bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion-Beam Mixing and Amorphization in Au/Zr Bilayers
Authors: Ding Fu-Rong , Okamoto P. R. , Rehn L. E. 
Published: March 2011

ABSTRACTAu/Zr bilayer films with inert-gas markers were produced by low energy (< 4 keV) implantation. Mass transport was measured during ion-beam mixing with 1 MeV Kr at several temperatures between 330 and 540K. Two distinct regimes of apparent Arrhenius behavior were found with activation enthalpies of 0.06 and 0.9 eV in the temperature range 330–440K and 460–540K, respectively. Microstructural changes during ion-beam mixing were studied in situ, in a high voltage electron microscope. Heterogeneous nucleation of an amorphous phase was observed during mixing. The results are compared with similar studies reported previously in Ni/Zr bilayer specimens.
The Effects of N2 and Ar as the Ambient Gas During Rapid Thermal Annealing of Tungsten Silicide
Authors: Smith Paul Martin , Thompson Michael O. 
Published: March 2011

ABSTRACTRapid thermal annealing of amorphous tungsten silicide thin films (W0.62 Si0 38) on Si at 1100°C in Ar and N2 ambient gases was studied. All films annealed in N2 exhibited good adhesion and remained smooth with no large grain growth. Films annealed in Ar showed grain nucleation and growth from the film perimeter until a critical stress was achieved, followed by stress-assisted grain growth. The resulting growth of large columnar grains caused the films to delaminate. Removal of the surface oxide/nitride layer from the silicide prior to annealing resulted in uniform nucleation and growth over the entire film during annealing in Ar, with no stress-assisted grain growth or film delamination. No difference, however, was observed during annealing in N2. These results suggest that a surface film produced during annealing in N2 slows the nucleation and growth and consequently enhances film adhesion.
A Comparison of Different Techniques for the Rapid Thermal Annealing of Ion Implants in Silicon
Authors: Wouters D. J. , Vanhellemont J. , Avau D. , Maes H. E. 
Published: March 2011

ABSTRACTIn this paper, a comparative study is presented of different techniques used for the annealing of arsenic ion implants in silicon. The used techniques are: lamp annealing using a bank of tungsten-halogen lamps, CW laser annealing and conventional furnace annealing. The annealing quality of the implanted layers is evaluated in terms of dopant activation, dopant diffusion and final extended defect states. The furnace annealing combines a good electrical dopant activation with nearly complete annihilation of the a/c dislocation loops, but substantial diffusion of the dopant profile is measured. Laser annealing gives good electrical activation with very low diffusion, but fails in removing end-of-range extended defects. Furthermore, latent electrical active defects of a donor-type are created. The tungsten halogen lamp annealing gives comparable activation and the diffusion is still lower than can be resolved by SIMS measurements, while growth and annihilation of the a/c dislocation loops is present but not yet completed. These experiments are in agreement with theoretical comparison of the different annealing techniques based on the effective (T,t) coordinates of each technique, which favours RTA processes in the high temperature - “seconds” -time range.
Rapid Thermal Processing of Thin Film Electroluminescent Display Materials
Authors: Kim D. M. , Qian F. , Solanki R. , Tuenge R. T. , King C. N. 
Published: March 2011

ABSTRACTRapid thermal annealing of the electroluminescent phosphors ZnS:Mn, SrS:CeF3 and ZnS:SmCl3 has been examined as a function of annealing temperature (500–750°C) and time of exposure (10–120 sec.). The resulting brightness and efficiency of luminescence are correlated with the different processing conditions used. The results indicate that the brightness can be significantly improved from the value obtained with furnace annealing without causing film delamination, blistering or fatigue effect.
Modeling of Pyrolytic Laser-Assisted Chemical Vapor Deposition: Effects of Kinetics and Choice Of Substrate
Authors: Skouby D.C. , Jensen K.F. 
Published: March 2011

ABSTRACTThe pyrolytlc laser-assisted deposition of metals Is modeled. A finite element approach is used to solve for temperatures and gas-phase concentrations In a transient calculation. The model accommodates the use of temperature-dependent physical properties as well as the occurrence of irregularly shaped deposits. Volcano-like deposits’ are predicted under certain conditions of gas pressure and laser intensity. The effect of using substrates with different thermal conductivities is investigated. Using adsorption-desorption kinetics such that the reaction rates have sharp maxima with respect to temperature, volcanoes of varying depths are modeled.
Buried Metal Deposition on Gallium Arsenide by Laser-Induced Thermochemical Reaction
Authors: Tokuda Jun , Takai Mikio , Gamo Kenji , Namba Susumu 
Published: March 2011

ABSTRACTTin oxide deposition was performed by focused argon ion laser irradiation in a tin tetrachloride gas atmosphere. Etching of gallium arsenide and tin oxide deposition were observed in a single scan of a laser beam under specific conditions. The center of the irradiated area was etched and then covered with deposit. Density ratio of 0/Sn obtained from the deposit by AES measurements was about 1.4 - 1.6. Additional hydrogen gas in ambient SnCl4gas reduced both tin oxide deposition and gallium arsenide etching. Deposition, at first, occurred at the outer side of the irradiated area and gallium arsenide etching occurred at the center of it. The amount of deposit depends on beam dwell time. Additional oxygen in ambient SnCl4gas improved deposited film quality: the deposited film with additional oxygen proved to be tin dioxide, which is an conductor.
193-Nm Excimer Laser-Assisted Etching of Polysilicon Films Using Cl2
Authors: Van Nguyen Son , Fridmann S. , Rembetski J. 
Published: March 2011

ABSTRACT193-nm excimer laser-assisted etching of polysilicon was studied in the presence of CI2. Maximum etch rates of 1.25 Å/pulse were obtained for pressures of about 400 torr and fluences exceeding 400 mJ/(cm2-pulse). The etch rate increased with both fluence (100-550 mJ/(cm2-pulse)) and pressure (50-800 torr). An adsorptive etch mechanism similar to NF3 etching has been proposed, where Cl2 molecules diffuse to the surface, adsorb, and then react after absorbing laser radiation. This is consistent with photon and molecular flux considerations and the availability of reaction sites. Thermal effects where Cl2 molecules decompose to Cl atoms on “hot” polysilicon surfaces may assist this process, and appear to dominate under conditions of lower pressure (<400 torr) and higher fluence. Etching caused by the gas phase formation of Cl atoms is minimal due to the low Cl2 absorption cross section at 193 nm.Simple projection etching results showed that micron lines can be etched in polysilicon by use of this chemistry.
Thermal and Photon-Induced Chemistry of Adsorbed Cadmium and Tellurium Alkyls
Authors: Stinespring C.D. , Freedman A. 
Published: March 2011

ABSTRACTExperimental studies of the thermal and photon-induced surface chemistry of two organometallic molecules, dimethyl cadmium and dimethyl tellurium, are reported for a variety of surfaces including Au, GaAs, Si, and SiO£. These studies followed ultrahigh vacuum compatible procedures and used x-ray photoelectron spectroscopy to characterize the chemical state and coverage of the adspecies formed at 295 K. The results showed considerable diversity in the thermal surface chemistry of the systems investigated. Depending on the substrate, physisorption and dissociative chemisorption to yield monomethyl and metal adspecies were observed. Irradiation of the physisorbed adspecies with 193 nm UV photons led to single photon photodecomposition and limited photodesorption. Similar irradiation of the monomethyl-adspecies caused only limited photodesorption.
Thin Films of Oxygen-Deficient Perovskite Superconductors by Laser Ablation
Authors: Bohandy Joseph , Adrian F. J. , Moorjani K. , Green W. J. , Kim B. F. 
Published: March 2011

ABSTRACTThin films of the new class of high temperature superconducting perov-skites have been prepared by laser ablation of t,he bulk materials with a pulsed, excimer laser operating at 193 nm. The films were deposited on room temperature substrates without post-deposition processing. The existence of superconducting regions in the inhomogeneous films was established by a novel microwave method which uses a slightly modified electron spin resonance spectrometer.
Laser Photochemical Growth of Amorphous Silicon at Low Temperatures and Comparison with Thermal Chemical Vapor Deposition
Authors: Eres D. , Lowndes D. H. , Geohegan D. B. , Mashburn D. N. 
Published: March 2011

ABSTRACTPulsed ArF (193 nm) excimer laser radiation has been used to dissociate disilane (Si2H6), resulting in photochemically controlled deposition of amorphous Si thin films. A high stability HeNe (6328 Å) laser was used for precise in situ monitoring of film deposition rates, under varying deposition conditions. A helium window purge nearly eliminated Si film deposition on the chamber windows. With the excimer laser beam parallel to the substrate, deposition of amorphous Si can be controlled entirely by the photon fluence (negligible background thermal growth) at temperatures from room temperature up to ~400°C. Reasonable photolytic deposition rates (>1 A/sec) are combined with "digital" control of film thickness (>0.02 A/laser pulse). Activation energies of 1.50 (±0.1) eV and 0.09 (±0.02) eV were found for pyrolytic and photolytic deposition, respectively.
A Chemical Study of Photo-CVD of Silicon Nitride in Mercury-Sensitized Reactions Between Silane and Ammonia
Authors: Wu Ching-Hsong 
Published: March 2011

ABSTRACTA photochemical system of mercury-sensitized reactions between silane and ammonia was studied to elucidate the gas-phase chemical processes involved in photo-CVD of silicon nitride. Several transient intermediates were detected and identified as silylated amines by the mass spectrometric isotope labeling method. These compounds containing both Si and N atoms appeared to be the precursors of silicon nitride. The chemical characteristics of silylated amines were studied under different experimental conditions. The reactivity and possible reaction paths for the formation of silylamine are discussed.
Characterization of Photo-Cvd Silicon Oxide
Authors: Padmanabhan R. , Miller B. J. , Saha N. C. 
Published: March 2011

ABSTRACTA photochemical vapor deposition technique was used to deposit silicon oxide films. A range of film properties was produced through changes in the process conditions. Refractive index, indicative of film composition, varied from 1.5 to 2.0, corresponding to oxygen rich and silicon rich conditions, respectively. Etch rate in buffered HF was a strong function of the refractive index, with higher index of refraction yielding lower rates. Film stress was tensile and the magnitude of the stress was again related to the index of refraction. Other properties that were evaluated included pinhole density and adhesion to Si. All the properties were directly relatable to the basic film composition.X-ray photo electron and Auger electron spectroscopy were used to characterize the composition of these films. The Si 2p photoelectron and the Si KLL Auger electron spectra were broad for higher refractive index films and upon deconvolution indicated the presence of different silicon containing species, the natures of which depended upon the actual index of refraction. For stoichiometric films, the predominant constituent was SiO2 and for non-stoichiometric films, varying amounts of Si2O, SiO, Si2O3 and SiO2 were all present.
Resonance Raman Spectra of Halogen Molecules Adsorbed on Metal Substrates
Authors: Matsushima Takeo , Kawasaki Masahiro , Sato Hiroyasu 
Published: March 2011

ABSTRACTResonance Raman spectroscopy was used to monitor the adsorption of halogen molecules (bromine and iodine) on metal substrates. The Raman bands of chemisorbed, physisorbed and crystalline species were found in the spectra. In the case of bromine, when the temperature was raised from 77 K, the band associated with the chemisorbed species increased in intensity with the concomitant decrease in intensity of the band of crystalline species. A similar increase in the band intensity of the chemisorbed species at the sacrifice of that of the crystalline species was found on continued laser irradiation. The saturation of the band intensity of chemisorbed species was found in the latter case, however. The continued evaporation of bromine vapor onto the substrate surface at 77 K with the simultaneous monitoring of the layer thickness revealed that the initial deposit of bromine onto the substrate did not lead to the chemisorbed species. The accumulation of the crystalline species occurred in its stead. The occurrence of the molecular transfer process from the crystalline species into the chemisorbed species was suggested. The Raman excitation profile showed that bromine molecules adsorbed on a substrate do not dissociate in the wavelength range studied (16000-22000 cm-1). The excitation profile is to be given by Albrecht's A term and roughly corresponds to the absorption spectrum of thin film of bromine on the substrate, which is very difficult to obtain directly.
Maskless Etching of SiO2 by Ion Beam Assisted Etching Technique
Authors: Xu Zheng , Gamo Kenji , Namba Susumu 
Published: March 2011

ABSTRACTCharacteristics of ion beam assisted etching (IBAE) for SiO2 have been investigated to reveal'a possibility for maskless etching using focused ion beams. The ion beam assisted etching was done by bombarding 50 keV unfocused ion beams in XeF2 atmosphere and effect of various etching parameter on etching characteristics have been investigated. These are the effects of XeF2 gas pressure, bombarding ion species, bombarding angle and H2 addition, etc. Significant enhancements up to 100 times larger than physical sputtering were achieved. The selectivity of SiO2 to Si could be tailored to specific requirements from 0.1 to 6 by changing the gas mixing ratio. The etching rate was approximately proportional to the energy deposition rate bombarded by ion beam on surface. Carbon contamination on surface after etching were improved by the introduction of XeF2 gas.
The Dopamt Diffusion Mechanism in Eicimer Laser Induced Molten Silicon
Authors: Sameshima Toshiyuki , Usui Setsuo 
Published: March 2011

ABSTRACTWe have calculated the degree of dopant diffusion which occurs during non-equilibrium incorporation of boron from the silicon surface into the molten silicon induced by a pulsed excimer laser. When a high-power lascr causes the melt front to proceed into the substrate faster than 8 m/s, p+ -doped regions are formed near the surface of the molten silicon because boron atoms cannot diffuse sufficiently fast for the junction depth to reach the maximum melt depth.
Metal Organic Chemical Vapour Deposition Growth of Epitaxial ZnSe/ZnS Multiple Layered Structures
Authors: Yates Heather M , Williams John O 
Published: March 2011

ABSTRACTZnSe-ZnS multilayers have been prepared by atmospheric. pressure metal organic chemical vapour deposition (M0CVD) using dimethylzinc, hydrogen sulphide and hydrogen selenide. Layer thicknesses down to 500Å have been obtained and the interfaces, as measured by secondary ion mass spectroscopy (SIMS) and electron microscopy, are regular. A notable improvement in interface abruptness was observed with better control of experimental procedures and more especially with the growth of a ZnSe buffer layer between the GaAs(100) substrate and multilayers.
Effect of Strain on Bound Excitons in High-Purity ZnSe Bulk and MOCVD Homoepitaxially-Grown ZnSe Layer
Authors: Asao Yoshiaki , Hayamizu Shunichi , Yamada Yoichi , Taguchi Tsunemasa , Hiraki Akio 
Published: March 2011

ABSTRACTBack-doping experiments with intentional donors (Al, Cl, Ga and In) and acceptor (Na) species have been conducted in the recrystallization travelling-heater-method (THM)-grown ZnSe single crystals. Sharp bound-exciton lines and associated two-electron or two-hole transitions appear clearly and their bind-ing energies can be accurately estimated using central cell corrections. Uni-axial stress measurements on the l1d line at 2.783 eV and on the l2In line at 2.7968eV confirm that the spatial symmetry of the localized centers which bind excitons is Td. Utilizing the present THM ZnSe crystal as a substrate for ZnSe layer with good optical-quality was homoepitxially grown by metalorganic-chemical- vapor-deposition and exhibited a strong donor-bound exciton line locating at 2.7964 eV, probably Al. Low-resistive n-type layer with 0.1ω·cm was achieved by doping with Al from trimethylaluminum source.
Formation of a New Blue-Shift Emission in Highly Be-Doped GaAs Grown by Molecular Beam Epitaxy
Authors: Makita Yunosuke , Mori Masahiko , Ohnishi Nobukazu , Phelan Paul , Taguchi Takashi , Sugiyama Yoshinobu , Tacano Munecazu 
Published: March 2011

ABSTRACTPhotoluminescence measurements of Be-doped GaAs, grown by molecular beam epitaxy, were carried out at low temperature as a function of acceptor concentration. Results revealed that besides the well-defined emission, [g-g], which is exclusively relevant to acceptor impurities, an additional specific emission, temporarily denoted by [g-g]α is formed near the band-edge, when the concentration of acceptors exceeds 1×1019 cm−3:. From the viewpoint of application it was suggested that also in case of acceptors, photoluminescence spectra can be practically used for the precise determina-tion the acceptor concentration.
Comparison of Low Temperature Photoluminescence of Bulk MBE Grown AlGaAs and GaAs Using a Graphite Generated Dimerb Versus a Standard Tetramer Arsenic Group-V Source
Authors: Brennan Thomas M. , Hammons B. E. , Smith M. C. , Jones E. D. 
Published: March 2011

ABSTRACTThe carbon concentrations in GaAs and AIGaAs grown by Molecular Beam Epitaxy (MBE) have been studied when a graphite generated dimeric arsenic species and a standard tetramer arsenic species are used as the group-V source. Photoluminescence and Van der Pauw-Hall measurements have been made to examine the material quality in reference to which arsenic species is used for film growth. Results indicate that a graphite crucible arrangement for the thermal cracking of As4 produces significant carbon contamination and is unacceptable for the MBE growth of GaAs and AlGaAs.
Magnetoreflectivity Study of Excitons in MBE Grown Zn1−xFex Se Crystals
Authors: Liu X. , Petrou A. , Prinz G. A. , Jonke B. T. , Krebs J. J. , Warnock J. 
Published: March 2011

ABSTRACTWe present a magnetoreflectivity study of the excitons in MBE grown Zn1−xFexSe crystals for x=0.017, 0.027 and 0.043. The excitonic spinsplitting was studied as function of magnetic field in both the Faraday and Voigt geometries. The exchange integrals were determined from the conduction and valence band spin-splittings. The exciton spin-splitting was also studied as function of temperature. This study yielded the value of the energy spacing of the Fe++ states and also verified that Zn1−xFexSe is a Van Vleck paramagnet.
Nucleation and Growth of Ultrathin Epitaxial Metal Silicides on Silicon
Authors: Batstone J. L. , Tung R. T. , Phillips Julia M. , Gibson J. M. 
Published: March 2011

ABSTRACTGrowth of epitaxial single crystal nickel and cobalt disilicide films on silicon is performed under UHV conditions by deposition of Co or Ni on silicon followed by a high temperature reaction to form the silicide. The uniformity and perfection of ultrathin epitaxial layers has been studied using transmission electron microscopy. Mechanisms controlling island growth are discussed. Island nucleation observed in pseudomorphic films of NiSi2 /Si(100) (∼60Å thick) is shown to be the result of the difference in symmetry between the NiSi2 and Si. Islands related by a translation vector a/4<111> show an equilibrium island separation of 15±1.5Å. The boundary between islands is described as a coreless defect. In comparison,, pseudomorphic layers of CoSi2 /Si(111) are observed up to thicknesses ∼30Å. Pinholes are commonly observed in CoSi2 /Si(111) thin films. Finite contact angles (∼50) between substrate and deposit suggest a desire for three-dimensional growth under equilibrium conditions.
Reduction of Defect Levels in Si and Si/Ce Layers Grown by MBE
Authors: Gibbings C.J. , Tuppen D C.G. 
Published: March 2011

ABSTRACTThe dislocation density in undoped Si-MBE layers grown on wafers without any chemical pre-cleaning has been studied. The oxide layer was removed using a low silicon flux. Factors influencing the dislocation density have been studied, including substrate type, growth temperature and the temperature at which oxide is removed. Dislocation densities below 10-3 cm-2 have been obtained. The defect density in p-type silicon doped with boron oxide has also been studied. The influence of boron oxide on dislocation density has been found to be negligible, even though incorporation of oxygen is large at growth temperatures ≤650°C. Boron oxide doped Si.88Ge.12 layers have also been grown and a similar level of dislocations has been found.
Epitaxial Growth of Copper, Silver and Gold on a Semiconducting Layered Material: Tungsten Disulfide
Authors: Doering D. L. , Ohuchi F. S. , Jaegermann W. , Parkinson B. A. 
Published: March 2011

ABSTRACTThe growth of copper, silver and gold thin films on tungsten disulfide has been examined as a model of metal contacts on a layered semiconductor. All three metals were found to grow epitaxially on the WS2. However, Cu appears to form a discontinuous film while Au and Ag grow layer by layer. Such epitaxial growth is somewhat surprising since there is a large lattice mismatch between the metals and the WS2.
Theory of Optical Transitions in SinGen(001) Strained Layer Superlattices
Authors: Hybertsen Mark S. , Schlüter Michael 
Published: March 2011

ABSTRACTSystematic trends for the minimum gap and low-lying direct optical transitions for superlattices alternating 2, 4 or 6 atomic layers of Si and Ge grown on Si(001) and Ge(001) substrates are calculated using the local density functional approach. Results of a many-body self energy calculation for the optical transition energies of the Si4Ge4/Si(001) case are compared to photocurrent and electroreflectance data. Emphasis is placed on the narrow type II heterostructure formed by the Si4Ge4 region between the Si(001) substrate and cap layer.
Properties of SiGe Alloys Grown on Si Substrates by Liquid Phase Epitaxy
Authors: Alonso M.I. , Trah H.-P. , Bauser E. , Cerva H. , Strunki H.P. 
Published: March 2011

ABSTRACTSi1−zGez single crystal layers were grown on Si(iii) by liquid phase epitaxy (LPE) over the entire composition range (0 ≤ x ( 1). Using Sn as solvent all compositions were produced; alloys with compositions 0 ≤ x ≤ 0.75 were obtained using In as solvent; the range 0.75 ≤ x ≤ 1 was covered with Bi solvent. The solvents used, the composition of the solution, the saturation temperature, and the cooling rate, were found to strongly influence the growth morphology.