Characterization of aluminum-doped zinc oxide thin films by RF magnetron sputtering at different substrate temperature and sputtering power

In this study, transparent conductive Al doped zinc oxide (ZnO: Al, AZO) thin films with a thickness of 40 nm were prepared on the Corning glass substrate by radio frequency magnetron sputtering. The properties of the AZO thin films are investigated at different substrate temperatures (from 27 to 150 °C) and sputtering power (from 150 to 250 W). The structural, optical and electrical properties of the AZO thin films were investigated. The optical transmittance of about 78 % (at 415 nm)–92.5 % (at 630 nm) in the visible range and the electrical resistivity of 7 × 10^?4 Ω-cm (175.2 Ω/sq) were obtained at sputtering power of 250 W and substrate temperature of 70 °C. The observed property of the AZO thin films is suitable for transparent conductive electrode applications.     

Low-temperature deposited Titanium-doped zinc oxide thin films on the flexible PET substrate by DC magnetron sputtering

Transparent conducting Titanium-doped zinc oxide thin films (TZO) with high transparency and relatively low resistivity were firstly deposited on water-cooled polyethylene terephthalate (PET) substrates at room temperature by DC magnetron sputtering. The microstructure, optical and electrical properties of the deposited films were investigated and discussed. The XRD patterns show that all the deposited films are polycrystalline with a hexagonal structure and have a preferred orientation along the c-axis perpendicular to the substrate. The electrical resistivity decreases when the sputtering power increases from 45 W to 60 W. However, as the puttering power continue increases from 60 W to 90 W, the electrical resistivity increases rapidly. When the puttering power is 60 W, the films deposited on PET substrate have the lowest resistivity of 4.72 × 10⁻⁴ Ω cm and a relatively high transmittance of above 92% in the visible range.     

Low-temperature deposited Titanium-doped zinc oxide thin films on the flexible PET substrate by DC magnetron sputtering

Transparent conducting Titanium-doped zinc oxide thin films (TZO) with high transparency and relatively low resistivity were firstly deposited on water-cooled polyethylene terephthalate (PET) substrates at room temperature by DC magnetron sputtering. The microstructure, optical and electrical properties of the deposited films were investigated and discussed. The XRD patterns show that all the deposited films are polycrystalline with a hexagonal structure and have a preferred orientation along the c-axis perpendicular to the substrate. The electrical resistivity decreases when the sputtering power increases from 45 W to 60 W. However, as the puttering power continue increases from 60 W to 90 W, the electrical resistivity increases rapidly. When the puttering power is 60 W, the films deposited on PET substrate have the lowest resistivity of 4.72 × 10⁻⁴ Ω cm and a relatively high transmittance of above 92% in the visible range.     

Indium zinc oxide semiconductor thin films deposited by dc magnetron sputtering at room temperature

Amorphous indium zinc oxide (IZO) thin films were prepared on glass substrates by dc magnetron sputtering at room temperature. The resistivity of IZO films could be controlled between 3.8 × 10⁻³ and 2.5 × 10⁶ Ω cm by varying the oxygen partial pressure during deposition, while keep the average transmittance over 83%. With IZO films as channel layers, whose surface root-mean-square roughness was less than 1 nm, thin film transistors were fabricated at room temperature, showing enhanced mode operation with good saturation characteristics, mobility of 5.2 cm² V⁻¹ s⁻¹, threshold voltage of 0.94 V and on/off ratio of ∼10⁴.     

室温直流磁控溅射制备ITO膜及光电性能研究

室温条件下,在玻璃衬底上,采用直流磁控溅射法制备了ITO膜.研究了溅射压强,氧流量和溅射功率等工艺参数对薄膜光电性能的影响.结果表明当Ar流量为44.2 sccm和溅射时间20 min等参数不变时,溅射气压0.7 Pa,氧流量0.62 sccm和溅射功率130 W为最佳工艺条件.并得到了电阻率5.02×10-4 Ω·cm,在可见光区平均透过率80%以上ITO薄膜.     

The properties of aluminum-doped zinc oxide thin films prepared by rf-magnetron sputtering from nanopowder targets

Aluminum-doped zinc oxide (ZnO:Al) films were deposited onto glass substrates by rf-magnetron sputtering at ambient temperature using, for the first time, doped nanocrystalline powder synthesized by the sol–gel method. The effects of aluminum on structural, electrical, morphological and optical properties were investigated. The films showed a hexagonal wurtzite structure and high preferential orientation in the (002) crystallographic direction. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the films morphology. The obtained samples have a typical columnar structure and a very smooth surface. The optical transmittance spectra showed transmittance higher than 90% within the visible wavelength region. A minimum resistivity of 5.436 · 10^− 5 Ω cm at room temperature was obtained for the 3.0 at.% Al-doped film.     

Lithium cobalt oxide thin films deposited at low temperature by ionized magnetron sputtering

Thin films of lithium cobalt oxides have been deposited by ionized magnetron sputter deposition with and without substrate heating. The technique uses a built-in radio frequency coil to generate an inductively coupled plasma (ICP) confined close to the substrate. The ICP plasma results in ion bombardment on the film surface, which serves as an extra energy input during film growth. Therefore, the film properties can be modified at a relatively lower temperature. The plasma irradiation induces variations of crystallography and morphology, as characterized by X-ray diffraction and scanning electron microscopy. The deposited films were tested as cathodes for lithium batteries, and the discharge curves were measured to compare the electrochemical properties of the deposited films. Applying suitable plasma irradiation, well crystallized LiCoO₂ phase was obtained at 350 °C (substrate temperature), which was much lower than the temperature (700 °C-750 °C) for conventional post anneal process. The LiCoO₂ films, fabricated under in-situ plasma irradiation and a relatively lower substrate temperature (350 °C), showed a discharge potential plateau at 4.3 V-3.8 V with a capacity of ∼ 110 mAh/g as discharged to 1.5 V.     

Titanium oxide thin films deposited by high-power impulse magnetron sputtering

Ionized physical vapor deposition processes are of great interest for surface modification because the flexibility of the thin film deposition process can be increased by ionizing the metallic vapor. Recently, high-power impulse magnetron discharges have been implemented to achieve high ionization rates.Thin films of titanium oxide have been deposited on glass and steel substrates using 450 × 150 mm rectangular titanium target in argon-oxygen atmosphere. The average power delivered to the plasma is ranging between 1.5 and 2 kW and peak current and voltage are respectively 200 A and 900 V.Films are characterized using Scanning Electron Microscopy, Grazing Incidence X-ray Diffraction and Optical Transmission Spectroscopy. One of the major findings is the presence of rutile deposited on steel substrate (even for 0 V bias grounded substrate) and the significant increase of the refractive index of the films deposited on glass compared to thin films deposited via conventional direct current bipolar pulsed magnetron sputtering. Films synthesized by high-power impulse magnetron sputtering are denser.     

Indium tin oxide films deposited by thermionic-enhanced DC magnetron sputtering on unheated polyethylene terephthalate polymer substrate

Indium tin oxide thin films were deposited onto polyethylene terephthalate substrates via thermionic enhanced DC magnetron sputtering at low substrate temperatures. The structural, optical and electrical properties of these films are methodically investigated. The results show that compared with traditional sputtering, the films deposited with thermionic emission exhibit higher crystallinity, and their optical and electrical properties are also improved. Indium tin oxide films deposited by utilizing thermionic emission exhibit an average visible transmittance of 80% and an electrical resistivity of 4.5 × 10⁻⁴ Ω cm, while films made without thermionic emission present an average visible transmittance of 74% and an electrical resistivity of 1.7 × 10⁻³ Ω cm.     

Effect of substrate temperature on the properties of pyrolytically deposited nitrogen-doped zinc oxide thin films

The effect of substrate temperature (T_s) on the properties of pyrolytically deposited nitrogen (N) doped zinc oxide (ZnO) thin films was investigated. The T_s was varied from 300 °C to 500 °C, with a step of 50 °C. The positive sign of Hall coefficient confirmed the p-type conductivity in the films deposited at 450 °C and 500 °C. X-ray diffraction studies confirmed the ZnO structure with a dominant peak from (1 0 0) crystal plane, irrespective of the variation in T_s. The presence of N in the ZnO structure was evidenced through X-ray photoelectron spectroscopy (XPS) analysis. The obtained high N concentration reveals that the 450 °C is the optimal T_s. Atomic force microscope (AFM) analysis showed that the surface roughness was increased with the increasing T_s until 400 °C but then decreased. It is found that the transmittance of the deposited films is increased with the increasing T_s. The optical band gap calculated from the absorption edge showed that the films deposited with T_s of 300 °C and 350 °C possess higher values than those deposited at higher T_s.     

直流磁控溅射有机衬底和玻璃衬底ZnO∶Al薄膜结构及特性的研究

利用直流磁控溅射法在有机薄膜衬底和普通玻璃衬底上制备出了具有良好附着性的ZnO∶Al透明导电膜,对制备薄膜的结构和光学特性进行了比较研究.研究发现:铝掺杂的氧化锌薄膜是多晶膜,具有六角纤锌矿结构;在衬底温度为100℃,溅射压强1.0 Pa,氧氩比为1∶2.58时,ZnO∶Al薄膜具有(002)择优取向,晶化也比较好,在可见光区的平均透过率分别达到了77.6%和82%.     

Properties of Ce-doped ITO films deposited on polymer substrate by DC magnetron sputtering

Ce-doped indium tin oxide (ITO:Ce) films were deposited on flexible polyimide substrates by DC magnetron sputtering using ITO targets containing various CeO₂ contents (CeO₂ : 0, 0.5, 3.0, 4.0, 6.0 wt.%) at room temperature and post-annealed at 200 °C. The crystallinity of the ITO films decreased with increasing Ce content, and it led to a decrease in surface roughness. In addition, a relatively small change in resistance in dynamic stress mode was obtained for ITO:Ce films even after the annealing at high temperature (200 °C). The minimum resistivity of the amorphous ITO:Ce films was 3.96 × 10^− 4 Ωcm, which was deposited using a 3.0 wt.% CeO₂ doped ITO target. The amorphous ITO:Ce films not only have comparable electrical properties to the polycrystalline films but also have a crystallization temperature > 200 °C. In addition, the amorphous ITO:Ce film showed stable mechanical properties in the bended state.     

Effect of substrate temperature on the structure and optical properties of ZnO thin films deposited by reactive rf magnetron sputtering

Zinc Oxide films were deposited on quartz substrates by reactive rf magnetron sputtering of zinc target. The effect of substrate temperature on the crystallinity and band edge luminescence has been studied. The films deposited at 300 °C exhibited the strongest c-axis orientation. AFM and Raman studies indicated that the films deposited at 600 °C possess better overall crystallinity with reduction of optically active defects, leading to strong and narrow PL emission.     

Effect of the substrate temperature on zirconium oxynitride thin films deposited by water vapour-nitrogen radiofrequency magnetron sputtering

ZrN_x films were deposited by radiofrequency reactive magnetron sputtering technique in nitrogen and water vapour atmosphere varying the working temperature from room temperature to 600 °C. The films' physical properties were investigated using X-ray diffraction, Secondary Ion Mass Spectroscopy, Atomic Force Microscopy and Transmission Electron Microscopy. It was found that the increase of temperature caused a decrease in the oxygen incorporation and a transition from cubic phase of Zr₂ON₂ to ZrN one. The formation of nanosized crystalline particles dispersed in the amorphous matrix was observed.     

The properties of Al doped ZnO thin films deposited on various substrate materials by RF magnetron sputtering

Transparent conductive Al-doped ZnO (AZO) thin films were deposited on various substrates including glass, polyimide film (PI) and stainless steel, using radio frequency magnetron sputtering method. The structural, electrical and optical properties of AZO thin films grown on various substrates were systematically investigated. We observe that substrate materials play important roles in film crystallization and resistivity but little on optical transmittance. X-ray diffractometer study shows that all obtained AZO thin films have wurtzite phase with highly c-axis preferred orientation, and films on glass present the strongest (002) diffraction peaks. The presence of compression stress plays critical role in determining the crystalline structure of AZO films, which tends to stretch the lattice constant c and enlarge the (002) diffraction angle. Although the films on the glass present the finest electrical properties and the resistivity reaches 12.52 × 10-4 Ωm, AFM study manifests that films on flexible substrates, especially stainless steel, bestrew similar inverted pyramid structure which are suitable for window material and electrode of solar cells. The average optical transmittance of AZO thin films deposited on glass and PI are both around 85% in the visible light range (400–800 nm).     

Thermoelectric properties of zinc antimonide thin film deposited on flexible polyimide substrate by RF magnetron sputtering

Zinc-antimony binary system is one of the most promising P-type thermoelectric materials for low cost intermediate temperature thermoelectric application. In this work, zinc antimonide thin film was deposited on the flexible polyimide substrate using zinc antimonide alloy target. All the samples were annealed in argon atmosphere at different temperatures and the thermoelectric properties of all the samples were significantly boosted. X-ray diffraction results displayed that single ZnSb phase was obtained when the annealing temperature above 300 °C. The thin film annealed at 325 °C possessed the carrier concentration of 3.59 × 10¹⁹ cm^?3, which was the most optimum carrier concentration. The maximum Seebeck coefficient of 280 μV K^?1 and the maximum power factor of 2.35 × 10^?3 Wm^?1 K^?2 was obtained at 260 °C. The Seebeck coefficient and the power factor increase with the increasing of the testing temperature. The thermoelectric properties of thin film annealed at 325 °C were better than other samples.     

Thickness dependent properties of nickel oxide thin films deposited by dc reactive magnetron sputtering

Nickel oxide thin films of various thicknesses were grown on glass substrates by dc reactive magnetron sputtering technique in a pure oxygen atmosphere with sputtering power of 150 W and substrate temperature of 523 K. Crystalline properties of NiO films as a function of film thickness were investigated using X-ray diffraction. XRD analysis revealed that (200) is the preferred orientation and the orientation of the films changed from (200) to (220) at film thickness of 350 nm. The maximum optical transmittance of 60% and band gap of 3.82 eV was observed at the film thickness of 350 nm. The lowest electrical resistivity of 5.1 Ω cm was observed at a film thickness of 350 nm, thereafter resistivity increases with film thickness.     

Effect of target properties on transparent conducting impurity-doped ZnO thin films deposited by DC magnetron sputtering

For the purpose of using transparent conducting impurity-doped ZnO thin films in liquid crystal display (LCD) applications, the relationship between the properties of dc magnetron sputtering (dc-MS) deposited thin films and the properties of the oxide targets used to produce them is investigated. Both Al-doped and Ga-doped ZnO (AZO and GZO) thin films were deposited on glass substrates using a dc-MS apparatus with various high-density sintered AZO or GZO disk targets (diameter of about 150 mm); the target and substrate were both fixed during the depositions. Using targets with a lower resistivity results in attaining more highly stable dc-MS depositions with higher deposition rates and lower arcing. In addition, dc-MS depositions using targets with a lower resistivity produced improvements in resistivity distribution on the substrate surface. It was found that the oxygen content in deposited thin films decreased as the oxygen content of the target used in the deposition was decreased. As a result, the dc-MS deposition of transparent conducting impurity-doped ZnO thin films suitable for LCD applications requires the preparation of significantly reduced AZO and GZO targets with low oxygen content.