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.     

Growth and characterization of indium tin oxide thin films deposited on PET substrates

Transparent and conductive indium tin oxide (ITO) thin films were deposited onto polyethylene terephthalate (PET) by d.c. magnetron sputtering as the front and back electrical contact for applications in flexible displays and optoelectronic devices. In addition, ITO powder was used for sputter target in order to reduce the cost and time of the film formation processes. As the sputtering power and pressure increased, the electrical conductivity of ITO films decreased. The films were increasingly dark gray colored as the sputtering power increased, resulting in the loss of transmittance of the films. When the pressure during deposition was higher, however, the optical transmittance improved at visible region of light. ITO films deposited onto PET have shown similar optical transmittance and electrical resistivity, in comparison with films onto glass substrate. High quality films with resistivity as low as 2.5 × 10^− 3 Ω cm and transmittance over 80% have been obtained on to PET substrate by suitably controlling the deposition parameters.     

Microstructure and properties of Al-doped ZnO thin films by nonreactive DC magnetron sputtering at room temperature following rapid thermal annealing

A series of Al-doped ZnO (AZO) thin films deposited by nonreactive DC magnetron sputtering at room temperature following rapid thermal annealing was studied to examine the influence of these Al doping concentration, sputtering power and annealing temperature on their microstructure, electrical and optical transport properties. AZO thin films with Al dopant of 3 wt% were oriented more preferentially along the (002) direction, bigger grain size and lower electrical resistivity The resistivity of AZO films decreases with the increase of Al content from 1 to 3 wt%, sputtering power from 60 to 100 W and the annealing temperature from 50 to 250 °C. Sputtering power and annealing had some effect on the average transmittance of AZO thin films. For AZO thin films with Al doping level of 3 wt%, the lowest electrical resistivity of 5.3 × 10⁻⁴ Ω cm and the highest optical transmittance of 88.7% could gain when the sputtering power was 100 W and the annealing temperature was 200 °C or above.     

Mn-doped ZnO transparent conducting films deposited by DC magnetron sputtering

Mn-doped zinc oxide (ZnO:Mn) thin films with low resistivity and relatively high transparency were firstly prepared on glass substrate by direct current (DC) magnetron sputtering at room temperature. Influence of film thickness on the properties of ZnO:Mn films was investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) 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. As the thickness increases from 144 to 479 nm, the crystallite size increases while the electrical resistivity decreases. However, as the thickness increases from 479 to 783 nm, the crystallite size decreases and the electrical resistivity increases. When film thickness is 479 nm, the deposited films have the lowest resistivity of 2.1 × 10^− 4 Ω cm and a relatively high transmittance of above 84% in the visible range.     

Deposition of Al-doped ZnO films on polyethylene naphthalate substrate with radio frequency magnetron sputtering

100 nm Al-doped ZnO (AZO) thin films were deposited on polyethylene naphthalate (PEN) substrates with radio frequency magnetron sputtering using 2 wt.% Al-doped ZnO target at various deposition conditions including sputtering power, target to substrate distance, working pressure and substrate temperature. When the sputtering power, target to substrate distance and working pressure were decreased, the resistivity was decreased due to the improvement of crystallinity with larger grain size. As the substrate temperature was increased from 25 to 120 °C, AZO films showed lower electrical resistivity and better optical transmittance due to the significant improvement of the crystallinity. 2 wt.% Al-doped ZnO films deposited on glass and PEN substrates at sputtering power of 25 W, target to substrate distance of 6.8 cm, working pressure of 0.4 Pa and substrate temperature of 120 °C showed the lowest resistivity (5.12 × 10^− 3 Ω cm on PEN substrate, 3.85 × 10^− 3 Ω cm on glass substrate) and high average transmittance (> 90% in both substrates). AZO films deposited on PEN substrate showed similar electrical and optical properties like AZO films deposited on glass substrates.     

Low temperature remote plasma sputtering of indium tin oxide for flexible display applications

Tin doped indium oxide (ITO) has been directly deposited onto a variety of flexible materials by a reactive sputtering technique that utilises a remotely generated, high density plasma. This technique, known as high target utilisation sputtering (HiTUS), allows for the high rate deposition of good quality ITO films onto polymeric materials with no substrate heating or post deposition annealing. Coatings with a resistivity of 3.8 × 10^− 4 Ωcm and an average visible transmission of greater than 90% have been deposited onto PEN and PET substrate materials at a deposition rate of 70 nm/min. The electrical and optical properties are retained when the coatings are flexed through a 1.0 cm bend radius, making them of interest for flexible display applications.     

Electrical,morphological and structural properties of RF magnetron sputtered Mo thin films for application in thin film photovoltaic solar cells

Molybdenum (Mo) thin films were deposited using radio frequency magnetron sputtering, for application as a metal back contact material in “substrate configuration” thin film solar cells. The variations of the electrical, morphological, and structural properties of the deposited films with sputtering pressure, sputtering power and post-deposition annealing were determined. The electrical conductivity of the Mo films was found to increase with decreasing sputtering pressure and increasing sputtering power. X-ray diffraction data showed that all the films had a (110) preferred orientation that became less pronounced at higher sputtering power while being relatively insensitive to process pressure. The lattice stress within the films changed from tensile to compressive with increasing sputtering power and the tensile stress increased with increasing sputtering pressure. The surface morphology of the films changed from pyramids to cigar-shaped grains for a sputtering power between 100 and 200 W, remaining largely unchanged at higher power. These grains were also observed to decrease in size with increasing sputtering pressure. Annealing the films was found to affect the resistivity and stress of the films. The resistivity increased due to the presence of residual oxygen and the stress changed from tensile to compressive. The annealing step was not found to affect the crystallisation and grain growth of the Mo films.     

Properties of indium tin oxide films deposited on unheated polymer substrates by ion beam assisted deposition

The optical, electrical and mechanical properties of indium tin oxide (ITO) films prepared on polyethylene terephthalate (PET) substrates by ion beam assisted deposition at room temperature were investigated. The properties of ITO films can be improved by introducing a buffer layer of silicon dioxide (SiO₂) between the ITO film and the PET substrate. ITO films deposited on SiO₂-coated PET have better crystallinity, lower electrical resistivity, and improved resistance stability under bending than those deposited on bare PET. The average transmittance and the resistivity of ITO films deposited on SiO₂-coated PET are 85% and 0.90 × 10^− 3 Ω cm, respectively, and when the films are bent, the resistance remains almost constant until a bending radius of 1 cm and it increases slowly under a given bending radius with an increase of the bending cycles. The improved resistance stability of ITO films deposited on SiO₂-coated PET is mainly attributed to the perfect adhesion of ITO films induced by the SiO₂ buffer layer.     

Effect of temperature on the properties of Al:ZnO films deposited by magnetron sputtering with inborn surface texture

Al:ZnO (AZO) films were deposited on glass substrate with inborn surface texture by magnetron sputtering at a power density as high as 7 W/cm². The sputtering parameters, such as argon working pressure and substrate temperature were varied from 1.0 to 6.0 Pa and from room temperature to 500 °C, respectively. All the films exhibited perfect (002) orientations with very weak (004) peaks measured by X-ray diffraction. A linear relationship between the growth rate of AZO film and working pressure was found. The AZO film with best electrical properties of all films obtained at room temperature was deposited at working pressure of 2.0 Pa. And the root-mean-square roughness tested by atomic force microscopy was 37.50 nm, which indicated that surface texture was successfully fabricated without further etching process. For higher substrate temperature a decrease in the resistivity was observed due to an increase in the mobility and the carrier concentration. Resistivity low as 9.044 × 10⁻⁴ ohm/cm was obtained at 500 °C and 2.0 Pa, the corresponding mobility and carrier concentration were 20.45 m²/Vs and 3.379 × 10²⁰/cm³, respectively. The grain size and the surface texture size tested by scanning electron microscopy also peaked at 500 °C. All the films showed a relatively high transmittance about 80%.     

Role of substrate temperature on the structural,optoelectronic and morphological properties of (400) oriented indium tin oxide thin films deposited using RF sputtering technique

RF sputtering process has been used to deposit highly transparent and conducting films of tin-doped indium oxide onto quartz substrates keeping the RF power constant at 250 W. The electrical, optical and structural properties have been investigated as a function of substrate temperature. XRD has shown that deposited films are polycrystalline and have (400) preferred orientation. Indium tin oxide layers with low resistivity values and high transmittance in the visible region have been deposited. Detailed Analyses based on X-ray diffraction, optical and electrical results are attempted to gain more insight into the factors that are governed by the influence of varying substrate temperature in this investigation. AFM pictures showed uniform surface morphology with very low surface roughness values. It has been observed that ITO films deposited in this study, keeping the substrate temperature at 150 °C, can provide the required optimum electrical and optical properties rendering them useful for developing many optoelectronic devices at a moderate temperature.     

Low resistivity transparent conducting CdO thin films deposited by DC reactive magnetron sputtering at room temperature

Transparent conducting cadmium oxide (CdO) films were deposited on PET (polyethylene terephthalate) substrate by DC reactive magnetron sputtering at room temperature. All the films deposited at room temperature were polycrystalline in rock-salt structure. Dependences of the physical properties of the CdO films on the oxygen partial pressure were systematically studied. The films deposited at low oxygen flow rate were (200) oriented, while the films deposited at an oxygen flow rate greater than 20 sccm were (111) oriented. The average grain size of the CdO films decreased as the oxygen flow rate increases as determined by XRD and SEM. The Hall effect measurement showed that CdO films have high concentration, low resistivity, and high mobility. Both the mobility and the concentration of the carrier decreased with the increase of the oxygen flow rate. A minimum sheet resistance of 36.1 Ω/□, or a lowest resistivity of 5.44 × 10^− 4 Ω cm (6.21 × 10²⁰/cm³, μ = 19.2 cm²/Vs) was obtained for films deposited at an oxygen flow rate of 10 sccm.     

Effects of deposition parameters on tantalum films deposited by direct current magnetron sputtering

Effects of deposition parameters on tantalum films deposited by direct current magnetron sputtering were studied. The results indicated that the electrical properties were relative to the oxygen and other impurities rather than to growth orientation. As the sputtering power increases from 25 to 100 W, the preferred-growth orientation of Ta films changes from (200) to (202) and the oxygen and impurities content in the films decrease. The temperature coefficient of resistance also reduces from −289.79 to −116.65 ppm/°C. The O/Ta ratio decrease and grain size reduction related to a change of electrical resistivity were observed at substrate temperatures in the range 300-500 °C. At 650 °C, partial stable α-Ta associated with a sharp decrease of the electrical resistivity was also found.     

Effect of sputtering power and annealing temperature on the properties of indium tin oxide thin films prepared from radio frequency sputtering using powder target

Indium tin oxide (ITO) thin films were deposited on quartz substrates by radio frequency (RF) sputtering with different RF power (100–250 W) using the powder target at room temperature. The effect of sputtering power on their structural, electrical and optical properties was systematically investigated. The intensity of (400) orientation clearly increases with the sputtering power increases, although the films have (222) preferred orientation. Increasing sputtering power is benefit for lower resistivity and transmittance. The films were annealed at different temperature (500–800 °C), then we explored the relationship between their electro-optical and structural properties and temperature. It has been observed that the annealed films tend to have (400) orientation and then show the lower resistivity and transmittance. The ITO thin film prepared by RF sputtering using powder target at 700 °C annealing temperature and 200 W sputtering power has the resistivity of 2.08 × 10^?4 Ω cm and the transmittance of 83.2 %, which specializes for the transparent conductive layers.     

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.     

Properties of RF magnetron sputtered indium tin oxide thin films on externally unheated glass substrate

Indium tin oxide (ITO) thin films were deposited by radio frequency (RF) magnetron sputtering onto glass substrates. The transparent and conducting ITO thin films were obtained on externally unheated glass substrate, without any post-heat treatment, and by varying the deposition process parameters such as the working pressure and the RF Power. The effect of the variation of the above deposition parameters on the structural, surface morphology, electrical, and optical properties of the thin films have been studied. A minimum resistivity of 2.36 × 10⁻⁴ Ω cm and 80% transmittance with a figure of merit 37.2 × 10⁻³ Ω⁻¹ is achieved for the thin films grown on externally unheated substrate with 75 W RF power and 0.5 mTorr working pressure.     

Deposition of low-resistivity gallium-doped zinc oxide films by low-temperature radio-frequency magnetron sputtering

The transparent and conductive gallium-doped zinc oxide (GZO) film was deposited on 1737F Corning glass using the radio-frequency (RF) magnetron sputtering system with a GZO ceramic target. (The Ga₂O₃ contents are approximately 5 wt. %). In this study, the effect of the sputtering pressure on the structural, optical and electrical properties of GZO films upon the glass or polyester film (PET) substrate was investigated and discussed in detail. The GZO film was grown under a steady RF power of 400 W and a lower substrate temperature from room temperature up to 200 °C. The crystal structure and orientation of GZO thin films were examined by X-ray diffraction. All of the GZO films under various sputtering pressures had strong c-axis (002)-preferred orientation. Optical transparency was high (> 80%) over a wide spectral range from 380 nm to 900 nm. According to the experimental data, the resistivity of a single-layered GZO film was optimized at  8.3 × 10^− 4 Ω cm and significantly influenced by the sputtering pressure. In further research, the sandwich structure of the GZO film/Au metal/GZO film was demonstrated to improve the electrical properties of the single-layered GZO film. The resistivity of the sandwich-structured GZO film was around 2.8 × 10^− 4 Ω cm.     

Preparation and properties of Mg0.2Zn0.8O:Al UV transparent conducting thin films deposited by RF magnetron sputtering at room temperature with rapid annealing

Mg_0.2Zn_0.8O:Al UV transparent conducting thin films were deposited by RF magnetron sputtering at room temperature with a rapid annealing process. Effects of sputtering power, argon gas pressure and annealing temperature on structure, optical and electrical properties of Mg_0.2Zn_0.8O:Al films were investigated. The experimental results show that Mg_0.2Zn_0.8O:Al thin films exhibit high preferred c-axis-orientation. The sputtering power, argon gas pressure and annealing temperature all exert a strong influence on the electrical resistivity of Mg_0.2Zn_0.8O:Al thin films due to the variation of carrier concentration and mobility in films derived from the change of effective doping and crystallinity. The lowest electrical resistivity of Mg_0.2Zn_0.8O:Al thin films is 3.5 × 10⁻³ Ω·cm when the sputtering power is 200 W, the argon gas pressure is 2.0 Pa and the annealing temperature is above 500 °C. The transparent spectrum range of Mg_0.2Zn_0.8O:Al thin films extend to ultraviolet band and the optical transmittance is between 80 and 90%, but the sputtering power, argon gas pressure and annealing temperature all exert little influence on optical transmittance.     

直流磁控溅射法制备掺钛氧化锌透明导电薄膜

采用直流磁控溅射法在室温水冷玻璃衬底上制备出高质量的掺钛氧化锌(ZnO:Ti)透明导电薄膜,研究了溅射功率对ZnO:Ti薄膜结构、形貌和光电性能的影响,结果表明,溅射功率对ZnO:Ti薄膜的结构和电阻率有显著影响.XRD表明,ZnO:Ti薄膜为六角纤锌矿结构的多晶薄膜,且具有c轴择优取向.当溅射功率为130W时,实验制备的ZnO:Ti薄膜的电阻率具有最小值9.67×10~(-5)Ω·cm.实验制备的ZnO:Ti薄膜具有良好的附着性能,可见光区平均透过率超过91%.ZnO:Ti薄膜可以用作薄膜太阳能电池和液晶显示器的透明电极.     

Structural, electrical and optical properties of ZnO:Al films deposited on flexible organic substrates for solar cell applications

Aluminum doped ZnO thin films (ZnO:Al) were deposited on glass and poly carbonate (PC) substrate by r.f. magnetron sputtering. In addition, the electrical, optical properties of the films prepared at various sputtering powers were investigated. The XRD measurements revealed that all of the obtained films were polycrystalline with the hexagonal structure and had a preferred orientation with the c-axis perpendicular to the substrate. The ZnO:Al films were increasingly dark gray colored as the sputter power increased, resulting in the loss of transmittance. High quality films with the resistivity as low as 9.7 × 10^− 4 Ω-cm and transmittance over 90% have been obtained by suitably controlling the r.f. power.     

Influence of RF power on structural,morphology, electrical,composition and optical properties of Al-doped ZnO films deposited by RF magnetron sputtering

In this study, influence of RF power on the structural, morphology, electrical, composition and optical properties of Al-doped ZnO (ZnO:Al) films deposited by RF magnetron sputtering have been investigated. Films were systematically and carefully investigated by using variety of characterization techniques such as low angle X-ray diffraction, UV–visible spectroscopy, Raman spectroscopy, Hall measurement, X-ray photoelectron spectroscopy, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy etc. Low angle X-ray diffraction analysis showed that the films are polycrystalline with hexagonal wurtzite structure and which was further confirmed by Raman spectroscopy analysis. Its preferred orientation shifts from (102) to (002) with increase in RF power. The average grain size was found in the range of 15–21 nm over the entire range of RF power studied. The FE-SEM analysis showed that grain size and surface roughness of ZnO:Al films increase in with increase in RF power. The UV–visible spectroscopy analysis revealed that all films exhibit transmittance >85 % in the visible region. The optical band gap increases from 3.37 to 3.85 eV when RF power increased from 75 to 225 W. Hall measurements showed that the minimum resistivity has been achieved for the film deposited at 200 W. The improvement in the electrical properties may attribute to increase in the carrier concentration and Hall mobility. Based on the experimental results, the RF power of 200 W appears to be an optimum sputtering power for the growth of ZnO:Al films. At this optimum sputtering power ZnO:Al films having minimum resistivity (8.61 × 10^?4 Ω-cm), highly optically transparent (~87 %) were obtained at low substrate temperature (60 °C) at moderately high deposition rate (22.5 nm/min). These films can be suitable for the application in the flexible electronic devices such as TCO layer on LEDs, solar cells, TFT-LCDs and touch panels.