Surface morphology and photoluminescence properties of ZnO thin films obtained by PLD

ZnO thin films on Si(111) substrate were deposited by laser ablation of Zn target in oxygen reactive atmosphere, Nd-YAG laser with wavelength of 1 064 nm was used as laser source. XRD and FESEM microscopy were applied to characterize the structure and surface morphology of the deposited ZnO films. The optical properties of the ZnO thin films were characterized by photoluminescence. The UV and deep level (yellow-green) light were observed from the films. The UV light is the intrinsic property and deep level light is attributed to the existence of antisite defects (Ozn). The intensity of UV and deep level light depends strongly on the surface morphology and is explained by the surface roughness of ZnO film. A strongly UV emission can be obtained from ZnO film with surface roughness in nanometer range.     

电化学沉积Nd掺杂ZnO薄膜的结构和光学性质的研究

用电化学沉积方法制备出了Nd掺杂的ZnO薄膜,并研究其结构和光学性质。X-射线衍射谱的结果表明Nd3 替代Zn2 进入到ZnO晶格中,并没有引起杂相的出现。吸收谱的分析表明,随着掺杂浓度的增大,吸收峰向短波长方向移动 ,即发生蓝移。光致发光谱的结果表明随着Nd3 掺杂浓度的增大,紫外峰强度减小,可见光部分强度增大了。     

Properties of Ni doped and Ni-Ga co-doped ZnO thin films prepared by pulsed laser deposition

ZnNiO and Zn(Ni,Ga)O thin films were prepared on glass substrates by pulsed laser deposition. The obtained films are of good crystal quality and have smooth surfaces, which have a hexagonal wurtzite ZnO structure with a highly c-axis orientation without any Ga or Ni related phases. Hall-effect measurements showed that the ZnNiO film is n-type, in which the carrier concentration would be greatly enhanced by the addition of Ga. Room temperature ferromagnetism is observed for the ZnNiO and Zn(Ni,Ga)O films. The addition of Ga into the ZnNiO films increases the electron concentration but weakens the room temperature ferromagnetism.     

Influence of preparation methods on photoluminescence properties of ZnO films on quartz glass

The influence of preparation methods on the photoluminescence properties of ZnO film was studied. Two methods were applied to fabricate ZnO films in a conventional pulsed laser deposition apparatus. One is high temperature （500-700℃） oxidation of the metallic zinc film that is obtained by pulsed laser deposition. The other is pulse laser ablation of Zn target in oxygen atmosphere at low temperature （100-250 ℃）. The photoluminescence property was detected by PL spectrum. The room temperature PL spectra of the ZnO films obtained by oxidation method show single violet luminescence emission centered at 424 nm （or 2.90 eV） without any accompanied deep-level emission and UV emission. The violet emission is attributed to interstitial zinc in the films. Nanostructure ZnO film with c-axis （002） orientation is obtained by pulsed laser deposition. The ZnO film deposited at 200 ℃ shows single strong ultraviolet emission. The excellent UV emission is attributed to the good crystalline quality of the film and low intrinsic defects at such low temperature.     

Growth of bismuth telluride thin film on Pt by electrochemical atomic layer epitaxy

An automated thin-layer flow cell electrodeposition system was developed for growing Bi2Te3 thin film by ECALE. The dependence of the Bi and Te deposition potentials on Pt electrode was studied. In the first attempt,this reductive Te underpotential deposition (UPD)/reductive Bi UPD cycle was performed to 100 layers. A better linearity of the stripping charge with the number of cycles has been shown and confirmed a layer-by-layer growth mode, which is consistent with an epitaxial growth. The 4 : 3 stoichiometric ratio of Bi to Te suggests that the incomplete charge transfer in HTeO reduction excludes the possibility of Bi2Te3 formation. X-ray photoelectron spectroscopy (XPS) analysis also reveals that the incomplete charge transfer in HTeO2^ occurs in Te direct deposition. The effective way of depositing Bi2Te3 on Pt consists in oxidative Te UPD and reductive Bi UPD. The thin film deposited by this procedure was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). A polycrystalline characteristic was confirmed by XRD. The 2 : 3 stoichiometric ratio was confirmed by XPS. The SEM image indicates that the deposit looks like a series of buttons about 0.3 - 0.4/~m in diameter, which is corresponding with calculated thickness of the epitaxial film. This suggests that the particle growth appears to be linear with the number of cycles, as it is consistent with a layer by layer growth mode.     

沉积温度对ZnO薄膜结构及发光性能的影响

利用Nd-YAG激光器(波长为1064nm,频率为10Hz)做光源,采用纯金属锌靶,以Si(111)为基体在有氧的气氛中通过激光烧蚀锌靶表面来制备氧化锌薄膜,研究基体温度对ZnO薄膜结构及发光性能的影响.通过XRD和AFM原子力显微镜来表征氧化锌薄膜的结构和表面形貌,其光学性质由光致发光谱来表征.结果表明:在450-550 ℃的条件下沉积的ZnO薄膜具有c-轴择优取向,500℃时c-轴取向最明显.具有c-轴取向的ZnO薄膜具有强的紫外光发射和弱的绿光发射,发光中心在518nm处的黄绿光发射主要归因于电子从导带底部到氧位错缺陷OZn能级之间的跃迁.     

Conductive and transparent Bi-doped ZnO thin films prepared by rf magnetron sputtering

Bi-doped ZnO thin films were grown on glass substrates by ratio frequency (rf) magnetron sputtering technique and followed by annealing at 400 °C for 4 h in vacuum (~ 10^− 1 Pa). The effect of argon pressure on the structural, optical, and electrical properties of the Bi-doped films were investigated. The XRD patterns show that the thin films were highly textured along the c-axis and perpendicular to the surface of the substrate. Some excellent properties, such as high transmittance (about 85%) in visible region, low resistivity value of 1.89 × 10^− 3 W cm and high carrier density of 3.45 × 10²⁰ cm^− 3 were obtained for the film deposited at the argon pressure of 2.0 Pa. The optical band gap of the films was found to increase from 3.08 to 3.29 eV as deposition pressure increased from 1 to 3 Pa. The effects of post-annealing treatments had been considered. In spite of its low conductivity comparing with other TCOs, Bi-doping didn't appreciably affect the optical transparency in the visible range of ZnO thin films.     

Influence of growth temperature on the optical and structural properties of ultrathin ZnO films

This study investigates the effect of growth temperature on the optical and structural properties of ultrathin ZnO films on the polished Si substrate. Thickness of the ultrathin ZnO films deposited by atomic layer deposition (ALD) method was about 10 nm. Photoluminescence (PL), X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques were used to measure the properties of ultrathin ZnO films. Experimental results showed that the ultrathin ZnO film deposited at 200 °C had excellent ultraviolet emission intensity, and the average roughness of the film surface was about 0.26 nm.     

Relative photoluminescence of ZnO nanorods size-controlled by changing the precursor ratio in metal organic chemical vapor deposition

The photoluminescent (PL) properties of vertically and laterally well-oriented ZnO nanorod arrays (NRAs) synthesized by metalorganic chemical vapor deposition on Al₂O₃ (0001) substrates were investigated. The size of the NRAs was controlled by systematic tuning of the precursor ratio. Regardless of the size of the NRAs, the PL properties were the same when measured at room temperature and at low temperatures. This observation suggests that changing the precursor ratio is a good way of controlling the size of ZnO NRAs while maintaining consistent PL properties.     

预沉积ZnO薄膜对ZnO−MoS2/ZnO复合涂层结构与性能影响

目的 通过优化原子层沉积工艺获取不同厚度ZnO薄膜,研究ZnO薄膜晶体取向对ZnO?MoS2涂层生长结构的影响,获得具有优异摩擦学性能的ZnO?MoS2/ZnO复合涂层。方法 采用原子层沉积法在不锈钢基体上预沉积不同厚度的ZnO薄膜,再用射频磁控溅射技术继续沉积ZnO?MoS2涂层,制备ZnO?MoS2/ZnO固体润滑复合涂层。结果 X射线衍射分析发现,预沉积ZnO薄膜有诱导后续ZnO?MoS2涂层沉积生长的作用,预沉积100 nm厚ZnO薄膜的ZnO?MoS2/ZnO复合涂层显示出宽化的MoS2 (002)馒头峰,其截面形貌显示为致密的体型结构,获得的摩擦因数最低(0.08),纳米硬度最高(2.33 GPa),硬度/模量比显示该复合涂层的耐磨损性能得到提升;X射线光电子能谱分析结果表明,复合涂层表面游离S与空气中水发生反应程度大约为原子数分数5%,显示复合涂层耐湿性能较好;基于原子层沉积ZnO薄膜生长及其对后续ZnO?MoS2涂层生长的影响分析,提出了ZnO?MoS2/ZnO复合涂层磨损模型,阐明了ZnO薄膜对复合涂层结构及摩擦学性能的影响,并以该模型解释了200 nm厚 ZnO薄膜上沉积ZnO?MoS2涂层出现的摩擦因数由高到低的变化趋势及最终磨损失效现象。结论 合适的原子层沉积制备的ZnO薄膜有利于MoS2 (002)取向生长,可有效提升ZnO?MoS2/ZnO复合涂层的摩擦学性能;控制ZnO薄膜厚度,可实现ZnO薄膜与基底及ZnO?MoS2层间界面之间的优化结合,以制得具有较好摩擦学性能及使用寿命的ZnO?MoS2/ZnO复合涂层。     

Optical properties of nanosized ZnO films prepared by sol-gel process

Nanosized ZnO films were prepared by sol-gel process on quartz substrates. The effects of sol concentration and annealing temperature on the surface morphology, microstructure and optical properties of the films were investigated. The results show that the sols remain stable and usable for spin-coating within 7 d. The ZnO films have a homogeneous and dense surface with grain size about 30 nm. The ZnO thin film annealed at 500 ℃ for 1 h from the sol with Zn concentration of 0.8 mol/L shows an average transmittance of 94% in visible wavelength range. The optical band gaps in ZnO films by various annealing temperatures are from 3.265 eV to 3.293 eV. The violet emission located at 438 nm is probably due to the recombination transitions relating to the interface traps at the grain boundaries.     

Zn靶与掺铝ZnO靶共溅射制备ZnO:Al薄膜及其性能

采用Zn靶和ZnO(掺2%Al2O3(质量分数))陶瓷靶在玻璃衬底上共溅射沉积Al掺杂ZnO薄膜,即ZnO:Al透明导电薄膜,研究Zn靶溅射功率(0～90 W)和衬底温度(室温、100℃和200℃)对薄膜结构、形貌、光学和电学性能的影响。结果表明:按双靶共溅射工艺制备的ZnO:Al薄膜的晶体结构均为六角纤锌矿结构,且随着Zn靶溅射功率的增加,薄膜的结晶质量呈现出先改善后变差的规律,薄膜中的载流子浓度逐渐升高,电阻率逐渐降低,而薄膜的光学性能受其影响不大;随着衬底温度的升高,薄膜的结晶性能得到改善,薄膜的可见光透过率增强,电阻率降低。     

金属前驱体区域选择性原子层沉积机制

基于区域选择性原子层沉积(AS-ALD)技术的自下而上制造工艺近年来在半导体、催化剂等领域得到了迅速发展.AS-ALD本质上是在同种材料的不同位点或异种材料表面实现目标产物在生长区域的选择性沉积,并且抑制在非生长区域的沉积.目前,实验上已经发展了多种表面抑制、活化技术,或者利用材料表面不同位点的固有差异实现金属前驱体的...     

Utilisation of continuous atomic layer deposition process for barrier enhancement of extrusion-coated paper

The feasibility of a novel continuous atomic layer deposition process in improving the barrier properties of extrusion-coated papers was investigated. The polymer coatings on paper were low-density polyethylene, polypropylene, polyethylene terephtalate and polylactide. The new method was tested by depositing 100 nm aluminium oxide layers on the polymer side of the structures. According to test results, the aluminium oxide layer produced significant barrier improvements. The water vapour and oxygen transmission rates measured were approximately 3-5 times lower than those of the untreated samples. Even better improvements were found for the water vapour transmission rates of polyethylene terephtalate and polylactide coated papers being over 10 times lower than for the untreated structures. It is proposed that the better water vapour barrier improvements were found because of these polymers' disposition to water sorption in the non-processed samples. The continuous atomic layer deposition process caused also considerable changes in the topography and morphology of some polymers, which reduced the barrier properties and applicability of the structures. Further research is needed to enable the use of lower process temperatures in the continuous atomic layer deposition process, which would improve the feasibility of the new method.     

ZnO薄膜的脉冲激光沉积及性能研究

利用脉冲激光沉积技术在氧的活性气氛下烧蚀锌靶,在石英玻璃衬底上沉积获得ZnO薄膜,分析并研究了薄膜的微观组织及表面形态及激光能量密度、基体温度、氧压等工艺参数对沉积ZnO膜的影响.结果表明,在基体温度为450～550 ℃、氧压为31 Pa、激光能量密度为31 J/cm2条件下,膜表面完全氧化,ZnO沿(002)晶面生长;当基体温度为500 ℃时,ZnO薄膜光学性能优异.     

Approaching the limits of dielectric breakdown for SiO2 films deposited by plasma-enhanced atomic layer deposition

This study explores the ultimate limit in dielectric breakdown of SiO₂ thin films deposited by gas-phase, plasma-enhanced atomic layer deposition. Thickness-dependent breakdown behaviors similar to conventional, thermally grown SiO₂ thin films were observed for the first time on ALD films, where the dominant breakdown mechanisms were impact ionization, trap creation and anode hole injection, respectively. By suppressing these mechanisms, we show a reversible degradation in SiO₂ after the onset of Fowler–Nordheim tunneling before permanent dielectric damage occurs. The reversible window was only observable in films thinner than 10 nm. The SiO₂ thin films ultimately reached irreversible breakdown at a field strength of 2.7 V nm^?1, where Si–O bonds were destroyed due to impact ionization and accelerated electrons.     

射频反应磁控溅射制备氮化铜薄膜

使用射频反应磁控溅射法,在不同的射频功率和气体流量比下制备了氮化铜薄膜,并用X射线衍射仪和原子力显微镜对薄膜的结构进行表征。研究结果表明:薄膜呈现择优生长规律,由低气体流量比的Cu3N(111)晶面转向高分压的(100)面;薄膜的光学带隙在1.44～1.69eV之间,电阻率在60～5.6×105Ω.m之间,二者都随气体流量比的增大而增大。     

Realization of stable p-type ZnO thin films using Li-N dual acceptors

Lithium and nitrogen dual acceptors-doped p-type ZnO thin films have been prepared using spray pyrolysis technique. The influence of dual acceptor (Li, N) doping on the structural, electrical, and optical properties of (Li, N):ZnO films are investigated in detail. The (Li, N):ZnO films exhibit good crystallinity with a preferred c-axis orientation. From AFM studies, it is found that the surface roughness of the thin films increases with the increase of doping percentage. The Hall Effect measurements showed p-type conductivity. The Hall measurements have been performed periodically up to seven months and it is observed that the films show p-type conductivity throughout the period of observation. The samples with Li:N ratio of 8:8 mol% showed the lowest resistivity of 35.78 Ω cm, while sample with Li:N ratio of 6:6 mol% showed highest carrier concentration. The PL spectra of (Li, N):ZnO films show a strong UV emission at room temperature. Furthermore, PL spectra show low intensity in deep level transition, indicating a low density of native defects. This indicates that the formation of intrinsic defects is effectively suppressed by dual acceptor (Li, N) doping in ZnO thin films. The chemical bonding states of N and Li in the films were examined by XPS analysis.     

Effect of annealing treatment on the structural, optical, and electrical properties of Al-doped ZnO thin films

Highly conductive and transparent Al-doped ZnO (AZO) thin films were prepared from a zinc target containing Al (1.5 wt.%) by direct current (DC) and radio frequency (RF) reactive magnetron sputtering. The structural, optical, and electrical properties of AZO films as-deposited and submitted to annealing treatment (at 300 and 400 ℃, respectively) were characterized using various techniques. The experimental results show that the properties of AZO thin films can be further improved by annealing treatment. The crystallinity of ZnO films improves after annealing treatment. The transmittances of the AZO thin films prepared by DC and RF reactive magnetron sputtering are up to 80% and 85% in the visible region, respectively. The electrical resistivity of AZO thin films prepared by DC reactive magnetron sputtering can be as low as tering have better structural and optical properties than that prepared by DC reactive magnetron sputtering.     

Effect of AlN intermediate layer on growing GaN film by hydride vapor phase epitaxy

Thick GaN layer deposited by hydride vapor phase epitaxy (HVPE) on a metalorganic chemical vapor deposition (MOCVD) GaN template with a thin low temperature (LT) AlN intermediate layer was investigated.High resolution X-ray resolution diffraction (HRXRD) shows that the crystalline quality of thick GaN layer was improved compared with the template.As confirmed by atomic force microscopy (AFM) observations, the surface morphology of AlN intermediate layer helps to improve the nucleation of GaN epilayer.Photoluminescence (PL) spectra measurement shows its high optical quality and low compressive stress, and micro Raman measurement confirms the latter result.Thus, the deposition of the LT-AlN interlayer has promoted the growth of an HVPE-GaN layer with an excellent crystalline quality.