bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Indium Depletion on the Composition of OMVPE Grown GaInAs
Authors: Agnello Paul D. , Chinoy Percy B. , Ghandhi Sorab K. 
Published: March 2011

AbstractThis paper describes an experimental and theoretical study of indium depletion during the OMVPE growth of GaInAs. A mathematical model for mass, momentum and energy transfer, together with decomposition of the indium species was developed. The model was compared with experimental results over a range of growth parameters that included susceptor temperature, slope, reactor pressure and reactant partial pressures. Excellent agreement was obtained for a model based on the homogeneous decomposition of a triethylindium-arsine adduct to a stable product via an irreversible bimolecular reaction, with an activation energy of 11.9 kcal/gmol. The model may be used for optimization of compositional uniformity and growth over a wide range of reactor conditions.
A High Resolution Cross-Section Transmission Electron Microscopy Study of Epitaxial rare Earth Fluoride / GaAs(111) Interfaces Prepared by Molecular Beam Epitaxy
Authors: Chien C.J. , Farrow R.F.C. , Bravman J.C. 
Published: March 2011

AbstractWe report the first HRXTEM study of epitaxial rare earth fluoride/ GaAs(111) interfaces. Such interfaces are of interest because they are the starting point for growth of buried epitaxial rare earth / rare earth fluoride sandwich structures which exhibit interesting and non bulk-like magnetic properties. Also, the optical transitions in ultrathin epitaxial NdF3 films may be influenced by strain and defects in the NdF3 film and the nature of the interface to GaAs.We find that the rare earth fluoride / GaAs interfaces are semi- coherent but chemically abrupt with the transition taking place within 3Å. However, the interface is physically rough and multiple monolayer steps in the GaAs surface tend to lead to tilt boundaries in the fluoride. The origin of these steps is believed to be thermal etching of the GaAs during the heat-cleaning stage prior to epitaxy. The surface of the fluoride film is much smoother than the initial GaAs surface indicating planarization during epitaxy.
X-Ray Topographic Analysis of Strain Fields Associated with Micron-Sized Gratings on Si(100) Surfaces
Authors: Jardine A.P. , Dudley M. , Tolis G. , Yao G-D. , Durbin S.M. 
Published: March 2011

AbstractSi(100) single crystals containing circular gratings etched into the surface using reactive ion etching were analysed using both monochromatic and white beam reflection X-ray topography. Some features of observed X-ray topographic contrast associated with the gratings were modelled using a diffracting zone model, based on a simple radial in-plane strain field. Reasonable agreement was obtained between this model and observations.
Structural Stability of Amorphous Semiconductor Superlattices
Authors: Persans P. D. , Ruppert A. F. , Abeles B. , Wu Y. J. , Pantojas V. , Liang K. S. , Hughes G. 
Published: March 2011

AbstractWe report recent results of studies of the structure and thermal stability of periodic multilayers based on hydrogenated amorphous silicon, hydrogenated amorphous germanium, silicon nitride and silicon oxide. By varying the sublayer thickness from 1 nm to 20 nm it is possible to extract information on the range and magnitude of relaxation and interdiffusion in these metastable materials. It is also possible to gain information on the influence of interfaces on crystallization and relaxation. The principal techniques discussed here are Raman scattering, optical absorption and high resolution x-ray reflectivity.
Structural and Electronic Properties of Pb/Cu Multilayers
Authors: Neerinck D. , Temst K. , Vanderstraeten H. , Van Haesendonck C. , Bruynseraede Y. , Gilabert A. , Schuller Ivan K. 
Published: March 2011

AbstractWe have performed extensive structural and electronic transport measurements of Pb/Cu multilayered structures. The high-angle x-ray diffraction spectrum indicates the presence of continuous interfacial disorder. In the low-angle x-ray spectrum, pronounced minima occur at positions given by q = 2π/Λ, where Λ is the bilayer thickness. This is in sharp contrast to the results for Pb/Ge (crystalline/amorphous) multilayers, where minima are observed at positions q = 2π / tPb with tPb the Pb thickness. These low-angle x-ray spectra can be explained by taking into account lateral coherence and continuously distributed thickness fluctuations. The effect of this interfacial disorder on the electronic properties is investigated by measuring the low-temperature resistivity and the superconducting transition temperature of the multilayers. The calculated values for the elastic mean free path in the individual layers confirm the presence of strong interfacial scattering. The thickness dependence of the critical temperature is explained by taking into account an interfacial barrier with penetration probability σ ≃ 0.5.
Structural Stability of Heat Treated W/B4C Multilayers
Authors: Jankowski A.F. 
Published: March 2011

AbstractThe utilization of W/B4C multilayer structures as Bragg diffractors rests in their reflective efficiency and dependability, both of which rely on the stability of the layered structure. The layers within the vapor deposited multilayers, often amorphous, are typically metastable, hence susceptible to thermally induced structural change. In fact, crystallization and compound formation are known to occur in annealed multilayer systems. In this study, multilayers of W/C and W/B4C were vacuum heat treated, then structurally examined. A comparison between the pre- and post- heat treated structures of the two multilayer systems, accomplished using diffraction and electron microscopy, indicate structural stability in the W/B4C multilayers as opposed to structural degradation noted for the W/C system.
Photoreflectance of a GaAs/In0.5 Ga0.5 P (ordered) Single Quantum Well Grown by Atomic Layer Epitaxy
Authors: Yin X. , Pollak Fred H. , McDermott B.T. , Reid K.G. , Bedair S.M. 
Published: March 2011

AbstractWe have studied the photoreflectance spectrum at 300K from a GaAs/In0.5 Ga0.5p (ordered) single quantum well fabricated by atomic layer epitaxy. Comparison of the energies of the observed intersubband and barrier transitions with an envelope function model calculation yields a valence band offset of 350 ± 20 meV.
Electrical and Optical Characterization of InSb Grown on GaAs by MBE
Authors: Thompson Phillip E. , Waterman James , Kurtgaskill D. , Stahlbush Robert , Gammon Daniel , Davis John L. 
Published: March 2011

AbstractInSb has been grown on semi-insulating GaAs substrates by molecular beam epitaxy. By growing an InSb buffer layer at 300 C prior to the main InSb layer growth at 420 C, the effect of the 14% lattice mismatch between GaAs and InSb was minimized. A typical 5 µrn InSb film had a room temperature carrier concentration and electron Hall mobility of 2 × 1016/cm3 and 6×104 cm2/Vs, respectively. At 77 K these values became 2 × 1015/cm3 and 1.1 ×105 cm2/Vs. Temperature dependent Hall measurements revealed a peak in the mobility at 85 K and 70 K for the 5 and 10 µm samples. Capacitance-voltage measurements using MIS capacitors produced 77 K carrier concentrations in agreement with the low fieldHall measurements. Carrier lifetimes were determined by photoconductive response measurements. Lifetimes of 20 ns and 50 ns were determined for the 5 and 10 µm films. For comparison, the carrier lifetime in bulk n-type InSb was found to be 200 ns. Optical characterization by room temperature IR transmission spectroscopy showed a broad absorption edge, with an absorption coefficient of 1.4 × 103/cm at a wavelength of 6 µm. Epilayer thickness was determined from observed interference fringes. Raman spectroscopy showed that each epitaxial layer had a spectrum equivalent to that of bulk InSb.
Magneto-Optical Studies of GaAs-AlGaAs Modulation Doped Quantum Wells Under Hydrostatic Pressure
Authors: Zhou Weimin , Perry Clive H. , Worlock John M. 
Published: March 2011

AbstractHigh pressure photoluminescence measurements on modulation doped GaAs-AlGaAs quantum well structures have been performed for the first time with applied magnetic fields up to 15 Tesla. We have observed Landau fans from interband transitions of the 2D free electron gas between 0 and 8.5 kbar. In this pressure range the electron effective mass in GaAs increased at the rate of 2.6% per kbar. Above 9 kbar, the free Landau transitions disappeared and bound magneto-exiton behaviour dominated the spectrum. The influence of pressure on the band-gaps causes a controlled trapping of the free electron from the GaAs well to Si donors (DX centers) in the AlGaAs layers. Above 9 kbar the pressure coefficient of the GaAs band gap was found to be 10.4 meV/kbar which is comparable to the accepted value in undoped GaAs quantum well structures.
Index of Refraction Anisotropy in InGaAs/InP Heterostructures Measured by Ellipsometry
Authors: Bennett Brian R. , Del Alamo Jesús A. 
Published: March 2011

AbstractWe applied ellipsometry to characterize layers of InxGa1-xAs grown by molecular beam epitaxy on (001) InP. Samples with mismatched layers exhibit significant anisotropy in the index of refraction. We explain these observations by the presence of misfit dislocations which form in an asymmetric pattern. This results in asymmetric strain and, via piezo-optical effects, an anisotropy in the optical properties. This effect makes ellipsometry a more sensitive technique than double-crystal x-ray diffraction for detecting misfit dislocations in these heterostructures.
Stress Evaluation Method using Raman Spectroscopy
Authors: Mashimoto Y. 
Published: March 2011

Local stress measurement is becoming very important to evaluate electrical and reliability property of semiconductor. Raman spectroscopic method has been established to measure local stress at the area of one micron in diameter. The measurement problems came from the characteristics of a spectrometer have been solved by the following.–Ar Plasma line is utilized to calibrate wave numbers.–Gaussian and Lorentz distribution are utilized to determine the peaks of Plasma line and RAMAN shift.This method with introduction of a certain assumption can be applied to the stress measurement not only for Silicon single crystal like trench structure, but for deposited thin layers like silicon oxide or silicon nitride, and plastic packaging material.This paper describes the measurement methods of local stress, data processing techniques of measurement data and several examples of the measurement on a semiconductor thin layer and packaging plastic.
X-Ray Diffraction Study of Inalas-Ingaas on Inp High Electron Mobility Transistor Structure Prepared by Molecular-Beam Epitaxy
Authors: Liu H.Y. , Kao Y.C. , Kim T.S. 
Published: March 2011

AbstractHigh-Electron Mobility Transistors (HEMTs) can be prepared by growing alternating epitaxial layers of InAlAs and InGaAs on InP substrates. Lattice matched HEMTs are obtained by growing layers of InxAl(1-x)As and InyGa(1-y)As with x ≃ 0.5227 and y ≃ 0.5324. Varying the values of x and y by controlling the individual flux during molecular-beam epitaxial (MBE) growth, one can obtain pseudomorphic HEMTs. Pseudomorphic HEMTs may have superior electronic transport properties and larger conduction band discontinuity when compared to an unstrained one. The precise control of the composition is thus important to the properties of HEMTs. This control is however very difficult and the values of x and y may vary from run to run.We will demonstrate in this paper the capability of a double crystal rocking curve (DCRC) on the structure characterization. All the structure information: including composition and thickness of both the buffer and top InAlAs layers and the active channel InGaAs layer, can be obtained from one x-ray diffraction measurement. It is accomplished through a computer simulation process of DCRCs. The structure parameters of the epitaxial layers are used to calculate (simulate) the DCRCs. The simulated one is then to compare with the experimental curves. During the simulation one or more of these structure parameters are adjusted until the best fitted DCRC is obtained. The limitation of DCRC in measuring small variations in layer thickness as well as the small changes in composition for both InAlAs and InGaAs layers will be discussed.
Heterojuncion Study of Ga0.92In08as(P+)/GaAs(n) Diodes: Correlation of Electrical and Strucrural Characteristics
Authors: Choi Y.W. , Wie C.R. , Evans K.R. , Stutz C.E. 
Published: March 2011

AbstractDifferent in-plane mismatch was introduced by varying the Ga 0.92In0.08As(p+) epilayer thickness (h-0.1, 0.25, 0.5 and lum) on GaAs(n)/GaAs(n+) structure. For sample with h-lum, quasi-Fermi level pinning effect was observed in low temperature forward Current-Voltage characteristic due to high density misfit dislocation. From Vint measurement at low frequency limit in C-2 vs Voltage plot, interface state density Nss was obtained. From Capacitance-Voltage measurements at different frequencies, single-level interface state density Ns was estimated using Schokley-Read-Hall statistics. Both Nss and Ns show their linear relation with epilayer in-plane mismatch. Admittance Spectroscopy shows an interface trap level at about Ev + 0.36 eV with the hole capture cross section cp = 2.7×10-15 cm-2 for the h-lum sample, and at Ev + 0.21 eV with cP = 2.4×10-16 cm-2 for the h-0.5um sample.
Thermal Stability of Si/Si0.85Ge0.15/Si Modulation Doped Double Heterostructures
Authors: Wang P.J. , Meyerson B.S. , Fahey P.M. , LeGoues F. , Scilla G.J. , Cotte J. M. 
Published: March 2011

AbstractThe thermal stability of Si/Si0.85Ge0.15/Si p-type modulation doped double heterostructures grown by the Ultra High Vacuum/ Chemical Vapor Deposition technique has been examined by Hall measurement, transmission electron microscopy, secondary ion mass spectroscopy, and Raman spectroscopy. As deposited heterostructures showed two-dimensional hole gas formation at the abrupt Si/SiGe and SiGe/Si interfaces. Annealing at 800 °C. for 1 hr. caused the diffusion of boron acceptors to the heterointerfaces, degrading the hole mobilities observed in the two dimensional hole gas. Rapid redistribution of boron, causing a loss of the 2 dimensional carrier behavior, was observed after a 900 °C, 0.5 hr. anneal. Neither Ge interdiffusion nor the generation of misfit dislocations were observed in the annealed heterostructures, evincing the defect-free crystal quality of these as-grown strained heteroepitaxial layers. The superior stability of these heterostructures have strong positive implications for Si:Ge heterojunction devices.
Epitaxy of SimGen Atomic Layer Superlattices
Authors: Baribeau J.-M. , Lockwood DJ. , Rowell N.L. , Dharma-Wardana M.W.C. , Houghton D.C. , Kechang Song 
Published: March 2011

AbstractWe report the MBE growth of various (SimGen)p atomic layer superlattices (ALS) and their characterization by Raman scattering spectroscopy, x-ray diffraction and photoluminescence. The structural properties of ALS prepared on (100) Si, (100) Ge and on various Si1-xGex (0.5<×<1) buffers were compared. Phonon peaks due to folding of acoustic modes were seen by Raman scattering spectroscopy in the frequency range 15-250 cm-1. The observed Raman spectra from the ALS were interpreted on the basis of a theoretical analysis of these systems. The study provided an estimation of the interfacial sharpness of the ALS. The photoluminescence investigation on annealed specimens revealed features between 800 and 900 meV that were ascribed to known dislocation lines in Si. No strong luminescent signal that could be unambiguously related to a direct bandgap behavior was detected.
Effects of Different CH4-H2 Gas Compositions on the Morphology and Growth of Diamond Grown by Hot Filament CVD
Authors: Farabaugh Edward N. , Feldman Albert 
Published: March 2011

ABSTRACTDiamond films have been grown on single crystal Si and polycrystalline mullite substrates by hot filament chemical vapor deposition. Both substrates offer a good thermal expansion match with diamond. Gas mixture ratios of CH4 :H2 ranged from 0.1–1.0%. The remaining deposition parameters were: substrate temperature, 750°C; filament temperature, 1800°C; gas pressure, 5×103 Pa; gas flow rate, 52 seem except for the 0.1% CH4 :H2 ratio deposition in which the flow rate was 120 seem. Film thicknesses were determined from cross sectional SEM micrographs. The average growth rates on the mullite increased nearly linearly with increasing CH4 gas fraction, ranging from 0.05 μm/hr to 0.21 μm/hr. Growth rates on the Si substrates were slightly lower for identical growth conditions. Surface SEM micrographs revealed that the roughness of the films decreased with increasing CH4 gas fraction during deposition. X-ray diffraction patterns showed that crystalline grain size in the films decreased with increasing CH4 gas fraction. No preferred crystallographic orientation was seen in the diffraction patterns. Isolated particles were also grown on Si substrates under the same deposition conditions as the film growth. As the CH4 gas fraction increased, the particle growth displayed increasing rates of secondary particle nucleation resulting in a less well faceted morphology.
Application of a Thermobalance for studying Deposition kinetics of Diamond Films
Authors: Czarnecki Jerry , Thumim David 
Published: March 2011

ABSTRACTWeight recording using a thermobalance type Cahn TG-171 has been applied to study Hot, Filament Enhanced Chemical Vapor Deposition (HFCVD) of carbon films from methane. Changes in the deposition rates during each individual process may indicate four stages of the deposition kinetics: 1- generation of nuclei (slow, linear); 2- growth on nuclei (exponential increase); 3- aggregation of crystals (slowing); 4- growth on the surface of diamond film, completely covering the substrate (linear). An attempt to determine the concentration of graphite in the deposited layer, based on differences in oxidation rates of diamond and graphite has been proposed, as supplementary to X-ray diffraction and Raman spectroscopy.
Investigations of Excimer Laser Effects on CVD Diamond Growth
Authors: Pehrsson Pehr E. , Nelson H. H. , Celii F. G. 
Published: March 2011

ABSTRACTWe investigated UV laser irradiation as a method to modify the surface and gas phase chemistry in a diamond growth apparatus. In particular, attempts were made to reproduce reported laser-enhanced deposition. The variables included the laser wavelength and intensity, the precursor gas (and hence the gas-phase absorption), the flow rate, and the gas inlet orientation with respect to the filament. The samples were analyzed using optical microscopy, Scanning Electron Microscopy, the Scanning Auger Microprobe, and micro-Raman scattering. In all cases, the laser radiation suppressed or had no effect on diamond deposition in comparison to the adjacent unirradiated regions. The crystals that did grow in the irradiated regions were similar in size and morphology to those from the unirradiated areas, suggesting ablation or nucleation site blockage as possible deposition suppression mechanisms. The results suggest a novel method for diamond film patterning.
Regrowth of Damaged Layers in Diamond Produced by Ion Implantation
Authors: Sandhu G. S. , Liu B. , Parikh N. R. , Hunn J. D. , Swanson M. L. , Wichert Th. , Deicher M. , Skudlik H. , Lennard W. N. , Mitchell I. V. 
Published: March 2011

ABSTRACTWe have used RBS/Channeling, perturbed angular correlation (PAC) and optical absorption to study the regrowth of disordered layers in diamond produced by implantation with carbon, or with carbon plus boron or indium ions. For C or C plus B implantation doses of 2 ×1015 cm−2 or less, complete recovery of channeling damage occurred after RTA at 1100°C or furnace annealing at 900°C. Optical measurements on samples implanted with high energy carbon ions show better recovery compared to the shallower implantations. PAC results showed that co-implantation with C and In caused a considerable fraction (∼15%) of the In-atoms to occupy well-defined lattice sites characterized by an electric field gradient having its major component along <111>, and a frequency of 116 MHz.
Selective Nucleation of Single Crystal CVD Diamond and its Applicability to Semiconductor Devices
Authors: Kawarada H. , MA J. S. , Yonehara T. , Hiraki A. 
Published: March 2011

ABSTRACTUsing selective nucleation at edges or corners of μ m-size dots of Si, periodically arrayed diamond particles have been reproducibly fabricated. The particles are grown from single nuclei and have nearly-single crystal features. The properties of the diamond arrays compared with polycrystalline films have been investigated using cathodoluminescence and Schottky diodes.
Domain Size Determination in Diamond Thin Films
Authors: LeGrice Y. M. , Nemanich R. J. , Glass J. T. , Lee Y. H. , Rudder R. A , Markunas R. J. 
Published: March 2011

ABSTRACTIn this study we develop a method which utilizes the linewidth of the diamond peak at 1332 cm−1 to determine the diamond domain sizes. We have carried out calculations based on the phonon dispersion curves of diamond and the breakdown of wavevector selection rules in Raman scattering. The linewidths of a series of diamond samples were calculated, and from this theory the dimensions of the diamond regions were obtained. The calculated domain sizes ranged from 57 to 100Å and were compared to values obtained from SEM micrographs which were between 5000 and 25000Å. This is consistent with other results which have found that domain sizes calculated from this theory are in general consistent with sizes determined from electrical conductivity measurements, not from microscopy techniques. In addition, this theory allows for the calculation of the amount of frequency shift due to microcrystallinity, so that the residual stress in the film can be found.
Characterisation of Thin Film and Single-Crystal CVD Diamond by Absorption and Luminescence Spectroscopy
Authors: Collins A. T. , Kamo M. , Sato Y. 
Published: March 2011

ABSTRACTPolycrystalline films and single crystals of diamond produced by microwaveassisted chemical vapour deposition (CVD) have been examined using absorption and cathodoluminescence spectroscopy. Measurements have been carried out on material as-grown, and after radiation damage by 2 MeV electrons.
CW Four-Wave Mixing in Synthetic Diamond
Authors: Redman D. A. , Rand S. C. 
Published: March 2011

ABSTRACTWe report efficient CW optical phase conjugation and resonantly enhanced four-wave mixing spectroscopy of the N-V color center in synthetic diamond. An ultra-narrow resonance is observed in the room temperature nearly degenerate four-wave mixing spectrum upon excitation within the vibronic band at 579 nm, furnishing the triplet manifold decay rate.
Characterization of Heavy Metal Contamination in Diamond Films Using Sims, Txrf, and RBS
Authors: Hockett R. S. , Knowles James 
Published: March 2011

ABSTRACTIntentionally contaminated DC and microwave plasma deposited diamond films were used to evaluate the characterization capability of SIMS, TXRF and RBS for heavy metal measurements. The results showed SIMS is the preferred analytical technique for heavy metal impurities in the diamond films, and TXRF for the top surface analysis of the substrate and pre-processed substrate. In addition TXRF may provide a quick, non-destructive qualitative characterization of the diamond film surface and bulk. The RBS can provide qualitative and quantitative information if the impurity levels are high enough (above 1013 atoms/cm2).