Low-energy Ion Fluxes Research Articles

Plasma sources sputtering nanoscale contaminants with low-energy ion flux on front-end mirrors in ITER optical diagnostics

New plasma sources are proposed to clean optical mirrors in diagnostic instruments of the ITER experiment considering RF discharges operating at low pressures (1–10 Pa) in inert gases. There are nearly twenty optical diagnostics where the front-end optical mirrors may require plasma cleaning. The mirrors vary in size and would need up to 400 W in the discharge to form ion fluxes capable of removing Be- and W-containing contaminants to restore the optical performance with tolerable damage to the mirror. The plasma sources suggested to clean contaminants include a vacuum matching circuit placed close to the mirror and a quarter wavelength band stop notch filter when mirror water cooling is needed. Long-term operation stability and cleaning homogeneity may employ a driving frequency variation to tune the circuit and a phase shift for RF voltages to clean two mirrors simultaneously. In this paper, the plasma sources based on 40 MHz RF discharge to clean first mirrors are studied experimentally for two ITER optical instruments: the Edge Thomson Scattering and the Visible Spectroscopy Reference System. Frequency tuning and phase shifting are studied in realistic configurations prototyping diagnostic port plug geometries.

Plasma low-energy ion flux induced vertical graphene synthesis

Vertical graphene (VG) is a promising material for energy-storage, sensor, and electronic applications, owing to excellent structural, mechanical, and electrical properties. An existing method for synthesizing VG is plasma-enhanced chemical vapor deposition under high plasma ion-energy interaction on carbon surface. However, since this method can cause substrate damage, device performance degradation, and internal defects in VG, a new synthesis method using low-ion-energy is required. Accordingly, it is necessary to understand how the plasma low-ion energy contributes to the nucleation and growth of VG by interaction with the surface, but the reported studies are limited to the high-ion-energy region. Here, we report on the effects of low-energy ion flux in plasma-induced growth of vertical graphene and found the key plasma parameter for the VG growth and nucleation in a low-ion-energy environment and successfully controlled the nucleation of VG. VG deposition and plasma parameter measurements were performed in a radiofrequency inductively coupled plasma. In the low-energy region, the growth rate and nucleation of VG depended strongly on ion density, and insufficient ion flux formed highly disordered carbon. Based on these findings, VG nucleation was controlled by tailoring the ion energy and density under conditions where disordered carbon was formed.

Martian ionosphere observed by Mars Express. 2. Influence of solar irradiance on upper ionosphere and escape fluxes

We present multi-instrument observations of the effects of solar irradiance on the upper Martian ionosphere and escape fluxes based on Mars Express measurements obtained over almost 12 years. It is shown that the variations in the upper ionosphere caused by solar irradiance lead to significant changes in the trans-terminator fluxes of low-energy ions and total ion losses through the tail. The observed dependence of the electron number density in the upper ionosphere at altitudes above 300 km on solar irradiance implies that the ionosphere at such altitudes was denser by a factor of ten during the periods of solar maxima in solar cycles 22–23. Correspondingly, the trans-terminator fluxes of cold ions and escape fluxes through the tail were also significantly higher. We estimate an increase of total ion losses through the tail during these solar maxima by a factor of 5–6.

Atomic fluorine densities in electron beam generated plasmas: A high ion to radical ratio source for etching with atomic level precision

Electron beam generated plasmas are generally characterized by a high plasma density (>1010 cm−3), and very low electron temperatures (<1 eV), making them well-suited for next generation processing techniques where high fluxes of low energy ions are desirable. In addition, both modeling and optical emission spectroscopy indicate relatively low concentrations of atomic radicals compared to discharges. Due to their relevance to industrial etching applications, this work focuses on the characteristics of electron beam generated plasmas produced in fluorine-containing chemistries (SF6, CF4, F2), with particular attention paid to atomic fluorine densities. Atomic F* emission is measured in Ar/SF6, Ar/CF4, and Ar/F2 mixtures and the Ar 750 nm/F 704 nm line ratios are then used to calculate the F atom densities as a function of reactive gas concentration, the first radical density measurement in this type of plasma to date. These results are compared with F atom density calculations performed using a zero dimensional non-local thermodynamic equilibrium Boltzmann code for Ar/SF6 and Ar/F2 mixtures to understand and verify the line ratio analysis. Good agreement between modeling and measurements points to a uniquely high ion-to-atomic radical density in electron beam generated plasmas.

Ultra-thin film microcrystalline silicon with high deposition rate and its application in tandem silicon solar cells

Reducing production cost to accelerate the industrialization process of thin film solar cells (TFSCs) makes it urgently demanded to elevate the deposition rate and reduce the needed thickness of absorbers in addition to the prerequisite performance improvement. Based on very high frequency plasma enhanced chemical vapor deposition process with a low bombardment energy and large ion flux, ultra-thin, high-deposition-rate, and high-performing hydrogenated microcrystalline silicon (c-Si:H) single- and related hydrogenated amorphous silicon (a-Si:H)/c-Si:H double-junction TFSCs are developed in this study. By tuning various process parameters (silane concentration, power, and pressure), the deposition rates and electrical properties of c-Si:H materials are studied in detail. Device-level c-Si:H intrinsic materials with a deposition rate of 10.57 /s and photosensitivity of 7.54102 can be obtained when depositing with a silane concentration of 9%, a power of 70 W, and a pressure of 2.5 Torr. By further applying device-level high-deposition-rate c-Si:H intrinsic materials in c-Si:H single-junction TFSCs on magnetron-sputtered and wet-etched aluminum-doped zinc oxide (ZnO:Al) substrates with optimized surface morphologies and photoelectrical properties, and by combining advanced device designs, an initial conversion efficiency of 7.49% can be achieved for pin-type ultra-thin and high-deposition-rate c-Si:H single-junction TFSCs (the thickness values of intrinsic layers are 1.1~m). To further improve the conversion efficiency of TFSCs, pin-type a-Si:H/c-Si:H tandem TFSCs are fabricated by using n-a-Si/n-c-Si/n-nc-SiOx:H/p-nc-SiOx:H as the tunnel recombination junctions (TRJs), which, however, have unaddressed issues that the wide band-gap nc-SiOx:H materials with a low conductivity strongly reduce the recombination rate of carriers, thereby resulting in the photo-generated carriers accumulating near the TRJs, weakening the built-in electric field in the top sub-cells and leading to an open circuit voltage (Voc) loss in a-Si:H/c-Si:H tandem TFSCs up to 115~mV far above average values. By simultaneously inserting the p- and n-type narrow-gap c-Si:H materials, which are highly defective and narrower than the band gap of nc-SiOx:H materials, into the TRJs to implement the electrically lossless interconnection between the a-Si:H top and c-Si:H bottom sub-cells, the Voc loss is successfully reduced to 43~mV and an initial efficiency of 12.03% (Voc=1.48~eV, Jsc=11.67~mA/cm2, FF=69.59%) is achieved for ultra-thin pin-type a-Si:H/c-Si:H tandem TFSCs with a total thickness of 1.48~m, thus paving the way for the low-cost production of TFSCs.

Spatially dependent cluster dynamics model of He plasma surface interaction in tungsten for fusion relevant conditions

In fusion reactors, plasma facing components (PFC) and, in particular, the divertor will be irradiated with high fluxes of low-energy (∼100 eV) helium and hydrogen ions. Tungsten is one of the leading candidate divertor materials for ITER and DEMO fusion reactors. However, the behaviour of tungsten under high dose, coupled helium/hydrogen exposure remains to be fully understood. The PFC response and performance changes are intimately related to microstructural changes, such as the formation of point defect clusters, helium and hydrogen bubbles or dislocation loops. Computational materials' modelling results are described here that investigate the mechanisms controlling microstructural evolution in tungsten. The aim of this study is to understand and predict sub-surface helium bubble growth under high flux helium ion implantation (∼1022 m−2 s−1) at high temperatures (>1000 K). We report results from a spatially dependent cluster dynamics model based on reaction–diffusion rate theory to describe the evolution of the microstructure under these conditions. The key input parameters to the model (diffusion coefficients, migration and binding energies, initial defect production) are determined from a combination of atomistic modelling and available experimental data. The results are in good agreement with results of an analytical model that is presented in a separate paper. In particular, it is found that the sub-surface evolution with respect to bubble size and concentration of the helium bubbles strongly depends on the flux and temperature.

Deposition and characterization of diamond-like carbon films by microwave resonator microplasma at one atmosphere

Diamond-like carbon (DLC) films have been deposited at atmospheric pressure by microwave-induced microplasma for the first time. Typical precursor gas mixtures are 250ppm of C2H2 in atmospheric pressure He. Chemically resistant DLC films result if the Si (100) or glass substrate is in close contact with the microplasma, typically at a standoff distance of 0.26mm. The films deposited under this condition have been characterized by various spectroscopic techniques. The presence of sp3 CH bonds and ‘D’ and ‘G’ bands were observed from FTIR and Raman spectroscopy, respectively. The surface morphology has been derived from SEM and AFM and shows columnar growth with column diameters of approximately 100nm. Likely due to the low energy of ions striking the surface, the hardness and Young's modulus for the films were found to be 1.5±0.3GPa and 60±15GPa respectively with a film thickness of 2μm. The hypothesis that a high flux of low energy ions can replace energetic ion bombardment is examined by probing the plasma. Rapid deposition rates of 4–7μm per minute suggest that the method may be scalable to continuous coating systems.

Nonthermal X-rays from low-energy cosmic rays: application to the 6.4 keV line emission from the Arches cluster region

The iron line at 6.4 keV provides a valuable spectral diagnostic in several fields of X-ray astronomy. It often results from the reprocessing of external X-rays by a neutral or low-ionized medium, but it can also be excited by impacts of low-energy cosmic rays. This paper aims to provide signatures allowing identification of radiation from low-energy cosmic rays in X-ray spectra showing the 6.4 keV line. We study in detail the production of nonthermal line and continuum X-rays by interaction of accelerated electrons and ions with a neutral ambient gas. Corresponding models are then applied to XMM-Newton observations of the X-ray emission emanating from the Arches cluster region near the Galactic center. Bright 6.4 keV line structures are observed around the Arches cluster. This emission is very likely produced by cosmic rays. We find that it can result from the bombardment of molecular gas by energetic ions, but probably not by accelerated electrons. Using a model of X-ray production by cosmic-ray ions, we obtain a best-fit metallicity of the ambient medium of 1.7 plus-minus 0.2 times the solar metallicity. A large flux of low-energy cosmic ray ions could be produced in the ongoing supersonic collision between the star cluster and an adjacent molecular cloud. We find that a particle acceleration efficiency in the resulting shock system of a few percent would give enough power in the cosmic rays to explain the luminosity of the nonthermal X-ray emission. Depending on the unknown shape of the kinetic energy distribution of the fast ions above 1 GeV per nucleon, the Arches cluster region may be a source of high-energy gamma-rays detectable with the Fermi Gamma-ray Space Telescope. At present, the X-ray emission prominent in the 6.4 keV Fe line emanating from the Arches cluster region probably offers the best available signature for a source of low-energy hadronic cosmic rays in the Galaxy.

VHF radio response of the near Earth space during solar activity growth in October, 2003

The analysis of observations of very high frequency radio noise intensity at the middle latitude on a frequency f=500MHz from 14th till 26th of October, 2003 is presented. These data are compared with the solar radio bursts in the range of frequencies 1–14MHz registered by RAD2 receiver of the WAVES device installed on board the WIND spacecraft.The sporadic enhancement of near Earth very high frequency radio noise were observed with the help of ground radio telescope preferably either in pre mid night hours or at daytime. In many cases between October 17 and 22 short-term increases of the fluxes of low energy electrons, protons and ions in the interplanetary space by hundreds of times, corresponded to VHF radio bursts. At the same time slow increasing of solar cosmic rays streams at Lagrange point L1 and on geostationary orbit during October, 21 and 22, did not affect the usual radio noise level. A strong solar flare of 1B/X5.5 class on October 23 contributed to a prolonged rise of the intensity level of spectral radio emission, including the night sector of magnetosphere. It is assumed that very high frequency radio bursts in the near Earth space may appear when the processes of penetration of interplanetary low energy charge particles into Earth plasmasphere take place.

Hydrogen-induced blistering mechanisms in thin film coatings

We report on the mechanisms of hydrogen-induced blistering of multilayer coatings. Blister formation is a result of highly localized delamination occurring at the two outermost metal-on-silicon interfaces. The number, size, and type of blisters formed varied depending on the composition and ion energy of the incident flux. The results are explained in terms of the multilayer structure being simultaneously susceptible to blistering via two independent mechanisms. A high density of small blisters developed when relatively energetic (several 100 eV) ions were present. Independently, a hydrogenation process that was facilitated by the presence of a small flux of low energy ions (≤50 eV) induced a low density of large blisters.

Low-energy ion fluxes and magnetic field on the inner boundary of the heliosphere

A comparison of temporal profiles of low-energy ion intensity and magnetic field magnitude in different periods of solar activity in the outer heliosphere is carried out using the data of the Voyager 1 and Voyager 2 spacecraft. It is shown that temporal, spectral, and statistical characteristics of particle fluxes and magnetic field in the heliospheric regions before and after the terminal shock in 2002–2008 had similar dynamics in different hemispheres. This similarity allowed one to assume that, in the region of the inner heliospheric boundary, a quasistable spatial structure existed moving together with the terminal shock in accordance with the solar wind pressure, as well as, probably, under the action of the interstellar medium. It was revealed that the spatial dimensions of most details of this structure are less on Voyager 2, which, probably, is due to variation of the solar activity level, difference in latitude of spacecraft disposition, and also the influence of the interstellar magnetic field.

The structure and properties of chromium nitride coatings deposited using dc, pulsed dc and modulated pulse power magnetron sputtering

The time averaged ion energy distributions and ion fluxes of continuous dc magnetron sputtering (dcMS), middle frequency pulsed dc magnetron sputtering (PMS), and modulated pulse power (MPP) magnetron sputtering plasmas were compared during sputtering of a Cr target in an Ar/N 2 atmosphere in a closed field unbalanced magnetron sputtering system. The results showed that the dcMS plasma exhibited a low ion energy and ion flux; the PMS plasma generated a moderate ion flux of multiple high ion energy regions; while the MPP plasma exhibited a significantly increased number of target Cr + and gas ions with a low ion energy as compared to the dcMS and PMS plasmas. Cubic CrN coatings were deposited using these three techniques with a floating substrate bias. The structure and properties of the coatings were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nanoindentation, microscratch and ball-on-disk wear tests. It was found that the deposition rate of the MPP CrN depositions was slightly lower than those of the dcMS depositions, but higher than in the PMS depositions at similar average target powers. The coatings deposited in the dcMS and PMS conditions without the aid of the substrate bias exhibited large columnar grains with clear grain boundaries. On the other hand, the interruption of the large columnar grain growth accompanied with the renucleation and growth of the grains was revealed in the MPP CrN coatings. The MPP CrN coatings exhibited a dense microstructure, fine grain size and smooth surface with high hardness (24.5 and 26 GPa), improved wear resistance (COF = 0.33 and 0.36) and adhesion, which are the results of the low ion energy and high ion flux bombardment from the MPP plasma.

Rotation magnet sputtering: Damage-free novel magnetron sputtering using rotating helical magnet with very high target utilization

Novel magnetron-sputtering equipment, called rotation magnet sputtering (ROT-MS), was developed to overcome various disadvantages of current magnetron-sputtering equipment. Disadvantages include (1) very low target utilization of less than 20%, (2) difficulty in obtaining uniform deposition on the substrate, and (3) charge-up damages and ion-bombardment-induced damages resulting from very high electron temperature (>3eV) and that the substrate is set at the plasma excitation region. In ROT-MS, a number of moving high-density plasma loops are excited on the target surface by rotating helical magnets, resulting in very high target utilization with uniform target erosion and uniform deposition on the substrate. This excellent performance can be principally maintained even if equipment size increases for very large-substrate deposition. Because strong horizontal magnetic fields (>0.05T) are produced within a very limited region just at the target surface, very low electron-temperature plasmas (<2.5eV for Ar plasma and <1eV for direct-current-excited Xe plasma) are excited at the very limited region adjacent to the target surface with a combination of grounded plate closely mounted on the strong magnetic field region. Consequently, the authors can establish charge-up damage-free and ion-bombardment-induced damage-free processes. ROT-MS has been applied for thin-film formation of LaB6, which is well known as a stable, low-work-function bulk-crystal material for electron emissions. The work function of the LaB6 film decreased to 2.8eV due to enhanced (100)-orientation crystallinity and reduced resistivity realized by adjusting the flux of low-energy bombarding ions impinging on the depositing surface, which work very efficiently, improving the performance of the electron emission devices.

Jovian periodicities (∼10 h, ∼40 min) on Ulysses’ Distant Jupiter Encounter observations around the Halloween CIR events

We analyzed data from four different instruments (HI-SCALE, URAP, SWOOPS, VHM/FGM) onboard Ulysses spacecraft (s/c) and we searched for possible evidence of Jovian emissions when the s/c approached Jupiter during the times of Halloween events (closest time approach/position to Jupiter: February 5, 2004/ R = 1683 R J, θ = ∼49°). In particular, we analyzed extensively the low energy ion measurements obtained by the HI-SCALE experiment in order to examine whether low energy ion/electron emissions show a symmetry, and whether they are observed at north high latitudes upstream from the jovian bow shock, as is known to occur in the region upstream from the south bow shock as well ( Marhavilas et al., 2001). We studied the period from October 2003 to March 2004, as Ulysses moved at distances 0.8–1.2 AU from the planet at north Jovicentric latitudes <75°, and we present here an example of characteristic Jovian periodicities in the measurements around a CIR observed by Ulysses on days ∼348–349/2003 ( R = 1894 R J, θ = 72°). We show that Ulysses observed low energy ion (∼0.055–4.7 MeV) and electron (>∼40 keV) flux and/or spectral modulation with the Jupiter rotation period (∼10 h) as well as variations with the same period in solar wind parameters, radio and magnetic field directional data. In addition, characteristic strong ∼40 min periodic variations were found superimposed on the ∼10 h ion spectral modulation. Both the ∼10 h and ∼40 min ion periodicities in HI-SCALE measurements were present in several cases during the whole period examined (October 2003 to March 2004) and were found to be more evident during some special conditions, for instance during enhanced fluxes around the start (forward shock) and the end (reverse shock) of CIRs. We infer that the Jovian magnetosphere was triggered by the impact of the CIRs, after the Halloween events, and it was (a) a principal source of forward and reverse shock-associated ion flux structures and (b) the cause of generation of ∼10 h quasi-periodic magnetic field and plasma modulation observed by Ulysses at those times.

Generation of space charge compensated low energy ion flux

The results of an experimental study of low-energy (<200 eV) ion flux generation with space charge neutralization are presented. Argon was used as a working gas. The working gas pressure in the vacuum chamber was 2-4 x 10(-2) Pa. Ion beam was extracted from the hollow cathode of main discharge plasma by a single mesh extractor with subsequent deceleration of ions to a required energy in a layer between the mesh and the beam plasma. The ion beam current was measured on the collector located on the distance of 30-60 cm from the discharge system. The penetration of electron component from the main discharge plasma through the mesh into the region of the ion beam drift space was realized by potential barrier reduction, in conditions of the optimal extractor potential with respect to the hollow cathode. The space charge neutralization of low-energy ion beam resulted in drift space plasma potential reduction and ion beam current growth. At the main discharge current of 1 A and main discharge voltage of 300 V, the ion beam current of up to 100 mA with the ion energy of 50-150 eV was obtained.

Deuterium retention in tungsten exposed to low-energy, high-flux clean and carbon-seeded deuterium plasmas

Depth profiles of deuterium trapped in tungsten exposed to a low-energy (≈200 eV/D) and high deuterium ion flux (about 1 × 10 21 D/m 2 s) in clean (We use the term ‘clean’ in quotation marks having in mind the impossibility to obtain absolutely clean plasma. In our case the conception ‘clean’ D plasma means the plasma without intentionally introduced carbon impurities.) and carbon-seeded D plasmas at an ion fluence of about 2 × 10 24 D/m 2 and various temperatures have been measured up to a depth of 7 μm using the D( 3He, p) 4He nuclear reaction at a 3He energy varied from 0.69 to 4.0 MeV. The deuterium retention in single-crystalline and polycrystalline W increases with the exposure temperature, reaching its maximum value at about 500 K (for ‘clean’ plasma) or about 600 K (for carbon-seeded plasma), and then decreases as the temperature grows further. It is assumed that tungsten carbide formed on the W surface under exposure to the carbon-seeded D plasmas serves as a barrier layer for diffusion and prevents the outward transport of deuterium, thus increasing the D retention in the bulk of tungsten.

Low temperature magnetron sputter deposition of polycrystalline silicon thin films using high flux ion bombardment

We demonstrate that the microstructure of polycrystalline silicon thin films depends strongly on the flux of low energy ions that bombard the growth surface during magnetron sputter deposition. The deposition system is equipped with external electromagnetic coils which, through the unbalanced magnetron effect, provide direct control of the ion flux independent of the ion energy. We report the influence of low energy (&amp;lt;27eV) Ar+ on the low temperature (&amp;lt;450°C) growth of polycrystalline silicon thin films onto amorphous substrates. We use spectroscopic ellipsometry, Raman scattering, x-ray diffraction, and cross sectional transmission electron microscopy to analyze the film microstructure. We demonstrate that increasing the flux ratio of Ar+ ions to silicon neutrals (J+∕J0) during growth by an order of magnitude (from 3 to 30) enables the direct nucleation of polycrystalline Si on glass and SiO2 coated Si at temperatures below 400°C. We discuss possible mechanisms for this enhancement of crystalline microstructure, including the roles of enhanced adatom mobility and the formation of shallow, mobile defects.

Low-energy ion precipitation during the Halloween storm

During the Halloween storm of October 29–31, 2003, four defense meteorological satellite program (DMSP) satellites detected fluxes of low-energy ions precipitating well equatorward of auroral electrons in the dawn/morning magnetic local time sector during the main phase. There were three southward turnings of the interplanetary magnetic field (IMF), leading to three intensifications of the ring current to DST values of −125, −310 and −350 nT. In each case the ion fluxes weakened dramatically and/or vanished during DST recoveries. DMSP only encountered short-lived episodes of subauroral ion precipitation in the dusk/evening sector. A brief survey of the DMSP database reveals that near-dawn, ion precipitation is a main-phase characteristic of all large magnetic storms. DMSP satellites also detected similar ion precipitation during the main phase of the March 1991 magnetic storm. During an outbound pass of the combined release radiation effect satellite (CRRES) through the inner magnetosphere it detected low energy (<1 keV) ion fluxes that were collocated with, but spectrally separated in energy from the ring current “nose structure”. As CRRES moved toward perigee in the dawn sector, it crossed similar low-energy (⩽500 eV) ions embedded in a broad ion population, located earthward of plasma sheet electrons. Simultaneously the DMSP F8 satellite detected spectrally similar low-energy ions precipitating at subauroral latitudes near dawn at the same invariant latitudes. To reconcile DMSP/CRRES observations with elementary concepts of allowed ion drift paths, the data suggest two source populations. The lowest-energy ions, of ionospheric origin, were initially energized earthward of the plasma sheet electron boundary in the evening local-time sector then co-rotated eastward. Higher-energy ions originated in the plasma sheet and drifted close to the Earth under the combined influences of time-varying convective electric fields and azimuthal gradients in the Earth's magnetic field generated by the stormtime ring current [Tsyganenko, N.A., Singer, H. J., Kasper, J. C., 2003. Storm-time distortion of the inner magnetosphere: how severe can it get? Journal of Geophysical Research, 108 (A5), 1209].

Effect of Low-Energy Ion Flux Irradiation on Synthesis of Superhard Nanocomposite Films

Ti–Si–N films were deposited on the grounded Si(100) substrates by inductively coupled plasma (ICP)-assisted magnetron sputtering. The incident ion flux density at the substrate was varied by controlling the RF power. The effects of low-energy ion flux irradiation on the growth, microstructure and mechanical properties of the Ti–Si–N films have been investigated. An increase in ion flux density causes a transfer of the preferred orientation from TiN(111) to TiN(200). Under the conditions of high-density (∼2.0 mA/cm2) low-energy (∼20 eV) ion irradiation, low-stressed superhard nanocrystalline TiN/amorphous Si3N4 (nc-TiN/a-Si3N4) film was synthesized at the relatively low deposition temperature of 300 °C.

Effects of Copper Doping on Structure and Properties of TiN Films Prepared by Magnetron Sputtering Assisted by Low Energy Ion Flux Irradiation

Ti–Cu–N films containing approximately 0–10 at. % Cu were deposited on Si(100) substrates with high-density low-energy ion flux irradiation by inductively coupled plasma (ICP)-assisted magnetron sputtering. The effects of Cu doping on film microstructures, morphology and properties were investigated. The addition of a small amount of Cu markedly modified the preferred orientation and morphology, and significantly increased film hardness. A Ti–Cu–N film containing 2 at. % Cu has a maximum hardness of approximately 42 GPa. This film was characterized as having a nanocomposite structure, consisting of nanocolumns of TiN crystallites with very small Cu crystallites inside the column boundaries. The hardness increase was attributed to a nanocomposite effect.