bluuebunny/crossref_metadata_2025_split huggingface dataset:
Depth-Selective Investigation of Fe-Silicides Formed After Molecular Beam Epitaxy, Using Conversion Electron MÖSsbauer Spectrometry.
Authors: Degroote S. , Kobayashi T. , Dekoster J. , Vantomme A. , Langouche G. 
Published: April 2011

ABSTRACTFe-Silicides were formed by annealing MBE-deposited thin Fe layers with a thickness in the range of 24 Å on (7x7) reconstructed Si(l11) substrates. Samples suitable for depth-selective investigations by CEMS (Conversion Electron Mössbauer Spectrometry) were prepared by using only the 57Fe isotope for a few monolayers of the total Fe film, and depositing these selectively right at the interface or separated from it. During the growth the substrate was held at room temperature. The silicide formation upon annealing to temperatures up to 900°C was monitored in situ with RHEED. From the CEMS studies a drastically different sample composition was inferred as a function of monolayer distance from the interface for the as-deposited samples and for annealing temperatures up to 400°C. Analysis of these spectra indicates the presence of metastable and stable iron silicides.
Chemical Mechanical Polishing for Planarization in Manufacturing Environment
Authors: Desai Mukesh , Jairath Rahul , Stell Matt , Toiles Robert 
Published: April 2011

ABSTRACTGlobal Planarization requirements of the deep sub-micron technology generation requires use of CMP as preferred planarization technique. In the past, CMP has been used extensively in the polishing of silicon wafers. However , there has been some reluctance to utilize this technology in the planarization of oxide films during IC manufacture. This has been driven primarily by issues regarding manufacturability , and therefore cost of ownership of CMP processes. Here the key process integration issues in CMP planarization of oxide films are outlined.An effect of consumable set is shown to be critical in achieving repeatable CMP performance via removal rate & non-uniformity. Various defects induced as a result of CMP are explained. Cost of ownership model is used to demonstrate the importance of minimizing such defects.
Electronic Structures of β-SiC(001) Surfaces and Al/β-SiC(001) Interface
Authors: Hu Xiao , Yan Hong , Ohuchi Fumio S. 
Published: April 2011

ABSTRACTSurface electronic structures of β-SiC reconstructed (001) surfaces and the Al/β-SiC(001) interface have been investigated by employing a tight-binding method. Distinct surface electronic characteristics corresponding to different surface reconstructions are discussed based on the interpretation of surface density of states. The calculations of the Al/β-SiC (001) interface indicate that aluminum deposition on β-SiC(001) surface may induce the substrate to return to the ideal unreconstructed surface and that Al-C interaction is stronger than Al-Si interaction. Al deposition on C-rich surfaces may form a better bonded interface than that on the Si-rich surfaces. Our findings are in good agreement with available experimental and theoretical results.
Computer Simulation of Si and C Atoms on SiC Surfaces
Authors: Matthai C C , Moran G J , Morrison I 
Published: April 2011

ABSTRACTThe molecular dynamics method employing an empirical potential energy function to describe the Si-C interaction has been used to determine the minimum energy sites for Si and C adatoms on C-terminated SiC (001) substrates. It is found that whereas a single C adatom lies on the carbon dimer bond, this site only becomes energetically favourable for silicon adatoms when they interact to form a dimer pair.
Diamond Chemical Vapor Deposition: Gas Compositions and film Properties
Authors: Bachmann Peter K. , Hagemann Hans-Jürgen , Lade Hartmut , Leers Dieter , Picht Frederike , Wiechert Detlef U. , Wilson Howard 
Published: April 2011

ABSTRACTRate, crystallinity and phase purity of vapor-grown diamond deposits are discussed. Emphasis is on microwave plasma CVD of diamond from C/H-, C/H/O-, C/H/F-, C/H/CI- and C/H/N-gas mixtures.The manufacture of wear-resistant diamond thin films, diamond vacuum window membranes and thick diamond heat spreader plates are used as examples to outline the influence of various deposition parameters on the performance of finished products and to describe the use of ternary gas phase compositional diagrams as tools for minimization of deposition technology and product optimization efforts.
Deposition of Flame Grown Diamond Films in an Enclosed Chamber
Authors: Doverspike Kathleen , Shamamian Vasgen A. , Freitas Jaime A. 
Published: April 2011

ABSTRACTPolycrystalline diamond films were synthesized using an oxy-acetylene flame in the open atmosphere and in an enclosed chamber. In the present work, we have shown that the 2.16eV defect band seen in the photoluminescence spectra from the central portion of the films grown in the open atmosphere show a dependence on the growth temperature. Films grown in the open atmosphere all exhibit a decrease in the crystalline quality when moving to the outside edge most likely due to the entrainment of nitrogen into the films.The present study was done in the enclosed chamber using an oxygen atmosphere via an oxygen flow around the torch. Films have been grown in the enclosed chamber that show only trace amounts of the 2.16eV band. Both the Raman and the photoluminescence spectra show that the films grown in the enclosed chamber are very uniform over the deposition area, which suggests that the degradation of the outer portion of the open atmosphere films may be the result of room air entrainment, and not a temperature variation across the substrate. In addition, when either lower purity oxygen is used or lower growth temperatures, we easily observe the 2.16eV band which may be the result of nitrogen impurities in the source gases.
Effects of Methane Concentration and Hydrogen Treatment on Preferred Orientation in Diamond Films Grown by Chemical Vapor Deposition
Authors: Ganesan D. , Sharma S. C. 
Published: April 2011

ABSTRACTWe have conducted x-ray diffraction, Raman spectroscopy, and scanning electron microscopy analyses of diamond films grown by hot filament assisted chemical vapor deposition (HFCVD). We present results on the relative abundance of the (111), (220) and (400) faces in polycrystalline diamond films as functions of CH4 concentration. The intensity of the (111) peak can be varied from about 20% to 60% by adjusting CH4 in CH4/H2 mixtures. We also present results on preferred orientation in films grown under varying hydrogen treatments. We discuss correlations between the preferred orientation, FWHM of the diamond peak in the Raman spectrum, and surface morphology of the films.
Structural Study of SIC/AIN Bilayers and Trilayers on SI and 6H-SIC
Authors: Prasad Beesabathina D. , Fekade K. , Wongchotigul K. , Spencer M. G. , Salamanca-Riba L. 
Published: April 2011

ABSTRACTThe growth morphology and microstructure of SiC/AlN/6H-SiC, SiC/AlN/SiC/Si, and SiC/AlN/Si heterostructures grown by LPCVD were studied using transmission electron microscopy. The SiC/AIN bilayers grown on 6H-SiC substrates were single crystalline and comprised of 3C-SiC and 2H-AlN. The epitaxial relationship between 2H-AlN and 6H-SiC is [0001]AlN//[0001]SiC. The SiC/AlN/SiC trilayers and the SiC/AIN bilayer grown on (001)Si were composed of 3H-SiC and 2H-AlN. However, the 2H-AlN layer was polycrystalline even though the (001)3C-SiC was single crystalline. The preferred orientation of the AlN layers in SiC/AlN/SiC/Si and SiC/AlN/Si are [0112] and [0002], respectively. The AlN/3C-SiC interface is relatively sharp compared to the AIN/Si interface in which an amorphous layer close to the interface was observed. In general, the polycrystalline AlN structure has two distinct layers: (1) nucleation layer and (2) bulk layer. High resolution lattice images of the polycrystalline AlN showed amorphous areas and small misoriented crystallites in the nucleation layer. The bulk layer consists of preferentially oriented large columnar grains.
Electron Cyclotron Resonance Plasma Chemical Vapour Deposition of Silicon Carbide Thin Films Using Ditertiary Butyl Selane
Authors: Boumerzoug Mohamed , Boudreau Marcel , Mascher Peter , Jessop Paul E. 
Published: April 2011

ABSTRACTSilicon carbide films were deposited by electron cyclotron resonance plasma chemical vapour deposition, using Ditertiary Butyl Silane (SiH2(C4H9)2), a non-corrosive organic compound, liquid at room temperature and stable in air, as precursor. Depositions were carried out in an Ar/H2 plasma at relatively low temperatures, below 400 °C. The influence of deposition parameters such as substrate temperature, gas flow rates, pressure, and microwave power, was systematically investigated and related to the Si:C ratios and the refractive index. The film composition was measured by Auger electron spectroscopy and the surface morphology was examined by scanning electron microscopy. The deposition rates and refractive indexes were extracted from the conventional ellipsometric functions, psi and delta. The results show that high quality silicon carbide of variable Si:C ratios and with very low levels of impurities are obtained.
Exposure of Diamond to Atomic Hydrogen: Secondary Electron Emission and Conductivity Effects
Authors: Malta D. P. , Posthill J. B. , Humphreys T. P. , Thomas R. E. , Fountain G. G. , Rudder R. A. , Hudson G. C. , Mantini M. J. , Markunas R. J. 
Published: April 2011

ABSTRACTSecondary electron (SE) yield was enhanced by a factor of ∼30 and surface conductance increased up to 10 orders of magnitude when O-terminated or non-terminated natural diamond (100) surfaces were exposed to atomic H. The SE yield from atomic H-exposed surfaces was spatially dependent on near-surface microcrystalline perfection enabling defect-contrast imaging in the conventional SE mode of the scanning electron microscope (SEM). Ultraviolet photoelectron spectroscopy (UPS) on atomic H-exposed surfaces revealed an intense low energy peak attributed to photoexcitation of secondary electrons into unoccupied hydrogen-induced states near the conduction band edge and their subsequent escape into vacuum. The low energy photoemission peak, enhanced SE yield and enhanced surface conductivity were completely removed via high temperature annealing or exposure to atomic O creating the denuded or O-terminated surfaces, respectively.
CVD-Growth of Low-Doped 6H SIC Epitaxial Films
Authors: Kordina O. , Henry A. , Hallin C. , Glass R. C. , Konstantinov A. O. , Hemmingsson C. , Son N. T. , Janzén E. 
Published: April 2011

ABSTRACTWe present a method for growing low-doped 6H SiC films using chemical vapour deposition in a hot-wall system. The study discusses the influence of temperature, growth rate and C/Si ratio on the purity of the layers. Furthermore, we make a comparison between methane and propane as carbon source, and investigate the influence of bake-out prior to growth. The films are characterised using low temperature photoluminescence. The relative intensity of the free exciton related luminescence as compared to impurity related bound exciton recombination is discussed in terms of material purity. A capacitance-voltage technique is used to determine the doping concentration.
Combined Structural and Optical Assessment of CVD Grown 3C-SiC/Si
Authors: Feng Z. C. , Tin C. C. , Yue K. T. , Hu R. , Williams J. , Liew S. C. , Foo Y. G. , Choo S. K. L. , Ng W. E. , Tang S. H. 
Published: April 2011

ABSTRACTA combined structural and optical assessment of cubic (3C-) SiC thin films grown on Si (100) substrates by chemical vapor epitaxy (CVD) is presented. The CVD growth was performed at both atmospheric and low (100 Torr) pressure, using a vertical reactor. The CVD-grown 3C-SiC films with different growth time were characterized by X-ray diffraction, Raman scattering and Fourier transform infrared (FTIR) spectroscopy to be single crystalline with a high degree of crystal perfection. The film thickness was determined from FTIR spectra. Variations of X-ray, FTIR and Raman spectra with different growth conditions and film thicknesses are studied comparatively. Related problems are discussed.
Movpe Growth of High Quality AlxGa1−xN/GayIn1-yN (x>0, y<1) Heterostructures for Short Wavelength Light Emitter
Authors: Akasaki I. , Amano H. 
Published: April 2011

ABSTRACTHigh-quality AlGaN/GaN and AlGaN/GalnN DHs were fabricated by MOVPE using low-temperature deposited AlN buffer layer. We applied the newly designed dual-flow-channel reactor, by which high-quality and well-controlled AlGaN and GalnN alloys and their heterostructures have been grown. AlGaN/GaN-DH shows low-threshold stimulated emission by optical pumping at room temperature for both edge and surface modes. The peak wavelength of stimulated emission for edge mode was 369.5nm. The peak wavelength of stimulated emission was affected by the strain due to heterostructure as well as the many body effect under high excitation. The wavelength for stimulated emission can be widely changed by using GalnN as the active layer. AlGaN/GalnN DH with InN molar fraction of the active layer of 0.09 shows room temperature low-threshold stimulated emission for edge mode by optical pumping with peak wavelength of 402.5nm. A few mW-class symmetrical AlGaN/GaN DH LED and anti symmetrical AlGaN/GalnN/GaN DH LED using low energy electron beam irradiation (LEEB1) treated Mg-doped P-AlGaN cladding layer were fabricated. These results show that column-Ill nitrides are promising for the realization of practical short wavelength LED and LD.
Buffer Layer Thickness and the Properties of InN Thin Films on AIN- Seeded (00.1) Sapphire And (111) Silicon
Authors: Kistenmacher T. J. , Ecelberger S. A. , Bryden W. A. 
Published: April 2011

ABSTRACTIntroduction of a buffer layer to facilitate heteroepitaxy in thin films of the Group IIIA nitrides has had a tremendous impact on growth morphology and electrical transport. While AIN- and self-seeded growth of GaN has captured the majority of attention, the use of AIN-buffered substrates for InN thin films has also had considerable success. Herein, the properties of InN thin films grown by reactive magnetron sputtering on AIN-buffered (00.1) sapphire and (111) silicon are presented and, in particular, the evolution of the structural and electrical transport properties as a function of buffer layer sputter time (corresponding to thicknesses from ∼50Å to ∼0.64 μm) described. Pertinent results include: (a) for the InN overlayer, structural coherence and homogeneous strain normal to the (00.1) growth plane are highly dependent on the thickness of the AIN-buffer layer; (b) the homogeneous strain in the AIN-buffer layer is virtually nonexistent from a thickness of 200Å (where a significant X-ray intensity for (00.2)AIN is observed); and (c) the n-type electrical mobility for films on AIN-nucleated (00.1) sapphire is independent of AIN-buffer layer thickness, owing to divergent variations in carrier concentration and film resistivity. These effects are in the main interpreted as arising from a competition between the lattice mismatch of the InN overlayer with the substrate and with the AIN-buffer layer.
Theoretical Studies of C(100) Surface Reconstruction and Reaction with CH2
Authors: Jing Z. , Whitten J. L. 
Published: April 2011

ABSTRACTThe reconstruction of the C(100) surface and its reaction with CH2 are studied by a cluster model at several theoretical levels [1–13]. For the reconstruction ofthe C(100) surface, the calculated surface dimer bond length is found to be very sensitive to the level of theoretical treatment and the spin state. A single-determinant SCF treatment gives a closed-shell singlet state, higher in energy than the triplet state, and with a dimer length of 1.401 Å, 0.279 Å shorter than the triplet. The correct ground state is a singlet, but a multi-determinant wavefunction is required for its description. At the CI level, the surface dimer bond length in the ground state is found to be 1.508 Å and the energy decrease on dimer formation with respect to the ideal C(100)-lxl surface is 2.28 eV per dimer. For the reaction of CH2 with C(100), no barrier is found for the chemisorption of CH2on the surface and the reaction is highly exothermic. The surface is converted from C(100)-2×1 to C( 100)-1×1 upon CH2 chemisorption.
Electrical Characterization of Aluminum Nitride Films on Silicon Grown by Chemical Vapor Deposition
Authors: Khan A. H. , Meese J. M. , Stacy T. , Charlson E. M. , Charlson E. J. , Zhao G. , Popovici G. , Prelas M. A. 
Published: April 2011

ABSTRACTAluminum nitride (AlN) films were grown on silicon (Si) substrates by chemical vapor deposition (CVD). The films were characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD). The refractive index of the AlN films was determined by ellipsometry. Current-voltage and current-temperature characteristics were performed on metal-AlN-p+ Si structures with Pt, Au and Al as metal electrodes. The characteristics showed that at high field and high temperature the carrier conduction mechanism in the film was dominated by Frenkel-Poole emission. The relative dielectric constant of the AlN films was estimated to be 9.66+0.3 from capacitance-voltage-frequency (C-V-f) measurements on Au-AlN-p+ Si.
Conductivity and Ftir Measurements of the Hydrogen Content of Heat Treated Diamond Films
Authors: Sung T. , Khasawinah S. , Popovici G. , Prelas M. A. , Spitsyn B. V. , Manning G. , Loyalka S. , Tompson R. V. 
Published: April 2011

ABSTRACTThe content of bonded hydrogen in hot filament grown diamond films was determined by Fourier transform Infrared (FTIR) measurements before and after annealing. The quantity of bonded hydrogen was found to remain unchanged on annealing in diamond films with high amounts of microcrystalline diamond and amorphous carbon. The hydrogen content was found to decrease on annealing ∼9 times in diamond film of good crystalline quality. The change of the bulk hydrogen content did not seem to be linked to changes in resistivity of the samples.
Blue Light Electroluminescence From Doped μc-SiC prepared by Excimer (ArF) Laser Crystallisation
Authors: Lau S. P. , Marshall J. M. , Dyer T. E. , Hepburn A. R. , DaVies J. F. 
Published: April 2011

ABSTRACTA novel method has been developed to prepare highly conductive and wide band gap doped (B2H6/PH3) microcrystalline silicon carbide (μ-SiC) by excimer (ArF) laser crystallisation. Doped a-SiC:H films were prepared by Plasma Enhanced Chemical Vapour Deposition (PECVD), both with and without H2 dilution. After crystallisation, this material has Taue gap of around 2.0 eV and exhibits a dark conductivity as high as 20 (Ωcm)-1, more than ten orders of magnitude higher than before the laser irradiation. This is shown to be mainly due to the formation of SiC microcrystallites in the laser crystallised a-SiC:H.In this paper, we report that this material can be utilised not only as the carrier injection layer in a-SiC:H based Thin Film Light Emitting Diodes (TFLEDs) but also as a luminescent layer. Blue light emission has been observed from a laser crystallised (LC) doped μc-SiC based electroluminescent device, the peak wavelength is around 490nm.The simplicity of excimer (ArF) laser crystallisation and its capability to fabricate poly-Si TFTs, makes this a promising novel method to realise fully integrated Si large area multi-colour displays.
Investigation of Structural Defects in 4H SiC Wafers
Authors: Tuominen M. , Yakimova R. , Glass R. C. , Tuomi T. , Janzén E. 
Published: April 2011

ABSTRACTFor high-power device applications SiC has better physical and electronic properties than the traditional semiconductor materials Si and GaAs. In this work, structural defects of 4H SiC wafers have been studied and partly compared with results from a previous study of 6H material. Optical microscopy, scanning electron microscopy, high-resolution X-ray diffraction and synchrotron X-ray topography were used for structural studies of 4H SiC.Optical micrographs show micropipes and larger specific defects - tubes and cracks. X-ray rocking curve peaks are broad and split revealing the mosaicity of the material. Synchrotron X-ray topographs show areas having a large number of defects, images of cracks and micropipes, and misorientated regions close to the micropipes.
A Dynamic Model of III-V Ternary Semiconductor Alloys in the Epitaxial Growth
Authors: Gu Bing-Lin , Yu Jing-Zhi , Hu Xiao , Ohno Kaoru , Kawazoe Yoshiyuki 
Published: April 2011

ABSTRACTA concentration wave method for several interpenetrating Bravais sublattices is presented by considering the intralayer and interlayer effective interactions and the difference between the surface layers and the deeper layers in III – V alloys. The ground state ordered structures of ternary III – V semiconductor alloys are deduced and a dynamic model is established.
GaInAs/GaInP Double Barrier Structures: Growth and Application in Tunneling Diodes
Authors: Reaves C.M. , Yen J.C. , Cevallos N A. , Mishra U.K. , DenBaars S.P. 
Published: April 2011

ABSTRACTWe have fabricated resonant tunneling diodes (RTD's) containing a GaInAs quantum well and strained GaInP barriers. These diodes exhibit good characteristics at 80 K with a peak to valley current ratio of 1.34 which is comparable to other reports for RTD in this material system. Additional RTD's were made using a InAs rich well region to study the effect of strain compensation. To investigate the properties of these structures, transmission electron microscopy (TEM) and low temperature photoluminescence (PL) were performed. TEM shows that both RTD structures contain misfit dislocations. PL measurements indicate that the dislocations are not significantly affecting the GaInAs quantum well.
Chemical Beam Epitaxial Growth of GaP and InP Using Alternative, Safer Precursors
Authors: Sadwick L.P. , Kim C.W. , Ryu H.H. , Hill C.W. , Stringfellow G.B. , Gedridge R. W. , Jones A.C. 
Published: April 2011

ABSTRACTPhosphorus (P)-based alloys are important for applications in areas including optoelectronics and high speed electronics. Gas phase technologies such as organometallic vapor phase epitaxy (OMVPE) and chemical beam epitaxy (CBE) have traditionally used the extremely dangerous hydride, phosphine (PH3). Less hazardous alternatives need to be found. Three such alternative P-sources are: tertiarybutylphosphine (TBP), bisphosphinoethane (BPE) and trisdimethylaminophosphine (TDMAP). InP and GaP growth results using TBP, BPE, and TDMAP along with a brief discussion of the pyrolysis of these alternative P-sources are presented. InP has been grown using ethyldimethylindium and pre-cracked BPE with excellent surface morphology and strong 10 K photoluminescence with a half width of 4.8 meV. The residual doping level typically was in the high 1015 to low 1016 cm-3 range. GaP has been grown at a substrate temperature of 480°C without precracking the TDMAP.
Growth and Doping of AlAs by Mombe
Authors: Abernathy C. R. , Pearton S. J. , Wisk P. W. , Hobson W. S. , Ren F. 
Published: April 2011

ABSTRACTA comparison of dimethylethylamine alane (DMEAA) and trimethylamine alane (TMAA) as aluminum sources and CBr4 and CC14 as carbon doping sources for deposition of AlAs by metalorganic molecular beam epitaxy (MOMBE) has been carried out. DMEAA was found to produce the lowest oxygen levels in AlAs, 5 x 1017 cm-3 VS. 1021 cm-3 for TMAA, even at growth temperatures as low as 500°C. This reduction is likely due to the absence of oxygenated solvents used during synthesis of the DMEAA. Undoped films grown from either source were fully depleted as-grown. Through the use of CBr 4, hole concentrations up to 4.5x1019 cm-3 were achieved in AlAs layers grown fiom DMEAA. Attempts to increase the hole concentration beyond this level resulted in a decrease in the hole concentration even though SIMS analysis showed the carbon concentration to increase with increasing dopant flow. Though the carbon sources did not appear to introduce additional oxygen, they appear to introduce other impurities, such as Cl and Br. Also, due to parasitic etching reactions with the adsorbed halogen, the use of these sources reduces the Al incorporation rate.