bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of DX Centers in GaAs1−xPx :Te
Authors: Kaniewski J. , Kaniewska M. 
Published: March 2011

ABSTRACTA capacitance study of GaAs1−xPx : Te. x > 0.2, obtained by vapor phase epitaxy, has revealed two DX centers, characterized by thermal activation energies ΔEA = 0.18 eV and ΔEB = 0.39 eV. and photoionization energies 0.6 eV and 1.1 eV, respectively. Both traps show strong non-exponential behavior in thermal emission and capture processes. It is shown that correct parameter values for DX centers can be determined from measurements of the transition region width. This method, which allows us to circumvent alloy effects, has been used to study DX center parameters as a function of the phosphorus content. It is demonstrated that the level B is linked to the X minimum, and that the barrier height for electron capture at this trap, with respect to the indirect minimum, is independent of alloy composition.
Interface Defects in GaAs and GaAs-AlxGa1−xAs Grown on Ge
Authors: Cho N.-H. , McKernan S. , Carter C. B. , Wagner D. K. 
Published: March 2011

ABSTRACTΣ=3 lateral twin boundaries and a Σ=19 boundary have been investigated by highresolution electron microscopy. The lateral twin boundary was produced by growth on single crystal (110) Ge substrate and was observed to facet parallel to the common (112) plane and the (111)/{115} planes. The Σ=19 boundary was grown on a bicrystal substrate and faceted parallel to the common {331} plane. In this case, convergent-beam electron diffraction was used to determine the polarity of the adjoining grains. A possible model for the atomic configuration is proposed for each of the observed boundaries. GaAs-AlxGa1−xAs heterolayers were grown on a (001) Ge substrates to examine the interaction of antiphase boundaries with heterojunctions.
The Nucleation and Propagation of Misfit Dislocations aear the Critical Thickness in Ge-Si Strained Epilayers
Authors: Kvam E. P. , Eaglesham D. J. , Maher D. M. , Humphreys C. J. , Bean J. C. , Green G. S. , Tanner B. K. 
Published: March 2011

ABSTRACTThe nucleation and propagation of misfit dislocations in Ge-Si strained epilayers on (100) Si have been investigated using transmission electron microscopy and X-ray diffraction topography at low lattice parameter mismatch (˜ 0.8%). Misfit dislocations nucleate as half loops which are predominantly unfaulted (> 90%) at the advancing growth interface. Under the driving force of the epilayer strain, unfaulted half loops glide and expand on inclined { 111 }planes toward the heterointerface (i.e. substrate/epilayer interface). These unfaulted half loops consist of a 60°-dislocation segment which lies along < 011> in a plane parallel to the heterointerface (i.e. (100)) and this segment is connected to the growth interface by two screw dislocation segments which both lie on the same inclined {111} glide plane. As 60° dislocations reach the heterointerface on each of the four inclined {111} variants, they form an orthogonal array of misfit dislocations which lie along [011] and [011]. At higher lattice parameter mismatch (˜ 2%), there appear to be some important changes in the dislocation behavior and these changes result in orthogonal arrays of heterointerface dislocations which are predominantly edge type (i.e. 90°dislocations).
The Formation and Cathodoluminescence Activity of Buffer Layer Edge Dislocations in In0.12Ga0.88As/GaAs Heterostructures
Authors: Fitzgerald E. A. , Kirchner P. D. , Petit G. D. , Woodall J. M. , Ast D. G. 
Published: March 2011

ABSTRACTThe defect structure of lattice-mismatched one micron In0.12 Ga0.88As epilayers on (001) GaAs was studied with scanning cathodoluminescence (CL) and transmission electron microscopy (TEM). CL examination of the GaAs buffer layer revealed the formation of a segmented network of defects below the interface. Cross-sectional TEM analysis shows that these defects are dislocation half-loops extending from the interface, and the vast majority of these loops lie on the GaAs side of the interface. The dislocations in the GaAs buffer layer were determined to be edge dislocations. Thus, CL images show that edge dislocations in this system are centers for non-radiative recombination. We propose that two 60° dislocations with opposite screw and interface tilt components can glide into the buffer layer to form edge dislocations. Potential energy plots for 60° dislocations near the interface and interacting with interface dislocations supports this model.
Defect and Dopant Control During Silicon Epitaxy Using B and Ge
Authors: Kola R. R. , Posthill J. B. , Salih A. S. M. , Rozgonyi G. A. , Bean K. E. , Lindberg K. 
Published: March 2011

ABSTRACTThe control of dopants, impurities and defects for VLSI of silicon integrated circuits requires a complex set of crystal and processing conditions to be satisfied simultaneously. In order to achieve the maximum yield and highest level of electrical performance for a given device design, we have manipulated the lattice constant and boron doping levels in CVD epitaxial silicon layers co-doped with germanium. By adjusting the ratios of germane and diborane in a dichlorosilane/hydrogen CVD reactor we have obtained buried high conducting layers which are strain-free and lattice matched to the Si substrate. Degenerate boron and boron and germanium codoped epitaxial layers on (100) p-type silicon substrates were investigated. Solubility, electrical activity limits and defect structure of boron in strained and strain-free silicon epitaxial layers were investigated by spreading resistance, SIMS profiling, X-ray and transmission electron microscopy techniques. Bright field and weak-beam dark field imaging of cross-sectional and plan-view specimens were used to confirm the presence or absence of precipitates and threading dislocations. A model has been proposed to describe the mechanism of threading dislocation formation in heavily boron-doped layers. We are now in a position to strategically locate co-doped Si(B, Ge) p++ layers as recombination zones or buried field plates to suit the needs of MOS latchup control, high speed and radiation hard devices, as well as the needs of defect free p++ etch stops for thin membranes and three-dimensional silicon structures.
Identification of An Interstitial Carbon – Interstitial oxygen Complex in Silicon
Authors: Trombetta J. M. , Watkins G. D. 
Published: March 2011

ABSTRACTThe Si-G15 EPR spectrum and the 0.79eV “C-line” luminescence spectra in silicon are shown to arise from an interstitial carbon - interstitial oxygen complex. The g-tensor and 13C hyperfine interaction tensor indicate the structure in the vicinity of the carbon atom while stress alignment studies reveal the configuration near the oxygen atom. The pairing of the two impurities leads to a lattice relaxation which serves to stabilize the complex against dissociation.
The Effect of Growth Ambients on the Local Atomic Structure of Thermally Grown Silicon Dioxide Thin Films
Authors: Fitch J. T. , Lucovsky G. 
Published: March 2011

AbstractThis paper represents a study of the local atomic structure of SiO2 films formed by thermal oxidation in dry oxygen, pyrolytic steam, and a variety of different sequences of these ambients. All oxidations were carried out at 850 °C. Local atomic structure was studied via infrared spectroscopy (IR). The growth ambient dependence of the frequency v, and half-width Δv, of the bond stretching feature, and the refractive index, n, was investigated. Consistent with previous work [1,2] it was found that.when the majority of the sample thickness was grown in steam the oxides were generally less dense than dry oxides. Also, the last ambient in a sequential oxidation process was found to have the most influence on the oxide properties. The observed variations in v, Δv, and n could be readily explained in terms of systematic changes in the bond angle at the oxygen bonding site between corner connected tetrahedra.
The Effects of Overlying Layers On The Ftir Spectra of Thin Thermal Oxides On Silicon
Authors: Cox J. Neal , Rastogi R. 
Published: March 2011

AbstractThe most intense feature in the infrared spectrum of SiO2 is the “νas band” near 1070 cm-1. Assigned to the asymmetric stretching mode, this peak exhibits a shoulder on the high frequency side of the band. In this study, Fourier transform infrared (FTIR) spectrophotometry is used to examine the effects of overlying, unpatterned layers of undoped polysilicon (poly) and of tungsten silicide (WSi) upon 0.08 μm of themal oxide grown on silicon. For the poly studies, the oxide is grown on both sides of double-side-polished wafers. 0.11 μm of poly is then deposited on each side of half of the set; 0.25 μm, on the remainder. For the WSi studies, 0.21 μm of undoped poly is deposited onto oxide grown on single-side-polished, low-oxygen wafers. WSi is then deposited on one side.For the poly set, the peak position (PP) of the “νas band” shifts from 1074 to 1071 to 1066 cm-1 when comparing the uncoated oxide, 0.11 μm poly/oxide, and 0.21 μm poly/oxide samples, respectively. As a result of the observed shifts, the high frequency shoulder becomes resolved as a broad, weak band centered near 1168 cm-1. Thus, the “νas band” appears to be a doublet, consisting of a weak high-frequency component that is insensitive to, and an intense low-frequency component that is sensitive to. overlying films. For the WSi set, the PP of the “νas band” shifts from 1068 to 1076 to 1083 cm-1 for the poly/oxide, WSi/poly/oxide, and annealed-WSi/poly/oxide samples, respectively. Possible causes for the doublet character of the “νas band” and mechanisms for the film-film interactions, such as hydrostatic pressure, are discussed.
Thermal Oxidation of Amorphous Silicon-Boron Alloy
Authors: Lau W. M. , Yang R. , Tong B. Y. , Wong S. K. 
Published: March 2011

AbstractThe thermal oxidation of amorphous silicon-boron alloy (prepared by low pressure chemical vapor deposition) with boron contents ranged from 0–40% at a temperature range of 25- 700 °C has been carried out. Crystalline silicon and polycrystalline boron have also been studied for comparison purposes. The resultant thin oxide overlayers were characterized by X-ray photoelectron spectroscopy. It was found that both the oxidation of Si and of B are enhanced by mixing of the two elements. The oxidation of boron is significantly slower than silicon. During oxidation of silicon-boron alloy, preferential oxidation of silicon occurs at the oxide/bulk interface and the silicon oxide overlayer advances into the bulk faster than the boron oxide.
Total Energy Calculation in α-SiO2 and β-Si3N4
Authors: Xu Yongnian , Ching W. Y. 
Published: March 2011

AbstractThe self-consistent electronic structures and total energies for the crystalline α-SiO2 and β-Si3N4 are studied by means of the first-principles orthogonalized linear combination of atomic orbitals method. The calculated band structures are compared with the earlier non-self consistent results. The total energies in the local density approximation are evaluated as a function of lattice parameters. Reasonable values of equilibrium lattice constants and cohesive energies are obtained but the bulk modulus for α-SiO2 is overestimated.
The Role of Electron and Hole Traps in the Degradation and Breakdown of thermally grown SiO2 Layers
Authors: Heyns M. M. , De Keersmaecker R. F. 
Published: March 2011

AbstractThe degradation and charge build-up of thermally grown silicon diozide layers (with thicknesses varying between 20 and 40 nm) during various stress experiments was investigated. The slow trapping instability generated during charge injection was demonstrated to originate from initially present hole traps. The generation of electron traps in the oxide layer close to the non-injecting interface during high-field stressing was established both for Al-gate and poly-Si gate structures. No evidence could be found for the generation of hole traps during high-field stressing. No bulk oxide charges were detected after a high-field stress, but only unstable near-interface charge trapping was evidenced.
Study of Spatial and Energetical Behavior of Slow Si-SiO2 Interface States By Tunnel-Dlts Under Fowler-Nordheim Stress
Authors: Vuillaume D. , Lakhdari H. , Bourgoin J. C. , Bouchakour R. , Jourdain M. 
Published: March 2011

AbstractWe study the behavior of the spatial and energetical distribution of the slow Si-SiO2 interface states ( i.e. the defects located in the strained SiO2 layer near the interface) when the Metal-oxide-semiconductor (MOS) structure is submitted to a high field electrons injection from the Si substrate. We have analysed the creation kinetics of these slow states in order to compare with the behavior of the fast interface states which are better studied. We demonstrate that the fast interface states are more rapidly generated than the slow states and that the creation kinetics of fast states reach a saturation at lower injected charge. We also find that the fast interface states generation is independent from the energetical location of the states in the Si bandgap. For the generation of slow states, we observe a weak dependence on the energetical location of the defects in the SiO2 bandgap, and a strong dependence on the depth location from the Si-SiO2 interface.
The SiO2/Si Interface Probed With Positrons
Authors: Nielsen Bent , Lynn K. G. , Leung T. C. , Welch D. O. , Rubloff G. 
Published: March 2011

AbstractThe effects of the heat treatment of Si covered with a thermally-grown ˜50 nm overlayer of SiO2 were probed by means of measurements of positron annihilation characteristics obtained with a variable-energy positron beam. From measurements at elevated temperature (˜500°C) it was observed that positrons implanted overlapping the SiO2/Si interface decay from a state with properties distinctively different from the state in Si and in SiO2. The nature of the annihilation characteristics indicates the presence of open volume defects.
Tem Studies of Silicon-Silicon Oxide Interface Roughness
Authors: Park Kyung-Ho , Sasaki T. , Matsuoka S. , Yoshida M. , Nakano M. 
Published: March 2011

AbstractInterfaces between two kind of substrate, a bulk silicon wafer and a laser-recrystallized Silicon-On-Insulator (SOI), and its thermally grown oxide have been studied. High resolution transmission electron microscopy (HRTEM) of cross sectional specimen shows that the roughness at the interface is atomically flat and nearly uniform for the bulk single crystal silicon and silicon oxide, while being nonuniform and rough as much as 20 nm height for the recrystallized silicon and silicon oxide interface. Consideration of interface between recrystallized silicon and silicon oxide, and the oxide surface above, the observed roughness at the interface is due to original grain boundaries of polycrystalline silicon which was used as the material for the laser recrystallized silicon formation. It is also discussed HRTEM of the interface between polycrystalline silicon and silicon oxide.
The Effects of Interface Roughness on Ellipsometric Measurements of Thin Oxides
Authors: Dunham Scott T. , Agrawal Bhawana 
Published: March 2011

AbstractMeasurements of film thickness using ellipsometry assume all interfaces to be ideally planar. This approximation works well for films much thicker than the roughness of the interfaces. For very thin films. the interface roughness can cause significant errors in thickness measurements. In this paper, we calculate the effect of interface roughness on oxide thickness measurements and use those calculations to account for some of the observed differences between film thickness measurements of thin oxides (< 200 A) as measured by ellipsometry and transmission electron microscopy.
Arsenic in SiO2 - Phase Segregation, Drift, and Diffusion Phenomena
Authors: Celler G. K. , Trimble L. E. , Sheng T. T. , West K. W. , Kosinski S. G. , Pfeiffer L. 
Published: March 2011

AbstractWe have recently determined that anomalously low diffusion of high dose As implants in SiO2 is caused by phase separation. In an inert ambient, As segregates into spherical As-rich droplets of 50 to 500Å in diameter, which are essentially immobile when heated isothermally, even at 1405 °C. In a temperature gradient the droplets move toward the heat source.The dependence of the segregation rate, drift, and diffusion on-the ambient and arsenic concentration is discussed here, and a new interpretation of the published arsenic diffusion data is provided.
Structure of Perturbed Twin Boundaries in Silicon
Authors: Garg Anita , Clark W. A. T. , Hirth J. P. 
Published: March 2011

ABSTRACTSilicon bicrystals containing Σ =3(60°/[111]1,2) twin boundaries have been fabricated by sintering together single crystal (IMi) :vafers (which deviated from the exact (111) by upto ±4′). Transmission electron microscopic investigation revealed the boundaries to be near-twin boundaries having a superposed tilt component. The grain boundary dislocation structure of these boundaries has been studied in a transmission electron microscope (TEM) and interpreted as arising from the interaction of a large tilt component with a smaller twist component, to give the observed low energy configuration.
Redistribution of Boron Implanted into TaSi2/Poly-Si Gates
Authors: Schwalke U. , Mazure C. , Neppl F. 
Published: March 2011

ABSTRACTThe redistribution of boron implanted into TaSi2/poly-Si gates after high temperature anneals has been studied as a function of the implantation dose and energy as well as implantation scheme, i.e. boron implantation either into the silicide or into the poly-Si prior to TaSi2 deposition. SIMS measurements indicate that boron can easily diffuse from TaSi2 into poly-Si and vice versa at 900 °C. Independent of the implantation scheme, the boron concentration within poly-Si was found to saturate at approximately 1 × 1019 at/cm3 for boron doses greater than 5 × 1014 at/cm2. The excess of boron always accumulates within the silicide. The observed boron redistribution behavior within polycrystalline TaSi2/poly-Si layers is discussed in terms of combined lattice and grain boundary diffusion as well as grain boundary segregation.
Control of Grain Boundary Location By Selective Nucleation Over Amorphous Substrates
Authors: Yonehara T. , Nishigaki Y. , Mizutani H. , Kondoh S. , Yamagata K. , Ichikawa T. 
Published: March 2011

ABSTRACTA selective nucleation based crystal-growth-technique over amorphous substrates is originated. The method manipulates nucleation sites and periods and hence, controls the grain boundary location by modifing the substrate surface. In Si, small Si3 N4 nucleation sites are formed, 1–2 pm in diameter, 100 μm in period, over Sio2. One Si nucleus is formed exclusively in the small area of Si3 N4 by CVD. The highly faceted and periodically located nuclei grow over SiO2 up to 100 μm in diameter before impingement. A MOS-FET fabricated inside the island operates comparably to the bulk Si control
Rapid Thermal Annealed Undoped LPCVD Si/Single Crystal Si Substrate Structures with an Implant of Si Near Interfaces
Authors: Ogawa S. , Okuda S. , Kouzaki T. , Yoshida T. , Yoshioka Y. 
Published: March 2011

ABSTRACTThe breaking up of a native oxide layer of a LPCVD amorphous Si/single crystal n+Si substrate interface by a rapid-thermal annealing was studied from the point of view of oxygen movement and morphological change. Oxygen atoms began to move at 1025 °C. After annealing at 1115 °C for 30sec, the quantity of oxygen atoms near the interface decreased dramatically and a silicon implant near the interface could enhance the decrease. More detailed observation was carried out by cross-section high-resolution transmission electron microscopy. After annealing at 940 °C for 30sec, the native oxide layer was continuous. On the qther hand, with a silicon implant near the interface, it changed into small oxide balls and an epitaxial growth occurred in the LPCVD layer with twins caused by these oxide balls. After annealing at 1115°C for 30sec, even without the silicon implant, a complete epitaxial growth occurred but it seemed that some SiOx particles dissolved into a single crystal Si layer near the interface.
Fabrication and Properties of Single, Double, and Triple Gate Polycrystalline-Silicon Thin Film Transistors
Authors: Proano R. E. , Soave R. J. 
Published: March 2011

ABSTRACTPolysilicon based Thin Film Transistors (poly-Si TFT's) with superior electrical performance can be achieved by maximizing the number of intrinsic point defect injected into the material during high temperature processing. These point defects will migrate to grain boundaries (GB's), enhance their mobility by facilitating climb, and allow the boundary to achieve a low energy configuration with a minimum of electrically active broken bonds. Proper processing of poly-Si TFT's therefore requires a redesign of the conventional processing cycle where, working with single crystal silicon, one minimizes the concentration of intrinsic point defects which otherwise precipitate out as Oxidation induced Stacking Faults (OSF's).TFT's were fabricated under nine different processing cycles to study the relationship between device performance and fabrication conditions. Device performance increased with higher gate oxidation temperature, elimination of HCI flow during gate oxidation, post hydrogenation, and multiple gates. Using conventional MOS processing steps only, n-type (p-type) devices were fabricated, which were capable of handling 40 volts VDS with a leakage current of 2×10−11 (6×10−12) A/μm and effective electron (hole) channel mobilities of 130 (50) cm2/Vs.
Hydrogen Passivation of Grain Boundaries in Polycrystalline Silicon Deposited by Molecular Beams
Authors: Jousse D. , Delage S. L. , Iyer S. S. , Crowder M. 
Published: March 2011

ABSTRACTGrain boundary properties of polysilicon deposited by molecular beams have been investigated by electron spin resonance and conductivity measurements. The variations of the conductivity activation energy with doping can be explained by a density of states model consisting mainly of two exponential bandtails, implying that dangling bonds play a minor role. A hydrogen plasma treatment at 500 °C reduces the spin density by a factor of three but also passivates weak Si-Si bonds thus leading to steeper bandtails. The possibility of hydrogen-related intra-grain gap states is also discussed.
Grain Boundary Characterization in Polysilicon by Light Beam Induced Current Topography and Image Processing
Authors: Masri K. , Boyeaux J. P. , Kumar S. N. , Mayet L. , Laugier A. 
Published: March 2011

ABSTRACTA high performance light-beam-induced-current (LBIC) analyser has been used to determine the recombination velocity at the grain boundary (S) and the minority-carrier diffusion length (L). For this purpose a Schottky diode (Cr/Si) was fabricated using a p-type silicon bicrystal (1Ω cm, Σ13 grain boundary). The contacts were obtained by a “cold” technology. The diffusion length, determined by the method proposed by Ioannou, was subsequently fitted into the model proposed by Marek to evaluate the recombination velocity by the curve-fitting of the experimental and theoretical photocurrent profiles. A value of S = 2.104 cm/s was thus obtained. The influence of the thin oxide layer at the Cr/Si interface is also discussed.
Photoluminescence Characterization of Thin Silicon-On-Insulator Films Produced by Oxygen Implantation
Authors: Weber J. , Baumgart H. , Petruzzello J. , Celler G.K. 
Published: March 2011

AbstractSingle crystal silicon films on top of a buried SiO2 layer were produced by implanting 1.7x10180+ions/cm2 at 150keV into (100) Czochralski silicon, followed by annealing at higher temperatures. The defect properties of the layers are studied after each processing step by low temperature photoluminescence measurements and transmission electron micrography (TEM). Dislocation-related photoluminescence signals correlate with their TEM observations in the same samples. The photoluminescence method proves to be a very versatile and convenient method for characterizing the quality of silicon-on-insulat or structures.