bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Application of Electronic Oxides for Solar Energy
Authors: Kestner James M. , Chorney Anna , Robbins Joshua J. , Huang Yen-jung , Vincent Tyrone L. , Wolden Colin A. , Woods Lawrence M. 
Published: June 2019

AbstractPlasma-enhanced chemical vapor deposition (PECVD) is being developed as a flexible coating technology for a variety of oxides. In this paper we discuss the synthesis of transparent conducting oxides (TCOs), insulating oxides and electrochromic oxides. Tin oxide was synthesized using mixtures of SnCl4 and O2. By proper control of processing conditions the resistivity of this material may be varied from 10-3 < ρ < 105 Ω-cm. Films of varying resistivity were employed as buffer layers in CdS/CdTe solar cells. Preliminary device results have demonstrated that integration of a tin oxide buffer layer was very beneficial for cell performance. In addition, we demonstrate the PECVD synthesis of WO3 from WF6/O2/H2/Ar mixtures. The plasma process space that yielded adherent, transparent tungsten oxide was established. The deposited films were both amorphous and reversibly electrochromic. High temperature annealing above 400°C converted the films into a polycrystalline state.
PZT and Electrode Enhancements of Mems Based Micro Heat Engine for Power Generation
Authors: Olson A.L. , Eakins L.M. , Olson B.W. , Bahr D.F. , Richards C.D. , Richards R.F. 
Published: June 2019

AbstractThe P3 Micro Heat Engine relies on a thin film PZT based transducer to convert mechanical energy into usable electrical power. In an effort to increase process yield for these were used on sputtered Ti/Pt bottom electrodes to compare roughness, grain size, and diffusion for annealing temperatures between 550 and 700 °C. For an optimized bottom electrode, process yield for various sized top electrodes were then studied for PZT thickness between 0.54 and 1.62 for reducing stress concentrations. Two PZT etching geometries on 2.3 μm thick Si/SiO2 membranes, with 1.5-3.5 mm side-lengths, were examined and one was used to increase the strain at failure by at least 40%. Integrating improvements in process yield and strain at failure, single PZT based MEMS devices capable of generating power of up to 1 mW and in excess of 2 volts have been demonstrated operating at frequencies between 300 and 1,100 Hz.
Low Temperature Growth Mechanism of GaN Crystal by Hydride Vapor Phase Epitaxy
Authors: Liu Hai-Ping , Chen In-Gann , Tsay Jenq-Dar , Liu Wen-Yueh , Guo Yih-Der , Hsu Jung Tsung 
Published: June 2019

AbstractThe low temperature growth of GaN crystal using epitaxy lateral overgrowth (ELO) on SiO2 dot pattern below 900°C by hydride vapor phase epitaxy (HVPE) have been studied. It is observed that the growth rate of GaN hexagonal pyramidal crystals along [1101] direction increases as growth temperature decreases. At low temperature of ∼ 850°C, hexagonal GaN columnar crystals with high index facet at the top can be observed. It is proposed that the surface diffusion length of precursors, such as NH3 and GaCl, decreases at lower temperature that reduces the probability of desorption and increase the lifetime. The condensation of Ga liquid droplets on the GaN surface will change the relative stability of {1101} facet. Therefore, the formation of high index planes such as {2122} facet on the top of hexagonal column along with the formation of stacking fault on the (0001) plane can be observed. A detailed study of the effect of growth temperature on the crystal growth mechanism will be presented.
The Refractive Index and Other Properties of Doped ZnO films
Authors: Cai A. L. , Muth J. F. , Porter H. L. , Kvit A. , Narayan J. 
Published: June 2019

AbstractOrdinary and extraordinary indices of refraction, film thickness and waveguide mode information of zinc oxide, zinc oxide doped with nitrogen and zinc oxide doped with tellurium were measured by using a prism coupling waveguide technique. The films were grown on c-axis sapphire substrates by pulsed laser deposition (PLD). High accuracy waveguide measurements show that the ordinary and extraordinary indices of refraction of ZnO samples change with the introduction of nitrogen or tellurium. The densification of films with annealing could also be tracked with precision refractive index measurement. The crystal structure and the optical properties of the films were also characterized by using x-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and cathodoluminescence (CL).
Influence of Ion Energy on the Reactive Ion Etching Induced Optical Damage of Gallium Nitride
Authors: Liem Suk Ing , Reeves Roger J. 
Published: June 2019

AbstractReactive Ion Etching (RIE) induces defects in semiconductor materials. These defects can serve as local non-radiative recombination centres for electron-hole pairs, affecting the radiative lifetimes and luminescence efficiencies of the semiconductors. Argon (Ar) and sulphur hexafluoride (SF6) gases were used as etching gases to investigate the influence of ion energy on the RIE induced optical damage of Gallium Nitride (GaN). The significant result of etching by Ar and SF6gases was that these etching induce defects, but as the total PL does not greatly change, it appears that this process is not increasing the density of nonradiative centres.
The Investigation of Preferred Orientation Growth of ZnO Films on the Ceramic Substrates
Authors: Chu Sheng-Yuan , Chen Te-Yi , Water Walter , Huang Tung-Yi 
Published: June 2019

AbstractPoly-crystal ZnO films with c-axis (002) orientation have been successfully grown on the lead-based ceramic substrates by r.f. magnetron sputtering technique. The deposited films were characterized as a function of deposition time and argon-oxygen gas flow ratio. Crystalline structures of the films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Highly oriented films with c-axis normal to the substrates can be obtained by depositing under a total pressure of 10mTorr containing 50% argon and 50% oxygen and r.f. power of 70W for 3 hours. The phase velocity, electromechanical coupling coefficient and temperature coefficient of frequency of SAW device with ZnO/IDT/PT-ceramic structure were investigated. It shows that the preferred oriented ZnO film is beneficial for improving the electromechanical coupling coefficient of SAW device.
Abnormal Rectifying Characteristics of a Mg Doped GaN Schottky Diode
Authors: Kim Jae Wook , Cho Byung Kyu , Lee Jhang Woo , Yu Phil W. 
Published: June 2019

AbstractElectrical properties of Ti/Al Schottky junctions formed on p-GaN layers are investigated using Hall, I-V and C-V measurements in the temperature range of 82∼500K. All data exhibit extremely strong low temperature carrier freeze out effects, assured by huge decreases of the Hall concentration, zero-bias capacitance and also diode current level as the temperature decreases below ∼150K. The dramatic decrease of current level at the low temperature range indicates that tunneling plays a more important role for the low temperature conduction and the junction shows ohmic-like I-V characteristics due to large series resistance. The barrier height estimated with the thermionic model varies with a strong temperature dependency from 1.21eV at 500K to 0.24eV at 82K. High frequency equivalent circuit analysis indicates that the corrected capacitance still shows a strong frequency dependency even after compensating the series resistance effect due to the slow response of Mg acceptor state. The transition frequency of the acceptor state, which is proportional to the emission rate of the deep level, is estimated to be 142KHz at room temperature. Low frequency C-V measurements provide a proper doping profile, revealing the ∼15nm thin layer with a high doping spike of ∼8×1018/cm3 near the sample surface and the constantly doped bulk layer with a doping level of ∼1017/cm3.
Electron Injection-Induced Effects in GaN: Physics and Applications
Authors: Chernyak Leonid , Burdett William 
Published: June 2019

AbstractElectron injection into p-type GaN and related compounds leads to a pronounced increase in the minority carrier lifetime. This increase is manifested in a multiple-fold elongation of the minority carrier diffusion length as is evident from the Electron Beam Induced Current (EBIC) measurements in-situ in a Scanning Electron Microscope. Minority carrier transport enhancement as a result of electron injection is consistent with the changes observed in the material's luminescent properties. Based on the activation energy for the electron injection-induced effects, we ascribe this phenomenon to charging of Mg-acceptor related levels. In addition, we demonstrate an impact of electron injection on responsivity of GaN p-i-n photodetectors.
Structural Properties of Free-Standing 50 mm Diameter GaN Wafers with (10

1

0) Orientation Grown on LiAlO2
Authors: Jasinski Jacek , Liliental-Weber Zuzanna , Maruska Herbert-Paul , Chai Bruce H. , Hill David W. , Chou Mitch M. C. , Gallagher John J. , Brown Stephen 
Published: June 2019

Abstract(1010) GaN wafers grown on (100) face of γ-LiAlO2 were studied using transmission electron microscopy. Despite good lattice matching in this heteroepitaxial system, high densities of planar structural defects in the form of stacking faults on the basal plane and networks of boundaries located on prism planes inclined to the layer/substrate interface were present in these GaN layers. In addition, significant numbers of threading dislocations were observed. High-resolution electron microscopy indicates that stacking faults present on the basal plane in these layers are of low-energy intrinsic I1 type. This is consistent with diffraction contrast experiments.
High Quality Sn-Doped In2O3 Films Grown by Pulsed Laser Deposition for Organic Light-Emitting Diodes
Authors: Kim Heungsoo , Horwitz James S. , Hong Kim Woo , Kafafi Zakya H. , Chrisey Douglas B. 
Published: June 2019

AbstractHigh quality Sn-doped In2O3 (ITO) thin films have been grown by pulsed laser deposition (PLD) on glass, flexible polyethylene terephthalate (PET) and single crystal yttria stabilized zirconia (YSZ) substrates for use in organic light emitting diodes (OLEDs). Critical electrode issues for the OLED are related to the optical transparency, electrical resistivity, work function and surface roughness of the ITO film. Our research has focused on improving the properties of the ITO film to increase the efficiency of the OLED. Films were deposited using a KrF excimer laser (248nm, 30 ns FWHM) at fluences of 2 J/cm2 at substrate temperatures ranging from 1 to 100 mTorr. For ITO films (∼ 100 nm thick) deposited at the optimized conditions, a resistivity of 4.1 × 10-4 Ω-cm, 2.2 × 10-4 Ω-cm, 1.8 × 10-4 Ω-cm was observed on PET, glass and YSZ, respectively. The average film transmission in the visible range (400 - 700 nm) was about 90 % and the film surface roughness was about 0.5 nm for the film grown on glass. The Hall mobility and carrier density for ITO films (300 nm thickness) were observed to be in the range of 28 - 34 cm2/V-s and 1.0 - 1.2 × 1021 cm-3, respectively. We have used the ITO films, deposited by PLD on glass, plastic and single crystal YSZ substrates, as an anode contact in OLEDs. The OLED device performance based on PLD ITO anodes is compared with that of the device fabricated on the commercial ITO anode.
Solids Characterization from Hydrothermal Tests with Spent Fuel
Authors: Uziemblo N.H. , Thomas L.E. , Schoenlein L.H. , Mastel B. , Jenson E.D. 
Published: June 2019

AbstractReacted solids from 200°C, 25 MPa tests with spent light water reactor fuel and other component materials of a high-level nuclear waste repository in basalt were analyzed by scanning electron microscopy, X-ray powder diffractometry, transmission electron diffraction, Auger electron spectrome- try, and microautoradiography. The work complements solutions analysis from the same tests conducted in Dickson-type rocking autoclaves for the Basalt Waste Isolation Project. Spent fuel reacted very slowly in fuel/water tests, exhibiting noticeable grain boundary etching and uranium silicate formation only after six months. Particle abrasion in the rocking autoclave produced fuel fines that remained apparently unaltered. In spent fuel tests with basalt or basalt and steel, iron smectite clay formed at the expense of mesostasis phases in the basalt. Low concentrations of β-emitters, probably Cs and Tc released from grain boundaries in the fuel, were incorporated in the clay. Steel corroded very slowly under the low-oxygen conditions of the tests, forming minor amounts of magnetite, hematite and wustite. The sluggishness of spent fuel/water and steel/water reactions is attributed to limited availability of oxygen under the test conditions.
Modelling Porewater Chemistry in Hydrated Portland Cement
Authors: Berner Urs R. 
Published: June 2019

AbstractExtensive employment of concrete is foreseen in radioactive waste repositories. A prerequisite for modelling the interactions between concrete and formation waters is characterisation of the concrete system. Available experimental data from high pressure squeezing of cement pore-water indicate that, besides the high pH due to alkali hydroxide dissolution, cement composition itself influences the solubility determining solid phases. A model which simulates the hydration of Portland cement assuming complete hydration of the main clinker minerals is presented. The model also includes parameters describing the reactions between the cement and blending agents.Comparsion with measured pore-water data generally gives a consistent picture and, as expected, the model gives correct predictions for pure Portland cements. For blended cements, the required additional parameters can, to some extent, be derived from pore-water analysis.
Attenuation of Pu, Am, Cs and Sr Mobility in Concrete
Authors: Jakubick A.T. , Gillham R.W. , Kahl I. , Robin M. 
Published: June 2019

AbstractSorption experiments with 85Sr, 137CS, 239pu and 241Am on four types of concrete (normal density, normal density with fly ash, high density and high density with silica fume) were carried out in a predominantly CaCl2 groundwater, in a predominantly NaCl groundwater and in nitrate solutions. Subsequently, autoradiography was used to identify the sorption pattern on the concrete surfaces. In order to distinguish the effects of chemical sorption from that of variable surface area, the effective surface area was used to derive reactive- surface-related distribution coefficients instead of the geometric- surface-related distribution coefficients.
Standardized Test Methods for Use in Waste Compliance Testing in the Department of Energy'S Waste Acceptance Process
Authors: Mellinger George B. 
Published: June 2019

Summary:Standardized test methods that are currently in use or under development appear to adequately cover most of the testing that may be required to demonstrate compliance with the WAPS. It may be important to complete standardization of those tests that are under development, and to develop additional standardized tests for those specifications for which no standardized tests exist. A significant amount of work would be involved in this effort. Therefore, before this effort is undertaken, DOE must decide whether there is a need for a set of standardized test methods that would receive an “official approval” for use in waste compliance testing. If a set of approved tests is needed, DOE would need to determine what types of tests to include in the “approved list”, who should develop these tests, and which organizations should review and approve the test methods. Test method review and approval might be accomplished through the use of the Materials Review Board (MRB), an organization that was created by DOE for the purpose of reviewing and approving key test methods and data related to the repository licensing process. Alternatively, other means of standardizing these tests might be considered, such as processing the tests through the American Society for Testing and Materials for publication as ASTM standards.If a set of approved tests is adopted, producers would not be required to use these tests; however, if a producer wished to propose other tests for compliance testing, it would be reasonable to require that such test procedures undergo a review/approval process similar to that which the officially approved tests had undergone. Once approved, these alternate procedures could be used for compliance testing.
Hydrogen Speciation in Hydrated Layers on Nuclear Waste Glass
Authors: Aines Roger D. , Weed Homer C. , Bates John K. 
Published: June 2019

AbstractThe hydration of an outer layer on nuclear waste glasses is known to occur during leaching, but the actual speciation of hydrogen (as water or hydroxyl groups) in these layers has not been determined. As part of the Nevada Nuclear Waste Storage Investigations Project, we have used infrared spectroscopy to determine hydrogen speciations in three nuclear waste glass compositions (SRL-131 & 165, and PNL 76-68), which were leached at 90°C (all glasses) or hydrated in a vapor-saturated atmosphere at 202°C (SRL-131 only). Hydroxyl groups were found in the surface layers of all the glasses. In addition, molecular water was found in the surface of SRL-131 and PNL 76-68 glasses that had been leached for several months in deionized water, and in the vapor-hydrated sample. The water/hydroxyl ratio increases with increasing reaction time; molecular water makes up most of the hydrogen in the thick reaction layers on vapor-phase hydrated glass while only hydroxyl occurs in the least reacted samples. Using the known molar absorptivities of water and hydroxyl in silica-rich glass the vapor-phase layer contained 4.8 moles/liter of molecular water, and 0.6 moles water in the form hydroxyl. A 15 micrometer layer on SRL-131 glass formed by leaching at 90°C contained a total of 4.9 moles/liter of water, 2/3 of which was as hydroxyl. The unreacted bulk glass contains about 0.018 moles/liter water, all as hydroxyl.The amount of hydrogen added to the SRL-131 glass was about 70% of the original Na + Li content, not the 300% that would result from alkali-hydronium ion (H30+) interdiffusion. If all the hydrogen is then assumed to be added as the result of alkali-H+ interdiffusion, the molecular water observed may have formed from condensation of the original hydroxyl groups according to:20H = H20 molecular + 00where 00 refers to a bridging oxygen, and OH refers to a hydroxyl group attached to a silicate polymer. The hydrated layer on the nuclear waste glasses appears to be of relatively low water content (4 to 7% by weight) and is not substantially hydroxylated. Thus, these layers do not have many of the properties associated with “gel” layers.
Natural Annealing of Alpha-Recoil Damage in Metamict Minerals of the Thorite Group
Authors: Eyal Y. , Lumpkin G. R. , Ewing R. C. 
Published: June 2019

AbstractMinerals of the thorite (ThSiO4) mineral group have been leached as fine powders in bicarbonate-carbonate solutions for time periods up to 288 days.The radioactivities of the solutions were measured for 238U, 234U, 232Th, 230Th and 228Th by alpha spectrometry, preceded by chemical separation and purification of U and Th. The results confirm the preservation of disordered regions of higher chemical reactivity in an already fully-damaged aperiodic structure. The damage is most evident for the short-lived nuclide 228Th and to a much lesser extent for the long-lived nuclide 234U because the alpha-recoil tracks anneal with time. The calculated mean life of an alpha-recoil track in these metamict thorium silicates is approximately 1,500 to 6,000 years. This study demonstrates that alpha-decay products are selectively leached from damaged, aperiodic materials, but the damage is subject to low-temperature annealing over relatively short periods of time.
Environmental Effects on Crack Characteristics for OSG Materials
Authors: Jacques Jeannette M. , Tsui Ting Y. , McKerrow Andrew J. , Kraft Robert 
Published: June 2019

AbstractTo improve capacitance delay performance of the advanced back-end-of-line (BEOL) structures, low dielectric constant organosilicate glass (OSG) has emerged as the predominant choice for intermetal insulator. The material has a characteristic tensile residual stress and low fracture toughness. A potential failure mechanism for this class of low-k dielectric films is catastrophic fracture due to channel cracking. During fabrication, channel cracks can also form in a time-dependent manner due to exposure to a particular environmental condition, commonly known as stress-corrosion cracking. Within this work, the environmental impacts of pressure, ambient, temperature, solution pH, and solvents upon the channel cracking of OSG thin films are characterized. Storage under high vacuum conditions and exposure to flowing dry nitrogen gas can significantly lower crack propagation rates. Cracking rates experience little fluctuation as a function of solution pH; however, exposure to aqueous solutions can increase the growth rate by three orders of magnitude.
Failure Analysis of Thermally Shocked NiCr Films on Mn-Ni-Co Spinel Oxide Substrates
Authors: Jeon Min-Seok , Song Jun-Kwang , Lee Eui-Jong , Kim Yong-Nam , Shin Hyun-Gyu , Lee Hee-Soo 
Published: June 2019

AbstractNiCr films were thermally evaporated on the Mn-Ni-Co-O thick-film substrates. The NiCr/Mn-Ni-Co-O bi-layer systems were tested in a thermal shock chamber with three temperature differences of 150, 175 and 200°C. The systems were considered to have failed when the sheet resistance of NiCr films changed by 30% relative to an initial value. As the cyclic repetition of thermal shock increased, the sheet resistance of NiCr coatings increased. The Coffin-Manson equation was applied to the failure mechanism of cracking of NiCr coatings and the SEM observation of cracks and delamination in NiCr coatings due to thermal cycling agreed well with the failure mechanism.
Nonlinear Transient Finite Element Analysis of the Relaxation Mechanisms in Strained Silicon Grown on SiGe Virtual Substrate
Authors: Karoui F. Sahtout , Karoui A. , Rozgonyi G. 
Published: June 2019

AbstractStrained-silicon (ε -Si) is essential for future nanoscale MOSFET devices. In this paper we report on the dynamics of strain relaxation in Si/SiGe heterostructures, investigated by transient nonlinear finite element analysis. The contribution to total misfit strain is found largely plastic in the graded SiGe layer and the top of the Si substrate, while it is mainly elastic in the strained Si layer and part of the SiGe constant layer. The calculated lattice parameter for the strained Si layer is about 5.47Å for Si0.8Ge0.2 and 5.52 Å for Si0.6Ge0.4. Calculated threading dislocation density was about 5.6x105 cm-2 for x=0.20 and 2.17x106cm-2 for x=0.40. A plastic strain rate of 8.4x10-3s-1 for Si0.8Ge0.2 and 4.1x10-2 s-1 for Si0.6Ge0.4 leading to a density of moving dislocations of ~2.2x109 cm-2 and ~ 1010cm-2, respectively, have been obtained. The elastic strain in the strained-Si layer appeared to increase with increasing the cooling rate, while plastic work was found to be independent of cooling rates.
A Model for Curvature in Film-Substrate System
Authors: Vanamu G. , Khraishi T. A. , Datye A. K. 
Published: June 2019

AbstractGrowth of lattice mismatched films creates bending in the whole structure. There has been great interest in the study of these curvatures in epitaxially-grown materials. An analytical solution for the radius of curvature produced by stresses developed in growing lattice mismatched materials has been obtained. The analyses were based on beam bending theory and strain partitioning theory introduced by our group earlier. The expressions for radius of curvature were obtained for a two-layer heterostructure. The variation of the radius of curvature with the relative thicknesses, relative lattice constants, and relative elastic constants of the layers was determined. The model was verified by applying it to a symmetric tri-laminate structure. The above model can also be extended to determine the curvature for multi-layered heterostructures.