Diamond thin films were growth using Tequila as precursor by Pulsed Liquid Injection Chemical Vapor Deposition (PLI-CVD) onto both silicon (100) and stainless steel 304 at 850 C. The diamond films were characterized by Scanning Electron Microscopy (SEM) and Raman spectroscopy. The spherical crystallites (100 to 400 nm) show the characteristic 1332 cm-1 Raman band of diamond.
Vanadium doped diamond-like carbon films prepared by unbalanced magnetron sputtering have been investigated by X-ray and ultraviolet photoelectron spectroscopy measurements for the purpose of revealing electronic structures including values of work function on the surfaces. In addition to these photoelectron measurements, X-ray diffraction measurements have been performed to characterize the crystal structures.
Polycrystalline diamond films with systematic change in microstructure that varies from microcrystalline to nanocrystalline structure are synthesized on Si by hot filament chemical vapor deposition. The morphology and structural properties of the grown diamond films are analyzed using field emission scanning electron microscope (FESEM), atomic force microscope (AFM), X-ray diffraction and Raman spectroscopy. The average roughness and grain size of the diamond films decrease with increase in CH4 to H2 ratio from 0.5 to 3 %. Also, structural disorder in these diamond films increases with decreas…
Ratio of the intensity of D- Raman peak and G- Raman peak (ID/IG) is often used for characterization of diamond-like carbon films, for example to estimate number and size of the sp2 clusters. In this paper we investigate how the interference effects in the film influence this ratio. It is shown that for films on silicon substrates the distortion of the real ratio can reach 10 % and for films on metals even 40 %. This should be taken into account if some conclusions are made from the measured ID/IG ratio.
Measurement of zeta potential of Ga and N-face gallium nitride has been carried out as function of pH. Both the faces show negative zeta potential in the pH range 5.5-9. The Ga face has an isoelectric point at pH 5.5. The N-face shows higher negative zeta potential due to larger concentration of adsorbed oxygen. Zeta potential data clearly showed that H-terminated diamond seed solution at pH 8 will be optimal for the self assembly of a monolayer of diamond nanoparticles on the GaN surface. Subsequent growth of thin diamond films on GaN seeded with H-terminated diamond seeds produced fully coal…
The growth of thin amorphous hydrogenated carbon films (a-C:H) on diamond (111) surface from the bombardment of CH2 radicals is studied using molecular dynamics simulations. The structural analysis shows that the local structure (e.g., the first coordination number of C atoms) of a-C:H depends critically on the content of hydrogen. The increase of kinetic energy of incident radicals leads to the decrease of hydrogen content, which subsequently changes the ratio of sp3 bonded C atoms in a-C:H.
The demonstration that Nanocrystalline Diamond (NCD) can retain the superior Young's modulus (1,100 GPa) of single crystal diamond twinned with its ability to be grown at low temperatures (<450 °C) has driven a revival into the growth and applications of NCD thin films. However, owing to the competitive growth of crystals the resulting film has a roughness that evolves with film thickness, preventing NCD films from reaching their full potential in devices where a smooth film is required. To reduce this roughness, films have been polished using Chemical Mechanical Polishing (CMP). A Logitech Tr…
Plasma surface modification was used to fabricate graphene on the top of insulating diamond-like carbon films. It is shown that by a combination of pulsed argon plasma treatment and thermal annealing at 350\degreeC is possible to achieve partial crystallization of amorphous carbon to graphene. The observed Raman spectra are typical for defected graphene - splitted D- and G-peaks and a broad 2D-peak. This result is very encouraging and we hope that by improving this technology it will be possible to fabricate defect-free graphene, which can be used in electronics without transfer to other subst…
The main aim of the present work is to estimate the effective elastic stiffnesses of a two-phase diamond/$β$-SiC composite thin film that is fabricated by chemical vapor deposition. The parameters of linear elasticity are determined by numerical homogenization. The database is sparse since for the 3D volume of interest only two micrographs displaying the phase distributions in perpendicular planes are available; micrographs each of a cross-section and the surface of the thin film. A representative volume element (RVE) is reconstructed by an optimization software and by means of identified mate…
The Hydrogenated Diamond Like Carbon (HDLC) thin films are deposited on Silicon substrate at room temperature using asymmetric capacitively coupled RF plasma with varying flow rates of methane. These films are undergone annealing at high vacuum and high temperature furnace. The as-prepared and annealed HDLC films have been depth profiled for hydrogen using the resonance at 6.44 MeV in nuclear reaction between fluoride ion beam and HDLC. The as prepared films exhibit non-uniform depth distribution of hydrogen: it decreases with depth. Annealing in vacuum brings about a significant desorption of…
Quantum information processing and integrated nanophotonics require robust generation of single photon emitters on demand. In this work we demonstrate that diamond films grown by microwave plasma chemical vapour deposition on a silicon substrate host bright, narrowband single photon emitters in the visible to near infrared spectral range. The emitters possess fast lifetime, absolute photostability, and exhibit full polarization at excitation and emission. Pulsed and continuous laser excitations confirm their quantum behaviour at room temperature, while low temperature spectroscopy is done to i…
Boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) Type Ib diamond substrates using microwave plasma assisted chemical vapor deposition. A modification in surface morphology of the film with increasing boron concentration in the plasma has been observed using atomic force microscopy. Use of nitrogen during boron doping has been found to improve the surface morphology and the growth rate of films but it lowers the electrical conductivity of the film. The Raman spectra indicated a zone center optical phonon mode along with a few additional bands at the lower w…
The boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) oriented Type Ib diamond substrates using a Microwave Plasma Chemical Vapor Deposition (MPCVD) technique. Raman spectrum showed a few additional bands at the lower wavenumber regions along with the zone center optical phonon mode for diamond. The change in the peak profile of the zone center optical phonon mode and its downshift were observed with the increasing boron content in the film. A modification in surface morphology of the film with increasing boron content had been observed by atomic force micr…
The atomic structure and physical properties of few-layered <111> oriented diamond nanocrystals (diamanes), covered by hydrogen atoms from both sides are studied using electronic band structure calculations. It was shown that energy stability linear increases upon increasing of the thickness of proposed structures. All 2D carbon films display direct dielectric band gaps with nonlinear quantum confinement response upon the thickness. Elastic properties of diamanes reveal complex dependence upon increasing of the number of <111> layers. All theoretical results were compared with available experi…
The deposition of nano-crystalline ZnS/diamond composite protective coatings on silicon, sapphire, and ZnS substrates, as a preliminary step to coating infrared transparent ZnS substrates from powder mixtures by the aerosol deposition method is presented. Advantages of the aerosol deposition method include the ability to form dense, nanocrystalline films up to hundreds of microns thick at room temperature and at a high deposition rate on a variety of substrates. Deposition is achieved by creating a pressure gradient that accelerates micrometer-scale particles in an aerosol to high velocity. Up…
The chemical nature of the chemical mechanical polishing of diamond has been examined by adding various redox agents to the alkaline SF1 polishing slurry. Three oxidizing agents namely, hydrogen peroxide, potassium permanganate and ferric nitrate, and two reducing agents, oxalic acid and sodium thiosulfate, were added to the SF1 slurry. Oxalic acid produced the fastest polishing rate while hydrogen peroxide had very little effect on polishing, probably due to its volatile nature. X-ray photoelectron spectroscopy (XPS) reveals little difference in the surface oxygen content on the polished samp…
In this present work, friction and wear behavior of UNCD thin film has been studied against three different sliding counterbodies i.e. Al2O3, SiC and steel balls. UNCD/steel sliding pair showed high friction coefficient in the beginning of the sliding process which decreased to the lower value after longer sliding passes. This behavior might be explained by oxidation mechanism. However, high friction value was observed in the case of UNCD/SiC and this was attributed to strong adhesive force acting across the sliding interfaces. Stable and low friction value was measured in UNCD/Al2O3 sliding c…
Diamond-like carbon (DLC) films are synthesized on Si using plasma enhanced chemical vapor deposition. The role of substrate bias and nitrogen doping on the structural evolution and local elastic modulus of DLC films are systematically investigated. Raman spectroscopic studies reveal that the amount of graphitic C=C sp2 bonding increases with substrate bias and nitrogen doping. The density and hydrogen concentration in the films are found to vary from 0.7 to 2.2 g/cm3 and 16 to 38 atomic %, respectively, depending upon the substrate bias and nitrogen concentration in the DLC films. Atomic forc…
Boron-doped diamond granular thin films are known to exhibit superconductivity with an optimal critical temperature of Tc = 7.2K. Here we report the measured complex surface impedance of Boron-doped diamond films in the microwave frequency range using a resonant technique. Experimentally measured inductance values are in good agreement with estimates obtained from the normal state sheet resistance of the material. The magnetic penetration depth temperature dependence is consistent with that of a fully-gapped s-wave superconductor. Boron-doped diamond films should find application where high ki…
Growth of $>$100 $μ$m thick diamond layer adherent on aluminium nitride is presented in this work. While thick films failed to adhere on untreated AlN films, hydrogen/nitrogen plasma treated AlN films retained the thick diamond layers. Clear differences in zeta potential measurement confirms the surface modification due to hydrogen/nitrogen plasma treatment. Areal Raman maps showed an increase in non-diamond carbon in the initial layers of diamond grown on pre-treated AlN. The presence of non-diamond carbon has minimal effect on the interface between diamond and AlN. The surfaces studied with …
Chemical vapour deposition (CVD) grown nanocrystalline diamond is an attractive material for the fabrication of devices. For some device architectures, optimisation of its growth on silicon nitride is essential. Here, the effects of three pre-growth surface treatments, often employed as cleaning methods of silicon nitride, were investigated. Such treatments provide control over the surface charge of the substrate through modification of the surface functionality, allowing for the optimisation of electrostatic diamond seeding densities. Zeta potential measurements and X-ray photoelectron spectr…
We present the electrical transport characteristics of a batch of nano-crystalline diamond films of varying nitrogen concentrations and explain the conduction mechanism by the disordered quasi-superlattice model applied to semiconductor heterostructures. Synthesized by the hot filament chemical vapour deposition technique, the degree of structural disorder in the films, confirmed from Raman spectroscopy, is found to be controllable, resulting in the transition of conduction mechanism from localized and activated to the metallic conduction regime. Hence through high field magneto-resistance mea…
Hole doping can control the conductivity of diamond either through boron substitution, or carrier accumulation in a field-effect transistor. In this work, we combine the two methods to investigate the insulator-to-metal transition at the surface of nanocrystalline diamond films. The finite boron doping strongly increases the maximum hole density which can be induced electrostatically with respect to intrinsic diamond. The ionic gate pushes the conductivity of the film surface away from the variable-range hopping regime and into the quantum critical regime. However, the combination of the stron…
A high-current annealing technique is used to fabricate nanogaps and hybrid diamond/graphite structures in boron-doped nanocrystalline diamond films. Nanometer-sized gaps down to 1 nm are produced using a feedback-controlled current annealing procedure. The nanogaps are characterized using scanning electron microscopy and electronic transport measurements. The structural changes produced by the elevated temperature, achieved by Joule heating during current annealing, are characterized using Raman spectroscopy. The formation of hybridized diamond/graphite structure is observed at the point of m…
Thick CVD diamond layers were successfully grown on (113)-oriented substrates. They exhibited smooth surface morphologies and a crystalline quality comparable to (100) electronic grade material, and much better than (111)-grown layers. High growth rates (15-50 μm/h) were obtained while nitrogen doping could be achieved in a fairly wide range without seriously imparting crystalline quality. Electron spin resonance measurements were carried out to determine NV centers orientation and concluded that one specific orientation has an occurrence probability of 73 % when (100)-grown layers show an equ…
Depth-Resolved Thermal Conductivity of HFCVD Diamond Films via Square-Pulsed Thermometry
School of Energy and Power Engineering, Huazhong University of Science and Technology（华中科技大学能源与动力工程学院）；Institute for Advanced Materials and Technology, University of Science and Technology Beijing（北京科技大学先进材料与技术研究院）；Shunde Graduate School, University of Science and Technology Beijing（北京科技大学顺德研究生院）；School of Energy and Power Engineering, Nanjing University of Science and Technology（南京理工大学能源与动力工程学院）
Improvement of Morphology and Electrical Properties of Boron-doped Diamond Films via Seeding with HPHT Nanodiamonds Synthesized from 9-Borabicyclononane
Atomically thin graphene exhibits fascinating mechanical properties, although its hardness and transverse stiffness are inferior to those of diamond. To date, there hasn't been any practical demonstration of the transformation of multi-layer graphene into diamond-like ultra-hard structures. Here we show that at room temperature and after nano-indentation, two-layer graphene on SiC(0001) exhibits a transverse stiffness and hardness comparable to diamond, resisting to perforation with a diamond indenter, and showing a reversible drop in electrical conductivity upon indentation. Density functiona…
We calculate the density of states (DOS) and the Mulliken population of the diamond and the co-doped diamonds with different concentrations of lithium (Li) and phosphorus (P) by the method of the density functional theory, and analyze the bonding situations of the Li-P co-doped diamond thin films and the impacts of the Li-P co-doping on the diamond conductivities. The results show that the Li-P atoms can promote the split of the diamond energy band near the Fermi level, and improve the electron conductivities of the Li-P co-doped diamond thin films, or even make the Li-P co-doped diamond from …
Ultrananocrystalline diamond/hydrogenated amorphous carbon composite thin films synthesized via coaxial arc plasma possess a marked structural feature of diamond grains embedded in an amorphous carbon and a hydrogenated amorphous carbon matrix which are the largest constituents of the films. Since the amorphous nature yields much larger light absorption coefficients as well as a generation source of photo-induced carriers with UV rays, these films can be potential candidates for deep-UV photodetector applications. From some previous studies p-type conduction of the films has been realized by d…
The origin of ultralow friction and high wear resistance in ultrananocrystalline diamond (UNCD) films is still under active debate because of the perplexed tribochemistry at the sliding interface. Herein, we report a comparative study on surface topography and nanoscale friction of tribofilms, in wear tracks of two sets of UNCD films having different structural characteristics. Despite both the films display ultralow coefficient of friction, the UNCD films grown under Ar atmosphere (UNCDAr) exhibit a high wear resistance while the wear rate is higher for the films grown in N2 (UNCDN). Friction…
Ultrananocrystalline Diamond Nanowire (UNCD NW) thin film was deposited on mirror polished silicon substrate (100) using Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) System with optimized deposition parameters in CH4 (6%)/N2 plasma media. The film exhibited wire like morphology with randomly oriented and homogeneously distributed ultranano diamond grains separated by an interphase boundary of graphitic and amorphous carbon (a-C) phases. Micro-tribological studies of film were carried out against Al2O3, SiC and steel balls in ambient atmospheric conditions. Initially, the fricti…
In the nitrogen-incorporated ultrananocrystalline diamond ((N)UNCD) films, representing an $n$-type highly conductive two-phase material comprised of $sp^3$ diamond grains and $sp^2$-rich graphitic grain boundaries, the current is carried by a high concentration of mobile electrons within the large-volume grain boundary networks. Fabricated in a simple thin-film planar form, (N)UNCD was found to be an efficient field emitter capable of emitting a significant amount of charge starting at the applied electric field as low as a few V/$μ$m which makes it a promising material for designing electron…
Molecular contamination of a grazing incidence collector for extreme ultraviolet (EUV) lithography was experimentally studied. A carbon film was found to have grown under irradiation from a pulsed tin plasma discharge. Our studies show that the film is chemically inert and has characteristics that are typical for a hydrogenated amorphous carbon film. It was experimentally observed that the film consists of carbon (~70 at. %), oxygen (~20 at. %) and hydrogen (bound to oxygen and carbon), along with a few at. % of tin. Most of the oxygen and hydrogen are most likely present as OH groups, chemica…
Herein, we report on the improvement of structural quality and enhancement of photoluminescence (PL) emission for an optimally N doped nanocrystalline diamond (NCD) film. Pure and N doped nanocrystalline diamond films are synthesized on Si by hot filament chemical vapour deposition using NH3:CH4:H2 at different nominal N/C ratios viz. 0, 0.13, 0.35, 0.50 and 0.75 in feedstock. X ray diffraction analysis reveal a systematic initial increase and then a decrease in crystallite size with N/C ratio in feedstock. Further, a monotonic increase in Raman line width and peak position of diamond band ind…
Polycrystalline diamond coatings have been grown on cemented carbide substrates with different aspect ratios by a microwave plasma CVD in methane-hydrogen gas mixtures. To protect the edges of the substrates from non-uniform heating due to the plasma edge effect, a special plateholder with pockets for group growth has been used. The difference in heights of the substrates and plateholder, and its influence on the diamond film mean grain size, growth rate, phase composition and stress was investigated. The substrate temperature range, within which uniform diamond films are produced with good ad…
We report direct imaging of boundary magnetization associated with antiferromagnetic domains in magnetoelectric epitaxial Cr2O3 thin films using diamond nitrogen vacancy microscopy. We found a correlation between magnetic domain size and structural grain size which we associate with the domain formation process. We performed field cooling, i.e., cooling from above to below the Néel temperature in the presence of magnetic field, which resulted in the selection of one of the two otherwise degenerate 180 degree domains. Lifting of such a degeneracy is achievable with a magnetic field alone due to…
The chemical vapor deposition of polycrystalline diamond (PCD) films is typically done on substrates seeded with diamond nanoparticles. Specular laser reflectance and a continuous film model have been used to monitor the thickness of these films during their deposition. However, most seeds are isolated during the early stages of the deposition, which questions the utility of applying such a continuous film model for monitoring deposition before film formation. In this work, we present a model based on the Rayleigh theory of scattering for laser reflectance at substrates with growing nanodiamon…
Although theoretical investigations indicate that the successful combination of graphene and diamond would give interesting properties, only a limited number of reports dealing with the subject have been published. Here, we present a rapid thermal process (RTP) which involves Ni as metal catalyst for a direct growth of graphene on diamond at a temperature of 800 $^{\circ}$C for 1 min. This process operates with a combination of a lower temperature and for a shorter duration than what has previously been reported. Thin Ni films with different thicknesses were deposited on top of (100) single cr…
We report a study of the relaxation time of the restoration of the resistive superconducting state in single crystalline boron-doped diamond using amplitude-modulated absorption of (sub-)THz radiation (AMAR). The films grown on an insulating diamond substrate have a low carrier density of about 2.5x10^{21} cm^{-3} and a critical temperature of about 2 K. By changing the modulation frequency we find a high-frequency rolloff which we associate with the characterstic time of energy relaxation between the electron and the phonon systems or the relaxation time for nonequilibrium superconductivity. …
We establish the dominant effect of anisotropic weak localization (WL) in three dimensions associated with a propagative Fermi surface, on the conductivity correction in heavily nitrogen doped ultrananocrystalline diamond (UNCD) films based on magneto-resistance studies at low temperatures. Also, low temperature electrical conductivity can show weakly localized transport in 3D combined with the effect of electron-electron interactions in these materials, which is remarkably different from the conductivity in 2DWL or strong localization regime. The corresponding dephasing time of electronic wav…
Detailed structural and electrical properties of ultra-nano-crystalline diamond (UNCD) films grown in H$_\text{2}$/CH$_\text{4}$/N$_\text{2}$ plasma were systematically studied as a function of deposition temperature ($T_d$) and nitrogen content ($\%$ N$_2$) to thoroughly evaluate their effects on conductivity. $T_d$ was scanned from 1000 to 1300 K for N$_2$ fixed at 0, 5, 10 and 20 $\%$. It was found that even the films grown in the synthetic gas mixture with no nitrogen could be made as conductive as 1$-$10$^{-2}$ $Ω$ cm with overall resistivity of all the films tuned over 4 orders of magnit…
