Deposition and properties of B-N codoped p-type ZnO thin films by RF magnetron sputtering

B-N codoped p-type ZnO thin films have been realized by radio frequency (rf) magnetron sputtering using a mixture of argon and oxygen as sputtering gas. Types of conduction and electrical properties in codoped ZnO films were found to be dependent on oxygen partial pressure ratios in the sputtering gas mixture. When oxygen partial pressure ratio was 70%, the codoped ZnO film showed p-type conduction and had the best electrical properties. Additionally, the p-ZnO/n-Si heterojunction showed a clear p-n diode characteristic. XRD results indicate that the B-N codoped ZnO film prepared in 70% oxygen partial pressure ratio has high crystal quality with (0 0 2) preferential orientation. Meanwhile, the B-N codoped ZnO film has high optical quality and displays the stronger near band edge (NBE) emission in the temperature-dependent photoluminescence spectrum, the acceptor energy level was estimated to be located at 125 meV above the valence band.     

Effects of oxygen partial pressure on resistive switching characteristics of ZnO thin films by DC reactive magnetron sputtering

Cu/ZnO/n⁺-Si structures were prepared by magnetron sputtering of a layer of ZnO thin film onto heavily doped silicon substrate, followed by thermal evaporation of a thin layer of metallic Cu. The resistive switching characteristics of Cu/ZnO/n⁺-Si structures were investigated as a function of oxygen partial pressure during ZnO deposition. Reproducible resistive switching characteristics were observed in ZnO thin films deposited at 20%, 33% and 50% oxygen partial pressure ratios while ZnO thin film deposited at 10% oxygen partial pressure ratio did not show resistive switching behavior. The conduction mechanisms in high and low resistance states are dominated by space-charge-limited conduction and ohmic behavior respectively, which suggests that resistive switching behaviors in such structures are related to filament formation and rupture. It is also found that the reset current decreases as oxygen partial pressure increases, due to the variation of oxygen vacancy concentration in the ZnO thin films.     

氧分压对PLD制备ZnO薄膜结构和发光性质的影响

采用脉冲激光沉积(PLD)技术,在Si(100)衬底上制备出高度c轴取向的ZnO薄膜。通过X射线衍射(XRD)谱,扫描电镜(SEM)和室温光致发光(PL)光谱的测量,研究了生长气氛压强的改变对薄膜结构和光致发光的影响。实验结果表明,当氧压从10Pa升高到100Pa时ZnO(002)衍射峰的半峰全宽(FWHM)增大。可以认为这是由于较高的氧压下,到达衬底表面的离子动能减小。这样部分离子没有足够的能量迁移到生长较快的(002)面,c轴取向变差,导致(002)衍射峰的强度降低,半峰全宽增大。随着氧压增大,紫外发光强度增强。这可能是氧压变大,薄膜的化学配比升高,说明化学配比对UV发光的影响要大于薄膜微结构的影响。改变氧气压强对薄膜的表面形貌也有较大的影响。     

Behavior of oxygen in zinc oxide films through thermal annealing and its effect on sheet resistance

Behavior of oxygen in sputtering deposited ZnO films through thermal annealing and its effect on sheet resistance of the films were investigated. The crystallinities of the ZnO film were improved by post-deposition annealing in vacuum. However, the sheet resistance of ZnO film was dramatically decreased after post-deposition annealing in vacuum at more than 300 °C, while O₂ desorbed from the film. The oxygen vacancies which acted as donors were formed by the thermal annealing in vacuum. The sheet resistance of the films was recovered by annealing in oxygen ambient. In this paper, ¹⁸O₂ gas as an oxygen isotope was used as the annealing ambient in order to distinguish from ¹⁶O, which was constituent atom of the ZnO films. SIMS analysis revealed that ¹⁸O diffused into the ZnO film from the top surface by ¹⁸O₂ annealing. Therefore oxygen vacancies formed by the post-deposition annealing in vacuum could be compensated by the annealing in oxygen ambient.     

Influence of oxygen partial pressure on the composition and orientation of strontium-doped lead zirconate titanate thin films

The influence of oxygen partial pressure during the deposition of piezoelectric strontium-doped lead zirconate titanate thin films is reported. The thin films have been deposited by RF magnetron sputtering in an atmosphere of high purity argon and oxygen (in the ratio of 9:1), on platinum-coated silicon substrates (heated to 650 degrees C). The influence of oxygen partial pressure is studied to understand the manner in which the stoichiometry of the thin films is modified, and to understand the influence of stoichiometry on the perovskite orientation. This article reports on the results obtained from films deposited at oxygen partial pressures of 1-5 mTorr. The thin films have been studied using a combination of X-ray photoelectron spectroscopy (XPS), glancing angle X-ray diffraction (GA-XRD), and atomic force microscopy (AFM). XPS analysis highlights the marked influence of variations in oxygen pressure during sputtering, observed by variations in oxygen concentration in the thin films, and in some cases by the undesirable decrease in lead concentration in the thin films. GA-XRD is used to study the relative variations in perovskite peak intensities, and has been used to determine the deposition conditions to attain the optimal combination of stoichiometry and orientation. AFM scans show the marked influence of the oxygen partial pressure on the film morphology.     

射频磁控溅射法制备ZnO薄膜的发光特性

利用射频磁控溅射法在硅衬底上制备出具有（002）择优取向的氧化锌薄膜，用波长为300nm的光激发，观察到在446nm处有一强的光致发光峰，它来自于氧空位浅施主能级上的电子到价带上的跃迁。并讨论了发光峰与氧压的关系以及退火对它的影响，且给出了解释。     

氧分压对磁控溅射制备ZnO薄膜的结构及光学特性的影响

采用射频反应磁控溅射法在玻璃衬底上成功制备出具有c轴高择优取向的ZnO薄膜,利用X射线衍射及紫外-可见吸收和透射光谱研究了氧分压变化对ZnO薄膜的微观结构及光吸收特性的影响。结果表明,当工作气压恒定时,用射频反应磁控溅射制备的ZnO薄膜的生长行为主要取决于成膜空间中氧的密度,合适的氧分压能够提高ZnO薄膜的结晶质量;薄膜在可见光区的平均透过率达到90%以上,且随着氧分压的增大,薄膜的光学带隙发生了一定程度的变化。采用量子限域模型对薄膜的光学带隙作了相应的理论计算,计算结果与对样品吸收谱所作的拟合结果符合较好,二者的变化趋势完全一致,表明ZnO纳米晶粒较小时,薄膜光学带隙的变化与量子限域效应有很大关系。     

不同氧分压下直流反应溅射ZnO薄膜的结构和光学特性

在室温,不同氧分压条件下,采用Zn靶直流反应溅射在石英衬底上制备了具有纤锌矿结构(002)择优取向的ZnO薄膜。薄膜的生长速率随氧分压的增大而减小,在20%-30%之间存在一个拐点,在此点之前,溅射产额减小的速率很快,而在此点之后,溅射产额减小的速率减慢了很多,当氧分压在30%以上时,溅射过程中Zn的氧化在靶表面就已经完成。通过单振子模型分析了薄膜的光学特性,采用X射线衍射的方法对薄膜的晶粒尺寸和应力进行分析。研究结果表明在氧分压20%以上时,薄膜在可见光波段具有较好的光学透明性和很高的电阻率。薄膜的光学折射率、晶面间距和内部应力均随着氧分压的增大而增大。并从薄膜生长机理上给出了理论解释。     

Optimization of parameters for deposition of Ga-doped ZnO films by DC reactive magnetron sputtering using Taguchi method

Ga-doped ZnO (ZnO:Ga) transparent conductive films were deposited on glass substrates by DC reactive magnetron sputtering. Taguchi method was used to find the optimal deposition parameters including oxygen partial pressure, argon partial pressure, substrate temperature, and sputtering power. By employing the analysis of variance, we found that the oxygen and argon partial pressures were the most influencing parameters on the electrical properties of ZnO:Ga films. Under the optimized deposition conditions, the ZnO:Ga films showed acceptable crystal quality, lowest electrical resistivity of 2.61 × 10⁻⁴ Ω cm, and high transmittance of 90% in the visible region.     

脉冲激光沉积(PLD)法生长高质量ZnO薄膜及其发光性能

采用脉冲激光沉积(PLD)法在单晶Si(100)衬底上生长ZnO薄膜,以X射线衍射(XRD)、原子力显微镜(AFM)和透射电镜(TEM)等手段分析了所得ZnO薄膜的晶体结构和微观形貌。优化工艺(700℃,20Pa)下生长的ZnO薄膜呈c轴高度择优取向,柱状晶垂直衬底表面生长,结构致密均匀。室温光致发光(PL)谱分析结果表明,随着薄膜生长时O₂分压的增大,近带边紫外发光峰与深能级发光峰之比显著增强,表明薄膜的结晶性能和化学计量比都有了很大的改善。O₂分压为20Pa时所生长的ZnO薄膜具有较理想的化学计量比和较高的光学质量。     

Effect of oxygen partial pressure on the structural and optical properties of ZnO film deposited by reactive sputtering

Effects of variation of the oxygen partial pressure on the structural and optical properties of zinc oxide (ZnO) thin films prepared by reactive radio-frequency sputtering were investigated. Measurements by X-ray diffraction (XRD) and atomic force microscopy (AFM) indicated that the crystallinity and the surface morphology were sensitive to the oxygen partial pressure. The interfacial and optical properties of the targeted films were investigated by spectroscopic ellipsometry (SE) characterization. Based on Tauc-Lorentz (TL) model, the optical constants of ZnO films were tentatively extracted in the photon energy ranging from 1.5 to 6.0 eV. Analyses by XRD and SE revealed that the oxygen partial pressure had effect on the orientation of the ZnO films, the surface morphology, the packing density, and the interfacial layers. And the relationship between crystallinity and interfacial layer, as well as the relationship between surface roughness and packing density was discussed. All these had a significant impact on the optical properties illustrated by SE analysis.     

氧气后处理对氧化锌薄膜紫外发射性质的影响

为了提高ZnO光发射效率和制备p型ZnO,对热处理的氧分压对薄膜的结构、形貌、光致光发射和ZnO/Si异质结的Ⅰ-Ⅴ特性的影响进行了研究.用直流反应溅射法在p型硅衬底上生长ZnO薄膜形成n-ZnO/P-Si异质结.在1000℃下用不同比例的氧和氨热处理,我们发现,在纯氮气中得到的样品有强的紫外发射(390nm),随氧气比例增大,紫外增强,同时绿光也产生并随之增强.但过大的氧分压反而产生多的受主缺陷,使越来越多的激发能量转移到发射能量低的绿光中心,从而使紫外减弱.在纯氧和无氧条件下热处理的俄歇谱表明纯氧下氧过量,而无氧下锌大大过量.ZnO/p-Si异质结的Ⅰ-Ⅴ特性表明,无氧热处理表现为典型的n-ZnO/p-Si异质结;而在纯氧气氛中处理后所得Ⅰ-Ⅴ曲线反向,这表明在高氧压下受主缺陷的产生,表明ZnO薄膜有可能由于高氧压热处理由n型转为p型.     

Mechanical reliability of transparent conducting IZTO film electrodes for flexible panel displays

The mechanical reliability of transparent In-Zn-Sn-O (IZTO) films grown using pulsed DC magnetron sputtering with a single oxide alloyed ceramic target on a transparent polyimide (PI) substrate at room temperature is investigated. All IZTO films deposited at room temperature have an amorphous structure. However, their optical and electrical properties change depending on the oxygen partial pressure applied during depositing process. At an oxygen partial pressure of 3%, the films exhibit a resistivity of 8.3 × 10⁻⁴ Ω cm and an optical transmittance of 86%. Outer bending tests show that the critical bending radius decreases from 10 mm to 7.5 mm when the oxygen partial pressure increases from 1% to 3%. In the inner bending test, the critical bending radius is independent of oxygen partial pressure at 3.5 mm, indicating excellent film flexibility. In the dynamic fatigue test, the electrical resistance of the films reduces by less than 1% for more than 2000 bending cycles. These results suggest that IZTO films have excellent mechanical durability and flexibility in comparison to ITO films.     

On the phase formation of titanium oxide thin films deposited by reactive DC magnetron sputtering: influence of oxygen partial pressure and nitrogen doping

This work describes about the control on phase formation in titanium oxide thin films deposited by reactive dc magnetron sputtering. Various phases of titanium oxide thin films were deposited by controlling the oxygen partial pressure during the sputtering process. By adding nitrogen gas to sputter gas mixture of oxygen and argon, the oxygen partial pressure was decreased further below the usual critical value, below and above which the sputtering yields metallic and oxide films, respectively. Furthermore, nitrogen addition eliminated the typical hysteretic behaviour between the flow rate and oxygen partial pressure, and significantly influenced the sputter rate. On increasing the oxygen partial pressure, the ratio between anatase and rutile fraction and grain size increases. The fracture cross-sectional scanning electron microscopy together with the complementary information from X-ray diffraction and micro-Raman investigations revealed the evolution and spatial distribution of the anatase and rutile phases. Both the energy delivered to the growing film and oxygen vacancy concentrations are correlated with the formation of various phases upon varying the oxygen partial pressure.     

Effect of substrate and annealing on the structural and optical properties of ZnO:Al films

ZnO:Al thin films with c-axis preferred orientation were deposited on glass and Si substrates using RF magnetron sputtering technique. The effect of substrate on the structural and optical properties of ZnO:Al films were investigated. The results showed a strong blue peak from glass-substrate ZnO:Al film whose intensity became weak when deposited on Si substrate. However, the full width at half maxima (FWHM) of the Si-substrate ZnO:Al (0 0 2) peaks decreased evidently and the grain size increased. Finally, we discussed the influence of annealing temperature on the structural and optical properties of Si-substrate ZnO:Al films. After annealing, the crystal quality of Si-substrate ZnO:Al thin films was markedly improved and the intensity of blue peak (∼445 nm) increased noticeably. This observation may indicate that the visible emission properties of the ZnO:Al films are dependent more on the film crystallinity than on the film stoichiometry.     

The influence of oxygen on the optical properties of RF-sputtered zinc oxide thin films

In this article, we investigate the effects of oxygen partial pressure in the deposition chamber on the optical properties of zinc oxide (ZnO) thin films; in particular, we examine the variation of the refractive index with oxygen flux.ZnO thin films were deposited by radio-frequency (RF) magnetron sputtering and studied by means of X-ray diffraction (XRD) and spectroscopic ellipsometry (SE). We have found a preferential c-axis growth of ZnO films, with slightly variable deposition rates from 2.6 to 3.8 Å/s. Conversely, the refractive index exhibits, from ultraviolet (UV) to near infrared (IR), a considerable and almost linear variation when the oxygen flux value in the deposition chamber varies from 0 to 10 sccm.     

玉米蛋白质基底上射频磁控溅射法制备ZnO薄膜

采用射频磁控溅射方法在蛋白质基底上成功地制备了ZnO薄膜,研究了不同靶基距、氩氧比和溅射功率条件对ZnO薄膜性质的影响。结果表明,较小的靶基距有助于ZnO薄膜的c轴择优取向生长。我们还发现,沉积于玉米蛋白质基底的ZnO薄膜存在不同程度的张应力,当Ar/（Ar+O₂）为0.7时,ZnO薄膜内的张应力最小。ZnO近带边发光峰有不同程度的红移,我们认为,这是由于晶界势垒和氧空位V_o造成的。随着溅射功率的增大,薄膜生长速率显著加快,晶粒尺寸增大,ZnO的近带边发光峰位逐渐趋向于理论值。     

掺钼ZnO透明导电薄膜的太赫兹电磁波传输性质

采用直流磁控反应溅射方法,通过调节氧分压在玻璃基底上制备了不同载流子浓度的掺Mo的ZnO（ZMO）透明导电薄膜.应用太赫兹电磁波时域光谱技术研究了ZMO导电膜的太赫兹电磁波透射性质及介电响应,得到了与频率相关的电导率、能量吸收和薄膜折射率,实验结果与经典Drude模型相符很好.ZMO导电膜的太赫兹电磁波脉冲透射性质表明,通过调节ZMO薄膜的载流子浓度,该导电膜可作为应用于衬底和光学器件等太赫兹电磁波频率范围的宽带抗反射涂层. 关键词： 太赫兹电磁波光谱 薄膜电导率 宽带抗反射 透明导电薄膜     

Effects of the oxygen partial pressure and annealing atmospheres on the microstructures and optical properties of Cu-doped ZnO films

Cu-doped zinc oxide (ZnO:Cu) films were deposited on p-Si (1 0 0) substrates at 200 °C under various oxygen partial pressures by using radio frequency reactive magnetron sputtering. The properties of the films were characterized by the X-ray diffraction spectroscopy (XRD), energy dispersive spectrometer, X-ray photoelectron spectroscopy (XPS) and fluorescence spectrophotometer with the emphasis on the evolution of microstructures, element composition, valence state of Cu, optical properties. The results indicated that the properties of ZnO:Cu films were significantly affected by oxygen partial pressures. XRD measurements revealed that the sample prepared at the ratio of O₂:Ar of 15:10 sccm had the best crystal quality among all ZnO:Cu films. XPS analysis results suggested that the valence of Cu in the ZnO films was a mixed state of +1 and +2, and the integrated intensity ratio of Cu²⁺ to Cu⁺ increased with the increment of oxygen partial pressure. The photoluminescence measurements at room temperature revealed a violet, two blue and a green emission. We considered that the origin of green emission came from various oxygen defects when the ZnO:Cu films grew in oxygen poor and enriched environment. Furthermore, the influence of annealing atmosphere on the microstructures and optical properties of ZnO:Cu films were discussed.     

Influence of the Plasma Kinetics on the Si/C Ratio of a-SixC1-x: H Thin Films Deposited by Reactive Magnetron Sputtering of a Si Target in Ar + CH4 Gas Mixtures

Possible sources of silicon and carbon atoms built-in amorphous hydrogenated silicon carbide thin films grown by reactive magnetron sputtering (RMS) in argon/methane gas mixtures are evaluated. It is found out that the plasma decomposition of methane molecules plays an essential role in providing of growing film surface by active hydrocarbon fragments, thus influencing significantly the film stoichiometry even though the methane partial pressure in the sputtering gas mixture is only 1.5–4.7%.