A thick (130 im) homoepitaxial diamond film was grown on a polished, single crystal {100} oriented natural type Ila diamond circular plate using high density microwave plasma chemical vapor deposition (MPCVD). The as-grown film shows facets around its perimeter, approaching the form of a cubo-octahedral crystal. The plate dimensions increased from 1.50 mm diameter and 0.25 mm thickness to 1.64 mm diameter and 0.38 mm thickness, corresponding to a growth rate of nearly 11 μm per hour. The substrate temperature during growth was approximately 900 C. The film was characterized by optical microscopy, Raman spectroscopy, photoluminescence spectroscopy (PL), and electron paramagnetic resonance (EPR) before and after deposition. The surface morphology of the as-grown film shows large growth steps and a few scattered penetration twins. The diamond film is transparent except for localized regions containing the twin defects. Raman spectroscopy shows a strong diamond peak at 1332 cm−1 superimposed on a background fluorescence. A broad Raman band at 1550 cm−1 is present on the surface defects and is indicative of an amorphous network of sp2-bonded carbon. The luminescence of the film reveals the presence of a nitrogen-vacancy pair. The homoepitaxially-grown diamond layer also exhibits the P1 substitutional nitrogen impurity with a concentration of 8 parts per million (ppm) as determined by EPR. No nitrogen impurities were detected in the original substrate before deposition. EPR is also used to confirm the single crystal nature of the grown diamond.

The possible sources of hydrogen contamination of Diamond-Like Carbon (DLC) films deposited using Unbalanced Magnetron (UBM) sputtering of carbon from a graphite target have been studied. Without deliberate introduction of hydrogen or hydrocarbon gas, magnetron sputtered DLC can contain significant amounts of hydrogen, from 4 to 23 %, by changing the base pressure (or residual gas pressure, rgp) of the deposition system from 3 × 10−6 to 4 × 10−5Torr. This hydrogen contamination contributes to a large change in the optical band gap (0.2 to 1.0 eV) and lowers the density of the films. The hydrogen content in the films comes from water vapor in the deposition system, mainly absorbed in the graphite target, which is dissociated and/or ionized in the plasma. Hydrogen gas has been introduced up to a pressure of 7 × 10−1Torr at a base pressure of˜1 × 10−1Torr in order to simulate high residual gas pressure conditions. The properties of the plasma and the films produced at high base pressures have been compared to those at a high partial pressure of hydrogen gas. For the plasma properties, the electron temperature, Te, and the ion density, ni, were measured by using a double Langmuir probe. The films were characterized by using Ultraviolet-Visible, Rutherford Backscattering/Elastic Recoil, and X-ray Photoelectron Spectroscopies (UV-VIS, RBS/ERS, and XPS).

We have modified the properties of diamond-like atomic-scale composite (DLASC) material of various thicknesses (5 μm – 70 μm) by means of (a) cw Ar-ion laser annealing using a focussed beam (˜ 2 μm spot size) and (b) thermal annealing (400°C≤ T ≤800°C for one hour). These DLASC films [amorphous “diamond-like/quartz-like” a-(C:H/Si:O)] constitute a novel class of diamond-related materials. The annealing effects were investigated by micro-Raman scattering. The laser annealing procedure shows that the structure of these films can be altered locally from amorphous to nano-crystallite depending not only on the parameters of the annealing process (annealing time, laser intensity) but also the mechanical properties (hardness and stress) of the DLASC films.

A model for the infrared radiation emitted by a film/substrate system has been developed which includes both the effects of interference in the growing film and of scattering from its rough growth surface. Predictions of the model for the time-dependence of the apparent temperature Tapp of the film/substrate system measured in-situ by both one-color and two-color infrared pyrometers are presented for the case of diamond growth on Si. Using this model, the following information can be obtained from in-situ pyrometric results in real time: the true temperature of the film/substrate system, the instantaneous film growth rate, and the rms surface roughness σ of the film.

(a) Polycrystalline diamond films have been grown on cylindrical Mo substrates by hot filament and microwave plasma CVD techniques using a gas mixture of hydrogen and methane. A single hot tungsten filament has been used to demonstrate the growth of adherent diamond films on large cylinders. To our knowledge this is the first report on such large cylindrical substrate (area: 41 cm2 ) using a single filament of active length of 3.75 cm. (b) Polycrystalline diamond films have been deposited by hot-filament technique for the first time using methane and hydrogen at an atmospheric pressure of hydrogen on flat substrates. The diamond growth has been performed at various pressures ranging from 34.5 to 750 Torr. The as-deposited films were analyzed by SEM and Raman to determine morphology and chemical nature, respectively.

A. Growth of Diamond Film on Molybdenum Cylinders

Oxidation resistance of diamond is an important characteristic to be considered in many high temperature microelectronics and other applications. We have tested the stability of CVD diamong by exposing to Ground State Atomic Oxygen (GSAO) at a temperature of 70°C. Polycrystalline diamond is quite stable at this temperature using GSAO. We have tested the stability of diamond using Excited State Atomic Oxygen (ESAO). Initially, CVD diamond was exposed to ESAO for 15 mind at 63°C and noted that the diamond was etched. We have also carried out the experiments at different time intervals such as 30 and mine. Etching rate of the diamond using ESAO is ≈ 0.2 – 0.25 μm/min at 63°C. We have successfully patterned the diamond using a Ni mask by exposing the sample to ESAO for longer time. ESAO has etched the diamond uniformly in all the directions of the diamond crystal as opposed to the molecular oxygen. Stability of the single crystal diamond has been tested using ESAO by using Ni mask material. We were able to etch the single crystal diamond (type Iia, 100 orientation) quite uniformly. An etching rate of single crystal diamond using ESAO was observed to be 0.3 μm/min.

Hydrogenated DLC films were synthesized by RF plasma deposition with and without magnetic enhancement, and their film stresses were investigated as a function of process parameters. Under investigated process conditions, Vb/P1/2 (where Vb is the self-bias voltage and P is the working pressure) is the appropriate scaling factor representing impinging ion energy. Film stress is influenced by not only ion impinging energy but also by ion to adspecies flux ratios. As ion energy increases, film stresses increase to a maximum value corresponding to the highest number of sp3 carbon bonds. As ion/adspecies flux ratio increases, the maximum stress value decreases and the corresponding ion energy increases. Induction of a magnetic field promotes film stresses as high as 15.2 GPa, which is one of the highest value reported in hydrogenated DLC films. The magnetic-induced increase of stress can be explained by increased ion/adspecies flux ratio, thus, enhanced sp3 formation. Rapid reduction of stresses observed at high ion energies may stem from the formation of graphite (sp2 bond) phases. Inclusion of hydrogen in the films is not directly responsible for the stress generation.

Amorphous B-N-C films with a variety of properties were deposited by PVD-magnetronsputter-ion-plating. Compared to nonconductive reactive r.f. BN-targets the semiconductive behaviour of specially produced B4C-targets permitted a d.c. reactive or non-reactive mode of deposition. These films are characterized by high hardness with decreased coefficient of friction. A tribological evaluation by modified pin-on-disk outline the wear protection effects in tribosystems with metal counter part. This work was partially financed by the Commission of the European Community under Brite/EuRam contract BRE2-CT93-0451.

Carbon nitride thin films have been prepared by plasma enhanced chemical vapour deposition of CH4 and N2 gas mixtures, by chemical transport from a hollow graphite cathode and by reactive sputtering of a high purity graphite target. The vibrational properties of the films have been studied by Fourier transform infrared spectroscopy (FTIR) and Raman microprobe spectroscopy. Optical emission studies from the plasmas were obtained in the range between 275 and 800 nm. Single, double and triple carbon nitrogen bonds were detected in the FTIR spectra by bands at 1230 cm-1, 1600 cm-1 and 2150 cm-1; their relative intensity being a function of the temperature of the species and the energy supplied to the plasma. A correlation was found between the nitrogen concentration in the films and the existance of strong emission lines of CN and N2+. In the sputtered samples, the substrate temperature and the amount of ion bombardment determined when the films were hard; i.e. Vicker's hardness values above 2500 HV. In the case of the sputtered samples, a temperature window was found which resulted in hard films.

We report here growth of thin films of Si-containing crystalline carbon-nitride by microwave plasma assisted CVD. The chemical composition of these films has been observed to be a strong function of the substrate temperature. A significant incorporation of Si into the CN network occurs for substrate temperatures exceeding 1000C. XPS analyses of these films indicate a multiple bonding structure between carbon and nitrogen and also indicate that a majority of the carbon atoms are tetrahedrally coordinated and covalently bonded with nitrogen. Investigations of the growth rate as a function of various deposition parameters revealed that Si substrates exhibit weight loss rather than deposition, suggesting that abstraction of Si atoms from the substrate surface by the chemically active radicals from the plasma is a dominant process. The species thus formed, i.e., the active radicals bonded with Si, appear to facilitate the subsequent reactions in the gas phase. A major achievement of this study is that there is no obvious deposition of any amorphous CN material.

The roles of HCl and H2 on the low temperature epitaxial growth of 3C-SiC on Si (100) in the SiH4-C2H-HCl-H2 system were examined. At a deposition temperature of 1000 °C with pure H2 as the carrier gas, the deposition rate decreased by approximately 70%, and the structure of the films changed from randomly oriented polycrystals, to textured polycrystals, to single crystals as the Cl/Si gas input ratio was increased from 0 to 40. Without any HCl present, the deposition rate did not change when the H2 carrier gas was replaced with up to 75% He. With a Cl/Si input ratio of 40, the growth rate decreased by approximately 70% as the He fraction was increased to 75%. Films deposited without HCl became more textured as H2 was replaced with He, and single crystal films were produce with a 75% He - 25% H2 mixture as the carrier gas. In contrast, with an input Cl/Si ratio of 40, all films were single crystal, but the rocking curve FWHM increased as H2 was replaced with He.

Cubic SiC thin films have been grown by supersonic jet epitaxy of single molecular precursors on Si(100), Si(111) and Separation by IMplanted OXygen (SIMOX) silicon on insulator (SOI) substrates at temperatures in the range 780 - 1000 °C. Real-time, in situ optical reflectivity was used to monitor the film growth. Films were characterized by ellipsometry, x-ray diffraction (XRD), and transmission electron microscopy (TEM). Monocrystalline, crack-free epitaxial cubic SiC thin films were successfully grown at 830 °C on carbonized Si(111) substrates using supersonic molecular jets of dimethylisopropylsilane, (CH3)2CHSiH(CH3)2, and diethylmethylsilane, (CH3CH2)2SiHCH3. Highly oriented cubic SiC thin films in the [100] direction were obtained on SIMOX(100) at 900 °C with dimethylisopropylsilane and on Si(100) at 1000 °C with diethylmethylsilane. A carbonized Si(100) surface was found to enhance SiC deposition from diethylmethylsilane at a growth temperature of 950 °C.

In this paper, we report on the growth and the study of Ti/TiN nanometric multilayers. The preparation of these films has been carried out by high vacuum diode r.f. sputtering. Growth was in-situ monitored by kinetic ellipsometry. Deposition temperature was kept to room and low temperature (-120°C) respectively in order to modify the interface properties and consequently to understand the effect of the interfaces on the film's mechanical properties.

The thickness of each layer was varied from 1 nm to 10 nm and alternately repeated in order to obtain a total thickness of 200 nm. After deposition, films were characterized by means of X-ray diffraction and grazing X-ray reflectometry for structural determination. This study shows that the TiN-Ti boundary is composed of TiNx, with x going from the nominal nitrogen concentration of the TiN layer to 0. This can be due either to a surface reaction of the incident titanium during the Ti sequence with the nitrogen present at the film surface or to a reaction of nitrogen with the target surface during the TiN sequence.

Crystalline C-N films composed of α- and β-C3N4, as well as other C-N phases, have been synthesized via bias-assisted hot-filament chemical vapor deposition using a gas mixture of nitrogen and methane. Scanning electron microscopy(SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the films. Lattice constants of the α- and β-C3N4 phases obtained coincide very well with the theoretical values. In addition to these phases, two new C-N phases in the films have been identified by TEM and XRD; one having a tetragonal structure with a = 5.65 Å, c = 2.75Å, and the second having a monoclinic structure with a = 5.065 Å, b= 11.5 Å, c = 2.801 Å and β = 96°. Their stoichiometric values and atomic arrangements have not yet been identified. Furthermore, variation in growth parameters, for example methane concentration, bias voltage, etc., can yield preferred growth of different C-N phases.

Novel precursor chemistry and ultrahigh-vacuum chemical vapor deposition have been used to deposit Si1-yCyth in films on (001) Si substrates. Films with carbon compositions ranging up to 20 at. % were deposited at substrate temperatures of 600–750°C using interactions of C(SiH3)4 or C(SiH2Cl)4 (C-H free precursors incorporating Si4C tetrahedra) and SiH4 gas mixtures. The composition of the resulting materials was obtained by Rutherford backscattering spectrometry including carbon resonance analysis. Cross-sectional transmission electron microscopy and infrared spectroscopy were used to provide microstructural and bonding information respectively. The effect of precursor chemistry on the composition and structure of the materials is discussed.

Various silicon carbide polytypes, such as 4H-, 6H- and 3C-SiC are clearly distinguished by the magnitude and rotational anisotropy of their optical second-harmonic (SH) response. The large dynamic range of the SH response of more than two orders of magnitude between these polytypes allows a fast and non-invasive mapping of 3C-SiC micron areas in 4H - and 6H-SiC epilayers. 3C-Microcrystallites of different oricutations are identified from SH rotational anisotropy scans.

Thermodynamic analysis was conducted to determine the conditions necessary for the selective epitaxial growth (SEG) of SiC on SiO2 masked Si substrates, and these results were compared to blanket SiC epitaxy on plain Si. For blanket SiC epitaxy, proper deposition conditions leading to single phase SiC without Si or graphite codeposition were found. For SiC SEG, the additional constraint that no significant SiO2 mask etching should occur, was considered. Taken in combination, both the SiC deposition and the Si0 2 etching processes were analyzed to ensure meaningful subsequent experiments. All process parameters, i.e., temperature, C/Si, CI/Si and H2/Si in the gas mixture significantly affect the growth conditions when epitaxy is possible. Either providing more carbon than silicon in the gas sources or adding HCl helps to suppress Si codeposition. For SiC SEG, lower deposition temperature (e.g. less than 1400 K) should be used to avoid damaging the SiO2 mask.

A new radiochromic thin-film sensor using the blue tetrazolium chloride salt (BT) dissolved in polyvinyl alcohol (PVA) has been developed for deep ultraviolet, and gamma and xray dosimetry systems. The radiation-sensitive blue tetrazolium (BT2+), pale yellowish before irradiaton, registers a permanent purple high-resolution image upon irradiation. The distinctive coloration in terms of increase of optical density (net absorbance, ΔA) at 552 nm is measured spectrophotometrically and is proportional to the amount of radiation energy absorbed per unit mass (absorbed dose, D). The films have broad monitoring range, being able to detect radiation doses as low as 1 kGy and as high as 75 kGy. The radiochromic images show a gradual postirradiation increase in absorbance, especially during the first 24 hrs. There is also a small but predictable variation in sensitivity with temperature during irradiation. Furthermore, the responses to gamma radiation are found to be dependent on absorbed dose rate, but can be minimized by increasing the dye precursor concentration (BT2+).

Heterojunction Quantum Well Lasers were tested under forward and reverse bias, by Scanning Electron Microscopy (SEM) working in Differential Voltage Contrast(DVC) mode. DVC utilizes the impact of electrical potential across a device on the emission of secondary electrons. DVC consists of storing and subtracting two digitized images of the tested device under zero bias and in an operational regime. Calibration of the resultant image provides for quantitative measurements of the potential across the device. The question of whether the DVC technique measures the electron affinity of a material or its work function or the thermodynamic potential has been addressed in recent papers, however questions remained regarding discrepancies between the expected Quasi Fermi Energy (QFE) and the measured values. The experimental part of our work concentrated on taking (QFE) profiles by DVC across a single quantum well laser operating in inverse population, threshold, and high power emission modes of photoemission. The intensity was measured by a calibrated photodetector aligned with the laser in the SEM chamber. The cleaved and yet operational lasers have as a central part a layer of In0.2Ga0.8As 600nm thick between two undoped layers of Al0.3Ga0.7As 0.1 μm thick each with cladding layer of n-type Al0.6Ga0.4As on one side and a similar p-type layer on the other. The shape of QFE indicated that eletrons and photons contribute to total energy over the intrinsic area. This QFE profiling across the laser reveals areas of electron and photon confinement.

The electro-chromic behavior of nickel oxide (NiOx) films, prepared by spin-coating, were analyzed for their structual and optical properties before and after cycling procedure in electrolyte. It was found that the chemical composition, refractive index, and thickness of the film changes significantly on hydration.