Browsing by Subject "Thin Films"

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Open Access
Atomic layer deposition of III-nitrides and metal oxides : their application in area selective ALD
(2017-07) Haider, Ali
III-nitride compound semiconductor materials (GaN, AlN, and InN) and their alloys have generated significant interest in both basic research and commercial applications mainly in the field of photonics, energy storage, nano-sensors, and nano-(opto)electronics. Wurtzite type III-nitrides exhibit direct band gaps, which extend from the ultra-violet (UV) to the mid-IR spectrum with values of 6.2, 3.4 and 0.64 eV for AlN, GaN, and InN, respectively. This feature allows the band gap of III-nitride alloys to be conveniently tuned by precisely controlling the composition for a particular application. Metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) are the most common successful techniques for achieving high-quality epitaxial III-nitride layers with low impurity concentrations and decent electrical properties. However, both of these methods employ high growth temperatures, which is neither compatible with the existing CMOS technology nor suitable for temperature-sensitive device layers (e.g. In-rich InxGa1-xN) and substrates (e.g. glass, flexible polymers, etc.). These limitations are the main driving source for a continuous exploration of alternative low temperature processes for the growth of III-nitride layers and their alloys. High aspect ratio III-nitride nanostructures in the form of nanowires and nanorods have been synthesized using different techniques including vapor-liquid-solid crystal growth, electrospinning, template based synthesis, and etching. Critical breakthroughs in fabrication of III-nitrides nanostructures have been achieved by above mentioned techniques but suffer from limited control over properties of nanostructures (shape, orientation, and size) and in some cases high growth-temperature requirement. A recent flurry of interest in developing high quality I-D III-nitride nanostructures derives from the desire to obtain flexible optoelectronic devices having wider applications. Template-assisted growth technique is one of the most promising approach to fabricate III-nitride nanostructures with precise control over shape, size, position, and distribution. In the first part of thesis, we have deposited InN and III-nitride alloys using hollow-cathode plasma assisted atomic layer deposition (HCPA-ALD) at low growth temperatures. The aim was to deposit III-nitride materials at lowest growth temperatures with decent crystalline quality and minimum impurity content. Depositions were carried out using group III organometallic precursors along with N2/H2 or N2 plasma as metal and nitrogen source, respectively. Process parameters including precursor pulse time, plasma flow duration, purge time, and deposition temperature are investigated and correlations were developed between process parameters and material properties. Refractive index of the InN film deposited at 200 C was found to be 2.66 at 650 nm. 48 nm-thick InN films exhibited relatively smooth surfaces with RMS surface roughness values of 0.98 nm, while the film density was extracted as 6.30 g/cm3. The effect of In content on structural, optical, and morphological properties of InxGa1-xN thin films was investigated. Grazing incidence X-ray diffraction (GIXRD) and transmission electron microscope (TEM) showed that InN and InxGa1-xN thin films were polycrystalline with hexagonal wurtzite structure. Spectral absorption measurements exhibited an optical band edge of InN around 1.9 eV. X-ray photoelectron spectroscopy (XPS) confirmed the deposition of InN and alloy thin films and revealed the presence of low impurity contents. Higher In concentrations resulted in an increase of refractive indices of InxGa1-xN ternary alloys from 2.28 to 2.42 at a wavelength of 650 nm. Optical band edge of InxGa1-xN films red-shifted with increasing In content, confirming the tunability of the band edge with alloy composition. Photoluminescence measurements of InxGa1-xN exhibited broad spectral features with an In concentration dependent wavelength shift. We have also studied the compositional dependence of structural, optical, and morphological properties of BxGa1-xN and BxIn1-xN ternary thin film alloys grown using sequential pulsed CVD. GIXRD measurements showed that boron incorporation in wurtzite lattice of GaN and InN diminishes the crystallinity of BxGa1-xN and BxIn1-xN sample. Refractive index decreased from 2.24 to 1.65 as the B concentration of BxGa1-xN increased from 35 to 88 %. Similarly, refractive index of BxIn1-xN changed from 1.98 to 1.74 for increase in B concentration value from 32 to 87 %, respectively. Optical transmission band edge values of the BxGa1-xN and BxIn1-xN films shifted to lower wavelengths with increasing boron content, indicating the tunability of energy band gap with alloy composition. Atomic force microscopy measurements revealed an increase in surface roughness with boron concentration of BxGa1-xN, while an opposite trend was observed for BxIn1-xN thin films. Moreover, we demonstrate vertical GaN, AlN, and InN hollow nano-cylindrical arrays (HNCs) integrated to Si(100) substrates using anodized aluminum oxide (AAO) membrane templated PA-ALD. Our fabrication and Si-integration strategy consists of the following process steps: (i) reactive ion etching (RIE) of Si using AAO membrane as hard mask material to achieve nanoporous Si substrate, (ii) conformal growth of III-nitride films on nanoporous Si via low-temperature PA-ALD, (iii) removal of PA-ALD coated III-nitride material from top surface of Si via plasma etching, and (iv) isotropic dry etching of surrounding Si to attain long-range ordered vertical III-nitride HNCs. The material properties of nanostructured III-nitride materials have been compared with the thin-film counterparts which were also grown using low-temperature PA-ALD. SEM images revealed that long-range ordered arrays of III nitride HNCs were successfully integrated in Si(100) substrates. TEM, GIXRD, and selected area electron diffraction (SAED) cumulatively confirmed that III-nitride HNCs possess hexagonal wurtzite crystalline structure. XPS survey and high-resolution scans detected presence of different elements and peaks at specific binding energies which confirmed the formation of III-nitride HNCs. The second part of the thesis deals with self-aligned thin film patterning of metal oxides using area selective atomic layer deposition (AS-ALD). Nanoscale process integration demands novel nano-patterning techniques in compliance with the requirements of next generation devices. Conventionally, top-down subtractive (etch) or additive (deposition/lift-off) processes in conjunction with various lithography techniques is employed to achieve film patterning, which become increasingly challenging due to the ever-shrinking misalignment requirements. To reduce the complexity burden of lithographic alignment in critical fabrication steps, self-aligned processes such as selective deposition and selective etching might provide attractive solutions. We demonstrate a methodology to achieve AS-ALD by using inductively couple plasma (ICP) grown fluorocarbon polymer film as growth inhibition layer. The fluorocarbon layer was grown using C4F8 feed gas in a conventional ICP-etch reactor. Our approach has been tested for metal-oxides including ZnO, Al2O3, TiO2, and HfO2. Additionally, we investigate the poly(methyl methacrylate) (PMMA) and polyvinylpyrrolidone (PVP) as growth inhibition layers for AS-ALD of TiO2. Contact angle, XPS, spectroscopic ellipsometer, energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) measurements were performed to investigate the blocking ability of polymer layers against ALD-grown films. Characterizations carried out revealed that effective blocking on fluorocarbon layer is achieved for ZnO film upto 136 growth cycles. On the other hand, a rather slow nucleation has been observed for HfO2 growth on fluorocarbon coated surfaces, while TiO2 and Al2O3 growth showed almost no delay with a growth rate equal to the ones on conventional substrate surfaces. For TiO2, PMMA revealed successful growth inhibition upto the maximum inspected growth cycles while PVP was able to block TiO2 growth upto 300 growth cycles. By exploiting this inhibition feature, thin film patterning has been demonstrated by growing ZnO films on photo lithographically patterned fluorocarbon/Si samples. We also demonstrate nanoscale patterned deposition of TiO2 using a PMMA masking layer that has been patterned using e-beam lithography.
Open Access
Atomic layer deposition of metal oxide thin films and nanostructures
(2013) Dönmez, İnci
With the continuing scaling down of microelectronic integrated circuits and increasing need for three-dimensional stacking of functional layers, novel or improved growth techniques are required to deposit thin films with high conformality and atomic level thickness control. As being different from other thin film deposition techniques, atomic layer deposition (ALD) is based on selflimiting surface reactions. The self-limiting film growth mechanism of ALD ensures excellent conformality and large area uniformity of deposited films. Additionally, film thickness can be accurately controlled by the number of sequential surface reactions. Gallium oxide (Ga2O3) thin films were deposited by plasma-enhanced ALD (PEALD) using trimethylgallium as the gallium precursor and oxygen plasma as the oxidant. A wide ALD temperature window was observed from 100 to 400 °C, where the deposition rate was constant at ~0.53 Å/cycle. The deposition parameters, composition, crystallinity, surface morphology, optical and electrical properties were studied for as-deposited and annealed Ga2O3 films. In order to investigate the electrical properties of the deposited films, metal-oxide-semiconductor capacitor structures were fabricated for a variety of film thicknesses and annealing temperatures. Ga2O3 films exhibited decent dielectric properties after crystallization upon annealing. Dielectric constant was increased with film thickness and decreased slightly with increasing annealing temperature. As an additional PEALD experiment, deposition parameters of In2O3 thin films were studied as well, using the precursors of cyclopentadienyl indium and O2 plasma. Initial results of this experiment effort are also presented. Accurate thickness control, along with high uniformity and conformality offered by ALD makes this technique quite promising for the deposition of conformal coatings on nanostructures. This thesis also deals with the synthesis of metal oxide nanotubes using organic nanofiber templates. Combination of electrospinning and ALD processes provided an opportunity to precisely control both diameter and wall thickness of the synthesized nanotubes. As a proof-ofconcept, hafnia (HfO2) nanotubes were synthesized using three-step approach: (i) preparation of the nylon 6,6 nanofiber template by electrospinning, (ii) conformal deposition of HfO2 on the electrospun polymer template via ALD using the precursors of tetrakis(dimethylamido)hafnium and water at 200 °C, and (iii) removal of the organic template by calculation to obtain freestanding HfO2 nanotubes (hollow nanofibers). When the same deposition procedure was applied on nanofibers with different average fiber diameters, thinner HfO2 wall thicknesses were obtained for the templates having smaller diameters due to insufficient exposure of precursor molecules to saturate their extremely large surface area. Thus, “exposure mode” was applied to obtain the desired wall thickness while coating high-surface area nanofibers. We present the experimental efforts including film deposition parameters, structural, elemental, and morphological properties of HfO2 nanotubes.
Open Access
Fabrication of mesoporous metal chalcogenide nanoflake silica thin films and spongy mesoporous CdS and CdSe
(Wiley Online Library, 2012-02-16) Türker, Y.; Karakaya, C.; Dag, Ö.
Mesoporous silica metal oxide (ZnO and CdO) thin films have been used as metal ion precursors to produce the first examples of mesoporous silica metal sulfide (mesoSiO2@ZnS, meso-SiO2@CdS) or silica metal selenide (meso-SiO2@ZnSe, meso-SiO2@CdSe) thin films, in which the pore walls are made up of silica and metal sulfide or metal selenide nanoflakes, respectively. A gentle chemical etching with a dilute HF solution of the meso-SiO2@CdS (or mesoSiO2@CdSe) produces mesoporous cadmium sulfide (meso-CdS) (or cadmium selenide, meso-CdSe). Surface modified meso-CdS displays bright blue photoluminescence upon excitation with a UV light. The mesoporous silica metal oxides are formed as metal oxide nanoislands over the silica walls through a self-assembly process of a mixture of metal nitrate salt-two surfactants-silica source followed by calcination step. The reactions, between the H2S (or H2Se) gas and solid precursors, have been carried out at room temperature and monitored using spectroscopy and microscopy techniques. It has been found that these reactions are: 1) taking place through the diffusion of sulfur or selenium species from the top metal oxide layer to the silica metal oxide interface and 2) slow and can be stopped at any stage to obtain mesoporous silica metal oxide metal sulfide or silica metal oxide metal selenide intermediate thin films.
Open Access
High-refractive-index measurement with an elastromeric grating coupler
(Optical Society of America, 2005) Kocabas, A.; Ay, F.; Dana, A.; Kiyat, A.; Aydınlı, Atilla
An elastomeric grating coupler fabricated by the replica molding technique is used to measure the modal indices of a silicon-on-insulator (SOI) planar waveguide structure. Because of the van der Waals interaction between the grating mold and the waveguide, the elastomeric stamp makes conformal contact with the waveguide surface, inducing a periodic index perturbation at the contact region. The phase of the incident light is changed to match the guided modes of the waveguide. The modal and bulk indices are obtained by measuring the coupling angles. This technique serves to measure the high refractive index with a precision better than 10(-3) and allows the elastomeric stamp to be removed without damaging the surface of the waveguide.
Open Access
Low temperature thin films transistors with hollow cathode plasma-assisted atomic layer deposition based GaN channels
(AIP Publishing LLC, 2014) Bolat, S.; Ozgit Akgun, C.; Tekcan, B.; Bıyıklı, Necmi; Okyay, Ali Kemal
We report GaN thin film transistors (TFT) with a thermal budget below 250 °C. GaN thin films are grown at 200 °C by hollow cathode plasma-assisted atomic layer deposition (HCPA-ALD). HCPA-ALD-based GaN thin films are found to have a polycrystalline wurtzite structure with an average crystallite size of 9.3 nm. TFTs with bottom gate configuration are fabricated with HCPA-ALD grown GaN channel layers. Fabricated TFTs exhibit n-type field effect characteristics. N-channel GaN TFTs demonstrated on-to-off ratios (ION/I OFF) of 103 and sub-threshold swing of 3.3 V/decade. The entire TFT device fabrication process temperature is below 250 °C, which is the lowest process temperature reported for GaN based transistors, so far. © 2014 AIP Publishing LLC.
Open Access
Micro and nanostructured devices for thermal analysis
(2008) Şenlik, Özlem
The recent advent of micro and nano devices increased the interest in small scale material properties, such as elasticity, conductivity or heat capacity, which are considerably different from their bulk counterparts due to, primarily, increasing surface to volume ratios. These novel properties must be analyzed by using ultra-sensitive devices since characterization of these properties is not possible with conventional probing instrumentation due to their large mass or volume which decreases signal to noise ratio. Microelectromechanical systems (MEMS) with short response time and high sensitivity are suitable for such measurements, such as very small mass detection (zeptograms) and calorimetry of small volume materials (yoctocalories). In this thesis a MEMS cantilever was used for thermomechanical characterization of thin film amorphous semiconductors. 100 nm thick As2S3 and Ge-As-Se-Te glasses were thermally evaporated onto a bilayer microcantilever. The microcantilever was deflected and vibrated by electrothermal actuation. By monitoring deflection, amplitude and phase of the cantilever oscillation, multiple glass transition and melting points were identified; the effects of the variation of thermal expansion coefficients (CTE), reversible and irreversible heat capacities and Young’s modulus of the thin film samples were observed simultaneously. Hence the possibility of the integration of calorimetry, thermomechanical analysis (TMA) and dynamical mechanical thermal analysis (DMTA) in a single MEMS device was demonstrate
Open Access
Molten Salt Assisted Self-Assembly (MASA) : synthesis of mesoporous silica-ZnO and mesoporous CdO thin films
(2012) Karakaya, Cüneyt
A series of mesostructured salt-silica-two surfactants (salt is [Zn(H2O)6](NO3)2, ZnX or [Cd(H2O)4](NO3)2, CdYand surfactants are cetyltrimethylammonium bromide (CTAB) and 10-lauryl ether, C12H25(OCH2CH2)10OH, C12EO10) thin films were synthesized by changing the Zn(II) or Cd(II)/SiO2 mole ratios. The films were prepared through spin coating of a clear solution of all the ingredients (salt, CTAB, C12E10, silica source (tetramethyl orthosilicate,TMOS, and water) and denoted as meso-silica-ZnX-n and meso-silica-CdY-n, where n is Zn(II) or Cd(II)/SiO2 mole ratios. The synthesis conditions were optimized by using the meso-silica-ZnX-1.14 and meso-silica-CdY-1.14 films and XRD, FT-IR spectroscopy, POM and SEM techniques. The stability of the films, especially in the high salt concentrations, was achieved above the melting point of salts. Slow calcination of the films, starting from the melting point of the salt to 450 oC has produced the mesoporous silica-metal oxide (ZnO and CdO) thin films, and denoted as meso-silica-ZnO-n and meso-silica-CdO-n, with n of 0.29, 0.57, 0.86, 1.14, and 1.43. The calcination process was monitored by measuring the FT-IR spectra and XRD patterns at different temperatures. Structural properties of the mesoporous films have been investigated using FT-IR spectroscopy, XRD, N2 sorption measurements, UV-Vis spectroscopy, SEM, TEM and EDS techniques. It has been found that the meso-silicaZnO-n and meso-silica-CdO-n films consist of nanocrystalline metal oxide nanoplates on the silica pore walls of the mesoporous framework. The formation of nanoplates of metal oxides was confirmed by etching the silica walls using diluted HF solution and by reacting with H2S and H2Se gases. The etching process produced CdO nanoplates without silica framework. The H2S and H2Se reactions with the CdO nanoplates or meso-silica-CdO have converted them to CdS and CdSe nanoplates or meso-silica-CdS and meso-silica-CdSe, respectively. Finally, a hypothetical surface coverage of metal oxide nanoplates has been calculated by combining the data of N2 sorption measurements, UV-Vis spectroscopy and TEM images and found that there is a full coverage of CdO and partial coverage of ZnO over silica walls in the meso-silica-CdO-n and meso-silica-ZnO-n thin films, respectively.
Open Access
Molten-Salt-Asisted self-Assembly (MASA)-synthesis of mesoporous metal titanate-titania, metal sulfi de-titania, and metal selenide-titania thin films
(Wiley Online Library, 2013) Karakaya, C.; Turker, Y.; Dag, Ö.
New synthetic strategies are needed for the assembly of porous metal titanates and metal chalcogenite-titania thin films for various energy applications. Here, a new synthetic approach is introduced in which two solvents and two surfactants are used. Both surfactants are necessary to accommodate the desired amount of salt species in the hydrophilic domains of the mesophase. The process is called a molten-salt-assisted self-assembly (MASA) because the salt species are in the molten phase and act as a solvent to assemble the ingredients into a mesostructure and they react with titania to form mesoporous metal titanates during the annealing step. The mesoporous metal titanate (meso-Zn2TiO4 and meso-CdTiO3) thin films are reacted under H2S or H2Se gas at room temperature to yield high quality transparent mesoporous metal chalcogenides. The H2Se reaction produces rutile and brookite titania phases together with nanocrystalline metal selenides and H2S reaction of meso-CdTiO3 yields nanocrystalline anatase and CdS in the spatially confined pore walls. Two different metal salts (zinc nitrate hexahydrate and cadmium nitrate tetrahydrate) are tested to demonstrate the generality of the new assembly process. The meso-TiO2-CdSe film shows photoactivity under sunlight.
Open Access
The phase behavior and synthesis of mesostructured coupled semiconductor thin films : MESO-CdS-TiO2
(2009) Okur, Halil İbrahim
Mesostructured [Cd(H2O)4](NO3)2 - titania - P123 ((PEO)20(PPO)70(PEO)20, PEO = -OCH2CH2-, PPO = -OCH(CH3)CH2-) materials have been investigated by changing the [Cd(H2O)4](NO3)2 and titania content of the structures. This has been achieved by making thick samples by casting and thin film samples by spin coating of a butanol solution of [Cd(H2O)4](NO3)2, P123, nitric acid and Ti(OC4H9)4. The film samples are named as meso-xCd(II)-yTiO2, where x is the Cd(II)/P123 and y is TiO2/P123 mole ratios. Increasing the titania amount in the media has transformed the samples from LC-like to soft and then to rigid mesostructured materials. Changing the amount of [Cd(H2O)4](NO3)2 salt in the media only influenced the mesostructure, such that no change on the mechanical properties is observed. However, the synthesis of rigid mesostructured titania materials required controlled humidity. The rigid film samples were prepared first by spin coating and then by aging under a 50% humidity oven. The mesostructure remains stable upon H2S reaction, in the soft and rigid materials region. However, only rigid samples stand to removal of nitrates from the media that is important to keep the CdS nanoparticles stable in or on the pore walls of mesostructured film samples. The phase behavior of the meso-Cd(II)-TiO2, the structural properties of the meso-xCdS-yTiO2 samples, coordination and elimination of the NO3 - ions and the particle size of the CdS nanocrystallites were investigated using diffraction (XRD), spectroscopy (FT-IR, Raman and UV-Vis absorption, EDS) and microscopy (POM, SEM, and TEM) techniques.
Open Access
RF-sputtering of doped zinc oxides thin films, the effect of low substrate heating deposition
(2017-01) Ahmed, Amira Ahmed Abdelmoneam Mohamed
Zinc Oxide (ZnO) has been studied since 1930’s as a candidate for the electronic applications, as it possesses a wide bandgap of 3.4 eV. While in the last 3 decades the technology of thin films were more interested in Doped zinc oxide (ZnO) for their promising potential for many applications including thin film transistors (TFTs), transparent conductive electrodes (TCEs), and thin-film photovoltaic solar cells. Mainly Indium doped and Gallium doped-zinc-oxide (IZO), (GZO) and (IGZO) thin films have drawn researchers’ attention due to their remarkable electrical, optical properties, making them good candidate for the next generation flexible optoelectronic applications. This thesis work studies the effect of deposition parameters on the crystallinity and optical properties of the thin films. In addition, the chemical composition, electrical and morphological properties of the thin films were studied in a comparative form between room temperature (RT)-grown thin films and those gown with substrate heating at 200 °C. First, a series of doped ZnO thin films were deposited by radio frequency RF-sputtering at (RT), as a function of pressure, plasma power, and argon (Ar) flow. Then a chosen deposition recipe was tested with substrate heating. Well-adhered, uniform, smooth and highly transparent films were observed. Although Literature has shown that IZO thin films exhibit amorphous nature at RT-deposition, in this work it was observed that IZO thin films exhibits crystalline nature at RT. Results indicated that low substrate heating has affected both of IZO and GZO more than it has to IGZO Thin films. The low heat effect was more effective on the crystallinity and optical characteristics of these thin films more than its effect on their other characteristics, as it will be demonstrated as we go over each characteristic. Thicker films of (~1m) were grown in order to evaluate the mechanical properties, including film hardness (H) and Young’s Modulus (E).
Open Access
Synthesis of high temperature wear resistant WC and WN coatings
(2012) Alagöz, Hüseyin
In this study, WC and WN thin films were synthesized using reactive magnetron sputter deposition in order to develop promising alternatives to the well known wearresistant coatings such as CrN, TiN, TiAlN and TiB2 etc. For this purpose, WC and WN coatings were deposited on Si(100) and steel (100Cr6) substrates by a Direct Current (DC) reactive magnetron sputtering system. X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were used to uncover the atomic structure of the films and the change in the chemical bonding states of the atoms. Also, the hardness measurements were performed using a nano-indentation tester on as-deposited films and after the films were subjected to 500°C for two hours. A pin-on-disc tribometer was used to investigate the wear-rates of these coatings at room temperature (RT) and 500°C under ambient atmosphere conditions using 6 mm in diameter Al2O3 balls. Scanning electron microscopy (SEM) was used to investigate the microstructure and measure the thickness of the coatings. Also, for chemical analysis energy dispersive spectroscopy (EDS) was used. Two sets of experiments were designed and performed for the preparation of WN coatings. In the first set, effect of N2 flow rates during deposition was investigated on the structure and properties of coatings deposited. The N2 flow rates were varied between 17% - 66% of the total flow (Ar+N2). The results of these experiments exhibited a significant drop for the hardness and wear rates of WN coatings deposited with increasing N2 flow rates when tested after 500°C treatment. On the contrary, RT wear test results indicated an improvement in the wear rates with increasing N2 flow rates. XRD data for the samples subjected to 500°C. XRD analysis indicated the presence of a soft tet-WO3 layer over the coatings treated at 500°C which is found to be the main culprit for the degradation of the tribological properties. In order to prevent the formation of this soft oxide layer on WN coatings, W/WN multilayer coatings were synthesized in the second set of experiments where the W layers were used as diffusion barriers for oxygen. After the optimization of deposition parameters for synthesizing W/WN multilayer coatings, subsequent tribological examinations indicated the multilayer coatings to be comparably wear resistant at both RT and 500°C. Furthermore, hardness of the multilayer coatings with optimized parameters were found to be around 20-25 GPa at RT and 15-20 GPa at 500°C and their corresponding wear resistances were measured to be ~2.0x10-6 mm3 /Nm at RT and ~4.0x10-6 mm3 /Nm at 500oC. As the second challenge, WC thin films were synthesized within the framework of this study. The first set of synthesis experiments was done using acetylene (C2H2) as the carbon source. It was found that increasing relative amount of C2H2 flow during sputter deposition resulted in the degradation of tribological properties of coatings due to amorphous carbon build-up in the films. To overcome this degradation of properties, alternative solid sputter targets such as B4C (as an alternative C source for 2nd set), W/B4C (composite targets) and W2C targets (for co-sputtering experiments of 3rd set) were used for the deposition of WC films. The results of the structural and chemical analysis indicated the presence of well-crystallized WC phases (WC and W2C) in the coatings sputter deposited from B4C targets. Comparatively, coatings deposited using solid WC and W2C targets resulted in coatings with the same phases. Tribological testing of these coatings indicated that WC films synthesized using B4C targets to have better mechanical performance after 500oC treatment while coatings co-sputtering from compound targets worked better at RT.