bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulating Functions Waveform Analysis of Multi-Exponential Transients for Deep-Level Transient Spectroscopy
Authors: Ransom C. M. , Chappell T. I. , Freeouf J. L. , Kirchner P. D. 
Published: March 2011

AbstractAn improved method for the analysis of multi-exponential transients with high resolution has been applied to DLTS. Full-waveform fittings, using the technique of Modulating Functions, are made to digitized transients captured by a computer. This technique is described and results for both simulated data (with noise) and real data are shown. The advantages over previously published techniques in resolution, calculation speed, insensitivity to truncation error and noise are discussed. Also, how this method allows for a determination of the number of components is presented.
Multi-Exponential Analysis of DLTS by Contin
Authors: Morimoto Jun , Kida Tatsuo , Miyakawa Toru 
Published: March 2011

AbstractDeep level transient spectroscopy (DLTS), which assumes a single exponential decay form for the transient junction capacitance, is the most commonly used method to characterize deep impurity levels in semiconductors. However conventional DLTS may lead to erroneous results if there are several closely spaced energy levels or the emission rate has a continuous spectrum. To overcome this difficulty a novel method named the multi-exponential analysis of DLTS by CONTIN (MEDLTS by CONTIN) is proposed. This method analyzes the emission rate to have a finite continuous spectrum S(λ) which appears in the transient junction capacitance C(t)=, by using the program “CONTIN” developed by Provencher in biophysics. Even if S(λ) includes two peaks at λ1 and λ2, those peaks can be distinguished for λ2/ λ1>2. As an example of the application of this method, deep levels in Si:Au were experimentally investigated. According to the three dimensional S(λ)-T2/λ-1/T representation, the single peak in the conventional DLTS was clarified to consist of two adjacent levels with activation energies and capture cross sections EB1=0.51eV, σB1=4.0×10−15cm2 and EB2=0.47eV, σB2=1.1×10−15cm2. With the assumption of the finite continuous spectrum S(λ) for the emission rate, MEDLTS by CONTIN permits one to get much information correctly. MEDLTS by CONTIN is superior to the conventional DLTS because it is a single-temperature scan, multi-exponential analysis instead of the conventional multi-temperature scan, single-exponential analysis.
Contactless Spatially Resolved Measurement of Bulk Free-Carrier Lifetime in Silicon Ingots
Authors: Johnson S. M. , Johnson L. G. , Hemphill R. 
Published: March 2011

AbstractA contactless spatially resolved measurement of bulk free-carrier lifetime in polycrystalline silicon ingots was accomplished using optically modulated free-carrier infrared absorption. Using a CW Nd:YAG laser (λ = 1.319 μm) for a probe and novel pulsed, tunable, infrared dye laser (λ = 1.10 to 1.13 μm) with photon energies near the Si bandgap, for a pump, the free-carrier lifetime was determined from transient absorption measurements to a maximum depth of 3.0 cm from the surface of an ingot. The spatial dependence of the free-carrier lifetime and the distribution of precipitates (determined from infrared probe transmission measurements) measured along the growth axis of an ingot were found to be strongly related to the spatial dependence of the I–V characteristics of large area solar cells fabricated from the subsequently wafered ingot.
Neutron-Zwischenreflex-Scattering from Point Defects in Crystals
Authors: Dosch H. , Peisl J. 
Published: March 2011

AbstractDiffuse neutron or x-ray scattering close to the Bragg peaks (Huang scattering) and far away from Bragg peaks (Zwischenreflex-scattering) supplies detailed information on point defects and small agglomerates in crystals [1]. The defect structure, i.e. the lattice location, the displacements of the near neighbours and the strength and symmetry of the long ranged displacement field can be determined. In order to demonstrate the power of this technique, we report on recent experimental results. Interstitially dissolved N and O in Nb are located on octahedral sites and create rather large displacements in their vicinity. Their long ranged displacement field shows the symmetry of the defect site. The light interstitials H and D in Nb are located on tetrahedral sites and their long ranged displacement field shows the symmetry of the host lattice. A rather complicated defect model is necessary in order to explain the local defect structure.
Mechanical and Microstructural Properties of Boron Implanted Beryllium
Authors: Kant R. A. , Knudson A. R. , Kumar K. 
Published: March 2011

ABSTRACTHigh dose boron implantation into instrument grade 1–400 beryllium has been found to produce a substantial increase of its wear resistance. A comparison of the friction and wear behavior resulting from two shapes of the boron depth distribution is made. The wear resistance provided by a boron layer of constant (flat) concentration was found to be superior to that of a gradually decreasing (graded) profile. Rutherford backscattering was used to determine the boron depth distribution profiles and transmission electron microscopy was used to examine the microstructure. Electron diffraction pattern analysis provides evidence for the formation of beryllium borides.
The Effect of Nitrogen Implantation on Martensite in 304 Stainless Steel
Authors: Vardiman R. G. , Bolster R. N. , Singer I. L. 
Published: March 2011

ABSTRACTMartensite will form in austenitic 304 stainless steel when it is deformed. Transmission electron microscope studies show that nitrogen ion implantation causes a reversion of the martensite to austenite. Specimens containing martensite resulting from fine surface polishing and heavy rolling are examined. The transformation is shown not to occur because of temperature increases during implantation. The effect is related to recent wear results in 304 stainless steel.
Mechanical Property Improvements on Ion Implanted Diamond
Authors: Hartley N. E. W. 
Published: March 2011

ABSTRACTA series of simple mechanical tests on single crystal diamond, diamond styli and diamond finishing tools has shown that frictional force, surface cracking and strength behaviour under simulated wear conditions can be improved as the result of N and Bion implantation at room temperature. Scratch tests on a polished macroscopic diamond of (111) planar orientation submitted to a total dose of 9.1015 N ions/cm2 revealed that a slight reduction in friction force occurred during dry sliding over the implanted region. Nitrogen implanted diamond gramophone styli held against a slowly rotating polished TiC disc under light load were found to significantly outlast unimplanted or carbon implanted samples, which generally failed abruptly on contact. In a third series of experiments, diamond tipped finishing tools used for high speed machining operationson acrylic plastic were implanted with N, B, and C ions to similar doses, all below 1016 per cm2. Nitrogen and boron implantations were found to improve the cutting life and quality of cut by as much as a factor 5, whereas carbon ions were much less effective.
Pulsed Laser Treatment of Virgin, Self and Europium Implanted Nickel: Evidence of Defect Impurity Interaction
Authors: Battaglin G. , Carnera A. , Della Mea G. , Mazzoldi P. , Jain Animesh K. , Kulkarni V.N. , Sood D.K. 
Published: March 2011

ABSTRACTWe present a comparative study (by 1.8 MeV 4He+ ion channeling) of virgin, self and Eu implanted single crystals of nickel, under irradiation with single ruby laser pulses. The as implanted Eu is nearly non-substitutional and remains so, even after laser treatment. The comparative defect dechanneling behaviour provides explicit evidence of defect-impurity interaction which may be suppressing the formation of an expected metastable solid solution in the Eu-Ni system, which possesses miscibility in the liquid phase. A clear surface Eu peak appears at 2.1 J/cm2.
Dynamical Behavior of the Subsurface Region in Alloys Under Ion Bombardment at High Temperatures
Authors: Lam N. Q. , Wiedersich H. 
Published: March 2011

ABSTRACTModifications of subsurface alloy composition by bombardment with ions of several keV energy were investigated theoretically, using a phenomenological model which includes the effects of various processes, such as preferential sputtering, displacement mixing, Gibbsian adsorption, radiation-enhanced diffusion, and radiationinduced segregation. The nonuniformity of damage rates, resulting from slow-down of the incoming ions, was also taken into account. The alloy composition evolution in time and space was calculated numerically for different temperatures, using concentrated Ni-Cu as a model alloy system. A good qualitative agreement between the present model calculations and recent experimental measurements was obtained.
Mechanical Properties of Ion-Implanted Thin Films and Interfaces
Authors: Miller G. L. , Soni M. , McDonald M. , Kaufmann E. N. , Fenstermacher R. L. 
Published: March 2011

ABSTRACTOne of the areas of interest in the ion-beam modification of materials is that of alteration of specifically mechanical properties. To this end a method has been developed allowing in situ investigation of the stress, Young's modulus and mechanical hysteresis of small samples during and following ion-implantation. The samples are typically in the form of ~ 2 mm ⨉ 2 mm squares a few thousand angstroms thick, deposited on a ~ 50µ thick metal support, and forming a mechanical marginal oscillator. The measurement is carried out by flexing the samples at ~ 500 Hz under a servo-stabilized sinusoidal strain with a peak value in the range 0 to ~ 10−3. The accuracy of the method is typically ~ 1% or better for the measured quantities.Results are presented showing strain dependent (nonlinear) mechanical effects, thermal annealing effects, ion implantation of boron into copper and ion-beam mixing of copper films on aluminum substrates.
Ultra-Microhardness Tests on Ion Implanted Metal Surfaces
Authors: Pethica J.B. , Oliver W.C. 
Published: March 2011

ABSTRACTTo measure the mechanical properties of ion implanted layers special microhardness tests with penetration depths less than 100 nm have been made. The results show that increases in hardness of up to 50 % may occur in a number of metals as a result of nitrogen ion implantation. Considerable carbon is also present in the implanted surfaces and when in the form of a distinct layer, may give an apparent softening of surfaces at high doses.
Sem and Aes Analysis of Ion Implanted Graphite
Authors: Shayegan M. , Elman B.S. , Mazurek H. , Dresselhaus M.S. , Dresselhaus G. 
Published: March 2011

ABSTRACTIon-implantation of graphite is characterized with respect to lattice damage and the distribution of implanted ions. Both the depth profile of the implanted ions and of the lattice damage are shown to follow the models previously developed for ion-implanted semiconductors. Auger electron spectroscopy (AES) is used to monitor the implantation profile. The surface damage is examined by scanning electron microscopy (SEM) while microcrystalline regions in an amorphous background are observed by scanning transmission electron microscopy (STEM).
Ion Beam Mixing of Sb Layers in Al
Authors: Paine Bruce M. , Nicolet Marc-A. , Banwell Thomas C. 
Published: March 2011

ABSTRACTWe have studied the atomic mixing of Sb layers in Al induced by irradiation with 110 keV Ar ions. Samples with 10 and 230 Å Sb layers sandwiched in Al were made by sequential vacuum deposition and analyzed by backscattering spectrometry. The mixing was characterized by finding the increase, σ2, in the variance of the Sb signal in the backscattering spectra. For 10 Å layers irradiated at 90 and 270 K, the profiles are Gaussian and σ2 increases linearly with dose of implanted Ar ions. The mixing is essentially independent of temperature up to ∼ 290 K, where it increases sharply. For 230 Å layers irradiated at 90 and 270 K, the profiles are approximately Gaussian but develop a flat top as the Al:Sb ratio approaches 1:1. At 90 K σ2 increases monotonically with dose up to 3.6 × 1016 Ar/cm2, but at 270 K it develops a plateau at a dose of ∼ 2.2 × 1016 Ar/cm2, which corresponds to Al:Sb = 1:1. No such plateau is observed at 90 K. Again, the mixing showed very little variation with temperature between 90 and 270 K, but rose abruptly above 300 K.
The Meyer-Neldel Relation and Analysis of the Field-Effect In Amorphous Silicon
Authors: Schropp Ruud E. I. , Snijder Jan , Verwey Jan F. 
Published: March 2011

ABSTRACTThe dependence of the conductance prefactor on the activation energy in accordance with the Meyer-Neldel relation has been observed in a-Si:H, by measuring the temperature dependence of the field-effect in a-Si:H thin-film transistors. The Meyer-Neldel rule is for the first time properly taken into account in the analysis of the field-effect, thereby considering the non-uniform shift of the Fermi-level as induced by the gate bias. The analysis also yields the flat-band voltage, which is an important parameter in the density of states evaluation. The density of states is shown to be considerably overestimated in conventional analysis.
Fluorine Incorporation and Annealing Properties of a-Si, Ge:H, F Alloys Studied by Elastic Proton Scattering and Ir Absorption
Authors: Schwarz R. , Okada Y. , Chou S. F. , Kolodzey J. , Slobodin D. , Wagner S. 
Published: March 2011

ABSTRACTWe report precise measurements of the fluorine content cF in amorphous silicongermanium alloy films (a-Si, Ge:H, F). The films were prepared by r.f. or d.c. glow discharge deposition. The fluorine concentration was measured by elastic scattering (NES) of 12 MeV protons and by IR absorption spectroscopy. Films measured by NES serve as calibration standards for other measurement techniques. Using the NES measurements, we update the published calibration coefficient for IR measurements for cF ranging from 0 to 10 at.%. The annealing properties up to 700°C of a-Si, Ge:H, F were studied by the gas evolution technique and by IR spectroscopy. Above 300°C the Si-F absorption peak decreases while the peak due to SiF4 molecules increases. No significant loss of F from the alloy films seems to occur up to 700°C.
Internal Photoemission Measurements for the Determination of Schottky Barrier Height on a-Si, Ge:H, F Alloys
Authors: Chu V. , Aljishi S. , Slobodin D. , Wagner S. 
Published: March 2011

ABSTRACTWe report measurements of internal photoemission from Ni, Au, and Pd contacts into a-Si, Ge:H, F alloys. The alloys were prepared by d.c. glow discharge decomposition of either SiF4 or SiH4 and GeF4, and H2. The sharp exponential drop in subgap absorption in these alloys, measured by the Constant Photocurrent Method (CPM), allows the determination of barrier heights using internal photoemission thresholds. The barrier heights of Ni, Au and Pd contacts are presented as a function of alloy composition. We find Ni has the lowest barrier heights while Au shows the highest barrier heights over the entire range of Eopt. We also find that for the Ni and Au contacts, ΦB varies as 1/2 the optical gap. In the case of Pd, ΦB shows a dependence of 1/3 the optical gap. We observed an increase in ΦB for Pd contacts when etched with a diluted HF solution prior to metallization. A similar increase in ΦD was not observed for the Au and Ni contacts.
Hydrogenated Amorphous Silicon Thin-Film Deposition by Direct Photo-Enhanced Decomposition of Silane Using an Internal Hydrogen Discharge Lamp.
Authors: Robertson P. A. , Milne W. I. 
Published: March 2011

ABSTRACTHydrogenated amorphous silicon (a-Si:H) thin films have been deposited from silane using a novel photo-enhanced decomposition technique. The system comprises a hydrogen discharge lamp contained within the reaction vessel; this unified approach allows high energy photon excitation of the silane molecules without absorption by window materials or the need for mercury sensitisation. The film growth rates (exceeding 4 Å/s) and material properties obtained are comparable to those of films produced by plasma-enhanced CVD techniques. The reduction of energetic charged particles in the film growth region should enable the fabrication of cleaner semiconductor/insulator interfaces in thin-film transistors.
Properties and Local Structure of Plasma-Deposited Amorphous Silicon-Carbon Alloys
Authors: Mohr W. C. , Tsai C. C. , Street R. A. 
Published: March 2011

ABSTRACTHydrogenated amorphous silicon-carbon alloy films were plasma-deposited from metnane and silane, varying gas ratio, R.F. power and substrate temperature. Carbon addition increases the optical gap, but also raises the dangling bond density while decreasing conductivity. Low C alloys can be gas-phase doped both p and n type. In the IR spectra the various Si-C stretching modes observed between 650 and 780 cm-1 are explained by back bonding variations. A tentative method of assigning this shift to back bonding of C to the Si is given. A distribution of modes is observed for all alloys, with each mode appearing even at 2% C. The distribution is sensitive to substrate temperature, but is stable after vacuum annealing to 400°C.
In Situ Studies of the Microstructure of a Si:H Surfaces and Interfaces
Authors: Collins R. W. 
Published: March 2011

ABSTRACTUsing in situ ellipsometry with a 3.4 eV probe, we have characterized the initial nucleation and interface structure of a-Si:H and μc-Si deposited on oxide/c-Si substrates. Multilayered a-Si:H/a-SiNx:H structures have also been studied and non-uniformities have been modeled. In none of the reported data could we model thin film growth with thickness independent optical functions. Once a film becomes opaque, ellipsometry is very sensitive to changes in the thickness of surface roughness layers. As a result, roughness on single and multilayered a-Si:H films has been studied as well as the renucleation that results from stopping and then restarting the a-Si:H growth plasma.
Hydrogenated Amorphous Silicon Alloys Prepared by CVD of Higher Silanes
Authors: Akhtar Masud , Weaklie Herbert A. 
Published: March 2011

ABSTRACTHydrogenated amorphous silicon may be deposited at relatively low temperatures, where the density of defects may be expected to be low, by the chemical vapor deposition (CVD) of higher silanes. This method is an attractive alternative to plasma deposition techniques. We describe here the preparation of a-Si:H and related alloys incorporating carbon, germanium, and fluorine. a-Si:H films were deposited on heated substrates in the range 365°C-445°C by CVD of Si2H6 and Si3H8. The optical gap (Eg) ranged from 1.4 to 1.7 eV and the properties of films deposited from either Si2 H6 or Si3 H8 were quite similar. Wide band gap (Eg=2 eV) alloys of a-SiC:H doped with boron were prepared by CVD of disilane, methyl silane, and diborane. We also prepared variable band gap a-SiC:H alloys by substituting F2C= CFH for methylsilane, and these films were found to have approximately 1–2% fluorine incorporated. The dark conductivity of the boron doped a-SiC:H alloys dep~sited from either carbon source ranged from ix10-7 to 6x10-7 (ohm-cm)-1. We also prepared low band aap alloys of Si and Ge by CVD of trisilane and germane. The band gap of a film containing 20% Ge was 1.5 eV; however, the photoconductivity of the film was relatively low.
Recent Advances in A-Si Solar Cell Technology in Japan
Authors: Kuwano Y. 
Published: March 2011

ABSTRACTRecent advances in a-Si solar cells in Japan are reviewed. Improvements in single-junction and multi-junction solar cells are described in three main points, namely, fabrication methods, materials, and cell structures. Recently, a conversion efficiency of 11.7% was obtained for a single-junction structure. For an a-Si/poly-Si stacked structure and an a-Si/(CdS/CdTe) 4 terminal structure, conversion efficiencies of more than 13% were achieved.Then recent advances in the prevention of the light induced degradation of a-Si solar cells is mentioned. Several methods which can improve the a-Si solar cell stability are described.Finally, the present status of the industrialization of a-Si solar cells and some of the latest applications are described together with their propects.
Status of Fluorinated Amorphous Silicon Alloy Multi-Junction Solar Cells
Authors: Yang Jeffrey , Ross Robert , Mohr Ralph , Fournier Jeffrey P. 
Published: March 2011

ABSTRACTWe present in this paper updated solar cell performance data on fluorinated amorphous silicon and fluorinated amorphous silicon-germanium alloys. We have achieved a 9.7% conversion efficiency for a singlejunction device using a-Si:Ge:F:H alloy having an optical band gap of 1.5 eV. We have also achieved 12.5% and 13.0% efficiencies, respectively, for dual-band-gap tandem and triple devices using a-Si:F:H and a-Si:Ge:F:H alloys. These represent the highest values reported to date for their respective configurations. Multi-junction solar cells exhibit excellent stability not only in terms of light-induced effect but also in terms of prolonged heating at elevated temperatures.
Effect of Superlattice Doped Layers on the Performance of a-Si:H P-I-N Solar Cells
Authors: Arya Rajeewa R. , Catalano Anthony , O'dowd James 
Published: March 2011

ABSTRACTSuperlattice doped layers of the type ABABAB … have been prepared where A is the wide bandgap a-Si:C:H doped layer and B is the narrow bandgap a-Si:C:H or a-Si:H doped layer. The bandgaps of the individual layers were modulated by changing the gas phase composition of methane during the plasma deposition. By varying the structure of the films, superlattice p-layers with resistivities in the range of 106 - 107 ohm-cm with optical bandgaps of 2.0 - 2.4 eV, and activation energies of 0.35 - 0.48 eV and superlattice n-layers with resistivities in the range of 104 - 105 ohm-cm with optical bandgaps of 1.86 - 2.03 eV and activation energies of 0.38 - 0.47 eV have been obtained.P-I-N solar cells have been prepared with both p and n layers comprised of superlattice structures. Conversion efficiencies as high as 10.86% have been achieved under simulated AM1.5 Global conditions. Measurements reveal a marked improvement in both built-in voltage and carrier collection length.
The Effects of Dopant Profiles on the Device Parapmetrs of p-i-n and n-i-p a-Si Solar Cells
Authors: Jeffrey F. R. , Vernstrom G. D. , Weber M. , Epstein K. A. 
Published: March 2011

ABSTRACTwe have studied the effects of intrinsic layer dopant profiles on the open circuit voltage and fill factor of p-i-n and n-i-p solar cells. Data is presented showing that boron profiling into the i-layer is responsible for the commonly observed difference in open circuit voltage between p-i-n and n-i-p devices. As only a shallow profile is required to produce this effect, it is proposed that the lower Voc samples are being limited by surface recombination at the p/i interface and that the boron profile reduces this recombination current. The fill factor for devices illuminated through the n+ layer is shown to be very sensitive to the depth of a boron profile, yet not so sensitive to the profile concentration. A maximum occurs for a profile penetrating slightly more than half way through the cell. Spectral response data clearly shows a shifting of high collection from the back to the front of the cell.
Transient Behavior of Phoioxcurrent in a-Si :H Solar Cells
Authors: Cuang Gad , Qing Miao , Baocheng Cao , Xiaoqin Guo , Guocai Dai 
Published: March 2011

AbstrctTime-dependent photocurrent response by the monochromatic square-pulsed excitation light of different wavelenths has been studied on the PIN a-Si:H solar cells. The experiments show that the shape of the photocurrent transient is distinctly changed by varying the photon energy of the excitation light and the applied biases. Our results can be explained by the relaxation of space charge distribution in the i-layer.