Showing papers on "Nitride published in 2006"

Pulsed laser deposition of thin films : applications-led growth of functional materials

Abstract: SECTION I. 1. Pulsed Laser Deposition of Complex Materials: Progress Towards Applications (D. Norton). SECTION II. 2. Resonant Infrared Pulsed Laser Ablation and Deposition of Thin Polymer Films (D. Bubb & R. Haglund). 3. Deposition of Polymers and Biomaterials Using the Matrix Assisted Pulsed Laser Eveporation (MAPLE) Process (A. Pique). 4. In situ Diagnostics by High Pressure RHEED during PLD (G. Rijnders & D. Blank). 5. Ultra-fast laser Ablation and Film Deposition (E. Gamaly, et al.). 6. Cross-beam PLD: Metastable Film Structures from Intersecting Plumes (A. Gorbunoff). 7. Combinatorial Pulsed Laser Deposition (I. Takeuchi). 8. Growth Kinetics During Pulsed Laser Deposition (G. Rijnders & D. Blank). 9. Large Area Commercial Pulsed Laser Deposition (J. Greer). SECTION III. 10. Coating Powders for Drug Delivery Systems Using Pulsed Laser Deposition (J. Talton, et al.). 11. Transparent Conducting Oxide Films (H. Kim). 12. ZnO and ZnO-related Compounds (J. Perriere, et al.). 13. Group III Nitride Growth (D. O'Mahony & J. Lunney). 14. Pulsed Laser Deposition of High-Temperature Superconducting Thin Films and Their Applications (B. Schey). 15. DLC: Medical and Mechanical Applications (R. Narayan). 16. Pulsed Laser Deposition of Metals (H. Krebs). SECTION IV. 17. Optical Waveguide Growth and Applications (R. Eason, et al.). 18. Biomaterials: New issues and Breakthroughs for Biomedical Applications (V. Nelea, et al.). 19. Thermoelectric Materials (A. Dauscher & B. Lenoir). 20. Piezoelectrics (F. Cracium & M. Dinescu). 21. Ferroelectric Thin Films for Microwave Device Applications (C. Chen & J. Horwitz). 22. Films for Electrochemical Applications (M. Montenegro & T. Lippert). 23. Pulsed Laser Deposition of Tribological Coatings (A. Voevodin, et al.). SECTION V. 24. Laser Ablation Synthesis of Single-wall Carbon Nanotubes: The SLS Model (A. Gorbunoff & O. Jost). 25. Quasicrystalline Thin Films (P. Willmott).

Strain-induced polarization in wurtzite III-nitride semipolar layers

Abstract: This paper presents growth orientation dependence of the piezoelectric polarization of InxGa1−xN and AlyGa1−yN layers lattice matched to GaN. This topic has become relevant with the advent of growing nitride based devices on semipolar planes [A. Chakraborty et al., Jpn. J. Appl. Phys., Part 2 44, L945 (2005)]. The calculations demonstrate that for strained InxGa1−xN and AlyGa1−yN layers lattice matched to GaN, the piezoelectric polarization becomes zero for nonpolar orientations and also at another point ≈45° tilted from the c plane. The zero crossover has only a very small dependence on the In or Al content of the ternary alloy layer. With the addition of spontaneous polarization, the angle at which the total polarization equals zero increases slightly for InxGa1−xN, but the exact value depends on the In content. For AlyGa1−yN mismatched layers the effect of spontaneous polarization becomes important by increasing the crossover point to ∼70° from c-axis oriented films. These calculations were performed u...

Enhanced thermal conductivity of polymer composites filled with hybrid filler

Abstract: This study aims at investigating package materials based on polymer matrix for microelectronics. The next generation package materials are expected to possess high heat dissipation capability in addition to low coefficient of thermal expansion (CTE) as the accumulated heat from high performance electronic devices should be removed for proper operation. In this study, various inorganic fillers including aluminum nitride (AlN), wollastonite, silicon carbide whisker (SiC) and boron nitride (BN) with different shape and size were used alone or in combination to prepare thermally conductive polymer composites. In case of AlN, titanate coupling agent was used for the surface treatment of fillers. The use of hybrid filler was found to be effective in increasing thermal conductivity of the composite probably due to the enhanced connectivity offered by structuring filler with high aspect ratio in hybrid filler. For given filler loading, the use of larger particle and surface treated filler resulted in composite materials with enhanced thermal conductivity. The surface treatment of filler also allowed producing the composites with lower CTE.

Fast and Reversible Surface Redox Reaction in Nanocrystalline Vanadium Nitride Supercapacitors

Abstract: Supercapacitors have been known for over thirty years but of late are emerging as attractive electrochemical energy-storage and conversion devices for future electrical vehicle application with complementary electrochemical characteristics to rechargeable batteries and fuel cells. Amongst the numerous materials studied to date, various forms of ruthenium oxides are clearly noteworthy, exhibiting superior electrochemical response. Unfortunately, the expensive nature of ruthenium has limited its technological viability. A new class of supercapacitors based on nanocrystalline vanadium nitride is reported here, which can deliver an impressive specific capacitance of 1340 F g when tested at a scan rate of 2 mV s. An even more impressive capacitance of 554 F g is noted at a higher scan rate of 100 mV s. Such a high capacitance, which exceeds that of RuO2·nH2O, is believed to be caused by a series of reversible redox reactions through hydroxy bonding confined to a few atomic layers of vanadium oxide on the surface of the underlying nitride nanocrystals, which exhibit a metallic electronic conductivity (rbulk = 1.67 × 10 6 X m). Such a modification of the nanocrystal surface chemistry may lead to the development of supercapacitors that exhibit very high and stable power densities. Supercapacitors are generally classified into electrical double layer capacitors (EDLCs), which build up electrical charge at the electrode/electrolyte interface as described by the Gouy–Chapman–Stern–Grahame model, and pseudocapacitors, which utilize a redox reaction at the interface at certain potentials. Both rely on the physicochemical changes that occur at the electrode/electrolyte interface. Hence, understanding the surface properties is crucial for achieving high power and energy densities. High-surface-area carbon-based materials are widely studied for EDLCs. On the other hand, crystalline RuO2 [1–3,7] and amorphous RuO2·nH2O [1,4–6] are well-known pseudocapacitors that exhibit a specific capacitance as high as 350 and 720 F g, respectively, due to the redox activity via proton adsorption in an acidic electrolyte. Despite the expensive nature of ruthenium oxide, it has been the focus of intense research since Ru offers a variety of oxidation states (II–IV) while exhibiting good electronic conductivity (rbulk = 2.8 × 10 6 X m). Vanadium also exhibits numerous oxidation states (II–V) similar to that of ruthenium in V2O5·nH2O, but its poor electronic conductivity (rbulk ≈ 1 ∼ 10 X m) renders the oxide unsuitable for use in high-rate electrochemical devices. However, exploiting the good electronic conductivity of the vanadium nitrides combined with the variety of oxidation states exhibited by V in vanadium oxides could lay the foundation for a new class of high-performance supercapacitors. The synthesis of these nanocrystalline vanadium nitrides with controlled surface oxidation (as in the present study) results in a unique class of supercapacitors without much loss in the overall electrical conductivity. Furthermore, the low cost, high molar density (≈6 g cm), and good chemical resistance of the transition metal nitrides render them excellent candidates for the next generation of supercapacitors. Although no detailed studies have been conducted, in the past Thompson and co-workers have explored transition metal nitrides and carbides for supercapacitors with moderate specific capacitances (< 226 F g). Amorphous V2O5·nH2O has also been tested for its supercapacitor response, but despite mixing a large amount of carbon (25 wt.-%) to improve its poor electronic conductivity (see above), the highest specific capacitance reported to date is 350 F g at a scan rate of 5 mV s. In this study, a low-temperature route based on a two-step ammonolysis reaction of VCl4 in anhydrous chloroform is used to synthesize nanocrystalline VN (see Experimental). The nanometer-sized crystals increase the susceptibility for surface oxidation, while the high surface area of the nitrides provides more redox-reaction sites. Such a VCl4/NH3 reaction, although known, tends to be largely influenced by the type of solvent used. X-ray diffraction (XRD) and highresolution transmission electron microscopy (HRTEM) are used to characterize the as-prepared and heat-treated VN nanocrystals. The as-prepared precursor consists of amorphous V(NH2)3Cl and crystalline NH4Cl, which transforms into the rock salt (Fm3m)-structured VN at 400 °C, which is C O M M U N IC A TI O N S

Nitride semiconductor light emitting device

Abstract: A nitride semiconductor light-emitting device has an active layer of a single-quantum well structure or multi-quantum well made of a nitride semiconductor containing indium and gallium. A first p-type clad layer made of a p-type nitride semiconductor containing aluminum and gallium is provided in contact with one surface of the active layer. A second p-type clad layer made of a p-type nitride semiconductor containing aluminum and gallium is provided on the first p-type clad layer. The second p-type clad layer has a larger band gap than that of the first p-type clad layer. An n-type semiconductor layer is provided in contact with the other surface of the active layer.

Piezoelectric Aluminum Nitride Vibrating Contour-Mode MEMS Resonators

Abstract: This paper reports theoretical analysis and experimental results on a new class of rectangular plate and ring-shaped contour-mode piezoelectric aluminum nitride radio-frequency microelectromechanical systems resonators that span a frequency range from 19 to 656 MHz showing high-quality factors in air (Qmax=4300 at 229.9 MHz), low motional resistance (ranging from 50 to 700 Omega), and center frequencies that are lithographically defined. These resonators achieve the lowest value of motional resistance ever reported for contour-mode resonators and combine it with high Q factors, therefore enabling the fabrication of arrays of high-performance microresonators with different frequencies on a single chip. Uncompensated temperature coefficients of frequency of approximately -25 ppm/degC were also recorded for these resonators. Initial discussions on mass loading mechanisms induced by metal electrodes and energy loss phenomenon are provided

Synthesis of novel transition metal nitrides IrN2 and OsN2.

Abstract: Two new transition metal nitrides, IrN2 and OsN2, were synthesized at high pressures and temperatures using laser-heated diamond-anvil cell techniques. Synchrotron x-ray diffraction was used to determine the structures of novel nitrides and the equations of states of both the parent metals as well as the newly synthesized materials. The compounds have bulk moduli comparable with those of the traditional superhard materials. For IrN2, the measured bulk modulus [K0 = 428(12) GPa] is second only to that of diamond (K0 = 440 GPa). Ab initio calculations indicate that both compounds have a metal:nitrogen stoichiometry of 1:2 and that nitrogen intercalates in the lattice of the parent metal in the form of single-bonded N-N units.

Synthesis and Characterization of the Nitrides of Platinum and Iridium

Abstract: Transition metal nitrides are of great technological and fundamental importance because of their strength and durability and because of their useful optical, electronic, and magnetic properties. We have evaluated a recently synthesized platinum nitride (PtN) that was shown to have a large bulk modulus, and we propose a structure that is isostructural with pyrite and has the stoichiometry PtN2. We have also synthesized a recoverable nitride of iridium under nearly the same conditions of pressure and temperature as PtN2. Although it has the same stoichiometry, it exhibits much lower structural symmetry. Preliminary results suggest that the bulk modulus of this material is also very large.

Nitride based semiconductor light emitting diode

Abstract: A nitride-based semiconductor LED includes a substrate; an n-type nitride semiconductor layer formed on the substrate; an active layer and a p-type nitride semiconductor layer that are sequentially formed on a predetermined region of the n-type nitride semiconductor layer; a transparent electrode formed on the p-type nitride semiconductor layer; a p-electrode pad formed on the transparent electrode, the p-electrode pad being spaced from the outer edge line of the p-type nitride semiconductor layer by 50 to 200 μm; and an n-electrode pad formed on the n-type nitride semiconductor layer.

Raman spectroscopy of single-wall boron nitride nanotubes.

Abstract: Single-wall boron nitride nanotubes samples synthesized by laser vaporization of a hexagonal BN target under a nitrogen atmosphere are studied by UV and visible Raman spectroscopy. We show that resonant conditions are necessary for investigating phonon modes of BNNTs. Raman excitation in the UV (229 nm) provides preresonant conditions, allowing the identification of the A1 tangential mode at 1370 cm-1. This is 5 cm-1 higher than the E2g mode in bulk h-BN. Ab initio calculations show that the lower frequency of bulk h-BN with respect to large diameter nanotubes and the single sheet of h-BN is related to a softening of the sp2 bonds in the bulk due to interlayer interaction.

Preparation and characterization of AlCrTaTiZr multi-element nitride coatings

Abstract: Multi-element nitride films of AlCrTaTiZr high-entropy alloy have been prepared in this study by reactive radio-frequency magnetron sputtering The influences of nitrogen flow ratio on the chemical composition, microstructure and mechanical properties of the deposited nitride films have been investigated The AlCrTaTiZr alloy film exhibited an amorphous structure, while a simple face-center-cubic solid-solution structure was observed in the nitride films prepared under different nitrogen flow ratios The multi-element AlCrTaTiZr nitride films exhibited much improved mechanical properties as compared with conventional nitride hard coatings of transition metals

High stress nitride film and method for formation thereof

Abstract: A silicon nitride film is formed on a substrate in a reaction chamber by introducing trisilane and a reactive nitrogen species into the chamber in separate pulses. A carbon precursor gas is also flowed into the chamber during introduction of the trisilane and/or during introduction of the reactive nitrogen species, or in pulses separate from the trisilane and reactive nitrogen species pulses. The carbon is used as a dopant in the silicon nitride film and advantageously allows a high stress silicon nitride film to be formed.

Method to increase the compressive stress of pecvd silicon nitride films

Abstract: Compressive stress in a film of a semiconductor device may be controlled utilizing one or more techniques, employed alone or in combination. A first set of embodiments increase silicon nitride compressive stress by adding hydrogen to the deposition chemistry, and reduce defects in a device fabricated with a high compressive stress silicon nitride film formed in the presence of hydrogen gas. A silicon nitride film may comprise an initiation layer formed in the absence of a hydrogen gas flow, underlying a high stress nitride layer formed in the presence of a hydrogen gas flow. A silicon nitride film formed in accordance with an embodiment of the present invention may exhibit a compressive stress of 2.8 GPa or higher.

Breakthroughs in Improving Crystal Quality of GaN and Invention of the p–n Junction Blue-Light-Emitting Diode

Abstract: Marked improvements in the crystalline quality of GaN enabled the production of GaN-based p–n junction blue-light-emitting and violet-laser diodes. These robust, energetically efficient devices have opened up a new frontier in optoelectronics. A new arena of wide-bandgap semiconductors has been developed due to marked improvements in the crystalline quality of nitrides. In this article, we review breakthroughs in the crystal growth and conductivity control of nitride semiconductors during the development of p–n junction blue-light-emitting devices. Recent progress mainly based on the present authors' work and future prospects of nitride semiconductors are also discussed.

High-pressure chemistry of nitride-based materials

Abstract: Besides temperature at one atmosphere, the applied pressure is another important parameter for influencing and controlling reaction pathways and final reaction products. This is relevant not only for the genesis of natural minerals, but also for synthetic chemical products and technological materials. The present critical review (316 references) highlights recent developments that utilise high pressures and high-temperatures for the synthesis of new materials with unique properties, such as high hardness, or interesting magnetic or optoelectronic features. Novel metal nitrides, oxonitrides as well as the new class of nitride-diazenide compounds, all formed under high-pressure conditions, are highlighted. Pure oxides and carbides are not considered here. Moreover, syntheses under high-pressure conditions require special equipment and preparation techniques, completely different from those used for conventional synthetic approaches at ambient pressure. Therefore, we also summarize the high-pressure techniques used for the synthesis of new materials on a laboratory scale. In particular, our attention is focused on reactive gas pressure devices with pressures between 1.2 and 600 MPa, multi-anvil apparatus at P < 25 GPa and the diamond anvil cell, which allows work at pressures of 100 GPa and higher. For example, some of these techniques have been successfully upgraded to an industrial scale for the synthesis of diamond and cubic boron nitride.

Effect of deposition conditions on mechanical properties of low-temperature PECVD silicon nitride films

Abstract: The effect of deposition conditions on characteristic mechanical properties – elastic modulus and hardness – of low-temperature PECVD silicon nitrides is investigated using nanoindentation. It is found that increase in substrate temperature, increase in plasma power and decrease in chamber gas pressure all result in increases in elastic modulus and hardness. Strong correlations between the mechanical properties and film density are demonstrated. The silicon nitride density in turn is shown to be related to the chemical composition of the films, particularly the silicon/nitrogen ratio.

Aligned AlN Nanorods with Multi-tipped Surfaces—Growth, Field-Emission, and Cathodoluminescence Properties

Abstract: Aluminum nitride, an important member of the group III nitrides with the highest bandgap of about 6.2 eV, has excellent thermal conductivity, good electrical resistance, low dielectric loss, high piezoelectric response, and ideal thermal expansion, matching that of silicon. The interest in field-emission (FE) applications of AlN materials has grown because they exhibit a negative electron affinity. Exhibiting a negative electron affinity means that electrons excited into the conduction band can be freely emitted into vacuum. In addition, high-current emission at a relatively low field is most attractive for FE applications. As a result, significant effort is being devoted to reducing the tip size and increasing the density of the emitting sites by using hierarchical nanostructures. Therefore, the synthesis of AlN nanostructures, such as nanowires, nanotubes, nanocones, nanotips, hierarchical comb-like structures, and nanobelts, with controlled high-aspect-ratio shapes and sizes is an important topic worthy of exploration. The promise that one-dimensional (1D) nanostructures may dramatically improve the desired properties for many applications has stimulated great enthusiasm. For example, FE properties of various AlN nanostructures have been investigated. The turn-on fields of various 1D aluminum nitride nanostructures have been measured, such as nanowires (8.8 Vlm), nanocones (12 Vlm), nanotips (3.1–4.7 V lm), and hierarchical comb-like structures (2.45–3.76 Vlm). On the other hand, reports on the luminescence properties of AlN nanostructures are scarce. The AlN nanocones have been observed to have an emission band centered at 481 nm, referred to as a deeplevel or trap-level state. In the present study, we report the growth of well-aligned AlN nanorods with hairy surfaces by a vapor–solid (VS) process. The well-aligned AlN nanorods with hairy surfaces reported here not only provide a new hierarchical nanostructure, but also serve as a promising candidate for FE emitters because of their low electron affinity and the geometry of the multiple-nanotip surfaces. Compared with previous reports on hierarchal growth of AlN nanostructures, in this communication we report a higher density of smaller nanotips (∼ 3–15 nm) that were radially grown on the surfaces of AlN nanorods. Each nanotip may serve as an ultrasmall emitter. In addition, growing well-aligned AlN nanorods on Si substrates is amenable to current technology for the fabrication of Sibased microelectronics devices. The subsequent characterization of their cathodoluminescence (CL) reveals that these hierarchical AlN nanostructures possess an intense emission peak, further suggesting potential applications in optoelectronic nanodevices. The structure of the as-grown products has been determined by X-ray diffraction (XRD). As shown in Figure 1, all of the diffraction peaks in the XRD pattern can be identified; they correspond to a hexagonal wurtzite-structured AlN crys-

Controlled dissolution of colossal quantities of nitrogen in stainless steel

Abstract: The solubility of nitrogen in austenitic stainless steel was investigated thermogravimetrically by equilibrating thin foils of AISI 304 and AISI 316 in ammonia/hydrogen gas mixtures. Controlled dissolution of colossal amounts of nitrogen under metastable equilibrium conditions was realized, with nitrogen contents as high as corresponding to an occupancy of y N=0.61 of the interstitial sublattice, i.e., about 38 at. pct N. Associated with the dissolution of these unprecedented nitrogen contents in an austenitic matrix a reversible volume expansion of the austenite lattice occurred for y N > 0.17. A simplistic model based on a statistical distribution fo the nitride forming elements over the octahedrons constituting the solid state agrees favorably with the experimental data.

Technique for the growth of planar semi-polar gallium nitride

Abstract: A method for growing planar, semi-polar nitride film on a miscut spinel substrate, in which a large area of the planar, semi-polar nitride film is parallel to the substrate's surface. The planar films and substrates are: (1) {101 1 } gallium nitride (GaN) grown on a {100} spinel substrate miscut in specific directions, (2) { 1013 } gallium nitride (GaN) grown on a {110} spinel substrate, (3) { 1122 } gallium nitride (GaN) grown on a { 1 100 } sapphire substrate, and (4) { 1013 } gallium nitride (GaN) grown on a { 1 1 00 } sapphire substrate.

Nanocrystalline TiN Derived by a Two-Step Halide Approach for Electrochemical Capacitors

Abstract: Titanium nitride (TiN) nanocrystallites exhibiting high specific surface area (∼128 m 2 /g) for electrochemical capacitor application were obtained by a two-step halide approach comprised of a room-temperature TiCl 4 (1)-NH 3 (g) reaction followed by heat-treatment under NH 3 atmosphere. The synthesized nitride powders were agglomerates containing spherical crystallites ∼ 10 nm in diam and exhibit a specific surface area ranging from 128 to 23 m 2 /g depending on the heat-treatment temperature. The specific capacitance evaluated by cyclic voltammetry in 1 M KOH electrolyte ranged from 238 to 24 F/g depending on the heat-treatment temperature and the scan rates employed. Structural characterization was performed using X-ray diffraction, helium pycnometry, N 2 adsorption for specific surface area measurements using the Brunauer-Emmett-Teller method, Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy. Results of these studies are presented and discussed.

Boron nitride nanotubes/polystyrene composites

Abstract: Boron nitride nanotube (BNNT)/polystyrene (PS) composite films were fabricated for the first time using high-quality BNNTs synthesized via a chemical-vapor-deposition method. The composite films exhibited good transparency. Tensile tests indicated that the elastic modulus of the films was increased by ∼21% when a ∼1 wt% soluble BNNT fraction was in use. Dispersion of BNNTs in PS and interfacial interactions between them were investigated using transmission electron microscopy. The film thermal properties, such as stability to oxidation and glass transition temperatures were measured. The experimental results and simple theoretical estimates indicate that BNNTs is a promising additive material for polymeric composites.

Flexible piezoelectric pressure sensors using oriented aluminum nitride thin films prepared on polyethylene terephthalate films

Abstract: We have investigated the high sensitive piezoelectric response of c-axis oriented aluminum nitride (AlN) thin films prepared on polyethylene terephthalate (PET) films. The AlN films were deposited using a radio frequency magnetron sputtering method at temperatures close to room temperature. The c axes of the AlN films were perpendicularly oriented to the PET film surfaces. The sensor consisting of the AlN and PET films is flexible like PET films and the electrical charge is linearly proportional to the stress within a wide range from 0to8.5MPa. The sensor can respond to the frequencies from 0.3 to over 100Hz and measures a clear human pulse wave form by holding the sensor between thumb and middle finger. The resolution of the pulse wave form is comparable to a sphygmomanometer at stress levels of 10kPa. We think that the origin of the high performance of the sensor is the deflection effect, the thin thickness and high elastic modulus of the AlN layer, and the thin thickness and low elastic modulus of the ...

Growth of planar non-polar {1 -1 0 0} m-plane gallium nitride with metalorganic chemical vapor deposition (MOCVD)

Abstract: A method of growing planar non-polar m-plane Ill-Nitride material, such as an m-plane gallium nitride (GaN) epitaxial layer, wherein the Ill-Nitride material is grown on a suitable substrate, such as an m-plane silicon carbide (m-SiC) substrate, using metalorganic chemical vapor deposition (MOCVD). The method includes performing a solvent clean and acid dip of the substrate to remove oxide from the surface, annealing the substrate, growing a nucleation layer such as an aluminum nitride (AlN) on the annealed substrate, and growing the non-polar m-plane Ill-Nitride epitaxial layer on the nucleation layer using MOCVD.

Dislocation-Free m-Plane InGaN/GaN Light-Emitting Diodes on m-Plane GaN Single Crystals

Abstract: m-Plane (10-10) nonpolar InGaN-based light emitting diodes (LEDs) with no threading dislocations or stacking faults have been realized on m-plane GaN single crystals by conventional metal organic vapor phase epitaxy. The crystalline properties of the material, together with the structures of the LED devices, have been observed by scanning transmission electron microscopy. It is shown that dislocation-free nonpolar nitride layers with smooth surfaces can be obtained under growth conditions involving high V/III ratios, which are the optimized growth conditions for c-plane GaN. The peak wavelength of the electroluminescence emission obtained from the finished devices is 435 nm, which is in the blue region. The output power and the calculated external quantum efficiency are 1.79 mW and 3.1%, respectively, at a driving current of 20 mA.

Decreasing the etch rate of silicon nitride by carbon addition

Abstract: Methods for forming silicon nitride hard masks are provided. The silicon nitride hard masks include carbon-doped silicon nitride layers and undoped silicon nitride layers. Carbon-doped silicon nitride layers that are deposited from a mixture comprising a carbon source compound, a silicon source compound, and a nitrogen source in the presence of RF power are provided. Also provided are methods of UV post-treating silicon nitride layers to provide silicon nitride hard masks. The carbon-doped silicon nitride layers and UV post-treated silicon nitride layers have desirable wet etch rates and dry etch rates for hard mask layers.

Light emission from silicon-rich nitride nanostructures

Abstract: Light-emitting Si-rich silicon nitride (SRN) films were fabricated by plasma enhanced chemical vapor deposition followed by low temperature (500–900°C) annealing. The optical properties of SRN films were studied by micro-Raman and photoluminescence spectroscopy and indicate the presence of small Si clusters characterized by broad near-infrared emission, large absorption/emission Stokes shift, and nanosecond recombination. Our results are supported by first-principles simulations indicating that N atoms bonded to the surface of nanometer Si clusters play a crucial role in the emission mechanism of SRN films. Light emission from SRN systems can provide alternative routes towards the fabrication of optically active Si devices.

Steady-State and Transient Electron Transport Within the III–V Nitride Semiconductors, GaN, AlN, and InN: A Review

Abstract: The III–V nitride semiconductors, gallium nitride, aluminum nitride, and indium nitride, have, for some time now, been recognized as promising materials for novel electronic and optoelectronic device applications. As informed device design requires a firm grasp of the material properties of the underlying electronic materials, the electron transport that occurs within these III–V nitride semiconductors has been the focus of considerable study over the years. In an effort to provide some perspective on this rapidly evolving field, in this paper we review analyses of the electron transport within the III–V nitride semiconductors, gallium nitride, aluminum nitride, and indium nitride. In particular, we discuss the evolution of the field, compare and contrast results determined by different researchers, and survey the current literature. In order to narrow the scope of this review, we will primarily focus on the electron transport within bulk wurtzite gallium nitride, aluminum nitride, and indium nitride, for this analysis. Most of our discussion will focus on results obtained from our ensemble semi-classical three-valley Monte Carlo simulations of the electron transport within these materials, our results conforming with state-of-the-art III–V nitride semiconductor orthodoxy. A brief tutorial on the Monte Carlo approach will also be featured. Steady-state and transient electron transport results are presented. We conclude our discussion by presenting some recent developments on the electron transport within these materials.

Ammonothermal Synthesis of III-Nitride Crystals

Abstract: Ammonothermal synthesis of nitrides is reviewed, with an emphasis on gallium and aluminum nitrides due to their important applications as direct wide band gap semiconductors. Since the crystallization process of nitrides involves the formation of some intermediate compounds during ammonothermal synthesis where a mineralizer is used, some ternary amides and ammoniates of aluminum and gallium with alkali metals or halides are also reviewed briefly. The ammonothermal crystallization of GaN and AlN bulk crystals, which is analogous to the hydrothermal growth of oxides, is introduced. Retrograde solubility, mineralizers, pressure−temperature−volume−concentration (PTVC) relations, phase relations, and transport growth of GaN in alkaline solutions are discussed in detail. Recent progress of GaN single-crystal growth by the ammonothermal technique is reported. We have grown GaN bulk single crystals up to 10 mm2 by 1-mm thick. Issues such as ammonia breakdown, impurity incorporation, and scale-up of the ammonother...

Glow discharge nitriding of AISI 316L austenitic stainless steel: Influence of treatment pressure

Abstract: The influence of treatment pressure on the characteristics of the modified surface layers produced by low-temperature d.c. glow discharge nitriding on AISI 316L austenitic stainless steel samples is investigated. Glow discharge nitriding treatments were performed at 703 K for 5 h at working pressures in the range of 1.5–20 hPa. Morphology and microstructure of the untreated and nitrided samples were studied by means of microscopy techniques, energy dispersion spectroscopy and X-ray diffraction analysis; microhardness measurements and corrosion resistance tests were also performed. The nitriding treatments produce a hardened surface layer consisting mainly of the so-called S phase. The presence of nitrides and the thickness of the modified layer depend on the used treatment pressure. When treatments are performed at 2.5 hPa, a fairly large amount of nitrides is observed in the modified layer, while when the nitriding pressure is lower or higher than 2.5 hPa, the nitride amount decreases and the layer becomes thinner. When the treatments are performed at 10 or 20 hPa, only a very small amount of chromium nitride is present as small surface precipitates. Metallographic analysis shows that many slip lines are present both at the surface and in the cross-section of the modified layer, presumably due to high stresses occurring during the formation of the layer. X-ray diffraction analysis of the S phase shows that its diffraction peaks are shifted from those of a perfect f.c.c. lattice; the observed shifts may be explained assuming that the S phase has an f.c.c. structure with a high density of stacking faults. Corrosion resistance tests, performed in 5% NaCl aerated solution with the potentiodynamic method, show that with the used treatment parameters nitriding at a pressure of 10 hPa or higher allows to obtain a significant improvement of the corrosion resistance in respect of the untreated alloy, reducing the anodic currents up to about 4 orders of magnitude.