bluuebunny/crossref_metadata_2025 huggingface dataset:
Trapping of Interstitials During Ion Implantation In Silicon
Authors: Culbertson R.J. , Pennycook S.J.
Published: March 2011

The solid phase epitaxial regrowth of silicon implanted with a group V dopant, such as antimony, results in excellent incorporation of the dopant atoms into silicon lattice sites. However, annealing at higher temperatures or longer times results in transient dopant precipitation with a diffusion coefficient up to five orders of magnitude above that of tracer diffusion and with a reduced activation energy.

This precipitation is accompanied by the nucleation of dislocation loops that are interstitial in nature, and the transient ceases as the dislocation loops develop. It is believed that Si interstitials are trapped in a stable defect complex during the implantation process.

Although they survive SPE these complexes dissolve at higher temperatures and release a large supply of interstitials which serve to promote dopant migration via an interstitialcy mechanism until they condense to form the observed dislocation loops. By following the Sb implantation with an implantation of B to an equivalent concentration profile the loop formation is efficiently suppressed. For higher B concentrations the Sb precipitation is no longer observed. Results for As implantation are similar to Sb except that As precipitates can not be directly observed. Calculations of the dopant and interstitial concentration depth distributions were also performed.
Temperature And Dose Dependence of An Amorphous Layer Formed By Ion Implantation
Authors: Richmond Eliezer Dovid , Knudson Alvin R.
Published: March 2011

A model is formulated to predict the width of an amorphous layer in Si produced by ion implantation. The dependency of the amorphous Si layer width on the ion implantation energy, dose, and temperature is computed.
Formation of Surface Layers of Icosahedral Al(Mn)
Authors: Knapp J. A. , Follstaedt D. M.
Published: March 2011

Surface layers of the icosahedral phase of Al(Mn) have been formed from thin, alternating Al/Mn layers deposited on Al or Fe surfaces by rapid electron-beam or laser melting, by ion beam mixing, and by solid-state diffusion. The electron beam and laser treatments are similar to other liquid quenching techniques used previously to form the phase, but have well defined temperature histories which allow us to place limits on the melting point of the icosahedral phase, the time needed for its nucleation from the melt, and its growth velocity. Ion beam mixing is a way of forming the icosahedral phase which is quite different from melt quenching; the phase is formed during ion beam mixing at temperatures of 100–200°C. For mixing at ≤60C an amorphous phase with icosahedral short-range order is formed; this phase can be converted to the icosahedral phase by subsequent annealing. Formation of the icosahedral phase by reacting the as-deposited layers in the solid state is a new technique not previously reported. The results presented here place new restrictions on proposed structural and thermodynamic models for the icosahedral phase.
Metastable Phases Produced In Nickel By High Dose La And 0 Implantation, And Pulsed Laser Melt Quenching
Authors: Sood D.K. , Pogany A.P. , Battaglin G. , Carnera A. , Mea G. Della , Kulkarni V.L. , Mazzoldi P. , Chaumont J.
Published: March 2011

Nickel single crystals implanted with La, 0 and La + 0, up to about 9 a/o concentrations were irradiated with spatially homogenised ruby laser pulses (16 ns FWHM) up to 3.7 J/cm2 in vacuum (s~ 10−2 Torr). Phase changes, defect structure and solute migration were studied before and after laser melt quenching using RBS/channeling, TEM and SEM techniques.

Both La and La + 0 implants produced a buried amorphous layer on top of a polycrystalline layer above the single crystal matrix. 0 implants did not produce an amorphous phase, but a buried layer containing polycrystalline Ni, metastable hcp Ni particles and a dense dislocation network was formed. Pulsed laser melt quenching of these implanted metastable phases lead to a variety of new phases - all crystalline.
Ion Beam Mixing In Binary Amorphous Metallic Alloys
Authors: Hahn Horst , Averback R. S. , Rubia T. Diaz De La , Okamoto P. R.
Published: March 2011

Ion beam mixing (IM) was measured in homogeneous amorphous metallic alloys of Cu-Er and Ni-Ti as a function of temperature using tracer impurities, i.e., the so called “marker geometry”. In Cu-Er, a strong temperature dependence in IM was observed between 80 K and 373 K, indicating that radiation-enhanced diffusion mechanisms are operative in this metallic glass. Phase separation of the Cu-Er alloy was also observed under irradiation as Er segregated to the vacuum and SiO2 interfaces of the specimen. At low-temperatures, the amount of mixing in amorphous Ni-Ti is similar to that in pure Ni or Ti, but it is much greater in Cu-Er than in either Cu or Er.
Improving the Structural and Electrical Properties of Epitaxial CaF2 on Si By Rapid Thermal Anneaing
Authors: Phillips Julia M. , Manger Mary L. , Pfeiffer Loren , Joy D. C. , Smith T. P. , Augustyniak W. M. , West K. W.
Published: March 2011

Rapid thermal annealing (RTA) has been shown to be a useful technique for improving the epitaxial quality of CaF2 films grown on Si(100) by molecular beam epitaxy. We have modified the annealing procedure to prevent crack formation, while still maintaining high film quality. Our work also shows RTA to be useful for improving the crystalline quality, chemical stability, and electrical characteristics of CaF2 films grown on Si(111). After RTA, the crystallinity of CaF2 films on Si(111), as measured by electron channeling, is indistinguishable from bulk single crystal CaF2, and the interface state density is reduced by nearly two orders of magnitude from that found in as-grown films.
Enhancing the Grain Size and {110} Texture of Polycrystalline Si Films By Seed Selection Through Ion Channeling: Implant-Dose Dependence
Authors: Kung Kenneth T-Y. , Reif Rafael
Published: March 2011

This work outlines an optimized seed selection through ion channeling (SSIC) process for enhancing the grain size and {110} texture of polycrystalline Si films grown by LPCVD on SiO2. These films, 0.44 μm thick, were self-implanted at normal incidence to various doses (1×1014 - 20×l014 cm-2) and then recrystallized at 600°C. An enhanced average grain diameter resulted after implantation and annealing, ranging from 0.10 to 2.0 μm (vs. the as-deposited 0.080 μm) and increasing with the implant dose. The grain size vs. implant dose behavior may be explained by a previously proposed stochastic model. An enhanced {110} texture was also observed after processing for implant doscs in the range 6×1014 - 14×1014 cm-2. The optimal dose was 11×1014 cm-2, for which the <110> directions were confined to within ±4° (vs. the as-deposited ±20°) of the surface normal. The overall results suggest a strong potential of SSIC in growing large-grain, restricted fibertextured polycrystalline Si thin films on amorphous insulators.
Morphology of Silicon Islands Grown By Selective Epitaxy Over Silicon Dioxide
Authors: Liu S.T. , Newstrom K. , Hibbs-Brenner M. , Stokes R.J. , Hoefflinger B. , Neudeck G. , Zingg R. , Bousse L. , Meindl J.D.
Published: March 2011

We studied the selective epitaxial deposition of silicon in patterned oxide-free regions over silicon dioxide in a RF-heated, commercial, reduced-pressure epitaxial reactor, using SiH2Cl2/HCl/H2 gas system. We found that etching into silicon occurs at the high end of HCl content, and nucleation on the silicon dioxide at the low end of HCl content. The selective epitaxial growth of silicon islands is obtained in between.
Si-MBE SOI
Authors: Lin T.L. , Chen S.C. , Wang K.L. , Iyer S.
Published: March 2011

100 μm-wide silicon-on-insulator (SOI) structures have been accomplished by utilizing silicon molecular beam epitaxial (Si-MBE) growth on porous silicon anid subsequent lateral-enhanced oxidation of porous silicon through pattern widows. A silicon beam method was used for insitu cleaning of Si surface at 750°C, and the effectiveness of this method was demonstrated by Auger electron spectroscopy and checked by the etch-pit density of the grown film. A two-step growth process of Si MBE was used to grow epitaxial layers of high quality. An electron mobility of 1300 cm2V-1s-1 was obtained by van der Pauw measurements.
Epitaxial Growth on Simox Wafers
Authors: Lam Hon Wai
Published: March 2011

The top silicon layer in as-implanted SIMOX wafer is usually too thin to support device fabrication. Hence, an epitaxial layer is usually grown on a SIMOX wafer after oxygen ion implantation and anneal. Because this epitaxial layer is typically very thin,less than 500 nm) and because of the material structure of the S1MOX wafer, special care has to.be exercised in order to obtain desirable epitaxial growth. This paper describes the unique problems of epitaxial growth on SIMOX.
The Effects of Annealing Temperature on the Characteristics of Buried Oxide Silicon-On-Insulator
Authors: Mao B.-Y , Chang P.-H. , Lam H.W. , Shen B.W. , Keenan J.A.
Published: March 2011

The effects of post implantation annealing on the properties of buried oxide silicon-on-insulator (SOI) substrates in the temperature range of 1150°C to 1300°C have been studied. Microstructural analyses showed that the crystallinity of the top silicon layer was improved at higher annealing temperature. Lower thermal donor generation at 450°C was observed in SOI annealed at higher temperature. The improvement in microstructure and lower thermal donor generation were correlated to the lower oxygen concentration in the top silicon film.
Crystalline Films on Amorphous Substrates by Zone Melting and Surface-Energy-Driven Grain Growth in Conjunction with Patferning
Authors: Smith Henry I. , Geis M. W. , Thompson C. V. , Chen C. K.
Published: March 2011

Two approaches to preparing oriented crystalline films on amorphous substrates are reviewed briefly: zone-melting recrystallization (ZMR) and surface-energy-driven grain growth (SEDGG). In both approaches patterning can be employed either to establish orientation or to control the location of defects. ZMR has been highly successful for the growth of Si films on oxidized Si substrates, but its applicability is limited by the high temperatures required. SEDGG has been investigated as a potentially universal, low temperature approach. It has been demonstrated in Si, Ge, and Au. Surface gratings favor the growth of grains with a specific in-plane orientation. In order for SEDGG to be of broad practical value, the mobility of semiconductor grain boundaries must be increased substantially. Mobility enhancement has been achieved via doping and ion bombardment.
The Microchemistry of the SiO2/Silicon Interface
Authors: M-Grovenor C.R.
Published: March 2011

This paper deals with the chemical microanalysis of the Si02/si terface by Pulsed Laser Atom Probe (PLAP). The PLAP technique is briefly described, emphasizing its unique advantages in the study of the chemistry of interfaces. A transition oxide layer of stoichiometry SiO has been identified by PLAP analyses of the Si02/S' interface in thermal and anodic oxides. Simple models of the structure of the interface incorporating this SiO layer are presented, and the possible role of this layer during oxidation is discussed.
A Technique for In—Situ Detection of Growth Dislocations
Authors: Peteves S. D. , Sarreal J. A. , Abbaschian G. J.
Published: March 2011

A formidable obstacle to develop the optimal conditions for growing dislocation—free crystals has been the lack of a direct technique to monitor the perfection of the solid/liquid (S/L) interface during growth. Recently we have developed a technique which detects, in—situ, the emergence of dislocation(s) at the crystallization front. This novel technique is based on the thermoelectric principles, and utilizesthe dependence of the Seebeck emf generated across the S/L interface upon the interface temperature, crystal orientation, and dopant concentration. The technique was used to directly measure the S/L interface temperature during growth of Ga and In—doped Ga. For the latter, the technique also shows the breakdown (instability) of the faceted interface, which leads to the entrapment of the In—rich bands. The applicability of the technique to monitor defect formation during crystal growth processes such as thin film zone, Czochralski, or liquid phase epitaxy will be discussed.
Electrical Characterization of Beam—Recrystallized Soi Structures Using a Depletion Mode Transistor
Authors: Vu D.P. , Chantre A. , Ronzani D. , Pfister J.C.
Published: March 2011

We show that a depletion mode transistor is a very versatile tool for the electrical characterization of SOI structures. We apply it to Si thin films recrystallized by a zone—melting technique in which grainboundaries are localized. Apart from the transportparameters, one can get from drain—source current the information usually determined from a MOS capacitor. Owing to the existence in such a transistor of two MOS structures, we are able to characterize both Si-SiO2 interfaces as well as the “bulk” of the Si film.
Process and Device Considerations for Small Grain Polysilicon Transistors
Authors: Shichijo H. , Malhi S.D.S. , Sundaresan R. , Banerjee S.K. , Lam H.W.
Published: March 2011

Polysilicon transistors offer the first entry into 3-dimensional ICs. This paper reviews some process and device considerations in using these devices in VLSI environments. The process issues include the choice of polysilicon grain size, layer thickness, doping, and methods of grain boundary passivation. The device considerations are closely related to the effects of grain boundaries in modifying the device characteristics. Three specific application examples are reviewed. It is concluded that polysilicon transistors offer new possibilities to enhance the performance of bulk technologies without resorting to any recrystallization techniques.
Two-Beam Laser Recrystallization of Silicon on an Insulating Substrate
Authors: Dasgupta Samhita , Jackson Howard E. , Boyd Joseph T.
Published: March 2011

Laser recrystallization of silicon on an insulating substrate has been carried out by irradiating polysilicon with both an Ar+ laser operating on all lines in the visible and a CO2 laser operating at 10.6 microns. These experiments were carried out over a variety of laser power densities and substrate temperatures. The use of the two lasers allowed for independent spatial control of temperature in both the polysilicon and the SiO2 layers and helped to reduce the strain at the polysilicon - SiO2 interface. We report the successful recrystallization of polysilicon films without substrate heating for two different silicon-on-insulator structures.
Sputter Deposited, Electrically Conductive, Oxidation Resistant Coatings
Authors: Rutledge Sharon K.
Published: March 2011

Significant polymer weight loss has been observed due to environmental ashing by atomic oxygen at low earth orbital (LEO) altitudes. Static charging during deployment and charging caused by the space plasma in LEO polar orbits may cause electromagnetic interference (EMI) problems on insulating polymer materials that are integral to such applications as high voltage solar arrays. Simultaneous ion beam sputter deposited coatings of indium-tin-oxide (ITO) with polytetrafluoroethylene (PTFE), carbon, air, or methane were investigated as potential solutions to these problems. The purpose of this research was to improve the flexibility of ITO coatings with these additives and to study the effect the addition of these materials had not only on the flexibility of ITO sputter deposited thin films but also on the conductivity and optical properties.
Can Amortization Bs Induced by Ion Mixing in Ag-Cu and Ag-Ni Systems?
Authors: Liu B. X. , Huang L. J. , Li J. , Ma S.
Published: March 2011

The extended Structural Difference Rule for amorphous phase formation states that an amorphous phase can be obtained by ion mixing with an alloy with a composition lying in a two-phase region in the equilibrium phase diagram. This criterion has to respond to the challenge that no amorphous alloy has been formed in some early studied systems exhibiting a two-phase region character, e.g. Ag-Cu(typical eutec-tic),Ag-Ni(almost entirely immiscible),etc‥

We performed ion mixing experiments for several systems at liquid nitrogen temperature using Xe ions with low current density. Amorphization was indeed observed in both Ag-Cu and Ag-Ni samples, as two halos were seen by TEM SAD immediately after adequate doses ion mixing. These not only support our two-pnase region rule, but also show the possibility of amorphization in a system(Ag-Ni) that has large positive heat of formation.
Computer Simulation of Marker Evolution Upon Ion Irradiation
Authors: Cui Fu-Zhai , Li Heng-De , Liu Bai-Xin
Published: March 2011

In ion beam mixing, the subject on the marker evolution of Si/Pt/Si target during 300 keV Xe ion irradiation has been an interesting topic of recent years. A cottputer simulation for this system by using the Monte Carlo code TCIS-4 is reported here. Dynamic target model was employed. Some radiation-enhanced diffusion and relaxation of the displacement cascades were also considered. Results of this simulation study reveal the evolution of Pt marker profile with fluences during bombardment. The shifts of Pt marker and the dispersions evaluated from the profiles agree fairly well with experimental date, demonstrating a reslistic model of the target being irradiated is important.
Epitaxial Growth of Transition Metal Silicides on Silicon
Authors: Chen L. J. , Cheng H. C. , Lin W. T.
Published: March 2011

Recent progresses in the epitaxial growth of refractory metal suicides, FeSi2 and manganese suicides on silicon are reviewed.

The formation and structures of epitaxial suicides are described. Factors affecting the suicide epitaxy are examined. The lattice match criteria for the growth of epitaxial suicides are assessed. The effects of anharmonicity in the interatomic force of overlayer on the heteroepitaxial growth and pseudomorphism are discussed. The properties and possible applications of epitaxial suicides are summarized. Prospects for the study of epitaxial suicides are addressed.
Initial Nucleation and the Effects on Epitaxial Silicide Formation
Authors: Nemanich R. J. , Doland C. M. , Fulks R. T. , Ponce F. A.
Published: March 2011

The initial nucleation processes for reactions of Pd and Ti on Si are studied by Raman scattering, and Auger electron spectroscopy. The epitaxial nature of the structures is verified by high resolution TEM. A model of the interface reaction is presented which describes the initial interdiffusion and subsequent nucleation. The aspects of nucleation in a thin film reaction are compared to nucleation processes in vacuum deposition. For Pd/Si a critical depostion thickness is observed which is related to a critical nuclei size. For Ti/Si higher annealing temperatures are required to bring about conditions for nucleation of the suicide.
MBE Growth of Epitaxial Calcium Fluoride on Silicon
Authors: Schowalter L. J. , Fathauer R. W.
Published: March 2011

The growth of an epitaxial insulator such as CaF2. on Si substrates and ita subsequent overgrowth with epitaxial sen iconduct ors have a number of important applications in the electronics industry. In addition, it presents a unique opportunity to study an insulator/semiconductor interface under controlled conditions. We have studied the growth of epitaxial CaF. on Si substrates and their subsequent overgrowth with Si or Ge under various conditions. While epitaxial growth of CaF2, (which has an fee lattice structure as does Si) can be obtained on (100), (110) and (111) oriented Si substrates, the best quality crystal growth and surface morphology is obtained on (111) substrates as the CaF. (111) surface has the lowest free energy. Atomic steps on the original Si substrate surface are shown to have a detrimental effect on the epitaxial growth of CaF2. I-V measurements on the epitaxial (111) films show that the intrinsic breakdown field strength exceeds 2 MV/cm, however, high-field induced ionization can cause thermal breakdown at lower voltages. C-V measurements typically show ∼1012 states/cm in the Si band gap as grown. However, it is possible to reduce this number to less than 10 by annealing procedures after growth.
Heteroepitaxy of Si and Ge on CaF2/Si (111)
Authors: Fathauer R. W. , Schowalter L. J. , Lewis N. , Hall E. L.
Published: March 2011

Si 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

The 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

A 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

In 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

The 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

Single 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

Ohmic 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

A 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

Amorphous 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

Silicon 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

The 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

We 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

The 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

A 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

The 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

Rectifying 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

Experimental 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

A 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

A 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

We 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

Si 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

PtSi 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

High 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

The 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.
Wear Properties of A Shock Consolidated Metallic Glass and Glass-Crystalline Mixtures
Authors: Vreeland Thad , Thadhani Naresh N. , Mutz Andrew H. , Thomas Susan P. , Nibert Roger K.
Published: March 2011

Powder flakes prepared from 50 μm thick melt spun ribbons of Markomet 1064 (Ni52.5 Mo38 Cr8 B1.5 wt%) were shock consolidatedin the unannealed and annealed condition. The unannealed flakes (microhardness 933 kg/mm2) are amorphous while flakes annealed at 900ºC for 2 hours have an fcc structure with a grain size of 0.3 μm and microhardness of 800 kg/mm2. The shock consolidated amorphous powder compact (250 kJ/kg shock energy)shows no crystal peaks in an X-ray diffractometer scan. Compacts of annealed powder (400 to 600 kJ/kg shock energies) contain amorphous material (18-21%) which was rapidly quenched from the melt formed at interparticle regions during the consolidation process. The microhardness of the amorphous interparticle material is 1100 kg/mm2. Wear properties of the compacts measured in low velocity pin on disk tests show low average dynamic friction values (∿0.03). The 60 hour cumulative wear appears to correlate with the energy of shock compaction and surface porosity of the compacts rather than the metallic glass content.
Catalytic Properties of Glassy and Crystalline Transition Metal Alloys Produced by RSP
Authors: Mahmoud S.S. , Forsyth D.A. , Giessen B.C.
Published: March 2011

The catalytic activity and selectivity of Pd80Si20, Pd35Zr65Ni30Zr70, Fe40Ni40B20, Fe85B15and Cu50Zr50alloy ribbons in their amorphous and crystalline states were studied in the hydrogenation of 1—hexene and phenylethyne, dehydrogenation of methylcyclohexane and dehydrocyclization of n—heptane. Pd80Si20was found to be the most active of the alloy catalysts studied. Most alloys were more active amorphous than in the crystalline state; however, the catalytic selectivities of the amorphous and crystalline states of each alloy were identical.
Magnetic after Effects and Magnetostriction of FE—Base Metallic Gzasses
Authors: Collins A.K. , O'Handley R.C. , Grant N.J.
Published: March 2011

Magnetic after effects (MAE's) have been studied in Fe—base and Co—base metallic glasses. Fe—base amorphous alloys shcw large MAE's due in part to the high magnetoelastic energy (large λs) whereas Co—basealloys exhibit much smaller MAE's due to their low magnetostriction. A detailed study of the acntribution of the magnetoelastic energy to the MAE's was done on the Fe83–xCrxB17 and Fe83–x NbxB17 glass systems.
Innovative Melt-Spinning Technique for Ferromagnetic Amorphous Ribbons
Authors: Yu H. Y. , Huang D. R. , Yao P. C. , Hsu S. E.
Published: March 2011

A new melt-spinning technique (field quenching) for ferromagnetic amorphous ribbon is suggested to produce better magnetic properties than conventional as-quenched amorphous ribbon. An external field is applied during the quenching either parallel or perpendicular to the casting direction. The magnetic moment and initial permeability are increased when the field direction is parallel to the casting direction. These effects are opposite when these two directions mentioned are perpendicular to each other.
Quasicrystals with 1-D Translational Periodicity and A Ten-Fold Rotation Axis
Authors: Bendersky L.
Published: March 2011

Studies of phase formation in rapidly solidified Al-Mn alloys (composition range 18-22 at% Mn) show that an icosahedral phase is replaced by another noncrystallographic phase, a decagonal phase. The decagonal phase is another example of quasicrystal: It has a noncrystallographic point group (10/m or lO/mmm) together with long-range orientational order and onedimensional translational symmetry. The decagonal phase is an intermediate phase between an icosahedral phase and a crystal both from the symmetry and from the solidification condition points of view.
Dispersoid Modification of Ti3Al-Nb Alloys
Authors: Rowe R. G. , Sutliff J. A. , Koch E. F.
Published: March 2011

Titanium aluminide alloys with matrix compositions of essentially Ti3Al plus 0, 5, 7.5, and 10 a/o Nb and with and without rare earth elements for dispersoid formation were prepared. The alloys were rapidly solidified by melt spinning. Ribbon was consolidated by HIP and extrusion at temperatures below the beta transus temperatures of the alloys. The effects of processing conditions and dispersoid additions on room temperature ductility and fracture toughness were studied.
Microstructure of Rapidly Solidified Ti3Al Alloys
Authors: Jackson A. G. , Teal K. R. , Eylon D. , Froes F. H. , Savage S. J.
Published: March 2011

The microstructures of ordered Ti3Al-lZr (alpha2 +Zr) and Ti-Al-Nb alloys produced by ingot metallurgy (IM) and by rapid solidification (RS) are compared. The RS Ti3Al-iZr (alpha2 structure) alloy displayed small antiphase domains (APD) of 10–20 nm in the as-produced condition, but large grain size. The latter observation is rationalized in terms of the cooling history used to produce the material. The RS Ti-Al-Nb alloy exhibited an equiaxed microstructure. The IM Ti-Al-Nb material displays a complete change in microstructure between 1010°C and 1035°C, indicating a narrow alpha+beta phase field.