bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heteroepitaxy of Si and Ge on CaF2/Si (111)
Authors: Fathauer R. W. , Schowalter L. J. , Lewis N. , Hall E. L. 
Published: March 2011

ABSTRACTSi and Ge layers have been grown on CaF /Si (111) by molecular beam epitaxy (MBE). The use of thin room-tempe rature predeposits [1] with Ge epitaxy has been found to improve the growth. Studies of the initial stages of Ge epitaxy indicate that island growth occurs, and evidence also indicates island formation occurs in the Si case as well. A qualitative model is presented which explains many of the features observed in these systems and suggests reasons for the superior growth of Ge compared to Si. Finally, use of a Ge Si, /Si superlattice is shown to improve Si epitaxy.
An Investigation Of The Cause Of Initial Band Bending Of A Cleaved Clean n-GaAs(llO) Surface
Authors: Chin K. K. , Cao R. , Miyano K. , McCants C. E. , Lindau I. , Spicer W. E. 
Published: March 2011

ABSTRACTThe cause of the initial band bending on a clean n-GaAs(llO) surface of so-called “poor quality cleavage” has been controversial. To study this problem, a new type of geometric factor multi-metal evaporator has been designed, which enables us to obtain reproducible metal coverages as low as 10−4 monolayers. By following the early stages of band bending induced by the deposition of noble metals Cu, Ag and Au on n-GaAs (110) surfaces of different cleavage quality, it is found that a certain amount of initial band bending of a clean GaAs(llO) surface of poor quality cleavage corresponds to a certain amount of noble metal coverage (usually lower than 0.01 ML). This phenomenon can be explained in the following way. Any initial band bending on a clean n-GaAs(HO) surface is due to surface defect states created by the cleaving. These cleavage induced defects may be of the same nature as the interface states created by deposited noble metal atoms. Our experimental results will be discussed in the framework of the unified defect model of the Schottky barrier formation on III-V semiconductors.
Lateral Reactions of Gaas with Ni Studied by Transmission Electron Microscopy
Authors: Chen S. H. , Carter C. B. , Palmstrøm C. J. , Ohashi T. 
Published: March 2011

ABSTRACTA new method has been developed for making self-supporting, thin films which can be used for the in situ study, by hot-stage, transmission electron microscopy, of the reaction between Ni and GaAs. The thin-film, lateral diffusion-couples have been used to study both the kinetics and the formation of new phases. The growth rate of the ternary compound, N2GaAs showed a parabolic time dependence. At an annealing temperature of 300*C, the present experimental results show that Ni is the diffusing species and that the Ga and As remain essentially immobile. Diffusion coefficients obtained by this method are in very good agreement with those which have been obtained using conventional thin-film techniques. The results of this new technique are particularly important in view of the difficulty in identifying the composition of the product phase by methods which do not have the same lateral resolution.
Studies of Electrical Current-Induced Liquid Phase Epitaxy of GaMAlXAs:Si
Authors: Zeng Xian-Fu , Yao Gang-Zhao , Huang Zhao-Haon 
Published: March 2011

ABSTRACTIn this paper, a novel system of electrical current induced liquid phase epitaxial apparatus is presented. Electroepitaxial growths of Ga,-xAlxAs on thin GaAs substrate were carried out at constant temperature with a dc current as the sole driving force. Constant composition Ga1−xAlxAs electroepilayers with mirror-smooth surfaces were obtained. The average rate of epitaxial growth in the system is linearly proportional to the current level passed through the substrate-melt interface. In particular, a new technique of obtaining Ga1−xAlxAs:Si p-n junctions at constant temperatures is presented for the first time: the “step-current” technique.
The Structure and Electrical Properties of Au Contacts to GaAs
Authors: Liliental-Weber Z. , Newman N. , Spicer W. E. , Grónsky R. , Washburn J. , Weber E. R. 
Published: March 2011

ABSTRACTThe structure and electrical properties of Au contacts to GaAs have been studied by analytical and high-resolution transmission electron microscopy (TEM) combined with electrical characterization and photoemission spec-troscopy (PES). The contacts were prepared by in-situ deposition of Au onto ultra-high vacuum cleaved n-GaAs (110) surfaces. The effects of annealing on the electrical, morphological and chemical properties of the Au:GaAs contacts were studied. It was shown that the formation of Schottky contacts is correlated with the change in stoichiometry of the GaAs substrate near the Au/GaAs interface. The change to ohmic behavior for the samples annealed above Au-Ga eutectic was explained by leakage currents at the periphery of the devices. TEM micrographs of the structures revealed the existence of elongated Au crystallites on the GaAs surface at the periphery of the contacts. These leakage currents were eliminated by removing the current path at the periphery using a mesa-etch.
Structural Characterization and Schottky Barrier Height Measurements of Epitaxial NiSi2 on Si
Authors: Hunt B. D. , Schowalter L. J. , Lewis N. , Hall E. L. , Hauenstein R. J. , Schlesrnger T. E. , McGill T. C. , Okamoto Masako , Hashimoto Shin 
Published: March 2011

ABSTRACTSingle crystal NiSi2 films of type A and type B orientations with thicknesses ranging from 70–600Å have been grown on (111), n-type Si substrates. TEM and channeling measurements indicate that these films are of excellent epitaxial quality with uniform orientations over the entire range of observation. HRTEM studies show regular and atomically abrupt interfaces for both NiSi2 orientations with occasional localized planar defects. I-V and photoresponse measurements of the Schottky barrier heights(SBH) of the type A films yield consistent values of 0.62±.01eV. However, for type B films I-V measurements give a SBH of 0.69±.01eV while the photoresponse results give 0.77±.05eV. This discrepancy can be explained quantitatively by a phenomenological model in which a small percentage of low barrier height regions is incorporated into the type B films.
Heterojunction Ohmic Contacts to Si Using Ge/Si n+/n+ Structures
Authors: Hafich M. J. , Gillenwater R. L. , Robinson G. Y. , Sheldon P. 
Published: March 2011

ABSTRACTOhmic contacts to n-type Si have been formed using a thin n layer of Ge grown by selective-area molecular beam epitaxy. The n+Ge is used to lower the metal-semiconductor barrier energy and thus reduce the contact resistivity of the thin film structure. Al/n+Ge/n+Si test devices were fabricated in a manner compatible with conventional VLSI processing and consisted of a 3500 A thick layer of arsenic-doped Ge grown at 250°C on a selectively diffused, phosphorus-doped Si substrate. Using both four terminal Kelvin and transmission line devices, unsintered Al/Ge/Si structures exhibited contact resistivities a factor of five lower than Al/Si control devices, in agreement with theoretical calculations based on a simple tunneling model for the metal/Ge/Si heterojunction ohmic contact.
Characterization of Thin PtSI/p-Si Schottky Diodes
Authors: Silverman J. , Pellegrini P. , Comer J. , Golvbovic A. , Weeks M. , Mooney J. , Fitzgerald J. 
Published: March 2011

ABSTRACTA series of PtSi on p-type Si diodes have been characterized in order to establish correlations among processing parameters, metallurgical features and electrical properties. Characterization techniques include analytical (TED, TEM), electrical (current-voltage characteristics), and optical (photoemission and absorption). The fabrication techniques involve e-beam evaporation of platinum layers at UHV levels onto VLSI grade (100) p-type silicon substrates. The silicide layers are formed via sub-eutectic solid state diffusion at 350°C. The main trends with thickness as well as possible interrelationships are described. An unexpected result is the presence of unreacted polycrystalline Pt and Pt2Si at the interface.
Schottky Barrier Formation on Electron Beam Deposited Amorphous Si1−xGex:H alloys and Amorphous (Si/Si1−xGex):H Modulated Structures
Authors: Christou A. , Tzanetakis P. , Hatzopoulos Z. , Kiriakidis G. 
Published: March 2011

ABSTRACTAmorphous Si:H and Si1−xGex:H films were prepared by mixing electron beam evaporated silicon with a molecular beam of germanium from a Knudsen cell and with a beam of ionized hydrogen produced by a 0–3 keV ion source. Aluminum Schottky barriers on two types of samples: (1) a-Si1−xGex:H with.15<×<.85 and (2) modulated structures of 50 × 100 Å layers of a-Si:H/a-Si.8Ge.2:H (10-5 Torr PH hydrogen) were investigated. Barrier height was found to depend on the Ge concentration and possible Fermi-level pinning due to the dangling bond deep level. The modulated structures showed a negative resistance region and a barrier height determined only by the composition of the first layer.
Wet and Dry Oxidation of Single Crystal β-SiC: Kinetics and Interface Characteristics
Authors: Palmour John W. , Kim H. J. , Davis R. F. 
Published: March 2011

ABSTRACTSilicon dioxide layers were grown on single crystal (100) β-SiC between 1000°C and 1200°C, in wet O2, dry O2, and wet Ar. All processes demonstrated a linear-parabolic relationship with time. Both wet processes had a slower rate than dry oxidation at 1050°C and below. The activation energies of the linear and parabolic rate constants were calculated for each process. The activation energy of the parabolic rate constant for wet oxidation was found to be inversely dependent on the amount of oxygen present as a carrier gas.The dry oxides exhibited a very flat surface; in contrast, SEM and XTEM reveal that wet oxidation preferentially oxidizes dislocation bands, causing raised lines on the oxide and corresponding grooves in the SiC. It is proposed that the much higher solubility of H2O in SiO2 as compared with that of O2 (103 at 1000°C), allows wet oxidation to be preferential.
Microstructure and Properties of Native Insulators Formed on Single Crystal Germanium
Authors: Gregory O. J. , Crisman E. E. , Severns J. , Stiles P. J. 
Published: March 2011

ABSTRACTThe phases, morphologies and microstructures of native oxides and nitrides, grown on the vicinal planes of germanium, are discussed. Thermal oxides, formed under high pressure, were shown to be primarily amorphous for (100) and (110) oriented substrates and intermixed with a crystalline hexagonal phase on the (111) surfaces. Thermal treatments, in one atmosphere of flowing ammonia gas, converted oxide films to mixtures of nitrides and oxynitrides with the nitrides found to be combinations of a- and β-Ge3N4. The α-phase formed from condensation of vapors above the surface whereas the β-phase was a solid-solid reaction product which initiates at the oxide/germanium interface. These two processes appeared to proceed independently of each other. Results of low angle X-ray diffraction (XRD), far infrared transmission (FIRT), scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy (XPS) are discussed.
Oxidation of AU-SI Alloy Films
Authors: Hewett G A. , Bohlin K. E. , Randoplh M. W. , Lau S. S. 
Published: March 2011

ABSTRACTWe have investigated silicon oxide formation on co-deposited Au-Si alloy films at low temperatures. Alloy compositions spanning the Au-Si binary phase diagram have been examined. It was found that alloys with compositions above 40 at. % Au were most efficient in promoting oxide formation. These results are compared with the Au on Si sample configuration where Si is transported through the Au before oxidizing. The possibility of using alloys to form Au lines with a self passivating oxide coating after patterning and oxidation is discussed.
Modelling Of Rapid Thermal And Furnace Oxide Growth
Authors: Rosser P. J. , Moynagh P. B. , Duckworth C. N. 
Published: March 2011

ABSTRACTThe reproducible growth of thin high quality silicon dioxide films is of fundamental importance to advanced VLSI processes. Oxides in the range 1–2 nm are required for electron tunnelling barriers in advanced BIPOLAR processes, and in the range 10–50 nm for the gate oxide in MOS processes.The excellent degree of control over time, temperature and ambient atmosphere that can be achieved in halogen lamp rapid annealing systems suggested the possibility of growing thin films of silicon dioxide on silicon very reproducibly.This paper compares the growth of oxides in an AG Associates' Heatpulse system with those grown in a conventional dry oxidation system. Oxides in the range 1–1000 nm have been grown in these systems and the thicknesses are compared with those predicted by the SUPREM 3 and Deal Grove models. Modifications to these models are suggested which allow for accurate prediction of thermal oxide growth above 2 nm.
Formation of Metal Nitrides by Nitrogen Implantation
Authors: Ma En , Liu Bai-Xin , Chen Xin , Li Heng-De 
Published: March 2011

ABSTRACTA systematic study was performed to investigate the ion beam induced metal nitride formation by direct nitrogen implantation into 10 selected metals, either of thin film or bulk material. An X-ray diffractometer, together with a specially-designed Seemann-Bohlin attachment, was employed to provide fast and reliable phase identification in the thin implanted layer. The results show that room temperature nitrogen implantation can lead to the formation of many, but not all, of the equilibrium metal nitrides. The formation of metal nitrides by implantation is discussed in terms of the thermodynamic condition and the readiness of structural trans format ion.
Microstructure of Metal-GaAs Interfaces
Authors: Kuan T. S. , Batson P. E. , Freeouf J. L. , Jackson T. N. , Wilkie E. L. 
Published: March 2011

ABSTRACTThe interfacial reactions and microstructures of metal-GaAs contacts are, in general, much more complicated and difficult to control than the corresponding metal-Si contacts. They are very sensitive to reaction temperature, ambient, metal layer thickness, and the GaAs surface cleaning procedure. Many of the ohmic and gate contacts to GaAs currently in use or under development for GaAs FET devices are comprised of more than one metal species and in some cases a doping element as well. In dealing with these complexities, information about the microstructure at the contact interface is critically needed: for the evaluation of a specific contact metallurgy, for the definition of an optimum fabrication process, and, most important of all, for generating new ideas for better contact schemes. In this paper, our TEM and STEM studies of several ohmic and gate contacts that are of technological interest will be described. Attention will be drawn to the link between the interfacial microstructures and their electrical behavior, the kinetics of interfacial reactions, and thermal stability. The current constraints on obtaining ideal, reliable and controllable metal-GaAs contacts will also be discussed.
Non-Destructive Characterization of Semiconductors Using Organic Thin Films
Authors: Forrest Stephen R. , Kaplan Martin L. , Schmidt Paul H. 
Published: March 2011

ABSTRACTRectifying junctions prepared by vacuum deposition of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and related compounds on both p- and n-type inorganic semiconducting wafers are used for their non-destructive evaluation. By evaporation of metal contact pads onto the organic layer, we can probe many of the fundamental -bulk and surface properties of the semiconductor.
A Study of the Photovoltaic effect of A Semiconductor Grain Boundary by A Scanning Laser Beam
Authors: Song Jerng-Sik , Yang Edward S. 
Published: March 2011

ABSTRACTExperimental observation of the photovoltaic effect of a semiconductor grain boundary with a scanning laser beam is analyzed assuming a single trap energy level. The photo-current is calculated from the recombination velocity and the concentration of minority carriers at a grain boundary which was derived from the continuity equation. Open circuit voltage across a sample is obtained from equating this recombination current to compensating thermionic emission current. Using recombination velocity and diffusion length as variables, tha calculated open circuit voltage is compared with experimental data.
An X-Ray Diffraction Attachment tor Thin Filam Analysis of High Sensitivity
Authors: Tao Kun , Dong Zhili , Chen Shunying , Wang Bingju 
Published: March 2011

ABSTRACTA Seemann-Bohlin X-ray diffration attachment has been developed recently. In addition, two new intensity factors are introduced to existing intensity formula of Seemann-Bohlin diffractometer. Its characteristic is that the glancing angle is rather small and that no crystal monochromator is put in the incident path. Compared with the conventional diffractometer, it is superior in many aspects: (1). Very high sensitivity in identifying the structures of solid surfaces and thin films, with the intensities being 7–20 times those of the conventional method. For example, in analysing a gold film of 70 Å thick by 1KW X-ray, a fairly good pattern was obtained up to 2θ=120° with the scanning speed of 4°(2θ)/min. (2). All diffraction peaks obtained give the information of the surface layer in nearly the same depth. It thus enables one to study the variation of the composition, the lattice constants, and the structures with depth. (3). It can also be used for thick polycrys-talline samples, and the intensities are 3–20 times those of the conventional diffractometer. This method can be used for various ordinary diffractometers.
Automatic Iterative Fitting of RBS Spectra From Multielement Samples
Authors: Eridon James , Was Gary 
Published: March 2011

ABSTRACTA computer code (BASF) has been constructed to perform automatic iterative fitting of smoothed Rutherford Backscattering Spectra using only the experimental spectrum and the parameter set defining the experiment. The code may be used to analyze anywhere from two to five elements. The code output consists of the total amount of each element present and a composition versus depth profile.The code's performance was verified experimental backscattering spectra. Samples consisting of nickel substrates onto which layers of nickel and aluminum have been alternately evaporated were used to produce backscattering spectra. These spectra, when analyzed, demonstrated that the code was able to determine the total aluminum content to within 5% and the ratio of aluminum to nickel within 1% of the thickness monitor readings taken during evaporation. The code has also shown the ability to recognize sharp interfaces in well resolved spectra. The ultimate limits on the code's accuracy are the resolution of the spectrum and the accuracy of the computed stopping powers.
Dopant Effects On The Kinetics Of Formation Of Platinum Silicides
Authors: Wittmer M. , Psaras P. A. , Tu K. N. 
Published: March 2011

ABSTRACTWe have investigated the growth kinetics of platinum suicide compounds on undoped and heavily arsenic doped polycrystalline silicon. The results are compared with published data on the growth kinetics of these suicides on other silicon substrate materials. From this comparison we conclude that dopants and the microstructure of the substrate material do not affect the activation energy of the growth kinetics which means that the growth mechanism of these suicides is not altered. Only the preexponential factor is lowered in some cases, pointing to a slowing of the speed of growth.
Effects of Ion Implantation Doping on the Formation of Titanium Silicide on the Diffusion Layers
Authors: Matsui H. , Ohtsuki H. , Ino M. , Ushio S. 
Published: March 2011

ABSTRACTSi samples, with and without masking oxide films, implanted with various doses of As, P, or BF2 have been evaluated on the formation of titanium suicides from titanium films. In all cases, suicide reaction for implantation with masking oxide films is more difficult than that for implantation without masking oxide films. Suicide reaction becomes more difficult with decreasing implant energy in the range over a critical dose. In the case of implantation with masking oxide films, knocked oxygen has been found at the surface of Si substrate. Suicide formation after removing the surface layers containing considerable amount of knocked oxygen with argon back-sputtering is as easy as suicide formation for implantation without masking oxide. The difficulty of Ti silicidation for implantation with masking oxide films is believed to be due to the effects of interference from knocked oxygen.
PtSi Contact Metallurgy by Different Formation Processes
Authors: Change Chin-An , Huang H. -C. , Segmüller A. , Turene F. E. , Cunningham B. , Sugerman A. , Totta P. A. 
Published: March 2011

ABSTRACTPtSi films have been formed using sputtered Pt and different annealing sequences and ambients. A clear dependence on the annealing sequence and ambient is observed for both the PtSi films and the passivating oxide layers formed. The single-temperature process at 550°C using forming gas (N2-H2 9:1), nitrogen and oxygen shows incomplete reactions between Pt and Si, with a surface oxide layer of poor resistance against etching in aqua regia. A three-temperature process using forming gas is shown to provide complete reactions between Pt and Si, with a surface oxide layer of excellent resistance against aqua regia. The three-temperature process using nitrogen or oxygen, however, fails to provide films of high quality, and the results are similar to those obtained by the single-temperature process in various gases.
Temperature Dependent Intermixing At The V/Ge(111) Interface
Authors: Del Giudice M. , Butera R. A. , Joyce J. J. , Ruckman M. W. , Weaver J. H. 
Published: March 2011

ABSTRACTHigh resolution core level photoemission results show the temperature evolution of the V/Ge(111) interface in the range from 300 to 600 K. Three well-defined chemical environments are present for Ge at 300K (the first is the substrate and the other two are reaction products with overall shifts of−0.5 and −0.95 eV). Increasing the temperature enhances Ge outdiffusion, and a homogeneous reacted layer forms when deposition and measurements are done isothermally at 475K. The activation energy for this diffusion process is very low (5 kcal/mole), indicating the importance of grain boundary diffusion at reacting, heterogeneous interfaces.
Devitrification of an FE43 CR25NI20 B12 Glass
Authors: Ando Teiichi , Hara Yutaka , Grant N.J. 
Published: March 2011

ABSTRACTThe kinetics of bcc crystallization and subsequent transformations in an Fe43Cr25Ni20B12 glass were monitored by magnetic measurements and X-ray diffrsaction. The metastable bcc phase (ferrite) which forms first transforms to austenite and a boride during isothermal annealing. At low temperatures the ferritegrows without significant partitioning of Fe, Cr and Ni. Increasing the annealing temperature results in alloy partitioning which is directly linked with the ferrite decomposition.