bluuebunny/crossref_metadata_2025_split huggingface dataset:
Damage Removal of Low Energy Ion Implanted BF2 Layers in Silicon
Authors: Myers E. , Hren J. J. 
Published: March 2011

AbstractRecent results indicate that thermal budgets associated with ion implantation induced end of range damage removal is affected by the presence of a free surface. Low energy BF2 implants (6 keV) were done into both single crystal and Ge preamorphized silicon substrates. Rapid thermal processing was used to study the residual end of range defect structure in the temperature range from 700 to 1000°C. 6 keV, 5E14 cm-2 BF2 implantation resulted in formation of continuous amorphous layers approximately 10 nm deep with a mean B penetration of approximately 7 nm. Conventional TEM analysis found the structures to be completely free of any spanning “hairpin” dislocations or stacking faults associated with the BF2 implant for all the annealing temperatures. For anneals between 700 °C and 900°C end of range damage formation resulted, but the size of the dislocation loops remained small. Annealing at 1000°C, 10 seconds showed no evidence of residual end of range damage. Location of the end of range damage region close to the free surface was found to decrease the thermal budget required for the removal of ion implantation induced radiation damage.
Correlation Between Defect Characteristics and Layer Intermixing in Si Implanted GaAs/AIGaAs Superlattices
Authors: Chen Samuel , Lee S.-Tong , Braunstein G. , Rajeswaran G. , Fellinger P. 
Published: March 2011

AbstractDefects induced by ion implantation and subsequent annealing are found to either promote or suppress layer intermixing in Ill-V compound semiconductor superlattices (SLs). We have studied this intriguing relationship by examining how implantation and annealing conditions affect defect creation and their relevance to intermixing. Layer intermixing has been induced in SLs implanted with 220 keV Si+ at doses < 1 × 1014 ions/cm2 and annealed at 850°C for 3 hrs or 1050°C for 10 s. Upon furnace annealing, significant Si in-diffusion is observed over the entire intermixed region, but with rapid thermal annealing layer intermixing is accompanied by negligible Si movement. TEM showed that the totally intermixed layers are centered around a buried band of secondary defects and below the Si peak position. In the nearsurface region layer intermixing is suppressed and is only partially completed at ≤1 × 1015 Si/cm2. This inhibition is correlated to a loss of the mobile implantation-induced defects, which are responsible for intermixing.
Removal of End-of-Range Ion Implantation Defects in Silicon by Near Noble and Refractory Silicide Formation
Authors: Lur W. , Cheng J. Y. , Chen L. J. 
Published: March 2011

AbstractComplete removal of end-of-range (EOR) defects in ion implanted silicon has been achieved by the formation and growth of near noble silicides (CoSi 2 and NiSi 2 ) and refractory silicides (MoSi 2 and WSi2). Continued generation of vacancies during the silicide growth was found to be essential to reduce EOR defects. The results are consistent with the suggestion of the presence of a vacancy diffusion barrier near the EOR defects
Observation of the Wurtzite Phase in OMVPE Grown ZnSe/GaAs: Effect on Implantation and Rapid Thermal Annealing
Authors: Jones K. S. , Yu J. , Lowen P. D. , Kisker D. 
Published: March 2011

AbstractTransmission electron diffraction patterns of cross-sectional TEM samples of OMVPE ZnSe on GaAs indicate the existence of the hexagonal wurtzite phase in the epitaxial layers. The orientation relationship is (0002)//(111); (1120)//(220). Etching studies indicate the phase is internal not ion milling induced. The average wurtzite particle size is 80Å-120Å. Because of interplanar spacing matches it is easily overlooked. Electrical property measurements show a high resistivity (1010ω/square) which drops by four orders of magnitude upon rapid thermal annealing between 700°C and 900 °C for 3 sec. Implantation of Li and N have little effect on the electrical transport properties. The Li is shown to have a high diffusivity, a solid solubility of ≈1016/cm3 at 800°C and getters to the ZnSeA/aAs interface.
Diffusion, Segregation, and Recrystallization in High-Dose Ion-Implanted Si
Authors: Pennycook S. J. 
Published: March 2011

AbstractUsing the new technique of Z-contrast scanning transmission electron microscopy (STEM), we have been able to study the segregation of Sb at an advancing SPE growth interface and the resulting interface breakdown. The first direct information is obtained on Sb diffusion in the amorphous phase, which is many orders of magnitude enhanced over tracer crystalline values. This controls both the dopant incorporation and the stability of the resulting supersaturated alloy. These results are compared to the behavior of the low melting point substitutional diffusers and the interstitial diffusers.
Development of Thermally Stable Indium-Based Ohmic Contacts to N-Type GaAs
Authors: Murakami Masanori , Kim H. J. , Price W. H. , Norcott M. , Shih Y. C. 
Published: March 2011

ABSTRACTDevelopment of low resistance ohmic contacts to n-type GaAs which withstand high temperature cycles without degrading their electrical properties is crucial for fabrication of high performance GaAs integrated circuits. Prior to our work, indium-based ohmic contact materials were not attractive for actual devices, because the contacts provided resistances higher than those of the widely used AuNiGe contacts, were thermally unstable after contact formation, and had rough surface morphology. Recently, based on analysis of the interfacial microstructure of these contacts, several thermally stable, low resistance In-based ohmic contacts to n-type GaAs have been developed in our laboratories using a standard evaporation and lift-off technique and annealing by a rapid thermal annealing method. The present paper points out the reasons for the poor electrical properties and thermal stability of the “traditional” In-based ohmic contacts, and reviews the recent progress.
The AuZn/GaAs Heterojunction: Evidence of Varying Solid State Reactions
Authors: Vendura George J. , Messier Russell , Spear Karl , Pantano Carlo , Drawl William 
Published: March 2011

ABSTRACTAu-Zn is one of several metal systems applied to p-GaAs to form ohmic contacts. Although it exhibits a fair degree of reliability, the thrust toward higher power and adverse environments raises concern. Observations indicate that the electrical and mechanical properties as well as the stability of AuZn/GaAs vary with Zn thickness. In this study devices with thin and thick layers were tested visually, mechanically and using SEM and X-ray diffraction techniques. Results revealed significantly different reactivity and product chemistry that could significantly affect overall device performance.
Methods to Decrease Defect Density in GaAs/Si Heteroepitaxy
Authors: Liliental-Weber Zuzanna 
Published: March 2011

ABSTRACTIn this paper, the fundamental mechanisms of procedures improving the structural quality of GaAs grown on Si are discussed. Patterned growth, strained layer superlattices and proper thermal cycling are promising approaches to achieve a high quality of GaAs layers grown on Si substrates.
The Use of Superlattices to Block the Propagation of Dislocations in Semiconductors
Authors: Blakeslee A.E. 
Published: March 2011

ABSTRACTSince the discovery in 1973 that GaAs/GaAsP superlattices can be grown with low dislocation densities, considerable interest has developed in utilizing superlattices as dislocation filters in multilayer semiconductor device structures. Many attempts to implement this process have been described, with varying degrees of success being achieved. Some investigators have reported favorable results; some have observed no effect; and in some cases the situation was actually made worse. This paper analyzes these reports and attempts to clarify the confusion that has arisen. Suggestions are made for improved effectiveness. Factors considered include the strain between layers, the layer thickness, the concept of critical thickness, the dislocation geometry, and the influence of buffer layers and growth conditions.
Growth of Gaas on Si Using Algap Intermediate Layer
Authors: Noto N. , Nozaki S. , Egawa T. , Soga T. , Jimbo T. , Umeno K. 
Published: March 2011

ABSTRACTWe have studied heteroepitaxial growth of GaAs on Si using an AlxGa1−xP intermediate layer in an atmospheric-pressure metal organic chemical vapor deposition (NOCVD) reactor. The crystallinity of the GaAs layer depends on AlP composition(x) of the intermediate layer. The bett crystal quality of GaAs layer is obtained when the AlP composition(x) of the intermediate layer is close to 0.5. The X-ray FWHX of 180 arcs and the etch pit density (EPD) of 2.5 × 107cm−2 were obtained in this GaAs/AlGaP/Si structure.
Nucleation Studies of Lattice Matched and Mis-Matched Heteroepitaxial Layers Using the GaAs/AlxGa1−xP/Si System.
Authors: George Thomas , Weber E. R. , Wu A.T. , Nozaki S. , Noto N. , Umeno M. 
Published: March 2011

ABSTRACTHeteroepitaxial growth of GaAs on Silicon substrates is being actively pursued, since this technology offers numerous potential benefits in terms of optoelectronic and high speed devices. However a complete understanding of the fundamental causes for film properties such as surface morphology and crystal quality is still lacking at the present time. We present here the results of a study of GaAs grown on Silicon substrates using AlxGa1−xP intermediate layers. This system offers the advantage of studying the effects of surface properties and bulk properties of heteroepitaxial films separately. Surface and interface properties are shown to be the dominant factors in the growth of AlxGa1−xP on Si, where the lattice match between the two materials is very good. For low Al mole fractions the layers tend to form islands indicative of 3D growth, whereas for x>0.4, the layers are planar indicative of 2D growth. Bulk properties such as the lattice constant mismatch are presumed to play a key role in the growth of GaAs on AlxGa1−xP intermediate layers, where it is shown that the GaAs still has an island type nucleation phase, even though surface and interface factors such as contamination and polar-on-nonpolar growth are avoided. In addition the nucleation of the GaAs on the AlxGa1−xP intermediate layers appears to be modified by the nature of the AlxGa1−xP layer i.e. whether the intermediate layer is in the form of islands or a planar layer. The final surface morphology and the crystalline quality of 3gtm GaAs films grown on AlxGa1−xP intermediate layers can be correlated to the initial nucleation.
Silicon Surface Passivation for Heteroepitaxy by Hydrogen Termination
Authors: Fenner D.B. , Biegelsen D.K. , Bringans R.D. , Krusor B.S. 
Published: March 2011

ABSTRACTResults are reported for XPS and LEED evaluations of Si(100) wafers cleaned, etched, andhydrogen terminated by various low — temperature, wet — chemical techniques. We have obtained especially promising results with the JPL spin — etch technique. Under quite practical tolerances for the spin etch, our XPS measurements indicate about lx10-2 monolayer (ML) of total residue. The LEED showed sharp spots in a (1x1) pattern. We review our experimental results and suggest an interpretation in termsof both the chemistry of silicon surfaces in contact with HF in a polar solvent, and thehydrodynamics of liquids on spinning surfaces.
Growth and Characterizations of Gaas on Inp with Different Buffer Structures by Molecular Beam Epitaxy
Authors: Liu Xiaoming , Lee Henry P. , Wang Shyh , George Thomas , Weber Eicke R. , Liliental-Weber Zuzanna 
Published: March 2011

ABSTRACTWe report the growth and characterizations of 31μm thick GaAs films grown on (100) InP substrates by MBE employing different buffer layer structures during the initial deposition. The buffer layer structures under study are: 1) GaAs layer grown at low temperature; 2) GaAs layer grown at low temperature plus two sets of In0.08Ga0.92As/GaAs strained layer superlattices (SLS) and 3) a transitional compositionally graded InxGal-xAs layer between the InP substrate and the GaAs film. After the buffer layer deposition, the growth was continued by conventionalMBE to a total thickness of 3μm for all samples. From the 77K photoluminescence (PL) measurement, it was found that the sample with SLS layers has the highest PL intensity and the narrowest PL linewidth. Cross-sectional transmission electron microscopy (TEM) studies showed that the SLS is effective in reducing the propagation of threading dislocations and explains the observed superior optical quality from the PL measurement.
Effect of Strain and Interface Interdiffusion on the Valence Band Offset at Si/Ge Interfaces
Authors: Hybertsen Mark S. 
Published: March 2011

ABSTRACTThe valence band offset for the Si/Ge interface is studied using the local density functional approach with a superlattice geometry. The effect of non-abrupt interfaces is modeled by including an interface layer of Si5 Ge0 5 ordered in a interface unit cell. The change in valence band offset is less than 0.01 eV. For an abrupt interface, the offset is found to be a function of strain in the Ge. The interface dipole is proportional to the perpendicular strain parameter which yields an interface contribution to the energy of the strained epitaxial Ge layers. The equilibrium strain parameter in epitaxial Ge differs from that in biaxially compressed bulk Ge.
The Growth Rates of Intermediate Phases in Co/Si Diffusion Couples: Bulk Versus Thin-Film Studies
Authors: Jan C. H. , Lin J. C. , Chang Y. A. 
Published: March 2011

ABSTRACTBulk diffusion couples of Co/Si were annealed at 800, 900, 1000, 1050 and 1100°C for periods ranging from 24 hours to one month. Growth rates of the intermediate phases, Co2Si, CoSi and CoSi2, as well as the composition profiles across the couples were determined by optical microscopy and electron probe microanalysis (EPMA). Using the solution to the multiphase binary diffusion equations and the experimental data, the interdiffusion coefficients for Co2Si, CoSi and CoSi2 are obtained as a function of temperature. The activation energies obtained are 140, 160 and 190 KJ/mole for Co2Si, CoSi and CoSi2, respectively. The generally small interdiffusion coefficient of CoSi2 and its high activation energy cause the growth rate of CoSi2 to be extremely small at low temperatures.The interdiffusion coefficients for Co2Si, CoSi and CoSi2 at 545°C are obtained by extrapolation of the high-temperatures data. Using these data and solving numerically the diffusion equations with the appropriate boundary conditions, the growth of Co2Si, CoSi and CoSi2 is calculated as a function of time. The calculated results are in good agreement with the experimental data reported in the literature. This study demonstrates clearly that the initial absence of the CoSi2 phase is due to diffusion-controlled rather than nucleation-controlled kinetics. This phenomenon may be quite common in many thin-fiflm metal/Si couples.
Investigation of the Interface Integrity of the Thermally Stable Wn/GaAs Schottky Contacts
Authors: Ding J. , Lee B. , Yu K. M. , Gronsky R. , Washburn J. 
Published: March 2011

ABSTRACTWNx,/GaAs Schottky contacts formed by reactive sputtering were found to be thermally stable up to an annealing temprature of ∼9400°C. The interface morphology and structure of this contact under high temperature annealing conditions ( > 700°C ) have been investigated by transmission electron microscopy (TEM) and x-ray diffractometry techniques. For the as-deposited samples, the thin film had an amorphous structure. After annealing at high temperatures, the amorphous phase transformed to α-W and W2N phases. However, the contact interface remained thermally stable up to 850°C. Cross-sectional TEM micrographs revealed that annealing at temperatures above 850°C resulted in the formation of ‘pockets’ beneath the interface. This phenomenon has been correlated with the electrical properties of the contacts, e. g., an enhancement of the barrier height of the contact. Comparisons between the interface morphology of this system and other refractory metal nitride contacts (e. g., TiN/GaAs) are also presented.
Phase Formation in the Pt/Inp Thin Film System
Authors: Olson D. A. , Yu K. M. , Washburn J. 
Published: March 2011

ABSTRACTInP substrates with 40nm metal films of Pt were encapsulated in SiO2, and isochronally annealed up to 600°C in flowing forming gas. The composition and morphology of the phases that formed were studied using x-ray diffraction, Rutherford Backscattering, and transmission electron microscopy.Results show that the Pt/InP system begins interacting at 300°C. TEM analysis of the 350°C anneal shows unreacted Pt and and additional polycrystalline phases, with no observed orientation relationship with the substrate. The Pt layer has been completely consumed by 400°C, with a uniform reacted layer indicated by RBS. At high temperatures (between 500°C and 600°C), the reaction products are PtIn2 and PtP2. The two phases show a tendency for phase separation, with a higher concentration of PtP2 at the InP/reacted layer interface. The phosphide phase also shows a preferred orientation relationship with the substrate.
Kinetics and Thermodynamics of Amorphous Silicide Formation in Nickel/Amorphous-Silicon Multilayer Thin Films
Authors: Clevenger L.A. , Thompson C.V. , de Avillez R.R. , Tu K.N. 
Published: March 2011

ABSTRACTCross-sectional transmission and scanning transmission electron microscopy and thermodynamic and kinetic analysis have been used to characterize amorphous and crystalline nickel silicide formation in nickel/amorphous-silicon multilayer thin films. An amorphous-nickelsilicide layer was formed between the nickel and amorphous-silicon layers during deposition. Heating caused crystalline Ni2Si to form at the nickel/amorphous-nickel-silicide interface. The composition of the amorphous-siicide was determined to be approximately 1 Ni atom to 1 Si atom. Thermodynamic analysis indicates that amorphous-nickel-silicide could be in equilibrium with nickel and amorphous-silicon if there were kinetic barriers to the formation of the crystalline silicides. Kinetic analysis indicates that the “nucleation surface energies” of the crystalline silicides, other than Ni3Si, must be 1.6 to 3.0 times larger than that of amorphous-nickel-silicide.
Thermal Equilibrium, Metastable and Irreversible Defects in a-Si:H
Authors: Street R. A , Winer K. 
Published: March 2011

ABSTRACTMeasurements are reported of metastable defect states in undoped a-Si: H, with the aim of understanding the relation between the different types of metastability. The temperature dependence of the thermal equilibrium defect density agrees well with a proposed thermodynamic model and their relaxation time varies with deposition conditions. The rate of light induced defect creation and annealing in samples deposited at low temperature and with a large initial defect density, decreases progressively as the irreversible defects are removed by annealing.
Space Charge Limited Current in A-Si:H Devices Using High Electric Fields
Authors: Van Den Heuvel J. C. , Van Oort R. C. , Bokhorst B. , Geerts M. J. 
Published: March 2011

ABSTRACTSpace Charge Limited Current (SCLC) measurements are used to obtain the density of gap states of intrinsic a-Si:H. If an electron is trapped by a positively charged defect, then the electron can be released by a high electric field which disturbs the SCLC measurement. A correction for this effect, which is called Poole-Frenkel emission, in SCLC measurements is derived and used to analyze current-voltage measurements performed on n-i-n a-Si:H devices. It is shown that the Poole-Frenkel emission is absent, and that this is in accordance with the contemporary models for the gap states in a-Si:H.We also studied the characteristic temperature which is based on the concept that the distribution of gap states is exponential, and concluded that this distribution is not exponential.
Electronic Structure of Compensated Dopants in Hydrogenated Amorphous Silicon
Authors: Yang L. H. , Fong C. Y. 
Published: March 2011

ABSTRACTWe use first principles pseudopotential method to study the electronic structures of compensated dopants in a realistic model of hydrogenated amorphous silicon. Boron and phosphorus atoms are treated as dopants. Two states in the gap are identified as the boron-phosphorus pair related states. The lower energy state, strongly localized around the boron atom, is obtained when the atom has a hydrogen atom as a nearest neighbor. The local environment does not affect the localization feature of the state. Other environment around the boron atom cause the charge distribution to be more extended in space. The higher energy state having its charge around the phosphorus atom does not show, strong localization at the phosphorus atom.
Properties and Application of Undoped Hydrogenated Microcrystalline Silicon Thin Films
Authors: Kanicki J. , Hasan E. , Kotecki D. F. , Takamori T. , Griffith J. H. 
Published: March 2011

ABSTRACTDevice quality undoped hydrogenated microcrystalline silicon has been prepared by plasma enhanced chemical vapor deposition under different conditions. The dependence of physical, chemical, structural, and electrical properties on the deposition conditions has been investigated. Conductive (conductivity above 10−3Ω−1 cm−1) and resistive (conductivity around 10−9Ω−1cm−1) layers having approximately the same grain size, at a given substrate temperature, have been deposited between 200 and 500°C at two different hydrogen dilutions. Independently of the hydrogen dilution, the average grain sized is dependent on the deposition temperature and the film thickness; and a maximum average grain size of about 40 nm has been achieved for a thick film deposited at 500°C. The density of paramagnetic defects also increases with increasing deposition temperature, which indicates that more dangling bond defects are introduced as the total area of the grain boundaries increases. The etch rate decreases with increasing deposition temperature, and for the films deposited at 250 and 500°C the etch rate has been measured to be 6.6 and 2.7 nm/min, respectively. Thin film transistors incorporating a microcrystalline channel have been fabricated and evaluated. The best device had the following properties: field effect mobility, threshold voltage, and on/off current ratio of about 0.8 cm2/V sec, below 5 V, and around 106, respectively.
Fluorine-Induced Microvoids in Amorphous Silicon
Authors: Langford A. A. , Mahan A. H. , Fleet M. L. , Bender J. 
Published: March 2011

ABSTRACTThe effects of fluorine incorporation on the microstructural and electronic properties of a-Si:H:F with 1–7 at.% F have been systematically studied. Films were prepared by direct photo-CVD of disilane with xenon difluoride as the fluorine source. The fluorine content was measured by infrared spectroscopy, xray photoelectron spectroscopy (XPS) and electron microprobe. Infrared spectra show that as the fluorine content increases, silicon dihydride bonding increases. Density measurements confirm that this is associated with an increase in microvoid content. With the increase in F and SiH2, the photoconductivity decreases over two orders of magnitude. A review of the literature shows that the appearance of SiH2 is a universal result of >1% F incorporation and is not limited to the present study. This suggests that fluorination of amorphous silicon is not beneficial for photovoltaic application.