The effect of hydrogen plasma treatment on the optical and electrical properties of Gallium Antimonide bulk single crystals is presented. Plasma exposure gives rise to a layer of defects on the surface. These defects introduce multiple trap levels in the band gap from which a slow emission of carriers is observed during the capacitance - voltage measurements. On removal of the defect layer by controlled etching, the effects of hydrogen passivation are seen. The results of optical measurements indicate that passivation of shallow acceptors is more efficient than that of the donors and in general the passivation efficiency depends on the doping level. Passivation of deep levels and extended defects like grain boundaries and dislocations has also been observed. The thermal stability of the passivated deep level and extended defects is higher than that of the shallow level.

SiO2 thin firms were fabricated in a remote electron cyclotron resonance (ECR) plasma by tctraethoxysilane (TEOS) as the silicon source. Oxygen was used as the plasma gas. A mesh was placed between the TEOS gas outlet and the substrate. In the present investigation a-SiO2 films were deposited with and without the mesh and film properties were studied comparatively. The deposition rate increased when the mesh was attached. The optimum deposition rate is observed when the mesh voltage was zero, that is the mesh was grounded. The deposition rates of both methods were also dependnt on the TEOS flow rate, applied microwave power and the substrate temperature. These three parameters have significant roles in controlling the film quality. Good quality SiO2 films can be obtained with a higher deposition rate when a mesh is attached.

Theoretical works have indicated that carbon nitride, in a β-C4N4 phase, would have optical and mechanical properties comparable to or exceeding those of diamond. In this effort, the formation of carbon nitride thin films was investigated using a Plasma Assisted Ion Beam Deposition (PAIBD). In this technique, a C- ion beam combined with a N2 or NH3 RF plasma source is used to synthesize carbon nitride films. These films were investigated as a function of both C- ion beam energy and the power of the plasma source. The C- ion energy was found to be a key parameter in the formation of carbon nitride. The films were evaluated by a variety of diagnostic techniques including Raman, AES, XRD and FTIR. Analysis confirms high nitrogen concentration in the synthesized films and the major portion of carbon being single bonds in the sp3 bond configuration, which is a characteristic of the tetrahedral -C3N4 phase. Tribology tests confirmed that the friction coefficient and the wear rate are comparable to diamond. The results show that the higher C- ion beam energy (-150 eV) forms insulating films with the highest single bond percentages in the range studied. We believe beam energy control is critical to the types of bonds formed.

During the past few years, there has been growing interest in aluminum nitride (A1N) thin films because of their excellent optical, electrical, chemical, mechanical and high-temperature properties. Ion beam assisted deposition (IBAD) was used to deposit A1N films on flat and curved substrates, including Si, SIMOX, sapphire, quartz, aluminum, stainless steel, and carbon, at temperatures substantially below 100°C. The objective was to enhance the physical and mechanical properties of A1N film by controlling the crystal size and structures.

Experimental results, as obtained by Rutherford backscattering spectroscopy (RBS) show the formation of stoichiometric A1N. Plan-view/cross-sectional transmission electron microscopy (TEM), clearly demonstrated the formation of a smooth, uniform A1N film. Electron diffraction and dark field TEM studies clearly show the growth of A1N crystallites with cubic and/or hexagonal structures and dimensions of 30 to 100A. The films are transparent and have good adhesion to all substrates. In addition to excellent high temperature (up to 1050°C measured) and chemical stability (shown through a variety of acid tests), these films have demonstrated extreme hardness, greater than two times that of bulk AIN.

Thin films of BNxOy have been deposited by rf Reactive Magnetron Sputtering from a BN target in Ar+ plasma (1 Pa) at different substrate bias conditions. The possibility of obtaining dense and hard BN coatings at a target-to-substrate distance larger than the mean free path of the B and N atoms has been investigated.

In order to deduce the plasma potential and the ion density near the substrates, the discharge characteristics have been measured by means of an electrostatic probe of the Langmuir type properly coupled to the glow discharge for avoiding the rf interference. From the probe data both flux and energy of the Ar+ ions have been determined and correlated to the net contents of boron and nitrogen as measured by means of the N(d,p) and 11Β(p,α) nuclear reactions. The results of this study show that in the investigated experimental conditions the flux of energetic Ar+ ions at the substrates is insufficient for promoting the formation of cubic BN as confirmed by XRD, FT-IR and nanohardness measurements. The reported data agree with recent literature findings and support the need of monitoring both the bombarding rate and energy of the Ar ions in rf discharges if the c-BN deposition is to be attained in a reproducible manner.

Oxides of silicon and zirconium have been deposited onto silicon, carbon and aluminium substrates by reactive sputtering using a 1 keV argon ion beam and a controlled partial pressure of oxygen. Using RBS, film composition was determined for a given partial pressure of oxygen and different Si or Zr deposition rates. There is evidence of retained argon in the film which is primarily due to argon ions reflected from the sputtered target. Cross-sectional TEM was used to examine the film microstructure and morphology. Both silica films and sub-stoichiometric zirconia films were found to be amorphous,whereas stoichiometric zirconia films were found to be polycrystalline with grain sizes in the range 10-20nm. A model has been developed to predict the composition of deposited films.

Hard, low-friction silicon-containing diamond-like carbon coatings (Si-DLC), were formed by Ar+ ion beam assisted deposition (IBAD), on 5 in. diameter silicon wafers. The diffusion pump oil precursor (tetraphenyl-tetramethyl-trisiloxane: (C6H5)4(CH3)4Si3O2) was evaporated through seven, 3 mm diameter, closely packed apertures (multinozzle/multi-aperture container) arranged in a hexagonal pattern, approximately 5 mm apart according to mathematical model [1[ developed at ARL describing the spatial distribution of film deposition from nozzles and apertures onto inclined substrates.The ion energy was kept at 40 keV whereas the ion current density and the oil evaporation temperature were varied to produce hard, lubricious and adherent films. The multinozzle array allowed the relatively uniform (± 20%) coverage of the entire 5 in. substrate. The thickness and the microhardness of the films were measured along the rectilinear surface coordinates of the substrate area. Depending on the deposition parameters the standard deviation of the coating thicknesses and Knoop micro-hardness varied from 14 to 30 percent respectively over the substrate. This is a significant improvement from the previously used single nozzle set up where the standard deviation of the coating thickness was 50 to 100 percent for 2 in. diameter substrates. The Knoop microhardness and the sliding friction coefficient of these coatings ranged from 10,000 to 20,000 MPa and 0.04 to 0.2 respectively. These values are in agreement with our previously reported single nozzle results [2].

Partially ionized beam deposition of Cu thin films on glass at room temperature were carried out to fabricate Cu laser mirrors with good structural and reflectance properties. At a constant film thickness of 600 Å, the grain size of as-grown Cu films increased with acceleration voltage, and there was no indication of defects such as cracks and/or large pores in the film surface as shown in scanning electron microscopy images. Root-mean-square(Rms) surface roughnesses of the films with thicknesses of 600 Å were measured by atomic force microscopy. RmS surface roughness increased when acceleration voltage increased from 0 kV to 2 kV, but decreased at the acceleration voltage of 3 kV. RmS surface roughness of the film grown at 4 kV, however, increased again. At the acceleration voltage of 3 kV, reflectance of the films increased with the film thickness until 600 Å and decreased at the film thickness of 800 Å. The reflectance results showed that the Cu film deposited at 3 kV had higher reflectance than that of others. Our results suggest that it is possible to grow the Cu film with good structural and optical properties on glass substrate at room temperature by partially ionized beam deposition.

Changes of crystallinity and surface roughness are discussed in terms of the average energy per deposited atom in the partially ionized beam(PIB) deposition. The average energy per deposited atom can be controlled by adjusting the ionization potential, Vi and acceleration potential, Va. The ion beam consists of a Cu ion beam and residual gas ion beam and residual gases as well as Cu particles that were ionized and accelerated to provide the film with energy required for film-growth. The relative contribution of residual gas ions and Cu ions to total average energy per deposited atom was varied with the ionization potential. At fixed ionization potentials of Vi=400 V and Vi=450 V, the average energy per deposited atom was varied in the range of 0 to 120 eV with acceleration potential Va, of 0 to 4 kV. The relative intensity ratio, 1(111)/I(200), of the Cu films increased from 6 to 37 and the root mean square(Rms) surface roughness decreased with an increase in acceleration potential at Vi=400 V. The relative intensity ratio, I(lll)/I(200), of Cu films increased up to Va=2 kV at Vi=2 kV, above which a decrease occurred, and the surface roughness of Cu films increased as a funtion of acceleration potential. The degree of preferred orientation was closely related with the average energy per deposited atom. The change of Rms roughness might be affected by ion flux, particle energy and preferred orientation.

Using He+ as probe particles, we have studied point defects in Mo thin films (5-1000 Å) deposited without and with Ar+ ion beam assistance (0.2–22 eV per Mo atom). It is found that the net effect of the ion beam is to produce rather than to annihilate point defects. Ar incorporation is only slight (-10-4). Annealing of the films leads to the thermal production of polyvacancies.

The high-intensity pulsed ion-beam (HIPIB)/solid interaction results in the generation of an ablated plasma ( ∼1020 cm-3; ∼1 eV) which can be used to advantage for the deposition of thin films. Presented are the results of investigation on the deposition by HIPIB of thin films of high-melting metals, i.e. W, Ta, Mo, Nb, as well as of Al and Cu. The kinetics of the layer-by-layer film growth has been studied using transmission electron microscopy (TEM), transmission electron diffraction (TED) and reflection ellipsometry. The experiments were performed on a TEMP-2 supercurrent accelerator (ion energy 500 keV; ion current density at the target 200 A/cm ; power density (0.7 – 1.5) 108 W/cm2; pulse duration 60 ns; pulse repetition rate 8-10 min-1). The deposition of the films was carried out at room temperature at a high rate of 0.6 – 4.0 mm/s using (100)Si, (001)NaCl, glass and glass ceramic substrates.

Defect characterization in n-type silicon after the reactive ion etching (RIE) in low-pressure plasmas containing fluorine and oxygen is performed by using photoluminescence (PL) and deep level transient spectroscopies (DLTS). It is shown that RIE treatment results in the formation of (i) luminescence centers giving rise to the C- and G- excitonic lines and broad emission bands related to radiation-induced defect complexes and extended defects and (ii) several electron traps located at 0.16 eV, 0.26 eV, 0.43 eV and 0.58 eV below the conduction band. The addition of oxygen to the SF6 and CF4 plasma is shown to cause nonuniform stress in the near surface region. This stress is responsible for the experimentally observed splitting of the C- and G-excitonic lines, a low energy shift of the phosphorous bound exciton lines, as well as the splitting of the DLTS spectra. It is shown that the stress field is highly inhomogeneous across the wafer, and is rather related to the RIE-induced extended defects than caused by the reaction layer formed on the Si surface.

Single crystal-like yttria-stabilized zirconia (YSZ) thin films have been deposited on amorphous quartz, polycrystalline zirconia, single crystal Si, and Hastelloy substrates using dual ion beam deposition (IBAD). These films are highly crystallographically aligned both normal to and within the film plane. The films are deposited at low substrate temperatures (<200°C), and the film orientation is substrate independent. θ-2θ X-ray diffraction, X-ray rocking curves, X-ray pole figures and X-ray phi scans are used to evaluate the film structure. High resolution cross-sectional TEM is used to examine the evolution of crystallographic film alignment on an amorphous quartz substrate. The data suggest that the evolution of biaxial alignment is nucleation controlled under these conditions.

Tin oxide thin films were grown on Si(100) substrates by a hybrid ion beam consisting of a partially ionized beam and a cold hollow cathode ion source. Tin metal particles were ionized and accelerated by a partially ionized ion beam source while oxygen gas was introduced or ionized oxygen was introduced upon the Si substrate. When oxygen gas was blown near the substrate during Sn metal evaporation, the composition of deposited tin oxide films revealed mainly Sn metal and SnO, whereas tin dioxide films with highly preferred orientation of SnO2<200 or SnO2<110 axis were successfully grown when ionized oxygen was assisted. The calculated value of the composition ratio of oxygen to Sn(O/Sn) by AES for the SnO2(200) film was approximately 1.98. Moreover, the binding energy of Sn 3d5/2 was determined to be at 486.74 eV by XPS measurement, and the result coincided well with that of standard SnO2 powder. Compared with two different deposition processes, ionized oxygen assistance during tin metal evaporation would be considered to effectively improve oxygen content for the formation of tin dioxide thin films.

Tin oxide films with highly preferred orientation along <101 axis were grown on Si(100) substrate by using reactive ion assisted deposition method. The impinging average ion energy per depositing Sn atom was changed from 10 to 100 eV/atom. Oxygen content in the deposited tin oxide films increased as average impinging ion energy were raised. The maximum XRD peak intensity appeared when the average energy of about 50 eV/atom was applied. From quantitative Auger electron spectroscopy, characteristic transitional Auger peaks of Sn MNN were shifted to lower kinetic energies as much as 4 ∼ 6±1.0 eV as the Sn4+ component became dominant in the deposited tin oxide films. On the basis of a tin 3d core level spectra analysis by XPS, it was determined that a sizable chemical shift of 1.0±0.02 eV occurred between stannous tin(Sn2+:SnO) and stannic tin(Sn4+:SnO2). The optical transmittance was also measured in the wavelength range from 200 to 800 nm for tin oxide films deposited on BK7 glass substrate.

A compact negative metal ion beam source for direct low energy metal ion beam depositions studies in ultra high vacuum (UHV) environment, has been developed. The ion source is based on SKION's Solid State Ion Beam Technology. The secondary negative metal ion beam is effectively produced by primary cesium positive ion bombardment (negative ion yield varies from 0.1-0.5 for carbon). The beam diameter is in the range of 0.2∼3.0 cm depending on the focusing and ion beam energy. The ion source produces negative ion currents of about 0.8 mA/cm2. The energy spread of the ion beam is less then ±5% of the ion beam energy. The energy of negative metal ion beam can be independently controlled in the range of 10-300 eV. Due to the complete solid state ion technology , the source can be operated while maintaining chamber pressures of less then 10-10 Torr.

A novel rectilinear negative carbon ion beam source for large-area coatings has been developed, based on SKION's Solid State Ion Beam Technology. The negative carbon ion beam is effectively produced by a primary cesium ion bombardment and the secondary negative carbon ion yield has been observed to be about 0.5. The ion source produces a negative carbon ion current density of 0.25 mA/cm2 at the extraction voltage of 4 kV. The ion beam energy can be independently controlled from 0 eV to 300 eV. Due to the rectilinear geometry for the production of ion beams, the scale-up of the ion beam in length direction can be easily obtained with no limit. Furthermore, the ion source uses no gas discharge to generate ion beams and does not use any hydrogen gas. The ion source can be operated in a high vacuum (<10-7 Torr), and the cesium vapors are filtered and recirculated. The ion source produces ultra-hard (50 GPa), atomically smooth (< 1 nm Ra), and hydrogen-free amorphous diamond-like-carbon (DLC) films over large areas.

Two types of the ion sources for ion beam assisted deposition using inert gases, oxygen or nitrogen are reported. Their design and operational features are presented. Each of them has the properties of two existing main types of the gridless Hall sources: an end-Hall source and the anode-layer version a closed-drift ion source. Basic distinction of the developed sources is the extended range of ion energies in high-current beam for optimization of deposition, cleaning and etching processes.

During 1995, a state-of-the-art intermediate voltage electron microscope (IVEM) has been installed in the HVEM-Tandem Facility with in situ ion irradiation capabilities similar to those of the HVEM. A 300 kV Hitachi H-9000NAR has been interfaced to the two ion accelerators of the Facility, with a spatial resolution for imaging which is nearly an order of magnitude better than that for the 1.2 MV HVEM which dates from the early 1970s. The HVEM remains heavily utilized for electron- and ion irradiation-related materials studies, nevertheless, especially those for which less demanding microscopy is adequate. The capabilities and limitations of this IVEM and HVEM are compared. Both the HVEM and IVEM are part of the DOE funded User Facility and therefore are available to the scientific community for materials studies, free of charge for non-proprietary research.

Analysis of fired rails from electromagnetic railguns indicates severe surface damage occurs due to high current arcing and tribological mismatch. We have explored the behavior of several nanoscale multilayered materials as possible routes to improve the thermomechanical properties of the rail and armature materials . Structures investigated include (i) Ti-Co alloy on Ta-Cu alloy on dlc (diamond-like carbon) on stainless steel; (ii) Ti-Co alloy on Ta-Cu alloy on dlc on Cu, (iii) Ti-Co alloy on Ta-Cu on Cu; and (iv) Ti-Co on Ta-Cu alloy on Al. The alloys were all 50:50 at% and film thicknesses were in the range 400-1000 Å. The films were formed using a repetitively pulsed vacuum arc plasma deposition method with substrate biasing- and IBAD-like techniques. The surfaces were characterized by scanning electron microscopy, transmission electron microscopy, Rutherford backscattering spectroscopy, optical microscopy, microhardness measurements, arc erosion resistance and scratch resistance tests. Preliminary results show improvement in the microhardness, arc erosion resistance and scratch resistance, most especially for the dlc-coated surfaces. This kind of multilayered approach to the fabrication of electromagnetic railgun and armature surfaces could be important for future advanced Electromagnetic EM Gun systems.