Synthesis of multilayered hexagonal boron nitride microcrystals as a potential hydrogen storage element

Top-down approach has been used to synthesize pure, highly crystalline, multilayered micron size crystals of hexagonal boron nitride (BNMCs) at the top of Silicon substrate at 800 °C by using bulk boron nitride powder as a precursor. The synthesized crystals have different interlayers spacing from left to right (0.33 nm, 0.37 nm and 0.35 nm) and at the center (~0.24 nm). The former spacing corresponds to d₍₀₀₂₎ spacing whereas the later corresponds to d₍₀₁₀₎ spacing in h-BN. The sharpness of the peaks in XRD, Raman and FTIR spectrums correspond to highly crystalline nature of BNMCs whereas the locations of the peaks verify the h-BN nature of BNMCs. The B-N bonded BNMCs with larger surface area can be an excellent choice as a hydrogen storage element.     

Characterization of magnetron sputtered carbon nitride films

A set of carbon nitride samples has been prepared by reactive magnetron sputtering. The only parameter varied was the nitrogen partial pressure p_N2. It turns out, however, that p_N2 has noticeable influence on the composition and the structure of the films only below 0.1 Pa. The composition of the bulk of the samples was investigated by elastic recoil detection (ERD), energy dispersive X-ray analysis (EDX), wavelength dispersive X-ray analysis (WDX) and Rutherford backscattering (RBS); although all of them give the same trend, some systematic differences were observed concerning the absolute values. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) measurements revealed that the surface is somewhat depleted in nitrogen. Sputter depth profiling could not be applied due to very strong preferential sputtering of nitrogen. X-ray diffraction (XRD) showed that the films are almost amorphous. Structural information was obtained from Fourier transform infrared spectroscopy (FTIR), EELS, and XPS; it turned out that the films are graphitic or paracyanogen-like with a density of approx. 2 g cm^-3. All of the characterization methods applied are discussed in view of the information they yield on carbon nitride films, and problems of their application to this special type of film.     

The microstructure and properties of energetically deposited carbon nitride films

The intrinsic stress, film density and nitrogen content of carbon nitride (CN_x) films deposited from a filtered cathodic vacuum arc were determined as a function of substrate bias, substrate temperature and nitrogen process pressure. Contour plots of the measurements show the deposition conditions required to produce the main structural forms of CN_x including N-doped tetrahedral amorphous carbon (ta-C:N) and a variety of nitrogen containing graphitic carbons. The film with maximum nitrogen content (~ 30%) was deposited at room temperature with 1.0 mTorr N₂ pressure and using an intermediate bias of − 400 V. Higher nitrogen pressure, higher bias and/or higher temperature promoted layering with substitutional nitrogen bonded into graphite-like sheets. As the deposition temperature exceeded 500 °C, the nitrogen content diminished regardless of nitrogen pressure, showing the meta-stability of the carbon–nitrogen bonding in the films. Hardness and ductility measurements revealed a diverse range of mechanical properties in the films, varying from hard ta-C:N (~ 50 GPa) to softer and highly ductile CN_x which contained tangled graphite-like sheets. Through-film current–voltage characteristics showed that the conductance of the carbon nitride films increased with nitrogen content and substrate bias, consistent with the transition to more graphite-like films.     

High dose N ion implantation effects on surface treated UNCD films

Ion implantation is commonly used to modify the surface or near-surface properties of materials. In this work, plasma treated ultrananocrystalline diamond (UNCD) films were implanted using 100 and 200 keV high dose (10¹⁶ ions/cm²) nitrogen ions and annealed. Detailed studies have been carried out to reveal the structural and chemical states of the surface treated UNCD films before implantation, as-implanted, and after annealing by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron field emission (EFE) measurements. The high dose N ion implantation induced the formation of amorphous phase, which are converted into graphitic phase after annealing, and improved the field emission properties of UNCD films. The improved field emission is attributed to the surface charge transfer doping mechanism.     

Fabrication of highly efficient TiO2/Ag/TiO2 multilayer transparent conducting electrode with N ion implantation for optoelectronic applications

Fabrication of highly conductive and transparent TiO₂/Ag/TiO₂ (referred hereafter as TAT) multilayer films with nitrogen implantation is reported. In the present work, TAT films were fabricated with a total thickness of 100 nm by sputtering on glass substrates at room temperature. The as-deposited films were implanted with 40 keV N ions for different fluences (1×10¹⁴, 5×10¹⁴, 1×10¹⁵, 5×10¹⁵ and 1×10¹⁶ ions/cm²). The objective of this study was to investigate the effect of N⁺ implantation on the optical and electrical properties of TAT multilayer films. X-ray diffraction of TAT films shows an amorphous TiO₂ film with a crystalline peak assigned to Ag (111) diffraction plane. The surface morphology studied by atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM) revealed smooth and uniform top layer of the sandwich structure. The surface roughness of pristine film was 1.7 nm which increases to 2.34 nm on implantation for 1×10¹⁴ ions/cm² fluence. Beyond this fluence, the roughness decreases. The oxide/metal/oxide structure exhibits an average transmittance ~80% for pristine and ~70% for the implanted film at fluence of 1×10¹⁶ ions/cm² in the visible region. The electrical resistivity of the pristine sample was obtained as 2.04×10⁻⁴ Ω cm which is minimized to 9.62×10⁻⁵ Ω cm at highest fluence. Sheet resistance of TAT films decreased from 20.4 to 9.62 Ω/□ with an increase in fluence. Electrical and optical parameters such as carrier concentration, carrier mobility, absorption coefficient, band gap, refractive index and extinction coefficient have been calculated for the pristine and implanted films to assess the performance of films. The TAT multilayer film with fluence of 1×10¹⁶ ions/cm² showed maximum Haacke figure of merit (FOM) of 5.7×10⁻³ Ω⁻¹. X-ray photoelectron spectroscopy (XPS) analysis of N 1s and Ti 2p spectra revealed that substitutional implantation of nitrogen into the TiO₂ lattice added new electronic states just above the valence band which is responsible for the narrowing of band gap resulting in the enhancement in electrical conductivity. This study reports that fabrication of multilayer transparent conducting electrode with nitrogen implantation that exhibits superior electrical and optical properties and hence can be an alternative to indium tin oxide (ITO) for futuristic TCE applications in optoelectronic devices.     

Long-term irradiation effects of visible light on amorphous carbon nitride films

The effect of long-term visible-light irradiation on the photo-induced deformation of amorphous carbon nitride (a-CN_x) films was investigated. a-CN_x films were deposited on SiO₂ substrates (30 × 2 × 0.05 mm³) using reactive radio frequency magnetron sputtering. Deformation of the a-CN_x films was measured using continuous wave (CW) or pulsed monochromatic light with a wavelength of 470 nm. Pulsed light irradiation was applied for a total of 60 min with an on/off pulse period of 60 s, while CW light irradiation was performed for 120, 190, and 759 min with different light intensities so that the total photon flux remained constant. In all cases, the extent of photo-induced deformation of the a-CN_x films before and after irradiation did not change. The chemical bonding states determined from X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy analyses indicated no significant changes after illumination. In addition, electron spin resonance (ESR) spectroscopy measurements indicated that there was no increase in the defect density after illumination. The long-term stability of a-CN_x films is one of the main advantages for their use in light-driven microactuator systems.     

Preparation of ultrathin PZT films by a chemical solution deposition method from a polymeric citrate precursor

Ultrathin PZT film was prepared using a chemical solution deposition method from polymeric citrate precursors. The PZT solution was spin-coated on an amorphous silica layer formed on a Si(1 0 0) substrate. The films were thermally treated from the substrate side with a low heating rate (1°/min) up to 700 °C and finally annealed for 10 h. Ultrathin PZT films without microstructural instability were prepared in spite of high temperature and long annealing time. AFM and HRTEM investigations revealed the formation of a well-developed dense microstructure consisting of spherical crystallites (4–7 nm). Low roughness (2.2 nm) of a ～26 nm thick layer was obtained for a two-layered PZT film. The grazing incidence X-ray diffraction (GIXRD) measurements confirmed the polycrystalline structure of ultrathin PZT films. Also, GIXRD and electron energy dispersive X-ray (EDS) analysis showed that compositional variations were smaller than expected, in spite of the long annealing time.     

Low-temperature fabrication of Ba1−xSrxTiO3 thin films with good dielectric properties on platinized silicon substrates

Ba_0.7Sr_0.3TiO₃ (BST) thin films 500 nm in thickness were prepared on technologically desirable Pt/TiO₂/SiO₂/Si(1 0 0) substrates by ion beam sputtering (IBS) and post-deposition annealing method. The effect of annealing temperature on the structural and dielectric properties of BST thin films was systematically investigated. A sharp transition in their tunable dielectric behaviours was observed in good agreement with the evolution of crystal structure from amorphous to crystalline phase. It was demonstrated that the perovskite phase could crystallize in BST films at a very low temperature, around 450 °C. The lowering of perovskite crystallization temperature in the BST films was explained in terms of the high energetic process nature of IBS technique. A high dielectric tunability of 42% at E (electric field intensity) = 500 kV/cm and a low loss tangent of 0.013 at zero bias were both obtained in the 450 °C-annealed film, thereby resulting in the highest figure-of-merit factor among all the different temperature annealed films. Moreover, the 450 °C-annealed film showed superior leakage current characteristics with a low leakage current density of about 10^?4 A/cm² at E = 800 kV/cm.     

Reaction of palladium thin films with an Si-rich 6H-SiC(0001)(3×3) surface

The reaction of Pd thin films evaporated in ultrahigh vacuum on a clean and Si-rich 6H-SiC(0001)(3×3) surface has been investigated in situ by low-energy electron diffraction (LEED) and photoelectron spectroscopy (UPS and XPS), and ex situ by atomic force microscopy (AFM) and glancing-incidence X-ray diffraction (GIXRD). For studying the interface formation, submonolayer amounts of Pd were sequentially deposited up to ∼20 Å on the substrate maintained at room temperature. This deposit was subsequently annealed to 600–800 °C. At room temperature, Pd starts to react with SiC when the thickness attains ∼2.5 Å, giving an interface Pd₂Si silicide. Under annealing the film is transformed into Pd₂Si islands standing on the SiC (1×1) surface. No extra-structure of C 1s is observed in the two cases; only an energy shift of about 0.25 eV is detected during the metal deposition, which is attributed to a change in the band bending. Further deposition of ∼100 Å of Pd on this annealed surface gives an epitaxial Pd(111) film, despite a lattice mismatch of more than 10% between the metal and the semiconductor. The film is disrupted after annealing at 600–800 °C. The combination of XPS, AFM and GIXRD analyses indicates that the film annealed at 800 °C is discontinuous and formed of sharp epitaxial Pd₂Si islands and graphite which probably surrounds the islands.     

Electrochromic Nb-doped WO3 films: Effects of post annealing

The Nb-doped WO₃ films were deposited by e-beam co-evaporation method using ceramic WO₃ targets and metal Nb slugs. The films were analyzed by glancing incident angle X-ray diffraction (GIAXRD), UV/visible spectrophotometer, electrochemical cyclic voltammetry, X-ray photoelectron spectroscopy (XPS). The as-prepared film is brown and amorphous in structure. The film has low transmission in optical visible region. The XPS results indicate that the as-deposited film is non-stoichiometric. By applying a negative potential, the as-deposited film does not show obvious electrochromic effect. However, the electrochromic properties of Nb-doped WO₃ films are improved by post annealing treatment at 350, 400, and 450 °C in oxygen atmosphere. The Nb-doped WO₃ films transform into crystalline structure and become transparent after post annealing treatment. The energy band gap, optical modulation, and color efficiency increase with annealing temperature.     

Novel amorphous precursor densification to transparent Nd:Y2O3 Ceramics

A novel approach of neodymium ion doped yttrium oxide (Nd:Y₂O₃) amorphous precursor compaction and sintering is being reported for the first time. Precursor of 2 at.% Nd³⁺ doped Y₂O₃ was synthesized by gelation of sol of yttrium and neodymium nitrates with l-alanine at 80 °C for 16 h followed by gel combustion in microwave. A part of microwave precursor was heat treated at 700 °C for 5 h to give the partially crystalline Nd:Y₂O₃ amorphous precursor. Thermogravimetric analysis (TGA) of partially crystalline amorphous precursor of Nd:Y₂O₃ gave 8.5% total weight loss indicating removal of maximum organics. X-Ray diffraction (XRD) showed broad peaks indicating incomplete crystallization of cubic Nd:Y₂O₃. Morphology was found to be close to spherical with particles in size range 17–19 nm by TEM. Another part of microwave precursor on calcination at 1000 °C for 3 h led to formation of fully crystalline Nd:Y₂O₃ with particles in size range of 35–85 nm. Both partially crystalline amorphous precursor and fully crystalline Nd:Y₂O₃ were compacted at 400 MPa by cold isostatic press and sintered at 1750 °C for 10 h under vacuum (10^?5 mbar). The partially crystalline Nd:Y₂O₃ amorphous precursor densified to 99% with 65% transmission at 2500 nm (0.5 mm thickness) compared to 96% densification with 34% transmission for fully crystalline Nd:Y₂O₃ without any sintering aids. Retention of cubic phase purity of Y₂O₃ was observed in both the ceramic pellets post sintering by XRD. Good grain fusion with grain growth to ≤2 μm was observed by scanning electron microscope (SEM) for partially crystalline Nd:Y₂O₃ amorphous precursor. Thus partially crystalline Nd:Y₂O₃ amorphous precursor nanopowders, with homogeneous close to spherical fine particles and high reactivity due to ionic mobility of amorphous phase, led to better densification.     

Nano-carbon nitride synthesis from a bio-molecular target for ion beam sputtering at low temperature

Nano-crystalline carbon nitride has been successfully synthesized at a temperature below 100 °C from an adenine(C₅N₅H₅) target sputtered by an Ar ion beam. Because adenine possesses a ring structure similar to the hypothetical β-C₃N₄ phase, the use of this bio-molecular compound as the target is believed to reduce the energy barrier of carbon-nitride growth. The effect of Ar ion-sputtering voltage on the film growth and the effect of extra-N-atom incorporation on the carbon-nitride film growth are examined in this study. Only a carbon film is formed with an ion energy of 500 V. For the ion-beam energy above 750 V, carbon nitride films are deposited, and there is some hydrogen incorporation in the films. The N/C composition ratio in the films could reach 1:1 and is independent on the ion beam voltage. The nitrogen is bonded with carbon within the films, as determined by the IR and XPS measurements. However, the films deposited at a higher ion voltage could possess some original functional groups of adenine. A strong and broad peak at a d-spacing of 0.32 nm, comparable to the calculated d-spacing of the β-C₃N₄(110), is observed in the XRD spectra of the carbon nitride films. The TEM results indicated that the film contained nano-crystalline grains. Several d values are also in good agreement with those of adenine and the calculated values of β-C₃N₄. The C/N ratios of the films are still kept at almost 1:1 with N atoms added during deposition. The XRD spectra and IR spectra of these films are all similar to the film deposited without nitrogen source.     

Thermal stability and surface modifications of detonation diamond nanoparticles studied with X-ray photoelectron spectroscopy

Detonation nanodiamond (ND) particles were dispersed on silicon nitride (SiN_x) coated sc-Si substrates by spin-coating technique. Their surface density was in the 10¹⁰–10¹¹ cm^?2 range. Thermal stability and surface modifications of ND particles were studied by combined use of X-ray Photoelectron Spectroscopy (XPS) and Field Emission Gun Scanning Electron Microscopy (FEG SEM). Different oxygen-containing functional groups could be identified by XPS and their evolution versus UHV annealing temperature (400–1085 °C) could be monitored in situ. The increase of annealing temperature led to a decrease of oxygen bound to carbon. In particular, functional groups where carbon was bound to oxygen via one σ bond (C–OH, C–O–C) started decomposing first. At 970 °C carbon–oxygen components decreased further. However, the sp²/sp³ carbon ratio did not increase, thus confirming that the graphitization of ND requires higher temperatures. XPS analyses also revealed that no interaction of ND particles with the silicon nitride substrate occurred at temperatures up to about 1000 °C. However, at 1050 °C silicon nitride coated substrates started showing patch-like damaged areas attributable to interaction of silicon nitride with the underlying substrate. Nevertheless ND particles were preserved in undamaged areas, with surface densities exceeding 10¹⁰ cm^?2. These nanoparticles acted as sp³-carbon seeds in a subsequent 15 min Chemical Vapour Deposition run that allowed growing a 60–80 nm diamond film. Our previous study on Si(100) showed that detonation ND particles reacted with silicon between 800 and 900 °C and, as a consequence, no diamond film could be grown after Chemical Vapour Deposition (CVD). These findings demonstrated that the use of a thin silicon nitride buffer layer is preferable insofar as the growth of thin diamond films on silicon devices via nanoseeding is concerned.     

Preparation,characterization and properties of Cr-incorporated DLC films on magnesium alloy

Cr-incorporated diamond-like carbon (Cr-DLC) films were deposited on AZ31 magnesium alloy as protective coatings by a hybrid beams deposition system, which consists of a DC magnetron sputtering of Cr target (99.99%) and a linear ion source (LIS) supplied with CH₄ precursor gas. The Cr concentration (from 2.34 to 31.5 at.%) in the films was controlled by varying the flow ratio of Ar/CH₄. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to investigate the microstructure and composition of Cr-DLC films systematically. An electrochemical system and a ball-on-disk tribotester were applied to test the corrosion and tribological properties of the film on the AZ31 substrate, respectively. At low Cr doping (2.34 at.%), the film mainly exhibited the feature of amorphous carbon, while at high doping (31.5 at.%), chromium carbide crystalline phase occurred in the amorphous carbon matrix of the film. In this study, all the prepared Cr-DLC films showed higher adhesion to AZ31 than the DLC film. Especially for the film with low Cr doping (2.34 at.%), it owned the lowest internal stress and the highest adhesion to substrate among all the films. Furthermore, this film could also improve the wear resistance of magnesium alloy effectively. But, none of the films could improve the corrosion resistance of the magnesium alloy in 3.5 wt.% NaCl solution due to the existence of through-thickness defects in the films.     

Monochromatic photoluminescence obtained from embedded ZnO nanodots in an ultrahard diamond-like carbon matrix

At room temperature, we observe the self assembly of nanoclusters in an amorphous matrix using a vacuum deposition technique. Self-assembled ZnO nanoclusters embedded in hard diamond-like amorphous carbon thin films, deposited by high vacuum Filtered Cathodic Vacuum Arc (FCVA) technique at room temperature without post-processing, have been observed. A selective self assembly of metal and oxygen ions in a 3-element plasma was observed. XPS distinctly showed presence of ZnO and DLC-mixture in 5, 7 and 10 at.% Zn (in target) films while maintaining high sp³ content. This in turn improved the Young's modulus value of the ZnO nanoclusters embedded in DLC film (~ 220 GPa) compared to bulk ZnO (~ 110 GPa). Films with ZnO detected were observed to exhibit absorption edge at 377 nm monochromatic UV light emissions. This corresponded to a band gap value of about 3.30 eV. The emission with greatest intensity (after normalization) was detected from 10 at.% Zn (in target) film where presence of ZnO nanoclusters (~ 40 nm) in DLC matrix were confirmed by TEM. This showed that well-defined crystalline ZnO nanoclusters contributed to strong PL signal. Strong monochromatic emissions detected hinted that no defect states were present.     

Wear-corrosion behavior of ultra-thin diamond-like carbon nitride films on aluminum alloy

Diamond-like carbon films exhibit high hardness, high wear resistance and a low friction coefficient. They are extensively utilized in the mechanical, electronic and biomedical industries. This work evaluates the effect of the thickness of ultra-thin diamond-like carbon nitride films on their corrosion properties and their wear-corrosion resistance in a mixed 1 M NaCl + 1 M H₂SO₄ solution using electrochemical methods. The corrosion current density and weight loss of all films during and after wear-corrosion test are also recorded. This work employs ion beam-assisted deposition (IBAD) to deposit DLC nitride films of various thicknesses (1.5, 2.0, 2.5 and 3.0 nm), containing 60% nitrogen gas in the form of a gaseous mixture of C₂H₂ + 60%N₂. The thickness of the films was measured using a transmission electron microscope (TEM). The atomic bonding structures of these DLC nitride films are analyzed using a Raman spectrometer and by electron spectroscopy for chemical analysis (ESCA). A scanning electron microscope (SEM) was adopted to elucidate the surface morphologies of the specimens after corrosion and wear-corrosion. The results indicated that all of the nitrogen-containing DLC films excellently protected the 5088 Al–Mg alloy substrate with an electroless plated Ni–P interlayer against corrosion, and that the degree of protection increases with the thickness of the film. In the wear-corrosion tests various potentials were applied during wear in the particular corrosive solution. The results further demonstrated that the wear-corrosion resistance of all the nitrogen-containing DLC films was as effective as corrosion protection, and that the wear-corrosion loss decreased as the film thickness increased.     

Etching process of hydrogenated amorphous carbon (a-C:H) thin films in a dual ECR–r.f. nitrogen plasma

Hydrogenated amorphous carbon (a-C:H) films deposited from CH₄ in a dual electron cyclotron resonance (ECR)–r.f. plasma were treated in N₂ plasma at different r.f. substrate bias voltages after deposition. The etching process of a-C:H films in N₂ plasma was observed by in situ kinetic ellipsometry, mass spectroscopy (MS), and optical emission spectroscopy (OES). Ex situ atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the etched film surface. XPS analysis proves that the nitrogen treatment on the a-C:H film, induced by r.f. substrate bias, causes a direct nitrogen incorporation in the film surface up to 15–17 at.% to a depth of about 20–40 Å depending on the r.f. bias. Various bonding states between carbon and nitrogen, such as tetrahedral sp³ C–N, and trigonal sp² C–N were confirmed by the deconvolution analysis of C 1s and N 1s core level spectra. The evolution of etching rate and the surface roughness in the film measured by AFM exhibit a clear dependence on the applied r.f. bias. MS and OES show the various neutral species in the N₂ plasma such as HCN, CN, and C₂N₂, which may be considered as the chemical etching products during the N₂ plasma treatment of a-C:H film.     

Colored films produced by electron beam deposition from nanometric TiO2 and Al2O3 pigment powders obtained by modified polymeric precursor method

Synthesis and the characterization of TiO₂:5%Co (green), TiO₃:5%Fe (brown-reddish), TiO₂:2%Cr (brown), Al₂O₃:5%Co (blue), Al₂O₃:5%Fe (brown-reddish) and Al₂O₃:2%Cr (light green) nanometric pigment powders using polymeric precursor (modified Pechini's method) is reported. Colored thick films were deposited on amorphous quartz substrates by electron beam physical vapor deposition (EB-PVD) using pellets of the pigment powders as target. The evaporation process was carried out in vacuum of 4 × 10⁻⁶ Torr and the amorphous quartz substrates were kept at 350 °C during deposition. The TiO₂-based pigment powders presented crystalline anatase phase and the Al₂O₃-based pigment powders showed corundum phase, investigated by X-ray diffraction (XRD). The average particle size of the pigment powders was about 20 nm, measured by scanning electron microscopy with field emission gun (SEM-FEG). Diffuse reflectance spectra and colorimetric coordinates L¹, a¹, b¹ using the CIE-L¹a¹b¹ method are shown for the pigment powders, in the 350–750 nm range. The colored thick films were characterized by transmittance (UV–Vis) and atomic force microscopy (AFM). The average film roughness was ∼5.5 nm and the average grain size obtained in the films was around 75 nm. Films with thickness from 400 nm to 690 nm were obtained, measured by talystep profiler. Transmission spectra envelop method has been used to obtain refractive index and thickness of the Al₂O₃ colored thick films.     

Effects of yttrium additions on the microstructure and charge transport properties of indium tin oxide semiconductors

The effects of yttrium (Y) additions (x=0, 0.05, 0.1, and 0.2) on the microstructure, chemical structure, and electrical properties of Y_xInSnO_y (YITO) thin films, prepared using a sol-gel process were examined. The transmission electron microscopy (TEM) observations showed that the undoped InSnO (ITO) film consisted of an amorphous structure with local crystalline domains on the film surface, whereas the Y additions (x=0.05, 0.1, and 0.2) to ITO suppressed the formation of the crystalline phase. X-ray photoelectron spectroscopy (XPS) analysis showed that the Y content decreased the concentration of oxygen vacancies owing to the strong incorporation of Y with oxygen. As a result of the Y incorporation, the carrier concentration of ITO films decreased. The saturation mobility (μ_sat), the on-off ratios (I_on/off), and the sub-threshold swing (S.S) of YITO films were 1.1 cm² V⁻¹ s⁻¹, ~10⁶, and ~0.5 V decade⁻¹, respectively, which are comparable with 1.7 cm² V⁻¹ s⁻¹, ~10⁵, and ~1.17 V decade⁻¹ of ITO film. Additionally, the initial threshold voltage (V_TH) was positive shift with increased of Y addition and V_TH shift (ΔV_TH) under the positive bias stress (PBS) results decreased by Y addition.     

The influence of ion beam assisted deposition parameters on the properties of boron nitride thin films

We studied ion beam assisted deposition of cubic boron nitride thin films on silicon (100) and high speed steel. The boron nitride films were grown by the electron beam evaporation of pure boron (99.4%) and the simultaneous ion bombardment of a mixture of nitrogen and argon ions from a Kaufman ion source. At a constant boron evaporation rate, the ion energy, ion current density, substrate temperature and process gas mixture was varied. The thickness of the films was kept between 200 and 300 nm. Boron nitride films with >80% of the cubic phase (determined by Fourier transform infrared spectroscopy) were obtained with nitrogen/argon mixtures of 50/50 at ion energies of 450 eV and substrate temperatures of 400°C. The current density amounted to 0.45 mA cm⁻² at a nominal boron rate of 200 pm s⁻¹. Cubic boron nitride films were deposited on high speed steel by introducing a titanium interlayer for adhesion improvement.