Showing papers on "Nitride published in 2004"

Photochemical Activity of Nitrogen-Doped Rutile TiO2(110) in Visible Light

Abstract: TiO2(110) single crystals, doped with nitrogen via an NH3 treatment at 870 K, have been found to exhibit photoactivity at photon energies down to 2.4 eV, which is 0.6 eV below the band-gap energy for rutile TiO2. The active dopant state of the interstitial nitrogen that is responsible for this effect exhibits an N (1s) binding energy of 399.6 eV and is due to a form of nitrogen that is probably bound to hydrogen, which differs from the substitutional nitride state with an N (1s) binding energy of 396.7 eV. Optical absorption measurements also show enhanced absorption down to 2.4 eV for the NH3-treated TiO2(110). A co-doping effect between nitrogen and hydrogen is postulated to be responsible for the enhanced photoactivity of nitrogen-doped TiO2 materials in the range of visible light.

Synthesis and characterization of a binary noble metal nitride

Abstract: There has been considerable interest in the synthesis of new nitrides because of their technological and fundamental importance. Although numerous metals react with nitrogen there are no known binary nitrides of the noble metals. We report the discovery and characterization of platinum nitride (PtN), the first binary nitride of the noble metals group. This compound can be formed above 45-50 GPa and temperatures exceeding 2,000 K, and is stable after quenching to room pressure and temperature. It is characterized by a very high Raman-scattering cross-section with easily observed second- and third-order Raman bands. Synchrotron X-ray diffraction shows that the new phase is cubic with a remarkably high bulk modulus of 372(+/-5) GPa.

Nanostructured nitride films of multi-element high-entropy alloys by reactive DC sputtering

Abstract: Multi-element high-entropy alloys are alloy systems with n (5≤n≤13) principal elements each having an atomic percentage no more than 35%. Using the alloys of Fe-Co-Ni-Cr-Cu-Al-Mn and Fe-Co-Ni-Cr-Cu-Al0.5 as target material in reactive sputtering, nitride films were deposited. The hysteresis curves of the two high-entropy alloys in reactive sputtering are quite different in comparison to those of elements or simple alloys. The film deposition rate decreased with increasing nitrogen gas flow and the highest film thickness was in excess of 2.5 μm. The alloy films are crystalline with structures of a mixed FCC and BCC or simple FCC solid solution, while the crystallinity of the nitride films decreased and approached amorphous with increasing nitrogen gas flow. The composition of the alloy films was similar to their original targets, and the nitrogen content of the nitride films increased with increasing nitrogen flow, to a maximum of 41.1 at.% nitrogen. The values of resistivity of the two alloy films were 108 and 135 μΩ cm, respectively, and those of their nitride films increased with nitrogen flow, to a factor of 3 of the alloy film. The rms surface roughness measured by AFM decreased significantly from 9 to 13 nm for the alloy films to only 1–3 nm for the nitride films. Values of hardness are about 4 GPa for alloy films and about 11 GPa for nitride films. The growth rate, the resistivity, and the hardness of the resulting nitride films were not affected too much by substrate bias due to the amorphous nature of the nitride films.

A Tetrahedrally Coordinated L3Fe−Nx Platform that Accommodates Terminal Nitride (FeIV⋮N) and Dinitrogen (FeI−N2−FeI) Ligands

Abstract: A tetrahedrally coordinated L3Fe−Nx platform that accommodates both terminal nitride (L3FeIV⋮N) and dinitrogen (L3FeI−N2−FeIL3) functionalities is described. The diamagnetic L3FeIV⋮N species featured has been characterized in solution under ambient conditions by multinuclear NMR (1H, 31P, and 15N) and infrared spectroscopy. The electronic structure of the title complex has also been explored using DFT. The terminal nitride complex oxidatively couples to generate the previously reported L3FeI−N2−FeIL3 species. This reaction constitutes a six-electron transformation mediated by two iron centers. Reductive protonation of the nitride complex releases NH3 as a significant reaction product.

Nitride based semiconductor device

Abstract: The present invention provides a nitride semiconductor device comprising an active layer of a quantum well structure, a first conductive clad layer and a second conductive clad layer. The first conductive clad layer is made of the quaternary nitride semiconductor InAlGaN having a lattice constant equal to or larger than that of the active layer and includes a first nitride semiconductor layer having an energy band gap larger than that of the active layer, a second nitride semiconductor layer having an energy band gap smaller than that of the first nitride semiconductor layer and a third nitride semiconductor layer having an energy band gap larger than that of the second nitride semiconductor layer, sequentially closer to the active layer.

Systems and methods of forming refractory metal nitride layers using disilazanes

Abstract: A method of forming (and apparatus for forming) refractory metal nitride layers (including silicon nitride layers), such as a tantalum (silicon) nitride barrier layer, on a substrate by using a vapor deposition process with a refractory metal precursor compound, a disilazane, and an optional silicon precursor compound.

Thickness dependence of the properties of highly c-axis textured AlN thin films

Abstract: The influence of film thickness on the material properties of aluminum nitride (AlN) thin films deposited on Pt(111) electrodes has been investigated experimentally by means of x-ray diffraction, dielectric response, atomic force microscopy, interferometry measurement of effective d33, and residual stress measurement. The thickness was varied between 35 nm and 2 μm. Full width at mid-height of the rocking curve decreased from 2.60 to 1.14°, rms roughness increased from 3.8 to 18.6 A, the effective d33, namely d33,f, from 2.75 to 5.15 pm/V. The permittivity eAlN was stable at 10.2, whereas the dielectric losses decreased from 1% to 0.1%. The breakdown electric field under dc voltages varied between 4.0 and 5.5 MV/cm.

Atomic Layer Deposition of Insulating Hafnium and Zirconium Nitrides

Abstract: Highly uniform, smooth, and conformal coatings of higher nitrides of hafnium and zirconium were produced by atomic layer deposition from homoleptic tetrakis(dialkylamido)metal(IV) complexes and ammonia at low substrate temperatures (150−250 °C) The precursor vapors were alternately pulsed into a heated reactor, yielding 115−120 A of metal nitride film for every cycle Successful depositions were carried out on silicon, glass, quartz, and glassy carbon All of the films showed good adhesion to the substrates, were chemically resistant, and did not oxidize over time The films were characterized by Rutherford backscattering spectrometry and ellipsometry These films were amorphous as deposited, as shown by X-ray diffraction and transmission electron microscopy Step coverage is 100% in vias with an aspect ratio of 40:1, as determined by scanning electron microscopy Evidence is given for the existence of nitrogen-rich phases with compositions Hf3N4 and Zr3N4 These two materials are insulating, transpare

Hydrogen adsorption on boron nitride nanotubes: A path to room-temperature hydrogen storage

Abstract: The adsorption of molecular hydrogen on boron nitride nanotubes is studied with the use of the pseudopotential density functional method. The binding energy and distance of adsorbed hydrogen is particularly calculated. It is found that the binding energy of hydrogen on boron nitride nanotubes is increased by as much as $40%$ compared to that on carbon nanotubes, which is attributed to heteropolar bonding in boron nitride. The effect of substitutional doping and structural defects on hydrogen adsorption is also studied and we find a substantial enhancement of the binding energy from that on perfect boron nitride. The current study demonstrates a pathway to the finding of proper media that can hold hydrogen at ambient conditions through physisorption.

Atomic layer deposition of barrier materials

Abstract: Methods for processing substrate to deposit barrier layers of one or more material layers by atomic layer deposition are provided. In one aspect, a method is provided for processing a substrate including depositing a metal nitride barrier layer on at least a portion of a substrate surface by alternately introducing one or more pulses of a metal containing compound and one or more pulses of a nitrogen containing compound and depositing a metal barrier layer on at least a portion of the metal nitride barrier layer by alternately introducing one or more pulses of a metal containing compound and one or more pulses of a reductant. A soak process may be performed on the substrate surface before deposition of the metal nitride barrier layer and/or metal barrier layer.

Electrical conductivity and gas sensing properties of MoO31

Abstract: Electrical conductivity and gas sensing properties of MoO3 are investigated. The electrical conductivity is found to be independent of oxygen partial pressure in the temperature range 510–773 K. Two distinct conduction processes were identified from the conductivity experiments carried out under ambient air, moist oxygen, and moist argon. The conductivity in the low temperature range (510–578 K) are attributed to species arising from the reversibly inserted water molecules into MoO3 lattice. The conduction process in the high temperature region (578–773 K) are attributed to the non-stoichiometry existing in the sample due to the presence of Mo5+ ions which was confirmed by EPR and XPS investigations. Sensing characteristics of MoO3 towards NH3, H2, and LPG were studied. Experiments showed that the ammonia sensing mechanism of MoO3 involved the formation of molybdenum suboxides and nitride.

Integration of ALD tantalum nitride for copper metallization

Abstract: A method and apparatus for depositing a tantalum nitride barrier layer is provided for use in an integrated processing tool. The tantalum nitride is deposited by atomic layer deposition. The tantalum nitride is removed from the bottom of features in dielectric layers to reveal the conductive material under the deposited tantalum nitride. Optionally, a tantalum layer may be deposited by physical vapor deposition after the tantalum nitride deposition. Optionally, the tantalum nitride deposition and the tantalum deposition may occur in the same processing chamber.

Evaluation of elastic modulus and hardness of thin films by nanoindentation

Abstract: Simple equations are proposed for determining elastic modulus and hardness properties of thin films on substrates from nanoindentation experiments. An empirical formulation relates the modulus E and hardness H of the film/substrate bilayer to corresponding material properties of the constituent materials via a power-law relation. Geometrical dependence of E and H is wholly contained in the power-law exponents, expressed here as sigmoidal functions of indenter penetration relative to film thickness. The formulation may be inverted to enable deconvolution of film properties from data on the film/substrate bilayers. Berkovich nanoindentation data for dense oxide and nitride films on silicon substrates are used to validate the equations and to demonstrate the film property deconvolution. Additional data for less dense nitride films are used to illustrate the extent to which film properties may depend on the method of fabrication.

Characterisation of porous silicon nitride materials produced with starch

Abstract: Porous silicon nitride is gaining interest for a number of applications including metal–ceramic thermal engineering components, biomaterials and catalyst supports. This paper describes the fabrication of porous silicon nitride ceramic materials using a fugitive additive, corn starch, which allows samples to be produced with different volume fractions of porosity from ∼0 to 0.25. The initial composition consisted of 92 wt.% Si 3 N 4 , 6 wt.% Y 2 O 3 and 2 wt.% Al 2 O 3 . Sintering was carried out at 1800 °C for 2 h under nitrogen. Relative density as a function of the fugitive additive content has been measured. Microstructural analysis reveals a dense matrix of elongated β-Si 3 N 4 grains surrounded by intergranular glass phase and containing large pores and cavities. Pore size, geometry and grain size have been measured for certain compositions. Young's modulus and modulus of rupture have been determined as a function of the volume fraction of porosity. The Young's modulus–porosity relationship has been compared with previous work in the literature and it was found that this dependency is close to that for a model for spherical pores in cubic stacking arrangement.

Dilute Nitride Semiconductors

Abstract: Contents Preface v CHAPTER 1 MBE GROWTH AND CHARACTERIZATION OF LONG WAVELENGTH DILUTE NITRIDE IIIV ALLOYS 1.1. Introduction 1.2. MBE Growth of Dilute IIIV Nitrides 1.3. Dilute Nitride Characterization 1.4. Energy Band and Carrier Transport Properties 1.5. Annealing and NIn Nearest Neighbor Effects 1.6. Summary Acknowledgements References CHAPTER 2 EPITAXIAL GROWTH OF DILUTE NITRIDES BY METAL-ORGANIC VAPOUR PHASE EPITAXY 2.1. Introduction 2.2. Epitaxial Growth of GaInAsN-based Structures 2.3. Long Wavelength GaAs-based Laser Performances 2.4. Conclusion Acknowledgements References CHAPTER 3 THE CHEMICAL BEAM EPITAXY OF DILUTE NITRIDE ALLOY SEMICONDUCTORS 3.1. Introduction to Dilute Nitride Semiconductors 3.2. The Chemical Beam Epitaxial/Metalorganic Molecular Beam Epitaxial (CBE/MOMBE) Growth Process 3.3. CBE of Dilute Nitride Semiconductors 3.4. Fundamental Studies of GaNx As (12 x ) Band Structure 3.5. The Compositions and Properties of Dilute Nitrides Grown by CBE 3.6. CBE-grown Dilute Nitride Devices 3.7. The Potential for Production CBE of Dilute Nitrides 3.8. Conclusions Acknowledgements References CHAPTER 4 MOMBE GROWTH AND CHARACTERIZATION OF IIIV-N COMPOUNDS AND APPLICATION TO InAs QUANTUM DOTS 4.1. Introduction 4.2. MOMBE Growth and Characterization of GaAsN 4.3. Relation of In and N Incorporations in the Growth of GaInNAs 4.4. Growth and Characterization of GaAsNSe New Alloy 4.5. Application of GaAsN to InAs Quantum Dots 4.6. Summary Acknowledgements References CHAPTER 5 RECENT PROGRESS IN DILUTE NITRIDE QUANTUM DOTS 5.1. Self-organized Quantum Dots 5.2. Dilute Nitride Quantum Dots 5.3. Recent Experimental Progress in GaInNAS QDS 5.4. Other Kinds of Dilute Nitride QDs 5.5. Summary and Future Challenges in Dilute Nitride QDs Acknowledgements References CHAPTER 6 PHYSICS OF ISOELECTRONIC DOPANTS IN GaAs 6.1. Nitrogen Isoelectronic Impurities 6.2. The Failure of the Virtual Crystal Approximation 6.3. Prevalent Theoretical Models on Dilute Nitrides 6.4. Electroreflectance Study of GaAsN 6.5. Resonant Raman Scattering Study of Conduction Band States 6.6. Compatibility with other Experimental Results 6.7. A Complementary Alloy: GaAsBi 6.8. Summary 6.9. Conclusion References CHAPTER 7 MEASUREMENT OF CARRIER LOCALIZATION DEGREE, ELECTRON EFFECTIVE MASS, AND EXCITON SIZE IN In x Ga1 2 x As 1 2 y N y Alloys 7.1. Introduction 7.2. Experimental 7.3. Single Carrier Localization in In x Ga1 2 x As 1 2 y N y 7.4. Measurement of the Electron Effective Mass and Exciton Wave function Size 7.5. Conclusions Acknowledgements References CHAPTER 8 PROBING THE UNUSUAL BAND STRUCTURE OF DILUTE Ga(AsN)QUANTUM WELLS BY MAGNETO-TUNNELLING SPECTROSCOPY AND OTHER TECHNIQUES 8.1. Introduction 8.2. Resonant Tunnelling Diodes Based on Dilute Nitrides 8.3. Magneto-Tunnelling Spectroscopy to Probe the Conduction Band Structure of Dilute Nitrides 8.4. Electronic Properties: From the Very Dilute Regime ( , 0.1%) to the Dilute Regime 8.5. Conduction in Dilute Nitrides and

HDP-CVD seasoning process for high power HDP-CVD gapfil to improve particle performance

Abstract: A method of operating a substrate processing chamber that includes, prior to a substrate processing operation, flowing a seasoning gas comprising silane and oxygen into said chamber at a flow ratio of greater than or equal to about 16:1 oxygen to silane to deposit a silicon oxide film over at least one aluminum nitride nozzle exposed to an interior portion of the chamber Also, a substrate processing system that includes a housing, a gas delivery system for introducing a seasoning gas into a vacuum chamber, where the gas delivery system comprises one or more aluminum nitride nozzles exposed to the vacuum chamber, a controller and a memory having a program having instructions for controlling the gas delivery system to flow a seasoning gas that has an oxygen to silane ratio greater than or equal to about 16:1 to deposit a silicon oxide film on the aluminum nitride nozzles

Synthesis and Structure of 2,5,8-Triazido-s-Heptazine: An Energetic and Luminescent Precursor to Nitrogen-Rich Carbon Nitrides

Abstract: Derivatized s-triazine (C3N3) precursors have seen significant recent use in the production of carbon nitride materials. Larger polycyclic molecular precursors, such as those containing an s-heptazine core (C6N7 or tri-s-triazine), may improve stability and order in carbon nitride products. In this Communication, we describe the synthesis and crystal structure of 2,5,8-triazido-s-heptazine (2). Synthesis of 2 was achieved from melon, an oligomeric s-heptazine synthesized by the pyrolysis of NH4SCN. Melon was converted to molecular 2,5,8-trichloro-s-heptazine, which was then transformed to the triazide upon reaction with (CH3)3SiN3. The crystal structure of 2 verifies that the s-heptazine is planar and the azides adopt a pinwheel-like C3h arrangement around the periphery. The s-heptazine core shows pi delocalization in the C-N bonds around the periphery (av. 1.33 A), while the internal planar C-N bonds are longer (1.40 A). The heptazine units pack into parallel, but offset, layered sheets in the crystal. The triazide 2 exhibits photoluminescence at 430 nm and rapidly and exothermically decomposes upon heating at 185 degrees C to produce a tan thermally stable carbon nitride powder with a formula near C3N4.

Methods for the reduction and elimination of particulate contamination with cvd of amorphous carbon

Abstract: A method is provided for forming an amorphous carbon layer, deposited on a dielectric material such as oxide, nitride, silicon carbide, carbon doped oxide, etc., or a metal layer such as tungsten, aluminum or poly-silicon. The method includes the use of chamber seasoning, variable thickness of seasoning film, wider spacing, variable process gas flows, post-deposition purge with inert gas, and post-deposition plasma purge, among others, to make the deposition of an amorphous carbon film at low deposition temperatures possible without any defects or particle contamination.

Fabrication of a carbon nanotube-embedded silicon nitride membrane for studies of nanometer-scale mass transport

Abstract: Membranes consisting of multiwall carbon nanotubes embedded in a silicon nitride matrix were fabricated for fluid mechanics studies on the nanometer scale. Characterization by tracer diffusion and scanning electron microscopy suggests that the membrane is free of large voids. An upper limit to the diffusive flux of D2O of 2.4 × 10-8 mol/m2 s was determined, indicating extremely slow transport through the membranes. By contrast, hydrodynamic calculations of water flow across a nanotube membrane of similar specifications predict a much higher molar flux of 1.91 mol/m2 s, suggesting that the nanotubes used in the membrane have a “bamboo” morphology. The carbon nanotube membranes were then used to make nanoporous silicon nitride membranes, which were fabricated by sacrificial removal of the carbon. Nitrogen flow measurements on these structures give a membrane permeance of 4.7 × 10-4 mol/m2 s Pa at a pore density of 4 × 1010 cm-2. Using a Knudsen diffusion model, the average pore size of this membrane is esti...

Band Gaps of InN and Group III Nitride Alloys

Abstract: We review the fundamental band gaps of wurtzite InN and group III nitride ternary alloys in the light of the recent discovery of the narrow band gap of InN. The results on the composition, temperature and hydrostatic pressure dependence of the band gaps of these alloys are summarized and discussed. The role of the Burstein–Moss shift for the accurate determination of the band gap is emphasized. The impact of the narrow band gap of InN on new device applications of group III nitrides is briefly discussed.

Method to form a contact hole

Abstract: A example method of forming of a contact hole by removing residue and oxide spacer beside a nitride spacer after a CF containing etch. We provide a gate structure with nitride spacers on the sidewalls of the gate. We provide a dielectric layer (oxide) over the substrate and gate structure. We form a contact photoresist pattern over the oxide dielectric layer. We etch the oxide dielectric layer using fluorocarbons (CxFy) to form contact openings and residual spacer. The photoresist is striped. Preferably, a NF 3 and N 2 and H 2 plasma treatment is performed to deposit a byproducts layer over the residual spacer. The byproducts layer and residual spacer are removed preferably using one of the following processes: (1) heat (2) DI rinse or (3) IR or UV radiation.

High‐Temperature Oxidation of Boron Nitride: I, Monolithic Boron Nitride

Abstract: High-temperature oxidation of monolithic boron nitride (BN) is examined at 900–1200°C. Hot-pressed BN and both low- and high-density chemically vapor-deposited BN are studied. The oxidation product is B2O3(l) and the oxidation kinetics are sensitive to crystallographic orientation, porosity, and impurity levels. The B2O3 product also reacts readily with ambient water vapor in the test furnace (ppm levels) to form the volatile species HBO2(g), leading to overall paralinear kinetics. The linear rate constant extracted from these experiments agreed with that predicted from diffusion of HBO2(g) across a static boundary layer.

Method for forming a low thermal budget spacer

Abstract: A method of forming a sidewall spacer on a gate electrode of a metal oxide semiconductor device that includes striking a first plasma to form an oxide layer on a side of the gate electrode, where the first plasma is generated from a oxide gas that includes O3 and bis-(tertiarybutylamine)silane, and striking a second plasma to form a carbon-doped nitride layer on the oxide layer, where the second plasma may be generated from a nitride gas that includes NH3 and the bis-(tertiarybutylamine)silane. The first and second plasmas may be formed using plasma CVD and the bis-(tertiarybutylamine)silane flows uninterrupted between the striking of the first plasma and the striking of the second plasma.

Preparation and characterization of electrochemically deposited carbon nitride films on silicon substrate

Abstract: Carbon nitride films (CNx films) were deposited on Si(100) substrates by the electrolysis of methanol–urea solution at high voltage, atmospheric pressure, and low temperature. The microstructure and morphology of the resulting CNx films were analysed by means of Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectrometry (FTIR), x-ray diffraction (XRD), and atomic force microscopy. The tribological properties of the CNx films were examined on an UMT-2MT friction and wear test rig. The Raman spectrum showed two characteristic bands: a graphite G band and a disordered D band of carbon, which suggested the presence of an amorphous carbon matrix. XPS and FTIR measurements suggested the existence of both single and double carbon-nitride bonds in the film and the hydrogenation of the carbon nitride phase. The XRD spectrum showed various peaks of different d values, which could confirm the existence of the polycrystalline carbon nitride phase. The hydrogenated CNx films were compact and uniform, with a root mean square roughness of about 18 nm. The films showed excellent friction-reduction and wear-resistance, with the friction coefficient in the stable phase being about 0.08. In addition, the growth mechanism of the CNx films in liquid phase electro-deposition was discussed as well. It was assumed that the molecules of CH3OH and CO(NH2)2 were polarized under high electric field, and the CNx film was formed on the substrate through the reaction of the –CH3 and –NH2 groups on the cathode.

Pendeoepitaxial methods of fabricating gallium nitride semiconductor layers on sapphire substrates, and gallium nitride semiconductor structures fabricated thereby

Abstract: More specifically, gallium nitride semiconductor layers may be fabricated by etching an underlying gallium nitride layer on a sapphire substrate, to define at least one post in the underlying gallium nitride layer and at least one trench in the underlying gallium nitride layer. The at least one post includes a gallium nitride top and a gallium nitride sidewall. The at least one trench includes a trench floor. The gallium nitride sidewalls are laterally grown into the at least one trench, to thereby form a gallium nitride semiconductor layer. However, prior to performing the laterally growing step, the sapphire substrate and/or the underlying gallium nitride layer is treated to prevent growth of gallium nitride from the trench floor from interfering with the lateral growth of the gallium nitride sidewalls of the at least one post into the at least one trench. Embodiments of gallium nitride semiconductor structures according to the present invention can include a sapphire substrate and an underlying gallium nitride layer on the sapphire substrate. The underlying gallium nitride layer includes therein at least one post and at least one trench. The at least one post each includes a gallium nitride top and a gallium nitride sidewall. The at least one trench includes a sapphire floor. A lateral gallium nitride layer extends laterally from the gallium nitride sidewall of the at least one post into the at least one trench. In a preferred embodiment, the at least one trench extends into the sapphire substrate such that the at least one post each includes a gallium nitride top, a gallium nitride sidewall and a sapphire sidewall and the at least one trench includes a sapphire floor. The sapphire floor preferably is free of a vertical gallium nitride layer thereon and the sapphire sidewall height to sapphire floor width ratio preferably exceeds about ¼. A mask may be included on the sapphire floor and an aluminum nitride buffer layer also may be included between the sapphire substrate and the underlying gallium nitride layer. A mask also may be included on the gallium nitride top. The mask on the floor and the mask on the top preferably comprise same material.