bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technical Basis for Codisposal of Gasification and Combustion Ash from the Plants at Beulah, North Dakota
Authors: McCarthy G. J. , Hassett D. J. , Manz O. E. , Groenewold G. H. , Stevenson R. J. , Henke K. R. , Kumarathasan P. 
Published: March 2011

ABSTRACTThe technical hasis for codisposal of gasification ash from the Great Plains Gasification Associates plant, combined with cementitious “scrubber ash” and bottom ash from the adjoining Antelope Valley generating station, both located in Beulah, North Dakota, has been explored. Nine blends containing only the ashes and tap water were fabricated into cylinders and tested for compressive strength and other physical properties. A blend having the ash proportions of the two plants was tested for leachability with respect to several regulated and minor elements. Mineralogical characterization by XRD was performed on the individual waste solids and the cured mixes. Most of the blends had compressive strengths greater than 400 psi after 7-day/38 C and 28-day/21 C curing. The 7-day treatment led to better consolidated test cylinders. Leaching behavior, evaluated by the EPA-EP and ASTM tests, was determined for As, Se, B, V, Mo, Ba, Sr, and K. Average fixation factors (the ratio of leaching expected from a weighted average of its components to the actual leaching of the specimen) of 2 to 4 were observed for the 7-day cured specimens and 1 to 2 for the 28-day specimens. Not all elements had reduced leaching in the fabricated specimens; Se and V leaching increased in the fabricated specimens. In addition to ash proportions, curing conditions (T, pH2O, time) and water to solid ratio appear to key parameters in obtaining well-consolidated and lower leachability products. XRD indicated that ettringite and minor calcite were the only crystalline reaction products of the cementitious reactions in the cured codisposal mix.
Fly Ash in Shale Stabilization for Highway Construction
Authors: Saleh M. , Laguros Joakim G. 
Published: March 2011

ABSTRACTThe expansive shales used for roadbeds in Oklahoma are traditionally stabilized with lime. Stabilization with a Class C (high-calcium) fly ash was explored and compared to an optimum design utilizing the conjunctive use of fly ash, lime and cement, in the laboratory and in a field experimental project. Periodic visual observations indicated that the performance of test sections was excellent. Analyses of field samples showed that fly ash, either alone or mixed with lime and cement, was effective in ameliorating the texture and plasticity of the shale by reducing the amount of clay size particles and by imparting higher strength levels to the shale. Laboratory samples showed better stabilization than field samples, but the field samples performed at an acceptable level in measurements of compressive and beam strength, cohesion, angle of internal friction and resistance to deflection. The microstructure of stabilized shale was studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Nonbasal (hkl) reflections in stabilized oriented specimens suggest that the clay particles acquire high resistance to dispersive forces. The reduction of the areas under the peaks help explain the strength gain observed. The SEM observations indicated newly formed hydration products, possibly calcium aluminum silicate hydrate crystals, and a rather dense degree of packing as manifested by the substantial reduction of void areas as a result of stabilization.
Using Rapid Thermal Annealing to Improve Epitaxial CaF2/CoSi2/Si(111) Structures
Authors: Phillips Julia M. , Augustyniak W. M. 
Published: March 2011

ABSTRACTWe have extended our studies of epitaxial insulator-metal-semiconductor heterostructures composed of CaF2 and CoSi2 layers grown on Si(111) substrates to cover a broader range of growth conditions. We find that rapid thermal annealing plays a crucial role in optimizing the epitaxial quality of the CaF2 layer over the entire range of conditions studied. The chemical stability of the fluoride layer is also enhanced by the annealing process.
Heteroepitaxy of Gallium Arsenide on Germanium Coated Silicon Substrates
Authors: Chu Shirley S. , Chu T. L. , Firouzi H. 
Published: March 2011

ABSTRACTSingle crystalline epitaxial GaAs layers have been grown on silicon substrates with a thin germanium interlayer. All semiconductor layers were deposited by the chemical vapor deposition technique. The surface condition of the silicon substrate is an important factor affecting the quality of GaAs/Ge films on silicon. P+/n homojunction solar cells of 0.25 cm2 area with an AM1 efficiency near 12% have been prepared.
A HgCdTe/CdTe/GaAs/Si Epitaxial Structure
Authors: Zanio K. , Bean R. , Hay K. , Fischer R. , Morkoc H. 
Published: March 2011

ABSTRACTFour layer HgCdTe/CdTe/GaAs/Si structures have been prepared by the sequential growth of (100) GaAs on (100) Si by MBE, (100) CdTe on GaAs/Si by congruent evaporation in UHV and (100) HgCdTe on CdTe/GaAs/Si by vapor transport. Infrared transmission, X-ray rocking curves, differential interference contrast microscopy and selected area electron channelling patterns characterize the structures.
High Speed GaAs Based Devices on Si Substrates
Authors: Morkoc Hadis 
Published: March 2011

ABSTRACTRemarkably good device performance at both dc and microwave frequencies has recently been obtained from GaAs based devices grown on Si substrates. In GaAs MESFETs on Si, current gain cutoff frequencies and maximum oscillation frequencies of fT = 13.3 GHz and fmax = 30 GHz have been obtained for 1.2μm devices, which is nearly identical to the performance achieved in GaAs on GaAs technology for both direct implant and epitaxial technology. For heterojunction bipolar transistors, current gain cutoff frequencies and maximum oscillation frequencies of fT = 30 GHz and fmax = 11.3 GHz have been obtained for emitter dimensions of 4×20μm2. In GaAs AlGaAs MODFETs. current gain cut-off frequencies of about 15 GHz with lμm gates were obtained on GaAs and Si substrates. The pseudomorphic InGaAs/GaAs MODFETs were also fabricated and found to be comparable to GaAs MODFETs although they should perform better. The structures were also shown to maintain their properties when put through ion implantation and annealing process. Given the performance already demonstrated in GaAs on Si devices and the advantages afforded by this technology, the growth of III-Vs on Si promises to play an important role in the future of heterojunction electronics.
High-Speed Photoconductive Detectors Fabricated in Heteroepitaxial GaAs Layers
Authors: Turner G. W. , Diadiuk V. , Le H. Q. , Choi H. K. , Metze G. M. , Tsaur B-Y. 
Published: March 2011

ABSTRACTResponse times of ∼60 and 25 ps (FWHM), respectively, have been measured for photoconductive detectors fabricated in GaAs layers grown by molecular beam epitaxy on silicon substrates and silicon-on-sapphire substrates. Photoconductive detectors, which can be readily combined with GaAs logic devices such as MESFETs to provide high-speed optical to electrical conversion, could be used in optical interconnects that are integrated with Si circuits on monolithic GaAs/Si wafers. Transconductance values of 120 mS/mm have been obtained for MESFET's fabricated in GaAs layers grown on silicon-on-sapphire substrates.
Structure and Properties of Ultrathin Ge-Si Superlattices
Authors: Bevk J. , Mannaerts J. P. , Feldman L. C. , Davidson B. A. , Lowe W. P. , Glass A. M. , Pearsall T. P. , Menendez J. , Pinczuk A. , Ourmazd A. 
Published: March 2011

ABSTRACTWe report the synthesis, structural characterization, and preliminary optical studies of ultrathin Ge-Si superlattices with individual sublayers smaller than the Si unit cell, grown by MBE on (001) silicon substrates. Structures are fabricated one monolayer at a time in a configuration GeGeSiSiGeGe..., resulting in either ordered alloys or complex cell superlattices. Rutherford backscattering and channeling experiments on these highly strained heterostructures indicate excellent crystallinity with tetragonal distortion as high as 3.5%. Electron diffraction patterns exhibit characteristic superlattice reflections indicative of one-dimensional layering with periodicity of four monolayers. X-ray scans along the growth direction at the (002) position in reciprocal space reveal a strong peak not observed in random GeSi alloys. This scattering is attributed indirectly to the GeSi ordered phase. The optical transition energies measured by Schottky barrier electroreflectance correspond to those expected from homogeneous alloys of the same composition; however, the width of optical transitions is less than 30 meV at room temperature, allowing a clear resolution of the splitting of the valence band by strain. Modification of the unit cell of the diamond lattice in this way should permit the design of materials with novel opto-electronic characteristics. Preliminary Raman and photoconductivity measurements are also reported.
MBE Growth of GaAs on Si: Problems and Progress
Authors: Kroemer Herbert 
Published: March 2011

ABSTRACTSeveral fundamental problems are reviewed that must be solved if GaAs on Si growth is to be achieved with device-quality already close to the GaAs/Si interface, rather than relying on thick buffer layers: (a) antiphase disorder, (b) interface charge and cross-doping, and (c) misfit dislocations. An extensive discussion is given of the mechanism by which antiphase disorder is suppressed on (100)-oriented substrates
The Growth of GaAs on Si by Molecular Beam Epitaxy
Authors: Koch S. M. , Rosner S. J. , Schlom Darrell , Harris J. S. 
Published: March 2011

ABSTRACTSuccessful growth of GaAs on Si has recently been demonstrated. This work is directed toward an understanding of the processes occurring during the growth and their effects on the quality of the GaAs epilayers. Reflection High Energy Electron Diffraction monitoring of the growth in situ shows that the islands that are initially formed coalesce into an epilayer with a 2×4 surface reconstruction. Ion channeling indicates that the crystallinity of the entire epilayer improves with coverage. Substantial reordering of the material occurs when buffer layers grown at low temperatures are annealed at 575°C before and during further growth at this temperature. Comparison of 300 nm layers differing in the growth temperature of the first 100 nm shows no variation in the crystallinity as determined by ion channeling. Surface morphology degrades, however, and 77K photoluminescence intensity rises with the initial growth temperature. The optical and structural properties of 2μm thick films are also discussed.
Dopant Incorporation of Boron Implanted Silicon During Rapid Thermal Annealing
Authors: Hung-Yu Liu Hung-Yu Liu , Peng-Heng Chang Peng-Heng Chang 
Published: March 2011

ABSTRACTSurface layer damage of boron implanted (100) silicon crystals were characterized by x-ray rocking curves using computer fitting procedures. The implantation was carried out at ion energy of 130 KeV with the dose of 1*1016 atoms/cm2. The in-depth strain distribution of the surface layer after rapid thermal annealing was discussed based on x-ray rocking curve observation. It is clearly revealed that the strain profile reverses completely from the positive (tensile) strain in the as-implanted condition to the negative (compressive) strain after annealing. This change is ascribed to the incorporation of boron atoms from interstitial sites to substitutional positions. The results were also compared with transmission electron microscopy (TEM) observations.
Effects of Tisix/Tinx/Al Contact Metallization Process on the Shallow Junction Related Properties
Authors: Sun S.W. , Pintchovski F. , Tobin P.J. , Hance R.L. 
Published: March 2011

ABSTRACTAn extremely reliable TiSix/TiNx diffusion barrier was formed by the rapid thermal annealing of a thin Ti layer which was sputtered into the contacts before Al metallization. The effects of this barrier metal process on the material properties of heavily implanted n+ and p+ regions were studied. The TiNx-to-TiSix thickness ratio is determined by the dominant reaction at the sintering temperature. Arsenic implanted in the substrate tends to substantially retard the silicidation of Ti. Substantial redistribution of both B and As across the silicide layer was observed during rapid thermal annealing. Film stress was found to be greatly affected by the annealing temperature. Contact resistance, contact electromigration and thermal stability of the structure were also investigated.
Rapid Thermal Processing — A User'S Perspective
Authors: Fulks R. T. 
Published: March 2011

ABSTRACTThe technique of rapid thermal processing (RTP) has evolved from research laboratory efforts to quickly heat small pieces of semiconductor material using pulsed or scanned lasers to high throughput, production RTP equipment capable of rapidly heating eight-inch silicon wafers to greater than 1000 deg C in 10 seconds. Furthermore, the initial application of annealing ion implantation damage has expanded to include silicide formation, oxide reflow, contact formation, hillock control and more recently oxidation and nitridation. Nearly a dozen vendors now produce RTP equipment and the potential user must answer the question — “Which equipment is best for me?” The researcher's principal concerns for RTP equipment are flexibility and control while the production engineer wants unifomity, reproducibility, and a reasonable throughput. Meanwhile, the device designer wants a “safe” process with no contamination or other adverse device degradation effects. This paper will focus on these and other issues associated with the use of rapid thermal processing from a user' perspective including some thoughts on where RTP may be headed in the future.
A Study of Diffusion, Clustering and Defects in As+ And Bf2+ Implanted Silicon During Scanning Electron Beam Annealing.
Authors: Hart Michael J. , Evans Alan G.R. , Amaratunga Gehan A.J. , Altrip John L. 
Published: March 2011

ABSTRACTScanning electron beam annealing techniques have been applied to the study of diffusion of implanted arsenic and boron difluoride. Electron beam anneals over the time range 0-180s (at Tmax), with peak temperatures in the range 1100-1200°C have been performed on uniformly implanted samples. Controlled slow cooling has been performed for some samples. Direct sample temperature measurements were made using a dual-colour pyrometer under control of a microcomputer, which provided data-logging and feedback control of temperature. The accurate temperature control achieved using this system is important for realistic diffusion modelling.Measurement of the resulting chemical and electrical dopant profiles, using SIMS, RBS and spreading resistance methodshas shown the presence of non-equilibrium diffusion at short times [6]. Channelling RBS studies used to investigate the activation and clustering behaviour of arsenic during the first stages of these very rapid anneals is reported.Modelling of the arsenic diffusion occuring for a range of implant doses subjected to these anneals has been performed,applying avariety of models, including a dynamic clustering model. This dynamic clustering model, based upon an equilibrium cluster model and a measured de-clustering rate, has been shown previously to give good agreementwith experiment. Forthese experiments, a modified de-clustering coefficient was needed to model the diffusion occuring for a wider range of arsenic implants. A solution of the Poisson equation for the internal electric field has also been incorporated.DLTS techniques have been used to study the defects remaining in diodes fabricated using these implagts andanneals. Trap densities of <5×1010cm−3 and leakages of <2×10−9 A.cm2 at −5V have been measured for the best devices, similar tothose observed for control furnace anneals.
Microwave Plasma LPCVD of Tungsten in a Cold-Wall Lamp-Heated Rapid Thermal Processor
Authors: Moslehi Mehrdad M. , Saraswat Krishna C. , Shatas Steven C. 
Published: March 2011

ABSTRACTA novel cold-wall single-wafer lamp-heated Rapid Thermal/Microwave Remote Plasma Multiprocessing (RTMRPM) reactor has been developed for multilayer in-situ growth and deposition of dielectrics, silicon, and metals. This equipment is the result of an attempt to enhance semiconductor processing equipment versatility, to improve process reproducibility and uniformity, to increase growth and deposition rates at reduced processing temperatures, and to achieve in-situ multiprocessing in conjunction with real-time process monitoring and automation. For high-performance MOS VLSI applications, a variety of selective and nonselective tungsten deposition processes were investigated in this work. The tungsten gate MOS devices fabricated using the remote plasma multiprocessing techniques exhibited negligible plasma damage and near-ideal electrical characteristics. The flexibility of the reactor allows optimization of each process step yet allows multiprocessing.
Defect Structures and Electrical Behavior of Rapid Thermally Annealed Ion Implanted Silicon
Authors: Sadana D. K. 
Published: March 2011

ABSTRACTThe importance of the knowledge of implantation induced damage structures in annealing studies is emphasized. The existence of various observed microstructures is reviewed and their distributions are presented schematically. It was found that although the usefulness of RTA in controlling dopant profiles is indisputable, the control of microstructure by RTA especially in “non-amorphized” or incompletely amorphized Si samples is questionable. Significance of complete surface amorphization to achieve better structural perfection on subsequent RTA or FA is discussed. An attempt was made to explain the published electrical data on rapid thermally annealed B+ and As+ implanted Si based on expected location and annealing behavior of defects for such implants. Recent structural and electrical results from B implanted pre-amorphized Si are presented.
Enhanced Diffusion During Rapid Thermal Annealing Of Indium And Boron In Double Implanted Silicon
Authors: Ganin E. , Sai-Halasz G. A. , Sedgwick T. O. 
Published: March 2011

AbstractExperimental results on the diffusion and precipitation of In and B doubly implanted into Si, followed by rapid thermal treatment are reported. It was observed that In redistributes itself and accumulates in defected regions. The amount of motion of each species is enhanced by the presence of the other. While the B influences In diffusion probably through the same mechanism that leads to concentration enhancement, the effect of In on B is not clear. There is no correlation with strain and no apparent chemical effects. Also the presence of B facilitates the sweeping out of In during low temperature solid phase regrowth.
Rapid Thermal Annealing of Oxygen-Vacancy Centers In O-Implanted Silicon
Authors: Stein H. J. 
Published: March 2011

ABSTRACTInfrared absorption by localized vibrational modes has been used to investigate rapid thermal annealing (RTA) of oxygen-vacancy (O-V) defects in O-implanted Si. At least three processes are involved in the annealing of O-V defects. An activation energy of 1.0 ± 0.2 eV for a process leading to O-V formation is attributed to O-V diffusion. The final O-V annealing stage is attributed to oxygen clustering around O2-V centers. Processes observed here in RTA are expected to be operative during implantation at the temperatures (400 to 600°C) used for production of silicon-on-insulator structures.
The Effect of Rapid Thermal Treatment on the Structural and Optoelectronic Properties of Epitaxial Gaas on Si Grown With or Without Ge Intermediate Layers
Authors: Lee El-Hang , Awal M.Abdul , Chan E. Y. , Opila R. L. , Jacobson D. C. , Pearton S. J. 
Published: March 2011

ABSTRACTCharacteristics of MOCVD GaAs grown on Si are compared before and after a rapid thermal treatment. The GaAs-on-Si samples were prepared both with and without a Ge intermediate layer, which is used to accomodate mismatches of lattice, thermal and chemical origin between GaAs and Si. Structural, interfacial, chemical, and electrical changes have been examined. RBS and Raman characterization showed improvement of GaAs crystallinity after RTA. In most cases, the interfaces were found to become sharper after RTA, but chemical interdiffusion was observed to cause some effect on the structural and electrical properties. For gold-contacted GaAs, RTA seems to degrade the electrical and optoelectronic properties via gold interdiffusion into GaAs. Comparative studies of the GaAs/Si and GaAs/Ge/Si samples suggests that the two respond somewhat differently to RTA.
Rapid Thermal Processing of Silicon Ion Implanted Channel Layers in GaAs
Authors: Hara Tohru , Gelpey Jeffrey C. 
Published: March 2011

ABSTRACTThe use of Rapid Thermal Processing (RTP) for the activation of silicon ion implanted channel layers in GaAs MESFET devices has been studied. Tungsten-halogen lamp and Water-wall DC arc lamp RTP have been compared. The arc lamp gave superior abruptness of the carrier concentration profile (78% at 850°C for 15 seconds or 1000°C for 2 seconds) and dopant activation greater than 60%. These parameters are important to achieve good MESFETs fabricated using arc lamp RTP was also studied. The transconductance (gm) of the devices usinq RTP was 78mS/mm which is much higher than achieved with similar samples using furnace annealing. Both capped and capless RTP was examined. Although capped annealing generally yields superior surface quality, the capless annealing provided good electrical properties in a process window which also yielded adequate surface quality and good devices.
Formation of Device Quality p-Type Layers in GaAs using Co-Implantation of Mg+ and As+ and Capless Rapid Thermal Annealing
Authors: Masum Choudhury A.N.M. , Armiento C.A. 
Published: March 2011

ABSTRACTLow (1 × 1014 cm-2) and high (1 × 1015 cm-2) dose implants of Mg+ in undoped GaAs have been activated using the enhanced overpressure proximity (EOP) rapid thermal annealing (RTA) technique. Hall measurements have yielded electrical activation efficiencies as high as 86% and 38% for low and high dose implants, respectively. For high dose implants, the outdiffusion of Mg+ from the wafer surface reduces the activation efficiency. A dramatic improvement in the activation for high dose Mg+ (1×1015 cm−-2, 100 keV) implants has been obtained by the co-implantation of As+. Compared with an activation of 18% for an implant of Mg+ only, the co-implantation of As has increased the activation to as much as 61% with a concomitant sheet resistance of 136 Ω/□. The placement of the As+ implant with respect to the position of the Mg+ profile has been found to play a significant role in the activation efficiency. This co-implantation technique in conjunction with the EOP-RTA method has been applied to the formation of thick p+ regions with high surface carrier concentrations, which has important applications in device fabrication for reducing contact resistance.
Rapid Thermal Annealing of High Energy Si Implants Into GaAs
Authors: Legge Ronald N. , Paulson Wayne M. 
Published: March 2011

ABSTRACTRapid thermal annealing (RTA) technology offers potential advantages for the processing of ion implanted GaAs. High energy implants of 300 keV or above are used for power MESFETs as well as in the ohmic contacts for low noise devices. The purpose of this paper is to investigate and characterize the RTA of Si implants into LEC GaAs using implant energies of 300keV and above, and a range of doses from 2.3 ×1012 to 3×1014 /cm2. The wafers were analyzed using capacitance-voltage and Hall measurements. Factors which cause variability in pinchoff voltage are identified and an RTA process comparable to conventional furnace annealing is presented for low dose implants. Superior implant activation is observed for higher dose implants through the use of higher annealing temperature.