographs showed the films to consist of two sublayers of distinct crystalline nature, whose relative thickness depends on the preparation conditions. With a strongly <220> textured microcrystalline structure, the overlayer snowed a columnar morphology, while the amorphous underlayer reached thicknesses of 350nm. Two additional striking features were observed by TEM: - The grains took two symmetrical orientations relative to the preferential [220] growth axis;- The interface between the amorphous and crystalline regions had a sawtooth pattern with a period around 300nm. In contrast to these microstructural results, the B-profile as measured by SIMS was found to be fiat accross the whole thickness. These local measurements are compared to the results of grazing X ray diffraction and Raman measurements. We observe and discuss a discrepancy between the X ray coherence length and the dimensions of the columns as observed by TEM. While optimized conditions lead to a vanishing amorphous sublayer, the more original features described above are tentatively interpreted taking into account the high compressive strains in the layers deposited at low plasma frequencies.
TEM Study and Hall Measurement of nc-Si Prepared by Controlled Deposition
Authors: Nakata Masami , Shimizu Isamu 
Published: March 2011

ABSTRACTWe report the results of a study in which we combined growth experiments with measurements of the nc-structure and of electrical transport Samples were prepared by plasma enhanced-CVD using SiF4 and H2 gases. We also added PH3 and H2 as control parameters for structural change. The microscopic structure was directly observed by TEM. Electron transport in nc-Si was investigated by Hall effect measurements performed at temperatures from 100K to 400K. We produced samples in which the Hall mobility was applied from general transport mechanism of poly crystalline silicon. However, from TEM observation, we conclude that dominant factor on electrical transport strongly depends on the sample structure, and nanocrystalline-silicon structure is so varied as to make it difficult to determine the transport mechanism without the observation of the microscopic structure.
Low Temperature Fabrication of Poly-Si TFTs using in-situ Chemically Cleaning Method
Authors: Kono Naoki , Nagahara Tatsuro , Fujimoto Kenji , Kashiwagi Yusaku , Kakinoki Hisashi 
Published: March 2011

ABSTRACTThin film transistors were fabricated using polycrystalline silicon (poly-Si) film which were directly deposited on Corning 7059 glass substrates by plasma chemical vapor deposition method at very low temperature of 450°C. No annealing procedure was carried out in the fabrication process. The dependences of the crystallinity and the electrical properties on the poly-Si film thickness were investigated for three kinds of films deposited under different conditions. These dependences on the film thickness were found to be strongly influenced by the deposition condition, especially the reaction gas pressure. By choosing optimum poly-Si deposition condition carefully, high performance TFTs have been fabricated by this novel method.