衬底温度对ZnO薄膜的结构和光学特性的影响

利用等离子体辅助分子束外延(P-MBE)设备在蓝宝石衬底上通过改变生长温度,制备了不同的ZnO样品.研究了衬底温度对ZnO的结构、光学和电学性质的影响.样品的晶体结构利用X射线衍射谱进行表征.X射线衍射谱表明,所有的ZnO样品都是(002)取向的六角纤锌矿结构.随着生长温度的升高,X射线的(002)衍射峰的半峰全宽逐渐...     

温度对Si上MOCVD-ZnO成核与薄膜生长特性的影响

采用金属有机化学气相沉积(MOCVD)方法在Si衬底上进行了ZnO的成核与薄膜生长研究。ZnO薄膜的形貌和结晶特性由成核和后期生长过程共同决定,初期成核温度决定了其尺寸和密度,进而影响后期ZnO主层的生长行为,但由于高温对后期ZnO纳米柱横向生长的抑制,纳米柱的尺寸并没有因为成核尺寸的增大而变大,因此在560℃得到了晶柱尺寸最大、密度最小的ZnO薄膜。最后通过改变成核温度,优化了ZnO外延膜的结晶质量。     

无催化法制备ZnO纳米针的结构及光学特性

采用无催化脉冲激光沉积(PLD)方法,在InP(100)衬底上生长纳米ZnO针状结构。采用扫描电子显微镜(SEM)、X射线衍射(XRD)以及光致发光(PL)谱等对ZnO纳米针的形貌、晶体结构和光学特性表征。SEM图像观察到ZnO纳米针状结构具有一定的取向性。XRD测试在2θ=34.50°处观测到强烈的ZnO(002)衍射峰,证实ZnO纳米针具有较好的c轴择优取向。室温PL谱在379nm处观察到了较强的自由激子发射峰(半峰全宽为13.5nm),而微弱的深能级跃迁峰位于484nm,二者峰强比值为11∶1,表明生长的纳米ZnO结构具有较高的光学质量。     

PLD方法制备的ZnO纳米柱结构及光学特性

采用无催化脉冲激光沉积(PLD)方法,在InP(100)衬底上生长纳米ZnO柱状结构。采用扫描电子显微镜(SEM)、X射线衍射(XRD)以及光致发光(PL)谱等表征手段对ZnO纳米柱的形貌、晶体结构和光学特性进行了观察。SEM图像观察到ZnO纳米柱状结构具有一定的取向性;XRD测试在2θ=34.10°处观测到强的ZnO(002)衍射峰,证实ZnO纳米柱具有较好的c轴择优取向;室温PL谱在379nm处观察到了强的自由激子发射峰(半峰全宽为19nm),未探测到深能级跃迁发射峰,表明生长的纳米ZnO结构具有很高的光学质量。     

ZnO/SiO2 复合薄膜的光学性能

采用溶胶-凝胶法在玻璃衬底上制备ZnO/SiO₂复合薄膜,分别用XRD、TEM、SEM对样品的结构和形貌进行表征,并研究了不同ZnO含量对复合薄膜透过率及荧光特性的影响。结果表明,样品经500 ℃退火处理生成了SiO₂和ZnO,其晶粒尺寸为18.7 nm,薄膜具有双层结构。复合薄膜的透过率随着其中ZnO含量的增加而降低,禁带宽度减小,光学吸收边红移。样品在355 nm波长激发下产生了384 nm的紫外发射峰和440 nm的蓝光发射带,并随ZnO含量的增加而增强,它们分别来自ZnO的电子-空穴复合发光和缺陷发光,及ZnO/SiO₂复合薄膜双层结构的缺陷发光。     

气相输运法制备ZnO薄膜(英文)

运用气相输运技术在不同的衬底上制备ZnO薄膜,同时对这些ZnO薄膜的表面形貌、晶体结构和光学特性进行表征。在扫描电子显微镜图像上可以看到,相比没有镀金的Si衬底,ZnO纳米颗粒在镀金的Si衬底上的生长尺寸较大。X射线衍射测试结果表明,在Si(111)和Si(100)衬底上生长的ZnO薄膜显示出不同的六角纤锌矿结构的衍射峰,但没有出现立方闪锌矿ZnO结构的衍射峰。在镀金的Si衬底上,ZnO薄膜生长取向主要为c轴方向。此外,所有ZnO样品的光致发光谱上均只出现一个狭窄且强的紫外峰,约在389 nm(3.19 eV)波长处。     

MgxZn1-xO/Au/MgxZn1-xO夹层透明导电薄膜的制备及光电性质研究

采用操作简单的溶胶-凝胶法和射频磁控溅射法在石英衬底上分别制备了MgxZn1-xO薄膜和MgxZn1-xO/Au/MgxZn1-xO夹层结构的透明导电薄膜并对样品进行退火处理。利用紫外-可见分光光度计、X射线衍射仪、光致发光、霍尔效应测试对在不同退火温度下薄膜的晶体结构、光学和电学性质进行表征分析,并研究退火温度对其影响。测试结果表明:所制备的薄膜样品均具有良好的c轴(c-axis)取向并呈现出六角纤锌矿结构。Mg组分的增加使得ZnO基薄膜的光学带隙逐渐增大,PL发光谱和吸收光谱的谱线出现了明显的蓝移现象,但薄膜的电学特性有所降低。而在MgxZn1-xO/Au/MgxZn1-xO夹层结构的薄膜样品中,Au夹层的存在使薄膜的光学性质变差,在紫外区域透光率约为60%。但薄膜的电学性质得到明显改善,相比MgxZn1-xO薄膜,其电阻率和迁移率显著提高。此外通过高温退火处理可以有效提高所制备薄膜的晶体质量,进一步提高样品电学特性,其中经过500℃退火后的薄膜迁移率达到了40.9cm2·Vs-1,电阻率为0.005 7Ω·cm。但随着退火温度的进一步升高,薄膜晶体尺寸从25.1nm增大到32.4nm,从而降低了该薄膜的迁移率。因此该夹层结构的MgxZn1-xO/Au/MgxZn1-xO薄膜对于促进ZnO基透明导电薄膜在深紫外光学器件中的应用有重要作用。     

生长温度对磁控溅射ZnO薄膜的结晶特性和光学性能的影响

采用反应射频磁控溅射方法，在Si (100) 基片上制备了具有高c轴择优取向的ZnO薄膜.利用 原子力显微镜、透射电子显微镜、X射线衍射分析、拉曼光谱等表征技术，研究了沉积温度 对ZnO薄膜的表面形貌、晶粒尺度、应力状态等结晶性能的影响；通过沉积温度对透射光谱 和光致荧光光谱的影响，探讨了ZnO薄膜的结晶特性与光学性能之间的关系.研究结果显示， 在室温至500℃的范围内，ZnO薄膜的晶粒尺寸随沉积温度的增加而增加，在沉积温度为500 ℃时达到最大；当沉积温度为750℃时，ZnO薄膜的晶粒尺度有所减小；在室温至750℃的范 围内，薄膜中ZnO晶粒与Si基体之间均存在着相对固定的外延关系；在沉积温度低于500℃时 ，制备的ZnO薄膜处于压应变状态，而750℃时沉积的薄膜表现为张应变状态.沉积温度的不 同导致ZnO薄膜的折射率、消光系数、光学禁带宽度以及光致荧光特性的变化，沉积温度对 紫外光致荧光特性起着决定性的作用.此外，探讨了影响薄膜近紫外光致荧光发射的可能因 素. 关键词： ZnO薄膜 表面形貌 微观结构 光学常数     

AlN缓冲层对ZnO薄膜质量的影响

采用脉冲激光沉积法以AlN为缓冲层在Si(100)衬底上制备了ZnO薄膜,并测量了样品的XRD谱、SEM图和PL谱.结果表明,AlN缓冲层可以提高Si衬底上外延生长ZnO薄膜的晶体质量.改变缓冲层的生长温度(50～500 ℃)所制备样品的测量结果表明,较低温度下生长的AlN缓冲层有利于制备高质量的ZnO外延层薄膜,其中AlN缓冲层生长温度为100 ℃时外延生长ZnO薄膜晶体质量最好.     

柔性衬底上ALD法低温制备的ZnO薄膜的光学和电学特性(英文)

以二乙基锌和水分别作为金属前驱体和反应物,利用原子层沉积方法(ALD)在柔性衬底上生长ZnO薄膜,讨论了生长温度对薄膜特性的影响。用AFM、XRD和HALL等对薄膜的表面形貌、晶体结构和电学性质进行表征,并且用PL光谱表征了其光学特性。实验结果表明,随着生长温度(低温下)的升高,薄膜的晶体质量和光学特性得到改善。当生长温度为170℃时,薄膜呈现良好的c轴择优取向,且具有较高的电子浓度(5.62×1019cm-3)和电子迁移率(28.2 cm2·V-1·s-1)。     

Growth of ZnO nanostructures by vapor–liquid–solid method

Zinc oxide nanorods have been grown by vapor–liquid–solid (VLS) catalytic growth. The optical properties and structures properties of the grown ZnO nanostructures have been studied by photoluminescence, high resolution X-ray diffraction and scanning electron microscopy. The results show that the formation of ZnO nanostructures is strongly influenced by the growth conditions and used substrates. It was found that oriented ZnO nanorods are grown more easily on a substrate with a similar crystalline structure as ZnO. By optimizing growth conditions, oriented-ZnO nanorods grown on Si(001) substrate with a diameter of around 300 nm and lengths of 20 to 35 μm have been achieved, and they show excellent optical properties. Laser action has been observed at room temperature by using optical pumping. PACS 81.05.Dz; 81.10.Bk; 81.16.Hc     

Surface enhanced Raman scattering and photoluminescence properties of catalytic grown ZnO nanostructures

Sword-like (diameter ranging from 40 nm to 300 nm) and needle-like zinc oxide (ZnO) nanostructures (average tip diameter ∼40 nm) were synthesized on annealed silver template over silicon substrate and directly on silicon wafer, respectively via thermal evaporation of metallic zinc followed by a thermal annealing in air. The surface morphology, microstructure, chemical analysis and optical properties of the grown samples were investigated by field emission scanning electron microscopy, X-ray diffraction, energy dispersive X-ray analysis, room temperature photoluminescence and Raman spectroscopy. The sword-like ZnO nanostructures grown on annealed silver template are of high optical quality compared to needle-like ZnO nanorods for UV emission and show enhanced Raman scattering.     

Fundamentals and properties of zinc oxide nanostructures: Optical and sensing applications

In this paper we will give an overview of the status of catalytic growth and of low-temperature chemical growth of ZnO nanostructures performed in our laboratory. Particularly results employing different substrates will be discussed. The second part deals with structural and optical properties of ZnO nanorods. The results from high resolution transmission electron microscope (HRTEM), scanning electron microscope (SEM), photoluminescence (PL), Cathodoluminescence (CL), and Electroluminescence (EL), on single nanowires will be shown. Our results on surface morphology, bulk and the position of the catalyst as well as the optical properties including UV emission, lasing and white emission will all be presented and discussed. In the third part experimental results from electroluminescence of ZnO nanorods on different substrates in the UV in addition to excellent white light emission obtained from samples grown at low temperature are to be given and discussed. Finally the sensing of molecules in water by ZnO nanorods will be discussed from a theoretical point of view. Also fundamental properties of polaritons and excitons in ZnO nanostructures are to be highlighted.     

Effect of different pH values on growth solutions for the ZnO nanostructures

In this study, high quality zinc oxide (ZnO) nanostructures were synthesized on glass slide substrates using modified chemical bath deposition (M-CBD) method at low temperature. Through the M-CBD technique the air bubbles will be injected into aqueous growth solution. The RF magnetron sputtering method was utlized to grow ZnO seed layer on the glass substrates. The effect of different pH values of aqueous growth solution on the morphology, elemental chemical composition, crystal structural and the optical properties of ZnO nanostructures have been investigated using field emission-scanning electron microscopy (FE-SEM), Energy dispersive analysis (EDX), X-ray diffraction (XRD), and UV-Visible Spectrometer, respectively. It was observed that altering pH values from acidic to alkaline (basic) by using ammonia solution (NH₃) induced the significant change in morphology from nanorods like ZnO to nano-amber flush rose like ZnO structures. Furthermore, increased pH values had an effect on the influence intensity of the preferred orientation plane (002) and average transmittance spectrum. Whilst the absorption band edge has been shifted to a lower energy region due to the quantum size effect. It was also found that the crystal size fluctuated between 36.30 nm and 84.33 nm with a different values of pH from 6.7 to 12. The ZnO synthesized at 6.7 of pH provided the best results regarding the high aspect ratio,structural and optical properties. At this pH value, ZnO growth revealed the nanorod structure with small diameters, size and a higher energy band gap value.     

水热法制备Co掺杂ZnO纳米棒及其光学性能

采用水热法在石英衬底上以Zn(CH3COO)2.2H2O和Co(NO3)2.6H2O水溶液为源溶液,以C6H12N4(HMT)溶液作为催化剂,在较低温度下制备了Co掺杂的ZnO纳米棒。采用X射线衍射(XRD)和扫描电子显微镜(SEM)对所生长ZnO纳米棒的晶体结构和表面形貌进行了表征,考察了Co掺杂对ZnO纳米棒微观结构和对发光性能影响的机制。结果表明:Co掺杂的ZnO纳米棒呈六方纤锌矿结构,具有沿(002)面择优生长特性,Co掺杂使ZnO纳米棒的直径变细;同时室温光致发光(PL)谱检测显示Co掺杂ZnO纳米棒具有很强的近带边紫外发光峰,而与深能级相关的缺陷发光峰则很弱。本研究采用水热法在石英衬底上于较低温度下生长出了具有较高光学质量的Co掺杂ZnO纳米棒。     

Controllable vertically aligned ZnO nanorods on flexible polyethylene naphthalate (PEN) substrate using chemical bath deposition synthesis

Zinc oxide (ZnO) nanorods were successfully grown on polyethylene naphthalate substrates with a seed layer using a wet chemical bath deposition method at a low temperature. Using various precursor concentrations, the diameter, length, and density of the ZnO nanorods were controlled, and their optical and crystallinity properties were investigated. X-ray diffraction and field emission scanning electron microscopy were used to examine the structure and morphology of the ZnO nanorods. The obtained ZnO nanorods were hexagonal and grew vertically from the substrate in the (002) direction along the c-axis. The low compressive strain values confirmed the high-quality crystal structure of the synthesized ZnO nanorods. A 0.050 M precursor concentration resulted in nanorods with a uniform diameter along their entire length and diameters ranging from 10 nm to 40 nm. The photoluminescence results indicated that the ZnO nanorods grown using a 0.050 M precursor concentration exhibited the sharpest and most intense PL peaks in the UV range compared with the other samples. Therefore, the precursor concentration considerably influenced the growth of the ZnO nanorods. These ZnO nanorods can be greatly applied for the development of flexible, elastic electronic, and optoelectronic devices.     

Flexible piezoelectric harvesting based on epitaxial growth of ZnO

A flexible piezoelectric harvester based on the epitaxial growth of an array ZnO nanorods with zigzag layers to enhance bending and compression deformation is investigated. The effects of the growth temperature, growth time, and growth concentration for ZnO epitaxial growth are determined on the flexible substrate. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the nanostructures and crystalline characteristics of the nanorods, respectively. Nanorod piezoelectric harvesting with screen printing technology was integrated on the polyimide substrate. The results show that epitaxial ZnO nanorods at a concentration ratio of (1:4), a growth time of 4 hours, and a growth temperature of 90°C have perfect crystal morphology for piezoelectric harvesting. The current-voltage characteristics exhibit Schottky-like behavior. During the harvesting process, the current output was highly reproducible and repeatable when the ultrasonic wave equipment was turned on and off. The current output after bending increases with increasing curvature radius due to a compression force during the bending process.     

衬底温度对MOCVD法沉积ZnO透明导电薄膜的影响

研究了衬底温度对MOCVD技术制备的ZnO薄膜的微观结构和光电特性影响. XRD和SEM的研究结果表明，衬底温度对ZnO薄膜的微观结构有显著影响，明显的形貌转变温度大约发生在175℃，低于175℃，薄膜呈镜面结构，晶粒为球状，高于177℃的较高温度范围，薄膜从“类金字塔”状的绒面结构演化为“岩石”状显微组织；随着温度增加，薄膜的晶粒尺寸明显增大.绒面结构的未掺杂ZnO薄膜具有17.96 cm²/V·s的高迁移率和3.28×10^-2 Ω·cm的低电阻率，对ZnO薄膜的进一步掺杂和结构优化有望应用于Si薄膜太阳电池的前电极. 关键词： MOCVD ZnO薄膜 透明导电氧化物 太阳电池