Direct Current Magnetron Co-sputtering Research Articles

Thermoelectric Characterization of Direct Current Magnetron Co-Sputtering Zinc Antimonide Thin Films

Direct current magnetron co-sputtering was used to deposit zinc antimonide thin films on BK7 glass substrates at room-temperature. Then the films were annealed at 573 K to 673 K for 1 hour in Ar atmosphere. The results indicate that the Seebeck coefficient of the thin films increase from 30.5 μVK-1to 132.5 μVK-1 when the annealing temperature changed. The electrical conductivity of the thin films increases from 3.45×103 to 6.86×103 Sm-1 and the Power Factor is enhanced greatly from 0.03×10-4 to 0.99×10-4 Wm-1K-2 when the annealing temperature reached 598 K. X-ray diffraction result shows that the major diffraction peaks of the thin films match those of β phase Zn4Sb3 and high crystalline thin films are achieved after annealing.

Effect of dopant on microstructure and conductivity of ZnO thin film

Al and Ti doped ZnO thin films have been prepared by direct current magnetron cosputtering and thermal oxidation. The effects of these dopants on the microstructural, morphological and electrical properties of deposited films have been studied. The SEM demonstrated that the undoped ZnO thin film consisted of globular ZnO with particle size of ∼100 nm. Scanning electron microscopy EDX analysis confirmed that the dopant content in the ZnO–Al and ZnO–Ti thin film was 2·78 and 3·75 at-% respectively. The particle in the ZnO–Ti thin film was blocky or granular with thorns and its size was several micrometers, while the particle in ZnO–Al thin film was porous granular and the size was ∼2 μm. Resistance value testing and R/R calculation revealed that pure ZnO thin film had the highest gas sensitivity.

Study on preparation and characteristics of Fe- and Mn-doped AlN thin films

Fe- and Mn-doped AlN thin films were prepared on Si substrates by direct current (DC) magnetron co-sputtering method in the atmospher of Ar and N2 mixture. The influences of sputtering currents and the target to substrate distance on the structure of the films were investigated by X-ray diffraction and Raman spectroscopy, respectively. Surface morphology and composition were studied by scanning electron microscope (SEM) with an energy dispersive X-ray spectroscopy (EDS) attachment. The magnetism of Mn- and Fe-doped AlN films was measured by vibrating sample magnetometer (VSM) at room temperature (RT). Processing of the Mn-doped AlN films produces Mn clusters in the samples. Due to the presence of the antiferromagnetism Mn clusters, ferromagnetism is either suppressed or disappears. The Fe-doped AlN films show ferromagnetism at RT, which should arise from the AlFeN ternary alloy. With the increase of the Fe target sputtering current, the Fe concentration is increased from 6.81 at.% to 16.17at.%; the saturation magnetization Ms is reduced from 0.27 emu·cm-3 to 0.20 emu·cm-3, and the coercive force Hc is increased from 57 Oe to 115 Oe, this is because the separation of Fe ions get shorter and the antiferromagnetic coupling is enhanced.

Thermal stability of CrTaN hard coatings prepared using biased direct current sputter deposition

CrTaN coatings were fabricated using reactive direct current magnetron co-sputtering on a Ti interlayer covering silicon substrates with various bias voltages. The CrTaN coatings were annealed at 600°C for 4–24h under a 50ppm O2–N2 atmosphere, and the effectiveness of the fabricated layers as a protective coating for glass molding dies was assessed. The effects of biased voltage on the structure, mechanical properties, surface roughness values, and oxygen diffusion depths were investigated. The results indicated that the coating prepared with a bias voltage of −25V exhibited mechanical properties that were superior to those of the other coatings used in this study. In addition, these properties (including nanohardness, Young's modulus, and the derivative H3/E2 ratio) increase after annealing at 600°C in a glass molding atmosphere (i.e., 50ppm O2–N2 atmosphere, with a smoother surface characteristic).

Oxidation study of Cr–Ru hard coatings

Cr–Ru alloy coatings with Cr content ranging from 47 to 83 at.% were deposited at 400 °C by direct current magnetron co-sputtering with a Ti interlayer on silicon substrates. With a total input power of 300 W, the Cr content in the Cr–Ru coatings increased linearly with the increasing input power of Cr. The intermetallic compound phase Cr 2Ru with columnar structure was identified for the as-deposited Cr 56Ru 44 and Cr 65Ru 35 coatings, resulting in an increase of hardness up to 15–16 GPa. To evaluate the performance of Cr–Ru coatings as a protective coating on glass molding dies, the annealing treatment was conducted at 600 °C in a 50 ppm O 2–N 2 atmosphere. The outward diffusion and preferential oxidization of Cr in the Cr–Ru coatings resulted in the variations of the crystalline structure, chemical composition distribution, and surface hardness after annealing. X-ray diffraction and transmission electron microscopy (TEM) proved that an oxide scale consisting of Cr 2O 3 formed on the free surface. Scanning electron microscopy and TEM observed the surface morphology and structural variation. The chemical composition depth profiles were analyzed by Auger electron microscopy, verifying the presence of a Cr-depleted zone beneath the oxide scale. The hardness of Cr 56Ru 44 and Cr 65Ru 35 coatings decreased to 11–12 GPa after annealing, accompanied by the replacement of the Cr 2Ru phase by the Ru phase.

Preparation and annealing study of CrTaN coatings on WC-Co

To prevent Co diffusion from cemented carbides at high working temperatures, we fabricated CrTaN coatings by reactive direct current magnetron co-sputtering onto 6wt.% cobalt cemented carbide substrates, to form diffusion barrier layers. The nitrogen flow ratio, N2/(Ar+N2), during the sputtering process was set at 0.4. The deposition rates of CrTaN coatings varied from 23 to 27nm/min. The CrTaN coatings crystallized into a columnar structure, without heating the substrates during the sputtering process and exhibited surface hardness and Young's modulus values of 16–27 and 211–383GPa, respectively. The CrTaN coatings were annealed at 500 and 600°C for 4h in air to evaluate the oxidation resistance and diffusion barrier performance. We also investigated oxidation resistance of the CrTaN coatings under a 50ppm O2–N2 atmosphere, to assess the fabricated layers effectiveness as a protective coating for glass molding dies.

Influence of Sputtering Power of Te and Annealing on Sb-Te Thin Films Fabricated by RF and DC Co-Sputtering

Antimony and tellurium were deposited on K9 glass via direct current and radio frequency magnetron co-sputtering. Antimony telluride thermoelectric thin films were simultaneously synthesized without post treatment. The influence of the sputtering power of Te and annealing of Sb-Te fabricated by magnetron sputtering were investigated. The maximum Seebeck coefficient of Sb-Te film was 212 μV/K which was obtained at the sputtering power of Sb 4W and Te 60W separately. When annealed at 300 °C, the electrical resistivity and Seebeck coefficient of the film are 6.67x104 S/m and 119 μV/K. The power factor increased to the highest value of 9.4×10-4 W/mK2 from 4×10-5 W/mK2 after post treatment of the as-deposited film.

Internal oxidation mechanism for Ta–Ru and Mo–Ru coatings

Ta–Ru and Mo–Ru alloy coatings with phases of intermetallic compounds are often used as protective coatings on die materials. After annealing under an oxygen containing atmosphere, the internal oxidation phenomenon resulted in the preferential oxidation of Ta or Mo in the coatings. This process created a phase separated structure consisting of continuous and alternative oxygen rich and deficient layers with a nano scale period beneath the free surface. The experiments in this study deposited Ta–Ru and Mo–Ru coatings with a Cr interlayer by direct current magnetron co-sputtering at 400 °C. Annealing treatments were conducted at 600 °C for short durations under controlled atmospheres consisting of 50 or 10,000 ppm oxygen with residual nitrogen or argon gas. The internal oxidation behavior in the initial stage was determined by evaluating the variations in crystalline structure, surface morphology and chemical composition. The laminated structure was examined by transmission electron microscopy. Results show distinct oxidation behaviors for Ta 47Ru 53 and Mo 46Ru 54 coatings. Internal oxidation phenomena appeared in Ta 47Ru 53 coatings annealed in both 50 and 10,000 ppm O 2 containing atmospheres. The Mo 46Ru 54 coatings exhibit external oxidation at 50 ppm O 2 containing atmosphere, and internal oxidation at 10,000 ppm O 2 containing atmosphere. Finally, this study proposes an internal oxidation mechanism for alloy coatings with an orientated structure.

Influence of oxygen partial pressure on electrical and optical properties of Zn 0.93Mn 0.07O thin films

The Zn 1− x Mn x O ( x = 0.07) thin films were grown on glass substrates by direct current reactive magnetron cosputtering. The influence of oxygen partial pressure on the structural, electrical and optical properties of the films has been studied. X-ray-diffraction measurement revealed that all the films were single phase and had wurtzite structure with c-axis orientation. The experimental results indicated that there was an optimum oxygen partial pressure where the film shows relative stronger texture, better nano-crystallite and lower surface roughness. As the oxygen partial pressure increases, the carrier concentration systematically decreases and photoluminescence peaks related to zinc interstitials gradually diminish. The minimal resistivity of 70.48 Ω cm with the highest Hall mobility of 1.36 cm 2 V −1 s −1 and the carrier density of 6.52 × 10 16 cm −3 were obtained when oxygen partial pressure is 0.4. All films exhibit a transmittance higher than 80% in the visible region, while the deposited films showed a lower transmittance when oxygen partial pressure is 0.4. With the increasing of oxygen partial pressure, the peak of near-band-edge emission has firstly a blueshift and then redshift, which shows a similar trend to the band gap in the optical transmittance measurement.

Annealing and oxidation study of Ta–Ru hard coatings

Refractory metal alloy coatings have been widely used as protective coatings on glass molding dies. The formation of intermetallic compounds in the coatings inhibits grain growth at high-temperature environment in the mass production of optical components. The current work presents Ta–Ru coatings with a Cr interlayer on cemented carbide substrates and silicon wafers deposited by direct current magnetron co-sputtering at 400 °C. The as-deposited Ta–Ru coatings possessed a hardness of 13–14 GPa and a surface roughness of 1.3–4.0 nm. The annealing treatments were carried out at 600 °C under two vacuum levels of 3 × 10 − 3 and 3 Pa, respectively. After annealing in vacuum at 3 × 10 − 3 Pa, the Ta–Ru coatings showed grain size, hardness, surface roughness and phase stability comparable to those of the as-deposited coatings. While annealing in vacuum at 3 Pa, preferential oxidation of Ta in the Ta–Ru coatings was verified by X-ray photoelectron spectroscopy, a variation of the chemical composition in depth was analyzed by Auger electron spectroscopy and the internal oxidation zone consisting of a laminated structure was observed by transmission electron microscopy.

Magnetic, magnetoresistance and electrical transport properties of Ni and Al co-doped ZnO films grown on glass substrates by direct current magnetron co-sputtering

200-nm-thick Zn 0.85Al 0.04Ni 0.11O films were deposited on glass substrates at 300 K and 573 K by co-sputtering ZnO:Al and Ni targets. A temperature dependence of magnetization and resistivity within 50–300 K and a room temperature magnetoresistance (MR) were measured. X-ray photoelectron spectroscopy was used to analyze chemical valences of Ni in the films. The films have the room temperature ferromagnetism. A magnetization of the film grown at 300 K decreases slightly and that of the film grown at 573 K decreases markedly with increasing temperature. The small negative MR is observed for the film deposited at 300 K while the positive MR is obtained for the film prepared at 573 K. For the film grown at 300 K, the carrier transport mechanism is thermally activated band conduction. However, the carrier transport mechanism in the film grown at 573 K is the Mott's variable range hopping in the temperature range below 100 K and the thermally activated band conduction above 140 K. The metallic Ni atoms and Ni 2+ ions exist in the films. The ferromagnetism is mainly attributed to the Ni clusters in the Zn 0.85Al 0.04Ni 0.11O film.

Microstructure and photoluminescence study of vanadium-doped ZnO films

Zn1−xVxO films (x = 0, 1.3, 1.9, 2.6, 3.5, 4.3 and 6.2 at%) were prepared on glass substrates via the direct current reactive magnetron co-sputtering method. The microstructure, band gap, photoluminescence and Raman scattering of these films have been systematically investigated. The structural and chemical state characterizations indicate that the crystallinity of Zn1−xVxO films (x ⩽ 2.6 at%) can be improved by V incorporation into the ZnO wurtzite lattice, but excess V will precipitate as V clusters when x ⩾ 4.3 at%, resulting in the deterioration of crystal quality. The defects in Zn1−xVxO films (x ⩽ 2.6 at%) can be suppressed by V doping, which induces the enhancement of the near band edge (NBE) emission. However, when x ⩾ 4.3 at%, defects adjacent to the V dopant quench the NBE emission. On the other hand, the band gap of the films gradually increases with the increase in V concentration, which is accompanied by the blue shift of the NBE emission.

Structural and physical properties of Ni and Al co-doped ZnO films grown on glass by direct current magnetron co-sputtering

Abstract About 200 nm-thick Ni and Al co-doped ZnO films were deposited on glass substrates at 300 and 573 K by co-sputtering ZnO:Al and Ni targets. When the sputtering power applied to the Ni target was adjusted to 11 and 18 W, the Zn 0.87 Al 0.04 Ni 0.09 O film and the Zn 0.85 Al 0.04 Ni 0.11 O film were obtained. All the films have a wurtzite structure and grow mainly with [1 0 0] and [1 1 0] orientations in the growing direction. The films consist of thin columnar grains perpendicular to the substrate. However, the high deposition temperature promotes the grain growth. For the Zn 0.87 Al 0.04 Ni 0.09 O films grown at 300 and 573 K as well as the Zn 0.85 Al 0.04 Ni 0.11 O film grown at 300 K, an optical transmittance increases monotonously from 20% to 60% on increasing the wavelength from 390 to 760 nm. However, the Zn 0.85 Al 0.04 Ni 0.11 O film deposited at 573 K exhibits a flat curve of the transmittance above 50% in the wavelength range of 500–760 nm. The films have an n-type semiconducting behavior at room temperature. The Zn 0.85 Al 0.04 Ni 0.11 O film grown at 573 K has the lowest resistivity (6.9×10 −2 Ω cm), the highest free electron concentration (1.0×10 20 cm −3 ) and the lowest Hall mobility (0.87 cm 2 /V s). The films, except for the Zn 0.87 Al 0.04 Ni 0.09 O film grown at 300 K, have the room temperature ferromagnetism. The Zn 0.85 Al 0.04 Ni 0.11 O film grown at 573 K has the highest saturation magnetization (5.6×10 −4 T), a saturation field of 2.5×10 5 A/m and a coercivity of 8.5×10 3 A/m.

Influencia del Flujo de Nitrógeno en la Estructura, Dureza y Resistividad de Recubrimientos de TiSiNO

Coatings of TiN and TiSiN were prepared by reactive direct current magnetron co-sputtering on steel and on silicon substrates, using a Ti target and a small Si plate in a reactive atmosphere of nitrogen, oxygen and argon. Using the Warren-Averbach method the structural changes were analyzed in function of the variation of the nitrogen flow. Stoichiometry calculations obtained by X-ray Energy Dispersive Spectroscopy and corroborated by Glow Discharge Spectroscopy, show that the TiSiNO coatings contain two solid solutions of TiSixN(Oy) and SiNxOy and have a strong domain on titanium oxynitrure phase. The sample made on steel and silicon wafers substrates with nitrogen flow of 3 sscm, presented the highest hardness and the lowest resistivity values, respectively, due to its preferential crystalline orientation, structure and crystalline phases present.

Mechanical and optical properties of quaternary Si–B–C–N films prepared by reactive magnetron sputtering

Quaternary Si–B–C–N films were prepared using reactive direct current magnetron co-sputtering of silicon, boron and carbon from a single C–Si–B target in nitrogen–argon gas mixtures at substrate temperatures of 180–350 °C. We focused on complex relationships between process parameters, elemental composition, bonding structure, and mechanical, tribological and optical properties of the deposited materials. The films, typically 1.0–2.4 μm thick, are found to be amorphous with a density of around 2.4 g cm − 3 . They exhibit a high hardness (up to 36 GPa) and a good adhesion to Si(100) substrates at a low compressive stress (1.0–1.6 GPa). A friction coefficient against Al 2O 3, ranging from 0.85 to 0.34, and a low surface roughness of approximately 1 nm were accompanied by the corresponding refractive index ranging from 1.8 to 2.2 (at 550 nm) and an extinction coefficient between 2 × 10 − 4 and 0.3. The Si–B–C–N films appear attractive for both tribological and optoelectronic applications.

Substrate orientation-induced distinct ferromagnetic moment in Co:ZnO films

Dilute (3.8 at.%) cobalt-doped ZnO thin films are deposited on LiTaO 3 (LT) substrates with three different orientations [LT(1 1 0), LT(0 1 2) and LT(0 1 8)] by direct current reactive magnetron co-sputtering. The experimental results indicate that Co atoms with 2+ chemical valence are successfully incorporated into the ZnO host matrix on various oriented substrates, and the substrate orientations have a profound influence on the crystal growth and magnetization of Co:ZnO films. A large magnetic moment of 2.42 μ B/Co at room temperature is obtained in the film deposited on LT(0 1 2), while the corresponding values of the other films deposited on LT(1 1 0) and LT(0 1 8) are 1.21 μ B/Co and 0.65 μ B/Co, respectively. Furthermore, the crystal growth mode of Co:ZnO films on various oriented LT, the relationship between the microstructures and corresponding ferromagnetic properties are also discussed.

Self-encapsulation of single-texture CoSi 2 nanolayer by TaSi 2

In this work, we have studied single-texture formation of CoSi 2 layer in heat-treated Co/Ta 0.7W 0.3/Si(100) structure. Moreover, self-encapsulation process of the CoSi 2 layer and surface roughness of the encapsulated layer, as a contact layer, has been examined. A direct current magnetron co-sputtering technique was employed to deposit a 10 nm Ta 0.7W 0.3 alloy intermediate layer. After growth of the layer on the Si substrate, a 25 nm Co layer was deposited using thermal evaporation method. Post-annealing process of the films was treated in an N 2(80%) + H 2(20%) ambient in a temperature range from 400 to 1000 °C for 60 min. X-ray diffraction analysis showed that a single-texture CoSi 2 layer with (100) orientation was formed in this structure in the temperature range of 800–1000 °C. The self-encapsulation process of the CoSi 2 layer has been also investigated by X-ray photoelectron spectroscopy. It was found that the CoSi 2 layer was encapsulated by a TaSi 2 layer in the temperature range of 800–900 °C. The sheet resistance of the CoSi 2 formed at 1000 °C was measured ∼ 10 μΩ cm. Atomic force microscopy images showed that surface roughness of the TaSi 2 surface was around 15 nm. Agglomeration of the TaSi 2 on the CoSi 2 layer resulted in increasing the surface roughness, at 1000 °C.

V 5 + ionic displacement induced ferroelectric behavior in V-doped ZnO films

V-doped ZnO films have been prepared on Si(111) substrates by direct current reactive magnetron cosputtering. Hysteresis loops of polarization–applied field characteristics with a remnant polarization of 0.2μC∕cm2 were obtained in (2.5at.%) V-doped ZnO films, indicating the ferroelectric behavior exists in this system. This is demonstrated by displacement-voltage curves, which show typical butterfly shapes. X-ray absorption near-edge structure (XANES) spectrum at V K edge shows that V is in the 5+ state replacing Zn. Furthermore, the calculations of the XANES spectra indicate that a V5+ ionic displacement of 0.15Å is responsible for the ferroelectric behavior.

Transition from diluted magnetic insulator to semiconductor in Co-doped ZnO transparent oxide

Epitaxial growth of Co-doped ZnO films has been prepared on Al2O3 (001) substrate by an efficient and low cost method, i.e., direct current reactive magnetron cosputtering. The correlation among local Co structure and magnetic, electric, and optical properties of Co:ZnO films has been carefully studied. Taking advantage of decreasing the oxygen partial pressure, we have demonstrated the transition from diluted magnetic insulators (DMIs) to semiconductors (DMSs) in Zn0.96Co0.04O films. Full multiple-scattering ab initio calculations of Co K-edge x-ray-absorption near-edge structure clearly provide a structure fingerprint to determine Co2+ replacing Zn2+ and a slight dissimilarity of local Co structure between DMIs and DMSs. Co:ZnO insulating films exhibiting more robust room temperature ferromagnetism than semiconducting films reveal that structure defects are seen to be responsible for the ferromagnetic ordering in Co:ZnO transparent oxide. Furthermore, optical transmittance measurements show a large redshift instead of Burstein-Moss effect (blueshift) from DMIs to DMSs. The present result reveals the good potential for its applications in magnetic transparent electrodes, such as magnetic metal-insulator-semiconductor diodes.

Characteristics of Ni-doped ZnO:Al films grown on glass by direct current magnetron co-sputtering

About 250 nm-thick Ni-doped ZnO:Al films were deposited on glass substrates at 300 K, 473 K and 673 K by direct current magnetron co-sputtering. Atomic ratio of Zn:Al:Ni in the film is 100:5:4. All the films have a ZnO wurtzite structure and grow mainly with their crystallographic c-axis perpendicular to the substrate. The films deposited at 300 K and 673 K consist of granular grains whereas the film grown at 473 K mainly has a dense columnar structure. The Ni-doped ZnO:Al film grown at 473 K has the lowest resistivity of 7.7 × 10 − 3 Ωcm. All the films have an average optical transmittance of over 90% in the visible wavelength range. The absorption edge of the film grown at 473 K shifts to the shorter wavelength (blueshift) relative to those deposited at 300 K and 673 K. When the substrate temperature reaches 673 K, the Ni-doped ZnO:Al film shows a magnetization curve at room temperature, indicating that the film has a hard magnetization characteristic. The saturation magnetization is about 1 × 10 − 4 T and the saturation field is about 3.2 × 10 5 A/m.