Magnetic properties of ZnO:Cu thin films prepared by RF magnetron sputtering

ZnO films and ZnO:Cu diluted magnetic semiconductor films were prepared by radio frequency magnetron sputtering on Si (111) substrates, with targets of ZnO and Zn0.99Cu0.01 O, respectively. The plasma emission spectra were analyzed by using a grating monochromator during sputtering. The X-ray photoelectron spectroscopy measurements indicate the existence of Zni defect in the films, and the valence state of Cu is 1. The X-ray diffraction measurements indicate that the thin films have a hexagonal wurtzite structure and have a preferred orientation along the c-axis. The vibrating sample magnetometer measurements indicate that the sample is ferromagnetic at room temperature, and the origin of the magnetic behavior of the samples is discussed.     

射频磁控溅射法制备ZnO:Cu薄膜的磁性研究

ZnO films and ZnO：Cu diluted magnetic semiconductor films were prepared by radio frequency mag-netron sputtering on Si （111） substrates, with targets of ZnO and Zn0.99Cu0.01O, respectively. The plasma emission spectra were analyzed by using a grating monochromator during sputtering. The X-ray photoelectron spectroscopy measurements indicate the existence of Zni defect in the films, and the valence state of Cu is 1＋. The X-ray diffraction measurements indicate that the thin films have a hexagonal wurtzite structure and have a preferred orientation along the c-axis. The vibrating sample magnetometer measurements indicate that the sample is ferromagnetic at room temperature, and the origin of the magnetic behavior of the samples is discussed.     

射频磁控溅射制备的ZnMgO薄膜结构和光学性能

采用射频磁控溅射法,在石英衬底上制备了Zn1-xMgxO(x=0.00～0.16)薄膜。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见分光光度计和光致发光(PL)光谱等分析了薄膜的结构、形貌和光学特性。结果表明:当x≤0.10时薄膜保持六角纤锌矿结构,而x=0.16时已出现MgO立方相;所有薄膜晶粒大小均匀,在100～150 nm之间;透光率在80%以上;薄膜带隙Eg与Mg含量呈线性关系;薄膜PL谱由较弱的紫外发光峰和较强的可见发光带组成,随Mg含量的增加紫外发光峰蓝移。     

Effects of discharge power on the structural and optical properties of TGZO thin films prepared by RF magnetron sputtering technique

The transparent semiconductors of Ti and Ga-incorporated ZnO (TGZO) thin films were prepared by radio frequency (RF) magnetron sputtering onto glass substrates. The effects of discharge power on the physical properties of thin films are studied. Experimental results show that all nanocrystalline TGZO thin films possess preferential orientation along the (002) plane. The discharge power significantly affects the crystal structure and optical properties of thin films. When the discharge power is 200 W, the TGZO thin film has the optimal crystalline quality and optical properties, with the narrowest full width at half-maximum (FWHM) of 1.76´10-3 rad, the largest average grain size of 82.4 nm and the highest average transmittance of 84.3% in the visible range. The optical gaps of thin films are estimated by the Tauc’s relation and observed to increase firstly and then decrease with the increase of the discharge power. In addition, the optical parameters, including refractive index, extinction coefficient, dielectric function and dissipation factor of the thin films, are determined by optical characterization methods. The dispersion behavior of the refractive index is also analyzed using the Sellmeier’s dispersion model.     

Influence of N2 introduction on structural and optical properties of V-doped ZnO thin films grown by low-temperature reactive RF magnetron sputtering

The influences of N₂ introduction to a sputtering gas on structural and optical properties of vanadium-doped ZnO (VZO) films, grown by using reactive RF magnetron sputtering on a quartz substrate at room temperature, were investigated. In the VZO films, V doping caused to form a large number of O vacancies (V_O) and degraded both the c-axis orientation and optical transmittance. While, on the contrary, the ZnO(002) diffraction intensity of 3.5-at.% VZO films increased adding N₂ with a partial pressure ratio (α_N2) >2% reaching a maximum at α_N2 =5%. The average optical transmittance (wavelengths: 450−800 nm) of the 3.5-at.% VZO films was also improved by the N₂ introduction and reached 74% at α_N2 =5%. As a result of the analyses of the chemical binding states of the incorporated N atoms via the Raman spectroscopy and XPS, it was confirmed that the O sites were substituted by the N atoms and the amount of incorporated N increased by the high V doping. From the above, the N₂ introduction was effective to suppress the V_O formation even in room-temperature-grown VZO films, so it enables to improve both the c-axis orientation and optical transmittance.     

低温磁控溅射制备CdS薄膜的结构和光学特性

用磁控溅射的方法在透明导电氧化物衬底上制备了CdS薄膜,制备时的衬底温度为30~200℃.X射线衍射测试结果表明在这一条件下制备的CdS薄膜是六角纤锌矿的多晶结构.扫描电子显微镜结果显示薄膜具有较好的晶体质量,这一结论也和拉曼光谱、紫外-可见吸收光谱、光致发光光谱的结果一致.拉曼光谱显示CdS薄膜内部的压应力随着制备温度的提高而增大.     

Effect of thickness on the structural,optical and electrical properties of RF magnetron sputtered GZO thin films

Gallium-doped zinc oxide (GZO) thin films with very high conductivity and transparency were successfully deposited by RF magnetron sputtering at a substrate temperature of 400 °C. The dependence of the film properties over the thickness was investigated. X-ray diffraction (XRD) results revealed the polycrystalline nature of the films with hexagonal wurtzite structure having preferential orientation along [001] direction normal to the substrate. The lowest resistivity obtained from electrical studies was 5.4×10⁻⁴ Ω cm. The optical properties were studied using a UV–vis spectrophotometer and the average transmittance in the visible region (400–700 nm) was found to be 92%, relative to the transmittance of a soda–lime glass reference for a GZO film of thickness 495 nm and also the transparency of the films decreases in the near IR region of the spectra. The mobility of the films showed a linear dependence with crystallite size. GZO film of thickness 495 nm with the highest figure of merit indicates that the GZO film is suitable as an ideal transparent conducting oxide (TCO) material for solar cell applications.     

射频磁控溅射沉积AZO透明导电膜研究

采用射频磁控溅射技术在玻璃衬底上沉积了AZO透明导电薄膜,应用灰关联-田口实验法设计了L9(34)混合直交表,研究了制程工艺对薄膜沉积速率、电阻率、光穿透率、结晶性的影响。结果表明沉积薄膜的最佳制程参数为射频功率120 W、溅射压强2 Pa、靶材-基板距离8.5 cm、薄膜沉积时间90 min;实验显示最佳制程参数下所得透明导电薄膜沉积速率为8.04 nm/min,电阻率为2.6×10–3.cm,可见光穿透率维持在84%左右。     

Characteristics of ZnO thin films prepared by radio frequency magnetron sputtering

We investigated in this study structural and nanomechanical properties of zinc oxide (ZnO) thin films deposited onto Langasite substrates at 200 °C through radio frequency magnetron sputtering with an radio frequency power at 200 W in an O₂/Ar gas mixture for different deposition time at 1, 2, and 3 h. Surface morphologies and crystalline structural characteristics were examined using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The deposited film featured a polycrystalline nature, with (1 0 0), (0 0 2), and (1 0 1) peaks of hexagonal zinc oxide at 31.75°, 34.35°, and 36.31°. As the deposition time increased, the ZnO film became predominantly oriented along the c-axis (0 0 2) and the surface roughness decreased. Through Berkovich nanoindentation following a continuous stiffness measurement technique, the hardness and Young’s modulus of ZnO thin films increased as the deposition time increased, with the best results being obtained for the deposition time of 3 h. In addition, surface acoustic wave properties of ZnO thin films were also presented.     

退火处理对磁控溅射制备Ga掺杂ZnO薄膜性能的影响

采用磁控溅射法在普通玻璃上制备了Ga掺杂ZnO(GZO)薄膜,研究了退火处理对GZO薄膜组织结构、表面形貌及光电性能的影响,并利用扫描电子显微镜、X射线衍射仪、紫外分光光度计、四探针测试仪等对GZO薄膜的表面形貌、晶体结构、透光率及电阻率等进行测量与表征。结果表明:400~800℃退火对GZO薄膜的生长方式影响较小,所制薄膜均在(002)晶向沿c轴择优取向,退火温度对薄膜表面形貌影响较大,退火温度为600℃时,薄膜表面致密、平整,结晶质量最好,薄膜的透光率超过95%,电阻率最低为4.9×10~(-4)?·cm。     

Electronic properties of zinc oxide thin films prepared by RF magnetron sputtering for varistor applications

ZnO thin films for varistor applications have been prepared by RF magnetron sputtering at a power of 0-1 kW using an argon pressure of 05 Pa. The films were polycrystalline with mean grain size typically 13 nm, and were preferentially oriented in the [002] direction. Optical absorption studies revealed a fundamental absorption edge at a wavelength of approximately 360 nm with a direct bandgap of 3.36 eV. van der Pauw measurements showed a decrease in resistivity from approximately 12ωm at thickness 50 nm to 0-5 ωm at thickness greater than 500 nm. Below 350 K the resistivity was essentially constant, while at higher temperatures an activation energy of approximately 0-2eV was observed, which was attributed to the effects of oxygen vacancies.     

Enhanced photoluminescence properties of Cu-doped ZnO thin films deposited by simultaneous RF and DC magnetron sputtering

Copper (Cu)-doped ZnO thin films were grown on unheated glass substrates at various doping concentrations of Cu (0, 5.1, 6.2 and 7.5 at%) by simultaneous RF and DC magnetron sputtering technique. The influence of Cu atomic concentration on structural, electrical and optical properties of ZnO films was discussed in detail. Elemental composition from EDAX analysis confirmed the presence of Cu as a doping material in ZnO host lattice. XRD patterns show that the films were polycrystalline in nature with (002) as a predominant reflection of ZnO exhibited hexagonal wurtzite structure toward c-axis. From AFM analysis, films displayed needle-like shaped grains throughout the substrate surface. The electrical resistivity was found to be increased with increase of Cu content from 0 to 7.5 at%. Films have shown an average optical transmittance about 80% in the visible region and decreased optical band gap values from 3.2 to 3.01 eV with increasing of Cu doping content from 0 to 7.5 at% respectively. Furthermore, remarkably enhanced photoluminescence (PL) properties have been observed with prominent violet emission band corresponding to 3.06 eV (405 nm) in the visible region through the increase of Cu doping content in ZnO host lattice.     

Properties of transparent conductive ZnO:Al thin films prepared by magnetron sputtering

Middle-frequency alternative magnetron sputtering was used to deposit transparent conductive ZAO (ZnO:Al) thin films with ZAO (98 wt%ZnO+2 wt%Al₂O₃) ceramic target on glass and Si wafers. The influences of the various deposition parameters on the structural, optical and electrical performances of ZAO films have been studied. The structural characteristics of the films were investigated by the X-ray diffractometer and atomic force microscope, while the visible transmittance, carrier concentration and Hall mobility were studied by UV-VIS and the Hall tester, respectively. The lowest resistivity obtained in the work was 4.6×10⁻⁴ Ω cm for the film with average transmittance of 90.0% within the visible wavelength range and sheet resistance of 32 Ω, which was deposited at 250 °C and 0.8 Pa.     

DC磁控溅射制备的TiNx薄膜组分及性能分析

利用DC磁控溅射法在p-Si(111)衬底上制备了TiNx薄膜.利用X射线能谱仪(EDX)、X射线衍射(XRD)、紫外/可见分光光度计、四探针电阻率测试仪等分析了薄膜的组分、结构和光电特性.结果表明,薄膜中N/Ti原子比接近于1;衬底温度对薄膜的择优取向影响显著,240℃附近是TiNx薄膜结晶择优取向由(111)向(200)转变的临界点;薄膜在近红外波段平均反射率随衬底温度的升高,先增大后减小;薄膜的电阻率随着衬底温度的升高而显著降低.     

直流磁控溅射法制备非晶态氧化钒薄膜光学特性研究

研究了直流反应磁控溅射工艺中衬底温度对氧化钒(V2O5)薄膜性能的影响,利用X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、X射线衍射(XRD)和紫外-可见光分光光度计(UV1700)分别对薄膜进行了表征.实验结果表明,除了组分和晶态,薄膜的形貌和光学性能受衬底温度的影响很大.随着衬底温度的升高,膜表面变得粗糙,膜厚减小.光学特性测试表明,当衬底温度从160℃升高到320 ℃,光学带隙从2.39 eV下降到2.18 eV.     

Effects of parameters on the performance of amorphous IGZO thin films prepared by RF magnetron sputtering

Amorphous indium-gallium-zinc oxide （IGZO） transparent conductive thin films are prepared on glass substrates by radio frequency （RF） magnetron sputtering. The effects of seven factors, which are substrate temperature, sputtering atmosphere, working pressure, sputtering power, annealing temperature, negative bias voltage and sputtering time, on Hall mobility, transmittance and surface roughness are studied through orthogonal experiments. The results show that the effects of working pressure, substrate temperature and sputtering atmosphere on performance of films are the most prominent. According to the experimental results and discussion, relatively reasonable process parameters are obtained, which are working pressure of 0.35 Pa, substrate temperature of 200 ℃, sputtering atmosphere of Ar, sputtering power of 125 W, sputtering time of 30 min, negative bias voltage of 0 V and annealing temperature of 300 ℃.     

Effect of processing parameter on structural,optical and electrical properties of photovoltaic chalcogenide nanostructured RF magnetron sputtered thin absorbing films

The aim of this work was to develop high quality of CuIn_1−xGa_xSe₂ thin absorbing films with x (Ga/In+Ga)<0.3 by sputtering without selenization process. CuIn_0.8Ga_0.2Se₂ (CIGS) thin absorbing films were deposited on soda lime glass substrate by RF magnetron sputtering using single quaternary chalcogenide (CIGS) target. The effect of substrate temperature, sputtering power & working pressure on structural, morphological, optical and electrical properties of deposited films were studied. CIGS thin films were characterised by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), Energy dispersive X-ray spectroscopy (EDAX), Atomic force microscopy (AFM), UV–vis–NIR spectroscopy and four probe methods. It was observed that microstructure, surface morphology, elemental composition, transmittance as well as conductivity of thin films were strongly dependent on deposition parameters. The optimum parameters for CIGS thin films were obtained at a power 100 W, pressure 5 mT and substrate temperature 500 °C. XRD revealed that thin film deposited at above said parameters was polycrystalline in nature with larger crystallite size (32 nm) and low dislocation density (0.97×10¹⁵ lines m⁻²). The deposited film also showed preferred orientation along (112) plane. The morphology of the film depicted by FE-SEM was compact and uniform without any micro cracks and pits. The deposited film exhibited good stoichiometry (Ga/In+Ga=0.19 and In/In+Ga=0.8) with desired Cu/In+Ga ratio (0.92), which is essential for high efficiency solar cells. Transmittance of deposited film was found to be very low (1.09%). The absorption coefficient of film was ~10⁵ cm⁻¹ for high energy photon. The band gap of CIGS thin film evaluated from transmission data was found to be 1.13 eV which is optimum for solar cell application. The electrical conductivity (7.87 Ω⁻¹ cm⁻¹) of deposited CIGS thin film at optimum parameters was also high enough for practical purpose.     

射频磁控溅射法制备GZO:Ti薄膜的微结构及其光学性质

采用射频(RF)磁控溅射工艺于玻璃衬底沉积了镓钛 共掺杂氧化锌(GZO:Ti)半导体薄膜,研究了沉积 温度对薄膜微观结构和光学性质的影响。通过X射线衍射仪(XRD)和紫外分光光度计对其晶体 结构和透射光谱特 性进行表征,同时利用光谱拟合法获取了薄膜的光学常数。研究结果表明,所有薄膜均具备 六角纤锌矿结 构和c轴择优取向特性,沉积温度对薄膜的微结构参数、光学 常数和光学带隙具有明显调控作用,当沉积 温度为653K时,GZO:Ti薄膜的晶粒尺寸最大(82.12nm)、位错密度最低(1.48×10－4 nm－2) 、微应变最小(0.001)、可见光区平均透射 率 最高(82.06%)及光学带隙值最大(3.57eV )。     

Studies of yttrium oxide films prepared by RF magnetron sputtering

Films of yttrium oxide (Y₂O₃) were deposited on Si substrates from a Y₂O₃ target by RF magnetron sputtering. MIS capacitors in the form of Al and Y₂O₃ (400 Å)-Si were then fabricated. The leakage current density was about 10^-6 A/cm² at 1.3×10⁶ V/cm, and the breakdown field of the films was about 2.75×10⁶ V/cm. The dielectric constant of the sputtered Y₂O₃ was found to be about 12-12.7     

Study of electrical and optical properties of CNx thin films deposited by reactive magnetron sputtering

The study concerns the CN_x thin films deposited by Low Pressure Hot Target Reactive Magnetron Sputtering (LP-HTRMS). The thin film resistance changes with relative humidity (RH) and optical properties have been studied in the range of 300-653 K. The temperature coefficients of resistivity changes were −2.5%/K at 300 K and −0.5%/K at 500 K. The activation energy of conductivity E_ρ was found to be 0.21 eV in the case of unannealed sample and 0.44 eV when the sample was annealed at 653 K. The CN_x thin films fastness to light was tested in the range of 200-2500 nm by measuring their transmittance. The calculations of absorption carrying out with Tauc formula proved the dominance of indirect optical transitions with Eg energy of 1.04 eV and direct transitions of Eg 2.05 eV. The UV radiation was fully absorbed and light transmission was ca. 90% in the range from visible radiation to far infrared of 1000-2500 nm. The CN_x thin films showed the high resistance sensitivity to RH changes. At T = 300 K resistance changed from 882 M Ω for 36% RH to 386 k Ω for 85% RH. The CN_x thin films susceptibility to humidity was observed in case of both DC and AC current (100 Hz to 10 kHz) measurements. The Si₃N₄ or SiC buffer adhesive layer was incorporated between CN_x film and substrate and its influence on CN_x electrical properties was observed.