High-resolution XTEM Research Articles

Microstructure and load bearing capacity of TiN/NbN superlattice coatings deposited on medical grade CoCrMo alloy by HIPIMS

In recent years significant progress has been made in the application of various ceramic, namely Metal nitride (MeN) functional coatings to engineer the surfaces of medical implants utilising metal-on-metal (MoM) articulation. This article reports on the load bearing capacity and structural response of TiN/NbN superlattice coatings deposited on medical grade CoCrMo alloy substrate under the application of localised load and the subsequent crack formation mechanism. The coatings have been deposited by mixed High Power Impulse Magnetron Sputtering-Unbalanced Magnetron Sputtering (HIPIMS-UBM) process. In the case of TiN/NbN coating deposited on CoCrMo substrate where Ecoating/Esubstrate is as high as 1.81 indicating that the substrate does not provide the necessary load bearing support for the brittle thin film, the utilisation of the Berkovich indentation technique proved to be a potent approach to study coating material as well as structural response to applied concentrated load. FIB/SEM analyses of the indented coatings revealed that in the hard-on-soft material systems cracks will initiate due to sub-coating substrate deformation and then propagate towards the coating surface. The FIB/SEM and low magnification XTEM analysis showed that an exceptionally strong TiN/NbN coating substrate adhesion bonding was achieved due to the utilisation of the HIPIMS pre-treatment. High resolution XTEM analyses revealed, for the first time, that during the indentation a collective rotation and alignment of the individual layers of the superlattice stack takes place without compromising coatings integrity which is clear evidence for the exeptionally high coating fracture toughness. The high toughness of the superlattice structured TiN/NbN coatings combined with their exceptionally high adhesion on madical grade CoCrMo ranks them as a strong candidate for medical implant applications.

Fracture-resistant thin-film metallic glass: Ultra-high plasticity at room temperature

We report the first example of room-temperature rubber-like deformation in thin-film metallic glasses (TFMGs), 260-nm-thick Zr60Cu24Al11Ni5 layers, under ultra-high shear strain. The TFMGs were deposited, with no external heating, on Zr-based bulk metallic glass (BMG) and Si(001) substrates by rf magnetron sputtering in a 3 mTorr Ar plasma. Cross-sectional transmission electron microscopy (XTEM) analyses and nanoindentation results reveal that the TFMGs undergo an incredibly large shear strain, estimated to be ∼4000%, during fatigue tests, and thickness reductions of up to 61.5%, with no shear-banding or cracking, during extreme nanoindentation experiments extending through the film and into the substrate. TFMG/BMG samples also exhibit film/substrate diffusion bonding during deformation as shown by high-resolution XTEM.

Mechanism of NiSi0.7Ge0.3 epitaxial growth by Al interlayer mediation at 700 ℃

The formation of Nickel based germanosilicides (NiSiGe) has attracted growing interest in the state-of-the-art metal oxide semiconductor field effect transistor (MOSFET) technology, because silicon-germanium alloy (Si1-xGex) is used as embedded source/drain stressor or channel material to enhance the hole mobility in the channel region. However, a major problem of NiSiGe film is that it has a poor thermal stability after annealing at high temperature (550 ℃), which leads to its agglomeration. In this work, we study the reaction between Ni and Si0.7Ge0.3 in the presence of an Al interlayer. Pure Ni (10 nm) film and Ni (10 nm)/Al (3 nm) bi-layers are deposited respectively on Si0.7Ge0.3 substrates by electron beam evaporation. Solid-phase reactions between Ni or Ni/Al and Si0.7Ge0.3 during rapid thermal processing in N2 ambient for 30 s are studied at 700 ℃. The un-reacted metal is subsequently etched in H2SO4 solution. The NiSi0.7Ge0.3 films are characterized by Rutherford backscattering spectrometry (RBS), crosssection transmission electron microscopy (XTEM), energy dispersive X-ray spectrometer (EDX), and secondary ion mass spectroscopy (SIMS) techniques. For the Ni/Si0.7Ge0.3 sample, the segregation of Ge at grain boundaries of nickel germanosilicides during the interfacial reactions of Ni with Si0.7Ge0.3 films and the subsequent formation of Ge-rich Si1-wGew (w0.3) are confirmed by the RBS and XTEM measurements. However, in the case of Al incorporation, a very uniform and smooth NiSi0.7Ge0.3 film is obtained with atomic NiSi0.7Ge0.3/Si0.7Ge0.3 interface. The orthorhombic NiSi0.7Ge0.3 is finally epitaxial grown on cubic Si0.7Ge0.3substrate tilted at a small as demonstrated by the High resolution XTEM. Furthermore, based on the EDX and SIMS measurements, it is found that most of the Al atoms from the original interlayer diffuse towards the NiSi0.7Ge0.3 surface, and finally form an oxide mixture layer. It is proposed that the addition of Al reduce Ni diffusion, balance the Ni/Si0.7Ge0.3 reaction and mediate the NiSi0.7Ge0.3 lattice constant. In addition, the main mechanism of epitaxial growth of NiSi0.7Ge0.3 film is analyzed in detail. In summary, Al mediation is experimentally proved to induce the epitaxial growth of uniform and smooth NiSi0.7Ge0.3 layer on relaxed Si0.7Ge0.3 substrate, providing a potential method of achieving source/drain contact material for SiGe complementary metal oxide semiconductor devices.

Rational Design of Monocrystalline (InP)yGe5–2y/Ge/Si(100) Semiconductors: Synthesis and Optical Properties

In this work, we extend our strategy previously developed to synthesize functional, crystalline Si(5-2y)(AlX)y {X = N,P,As} semiconductors to a new class of Ge-III-V hybrid compounds, leading to the creation of (InP)(y)Ge(5-2y) analogues. The compounds are grown directly on Ge-buffered Si(100) substrates using gas source MBE by tuning the interaction between Ge-based P(GeH3)3 precursors and In atoms to yield nanoscale "In-P-Ge3" building blocks, which then confer their molecular structure and composition to form the target solids via complete elimination of H2. The collateral production of reactive germylene (GeH2), via partial decomposition of P(GeH3)3, is achieved by simple adjustment of the deposition conditions, leading to controlled Ge enrichment of the solid product relative to the stoichiometric InPGe3 composition. High resolution XRD, XTEM, EDX, and RBS indicate that the resultant monocrystalline (InP)(y)Ge(5-2y) alloys with y = 0.3-0.7 are tetragonally strained and fully coherent with the substrate and possess a cubic diamond-like structure. Molecular and solid-state ab initio density functional theory (DFT) simulations support the viability of "In-P-Ge3" building-block assembly of the proposed crystal structures, which consist of a Ge parent crystal in which the P atoms form a third-nearest-neighbor sublattice and "In-P" dimers are oriented to exclude energetically unfavorable In-In bonding. The observed InP concentration dependence of the lattice constant is closely reproduced by DFT simulation of these model structures. Raman spectroscopy and ellipsometry are also consistent with the "In-P-Ge3" building-block interpretation of the crystal structure, while the observation of photoluminescence suggests that (InP)(y)Ge(5-2y) may have important optoelectronic applications.

Microstructure and superconducting properties of YBa2Cu3O7−δ thin films incorporated with a self-assembled magnetic vertically aligned nanocomposite

A thin layer of a vertically aligned nanocomposite (VAN) with separated phases of ferromagnetic Fe2O3 and non-magnetic CeO2, arranged as alternating nanopillars, is introduced in YBa2Cu3O7−δ (YBCO) thin films as either a cap or a buffer layer using a pulsed laser deposition method. Detailed microstructural characterization including XRD, high resolution XTEM and STEM is conducted and correlated with the superconducting properties to investigate the flux pinning properties introduced by the magnetic VAN layers. The Tc values of both doped samples are above 89 K and the measured at 65 K increased to 150% of that of the reference YBCO prepared under the same conditions. As the measurement temperature decreases, the magnetic pinning effect increases and the field dependent Jc(H ∥ c) is further improved to more than 200% of the Jc value of the reference YBCO sample. This suggests that the Fe2O3:CeO2 VAN can provide both ordered magnetic pillars and controlled defect density. Furthermore, the magnetic pillars are very effective pinning centers especially in the high field and low temperature regime.

Nanosynthesis Routes to New Tetrahedral Crystalline Solids: Silicon-like Si3AlP

We introduce a synthetic strategy to access functional semiconductors with general formula A(3)XY (A = IV, X-Y = III-V) representing a new class within the long-sought family of group IV/III-V hybrid compounds. The method is based on molecular precursors that combine purposely designed polar/nonpolar bonding at the nanoscale, potentially allowing precise engineering of structural and optical properties, including lattice dimensions and band structure. In this Article, we demonstrate the feasibility of the proposed strategy by growing a new monocrystalline AlPSi(3) phase on Si substrates via tailored interactions of P(SiH(3))(3) and Al atoms using gas source (GS) MBE. In this case, the high affinity of Al for the P ligands leads to Si(3)AlP bonding arrangements, which then confer their structure and composition to form the corresponding Si(3)AlP target solid via complete elimination of H(2) at ∼500 °C. First principle simulations at the molecular and solid-state level confirm that the Si(3)AlP building blocks can readily interlink with minimal distortion to produce diamond-like structures in which the P atoms are arranged on a common sublattice as third-nearest neighbors in a manner that excludes the formation of unfavorable Al-Al bonds. High-resolution XRD, XTEM, and RBS indicate that all films grown on Si(100) are tetragonally strained and fully coherent with the substrate and possess near-cubic symmetry. The Raman spectra are consistent with a growth mechanism that proceeds via full incorporation of preformed Si(3)AlP tetrahedra with residual orientational disorder. Collectively, the characterization data show that the structuro-chemical compatibility between the epilayer and substrate leads to flawless integration, as expected for pseudohomoepitaxy of an Si-like material grown on a bulk Si platform.

Microstructure of Epitaxial Y123 Films on ${\rm CeO}_{2}$-Buffered YSZ Prepared by Fluorine-Free MOD

Epitaxial YBa2Cu3O7 (Y123) films have been prepared by fluorine-free metalorganic deposition (MOD) using a metal acetylacetonate-based coating solution on cerium oxide (CeO2: 40 nm)-buffered yttria-stabilized zirconia (CbYSZ) substrates. The 210-nm-thick Y123 film demonstrated a high critical current density (Jc), the average Jc being 4.5 MA/cm2 at 77.3 K using an inductive method. However, with increasing thickness the Jc values decreased; the average Jc was 3.4 and 2.2 MA/cm2 for 400-nm- and 550-nm-thick films, respectively. In low-magnification cross sectional transmission electron microscopy (XTEM) images for the films, the stripe-like contrast due to the c-axis orientation of Y123 was clearly seen from the interface with CeO2 to the surface. The whole c-axis-oriented Y123 layers were very dense even in the 550-nm-thick film. Full width at half maximum (FWHM) of Deltaomega for the 308/038 reflections in XRD omega - 2thetas scanning decreased with increasing film thickness. High resolution XTEM images of the 550-nm-thick film showed wavy c-planes of Y123 due to the short stacking faults near the interface with CeO2 buffer and near the surface whereas the c-planes were very flat but contained long stacking faults in the middle part of the film. It is suggested that the absence of wavy stacking faults, which probably work as pinning centers, decreased Jc in the thicker films. Further decrease in Jc in the 550-nm-thick film is presumably caused by the roughness in the outer layer near the surface.

Cross-sectional Transmission Electron Microscopy of Interface Structure of β-FeSi2/Si(100) Prepared by Ion Beam Sputter Deposition

The effect of a silicon substrate surface pretreatment on epitaxial iron silicide film formation on a Si(100) substrate with ion beam sputter deposition (IBSD) was investigated. In this study, two surface pretreatment methods namely, thermal etching (TE) and sputter etching (SE) with subsequent thermal annealing, were employed. The interface structure between a β-FeSi2 film and a Si substrate was analyzed by cross-sectional observation using a transmission electron microscope (XTEM). High-resolution XTEM images showed that the lattice of the Si substrate is an almost perfect crystal immediately after the TE treatment. However, the TE treatment results in an undulated interface, and the deposited silicide contained coalesced β-FeSi2 islands. On the other hand, the dislocations and stacking faults produced by radiation damage were observed near the Si substrate surface for the SE treatment. Even though this treatment produced defects, the interface of the SE-treated epitaxial β-FeSi2(100) film had a smooth interface after the deposition at 973 K. It can be concluded that a moderate disorder of the silicon substrate surface treated by SE may well enhance the mixing of Fe and Si atoms for the epitaxial growth of β-FeSi2.

Epitaxial film growth of zirconium diboride on Si(0 0 1)

The structure of epitaxial ZrB 2 films grown on Si(0 0 1) substrates via the thermal decomposition of the unimolecular precursor Zr(BH 4) 4 was studied by X-ray diffraction, atomic force microscopy, and cross-sectional transmission electron microscopy (XTEM). In spite of the large lattice mismatch between the Si(0 0 1) substrate and ZrB 2, epitaxy occurs via a coincidence-misfit mechanism in which the strain between film and substrate is accommodated by edge dislocations along the film–substrate interface. While the growth axis of the ZrB 2 film lies along the [ 1 1 ̲ 0 0 ] direction, i.e. [ 1 1 ̲ 0 0 ] ZrB 2 / / [ 0 0 1 ] Si , the epitaxy produces two orthogonal domains as the result of a 6:5 misfit for [ 1 1 2 ̲ 0 ] ZrB 2 / / [ 1 1 ̲ 0 ] Si and a 13:12 misfit for [ 0 0 0 1 ̲ ] ZrB 2 / / [ 1 1 ̲ 0 ] Si along the same direction on the interface plane. These domains take the form of two-dimensional rectangular islands orthogonal to each other. The island–substrate and island–island interfaces were examined in detail with high-resolution XTEM and compared with theoretical models.

Influence of the bias voltage on the structure and the tribological performance of nanoscale multilayer C/Cr PVD coatings

Nanoscale multilayer C/Cr coatings have been deposited by utilising the combined steered cathodic arc/unbalanced magnetron sputtering technique. The coating microstructure and tribological performance have been investigated as a function of the bias voltage, ranging from Ub=−65 to −350 V. The XRD results revealed that C/Cr coatings are amorphous at low Ub, but became more crystalline when the Ub increased to −350 V. High-resolution XTEM analysis indicated coating densification and smoothening as well as formation of novel amorphous nanostructure, in which carbon-rich clusters are surrounded by a Cr-rich matrix, leading to the formation of self-organised multilayer structure as the bias voltage was increased from −65 to −350 V. An increase of the bias voltage from −65 to −350 V resulted in an increase in the hardness from 8 to 25 GPa and Young's modulus, E from 186 to 319 GPa. A pin-on-disc test showed that the friction coefficient was reduced from 0.22 to 0.16 when the bias voltage was increased from −65 to −95 V. However, a further increase in the bias voltage to −350 V led to an increase in the friction coefficient to 0.31. The lowest wear coefficient Kc∼6.25×10−17 m3 N−1 m−1 was achieved at Ub=−120 V. Standard HSS drills, 8 mm in diameter, coated with C/Cr have been tested using solution annealed AISI 304 stainless steel as the work piece material. An improvement of the lifetime by a factor of ∼9 has been achieved as compared to the uncoated tools. In this test, the C/Cr coating outperformed a number of commercially available PVD coatings, such as TiCN, TiAlCrN and showed similar performance to TiAlCrYN.

Solid state diffusion of Sn in polycyrstalline Al films

The formation of a wetting layer of Sn and the Stranski–Krastanov growth of Sn on a polycrystalline Al film surface has been proved recently. In the present experiments the influence of Sn on the structure evolution of Al films has been analyzed in detail. The films were prepared in HV by magnetron sputtering at 180 °C substrate temperature on Si wafers covered by the native oxide. Al and Sn were sequentially sputtered from a 100-mm diameter DC magnetron target. The samples consisted of an Al-base layer (400 nm), a Sn interlayer (10 nm) and an Al-capping layer (400 nm) and were investigated by analytical and high resolution X-TEM, AFM and scanning AES. If the Sn-interlayer is oxidized, no effect on the growth of the Al-capping layer is observable. If, on the other hand, the Sn-interlayer is prevented from oxidation grain growth is promoted in the Al-capping layer as confirmed by X-TEM and AFM. The capping layer contains intragranular line-like features roughly parallel to the substrate plane. Microanalysis shows the presence of Sn in the capping layer and indicates that Sn is associated with these linear features. The promotion of grain growth in the capping layer can be attributed to the permanent transport of Sn to the growth front via grain boundaries which was confirmed by dynamic scanning AES-measurements. The linear intragranular feature formation is explained by the oxidation of Sn on the free surface due to the residual oxygen present in the background gas.

Zn channeled implantation in GaN: damages investigated by using high resolution XTEM and channeling RBS

Zn (140 keV) channeled (along 〈0001〉) implantations in GaN are performed at room temperature and in a dose range from 1×10 13 to 4×10 16 cm −2, respectively. Channeling RBS measurements and the high-resolution XTEM investigations show the two damage regimes after implantation: one at the surface and another in the projected range. The damage level is very small at low doses and then gradually rises with increasing dose. The backscattering yield from the near surface region reaches the random level at doses higher than 2×10 16 cm −2 and the broken crystals and the amorphous in nanometer size are formed in the top thin surface layer after implantation at a dose of 3×10 16 cm −2. In the followed defective crystalline layer, the density of defects decreases with increasing the depth. The thread defects and loops are dominant in the region close to the surface at high dose and the clustered point defects are dominant in the deeper layer.

Lattice expansion induced by Zn channeled implantation in GaN

140 keV Zn channeled implantations in GaN are performed at room temperature and in a dose range from 1×10 13 to 4×10 16/cm 2, respectively. The lattice expansion is calculated from (0 0 0 2) and (0 0 0 4) X-ray diffractions of GaN after channeled implantation. Three dose dependence regimes are observed: the perpendicular lattice parameter initially increases with dose, subsequently varies slowly in an intermediate dose range, and finally diminishes at very high dose. The high-resolution XTEM observations show the different defects, such as the clustered point defect, the thread defects and loops, the broken crystals and the amorphous in nanometer sizes. The variation of lattice expansion is attributed to the changes of density and types of defects.

Early stages of interface reactions between AlN and Ti thin films

The early stages of interface reactions between AlN and Ti thin films were investigated using x-ray diffractions, Auger electron spectroscopy, cross section transmission electron microscopy (XTEM), and high resolution XTEM. The AlN/Ti bilayers were deposited on a molybdenum substrate using reactive and nonreactive magnetron sputtering techniques. After deposition, the bilayers were heat treated for 1–10 h at 600 °C in a nitrogen atmosphere. Decomposition of the AlN layer took place at the AlN/Ti interface and its products, Al and N, reacted with Ti to produce a AlN/Al3Ti/Ti2N/Ti3Al/α-(Ti, Al)ss phase sequence. This phase sequence is not consistent with the Ti–Al–N phase diagram and is believed to be the outcome of the particular conditions that prevail in the thin film and correspond to a particular set of kinetic parameters. A model that explains the development of the phase sequence and predicts its evolution after prolonged heat treatments is put forward. The applicability of such a solid-state reaction technique for producing functionally graded coating for wear and corrosion resistance applications is discussed.

Nanocavity formation processes in MgO( [formula omitted]) by light ion (D, He, Li) and heavy ion (Kr, Cu, Au) implantation

In studies on the controlled growth of metallic precipitates in MgO it is attempted to use nanometer size cavities as precursors for formation of metallic precipitates. In MgO nanocavities can easily be generated by light gas ion bombardment at room temperature with typically 30 keV ion energy to a dose of 10 16 cm −2, followed by annealing to 1300 K. It has been shown earlier by transmission electron microscopy (TEM) that the cavities (thickness 2–3 nm and length/width 5–10 nm) have a perfectly rectangular shape bounded by {1 0 0} faces. The majority of the gas has been released at this temperature and the cavities are stable until annealing at 1500 K. The depth location of the cavities and the implanted ions is monitored by positron beam analysis, neutron depth profiling, RBS/channeling and energy dispersive spectroscopy. The presence of metallic nanoprecipitates is detected by optical absorption measurements and by high-resolution XTEM. Surprisingly, all the metallic implants induce, in addition to metallic precipitates in a band at the mean ion range, small rectangular and cubic nanocavities. These are most clearly observed at a depth shallower than the precipitate band. In the case of gold the cavities are produced in close proximity to the crystal surface. The results indicate that in MgO vacancy clustering dominates over Frenkel-pair recombination. Results of molecular dynamics calculations will be used to discuss the observed defect recovery and clustering processes in MgO.

Enhancement of the direct optical transition in nanocrystallized GaAsN alloys

Using x-ray diffraction, cross-sectional transmission electron microscopy ~XTEM!, and infrared absorption techniques, we have investigated the effects of nanocrystallization on the structural and optical properties of GaAs0.99N0.01 grown by plasma-enhanced molecular-beam epitaxy. The x-ray diffraction results of postgrowth annealed samples with a protective Si3N4 cap exhibit significant lattice relaxation, structural inhomogeneity, and apparent nitrogen ‘‘loss,’’ indicating the occurrence of phase separation after thermal treatment. Highresolution XTEM confirms the formation of N-enriched GaAsN nanocrystals embedded at the GaAsN/Si 3N4 interface. Infrared absorption study demonstrates that the annealed sample has a strongly enhanced direct optical transition.

Epitaxial growth structure and physical properties of Fe film biased dc-plasma sputter deposited on MgO(001)

One hundred-nm-thick Fe film has been deposited on MgO(001) substrate at 250 °C by biased dc-plasma sputtering at 2.9 kV in Ar gas. A dc bias voltage Vs between 0 and −160 V was applied to the substrate during deposition. Reflection high energy electron diffraction, x-ray diffraction, cross sectional transmission electron microscopy (XTEM) and high resolution XTEM were used to investigate the structure of the films. Electrical resistivity at room temperature was measured by four-point probe method. Saturation magnetization of the films at room temperature was measured using a vibration sample magnetometer. As a result, when Vs=−140 V the Fe film could be epitaxially grown with Fe(001)[110]//MgO(001)[100] while the film retained a polycrystalline structure when Vs was higher or lower than −140 V. The minimum electrical resistivity and the maximum saturation magnetization were achieved at Vs=−140 V consistent with the result of the growth structure. In conclusion, when Vs=−140 V the Fe film can be epitaxially grown with the lower defect density under the bombardment of energetic Ar particles accelerated by Vs to increase the mobility of Fe adatoms and to resputter impurity species during the film formation.

The role of defects during amorphization and crystallization processes in ion implanted Si

Amorphization and crystallization processes in ion implanted Si have been investigated using cross-sectional transmission electron microscopy (XTEM) measurements and molecular dynamics (MD) simulations. Amorphization mechanisms in 5 MeV Si+ ion implanted Si were analyzed using XTEM measurements. High-resolution XTEM images of the amorphous/crystalline (a/c) Si interface region indicate that the a/c interface is very sharp and the amorphous Si transition occurs within a few atomic layers. Image simulations based on the divacancy and di-interstitial (D-D) pair model (Phys. Rev. B49 (1994) 16367) suggest that an accumulation of the D-D pairs gives rise to homogeneous amorphization in ion implanted Si and the threshold number of the D-D pairs is ∼0.3 per atom. MD calculations have been performed to simulate solid phase epitaxial growth of Si at a/c interfaces based on the ordinary Langevin equation employing the Tersoff potential for Si. It was found that crystal growth in the [001] direction occurred by attaching Si atoms in the amorphous phase at kink sites associated with {111} facets formed at the a/c interface, while in the [111] direction two-dimensional nucleation was first created on the flat (111) interface and then followed by layer-by-layer growth.

Homogeneous Amorphization in High-Energy Ion Implanted Si

We have investigated amorphization mechanisms in 5 MeV ${\mathrm{Si}}^{+}$ ion implanted Si using cross-sectional transmission electron microscopy (XTEM) measurements. Both microdiffraction patterns and high-resolution XTEM images of the amorphous/crystalline (a/c) Si interface region indicate that the a/c interface is very sharp and the amorphous Si transition occurs within a few atomic layers. Image simulations based on the divacancy and di-interstitial (D-D) pair model [Phys. Rev. B 49, 16 367 (1994)] suggest that an accumulation of the D-D pairs gives rise to homogeneous amorphization in ion implanted Si.

Characterization of cobalt films grown on MgO(001) by dc-biased-sputter deposition

Cobalt films (90 nm thick) were deposited on MgO(001) substrates at 250°C by dc-sputtering at 2.5 kV in pure argon gas. A bias voltage Vs between 0 and − 180 V was applied to the substrate during the deposition. Reflection high-energy electron diffraction, cross-sectional transmission electron microscopy (XTEM) and X-ray photo electron spectroscopy, as well as measurements of the temperature coefficient of resistivity and saturation magnetization (4πMs), all as a function of Vs, confirmed that the structural and physical properties of cobalt films are most improved at − Vs = 140 V with a Co(001)|MgO(001) and Co[010]|MgO[010] relationship. A structural study of cobalt films prepared at − Vs = 140 V by high-resolution XTEM revealed that the stress induced in cobalt films is relaxed by the generation of defects such as misfit dislocations, lattice expansion and partial lattice distortions.