两步化学法制备Co掺杂ZnO薄膜及其磁性研究

采用电化学和湿化学法结合的两步化学法制备了Co掺杂的ZnO薄膜.X射线衍射(XRD)结果表明Co掺杂没有改变ZnO薄膜的六角纤锌矿结构.扫描电镜(SEM)和透射电镜(TEN)结果表明薄膜是由ZnO单晶纳米棒组成.X射线光电子能谱(XPS)结果表明Co2替代了Zn2+,实现了有效的掺杂.磁性测量的结果表明,样品在室温下的磁性表现为顺磁性和铁磁性的结合.     

Co掺杂浓度对ZnO纳米棒结构和光学性能影响研究

采用水热法以不同浓度Co掺杂合成了具有六方纤锌矿结构的ZnO纳米粉体,通过X-射线衍射(XRD)、扫描电镜(SEM)、拉曼光谱、X射线光电子光能谱分析法(XPS)、(光致发光)PL谱等分别对样品的形貌、结构、光学性能进行了测试和表征.结果 表明:随着Co掺杂浓度的增大,纤锌矿ZnO的晶体结构没有改变,且Co以二价离子Co2+的形式掺杂进入ZnO晶格;同时花状ZnO纳米棒的均匀性变差,不同浓度Co掺杂ZnO纳米棒中均出现了少量且尺寸较小的单根纳米棒.PL光谱显示:随着Co掺杂浓度增大,样品的紫外发光峰没有明显地变化,而可见发光峰的强度先减小再增大,说明样品的缺陷先降低再提高.当Co掺杂的浓度为2.0;时,所制备的ZnO花状纳米棒可见发光峰相对最低,其具有较小的缺陷.     

钇掺杂多孔结构氧化锌纳米棒的制备与性能研究

采用两步法在二氧化锡掺氟(SnO2:F,FTO)导电玻璃基板上制备出钇(Y)掺杂多孔结构氧化锌(ZnO)纳米棒,首先利用浸渍-提拉法在FTO导电玻璃基板上制备ZnO晶种层,然后利用水热法在ZnO晶种层上生长Y掺杂ZnO纳米棒.研究了不同浓度Y掺杂ZnO纳米棒的晶相结构、微观形貌、化学组成及光学性能.实验结果表明:所制备的Y掺杂ZnO纳米棒为沿c轴择优取向生长的六方纤锌矿结构,随着Y掺杂浓度的增加,ZnO纳米棒(002)衍射峰强度先增大后减小,纳米棒的平均长度由1.3μm增加到2.6μm.ZnO纳米棒的形貌由锥状结构向柱状结构演化,纳米棒侧面的孔洞分布密度增加.所制备的Y掺杂ZnO纳米棒具有一个较弱的紫外发光峰和一个较强的宽可见发光峰.所制备样品的光学带隙随着Y掺杂浓度的增加而减小,其光学带隙在3.29～3.21 eV之间变化.利用Y掺杂ZnO纳米棒作为量子点敏化太阳能电池的光阳极可极大提高太阳电池的光电转换效率.     

Ni2+掺杂氧化锌阵列膜的水热合成及性能表征

采用低温水热法制备了Ni2+掺杂的ZnO阵列膜,研究了Ni2+掺杂对样品形貌、晶相结构和光谱特性的影响,并对可能的影响机理进行探讨.结果表明:Ni2浓度增加不会改变ZnO的纤锌矿结构,但在一定程度上可以起到控制其形貌及均匀度的作用.Ni2+掺杂量x≤0.007 mol/L时,有助于ZnO纳米棒沿c轴方向生长,提高结晶度,但ZnO的生长机理保持不变.Ni2+掺杂量较多时(x ＞0.007 mol/L),ZnO纳米棒的生长习性发生变化,其六方结构被破坏,水热膜由垂直于基片表面排列的纳米棒阵列转变为由结构不规则的多边形晶粒组成的密堆积排列.由于Ni2+固溶入ZnO晶格产生晶格畸变,引起薄膜内应力以及载流子浓度的变化,使得ZnO拉曼光谱的特征峰出现明显的降低和移动.光致发光谱表明,Ni2掺杂使ZnO纳米棒的紫外发光峰强度IUV与绿光发光峰强度IGR之比值IUV/IGR增大.     

Sn掺杂对ZnO薄膜结构和光电性能的影响

采用溶胶-凝胶浸渍提拉法在玻璃衬底上制备了Sn掺杂ZnO(SZO)薄膜。通过X射线衍射(XRD)和扫描电镜(SEM)研究了Sn掺杂对薄膜表面形貌和微结构的影响。XRD结果表明,所有ZnO薄膜样品都存在(002)择优取向。SEM结果表明随着掺杂浓度的增加,薄膜表面由颗粒向纳米棒转变。电学结果显示掺杂浓度为3at%时,电学性能最好,最低电阻率为6.9×10-2Ω.cm。室温光致发光谱(PL)显示所有的SZO薄膜样品在(325 nm光激发下)380 nm和398 nm两处都有发光峰,随着掺杂浓度的增大,398 nm处的发光强度先增大后减小,然后再增大;380nm处的发光强度始终增大,这些现象与薄膜的表面结构的变化有关。     

电沉积Co掺杂ZnO薄膜的光致发光及磁性研究

在ITO衬底上电沉积了Co掺杂ZnO薄膜.X射线粉末衍射(XRD)和扫描电子显微镜(SEM)结果表明Co掺杂并没有改变ZnO的六角纤锌矿结构,但可以在一定程度上改变晶体的形貌.室温光致发光光谱(PL)结果表明Co掺杂导致薄膜的带隙变窄.磁性测试结果表明,10; Co掺杂样品室温下呈现顺磁性,而5;Co掺杂样品在室温下呈现铁磁性,我们认为其铁磁性是由Co掺杂引起的缺陷导致的.     

铟镓共掺杂对n-ZnO纳米棒/p-GaN异质结生长行为和光电性能的影响

利用低温水热法在p-GaN薄膜上生长了铟(In)和镓(Ga)共掺杂的ZnO纳米棒。X射线衍射(XRD)、X射线光电子能谱(XPS)和X射线能量色谱仪(EDS)结果表明,In和Ga已固溶到ZnO晶格中。扫描电子显微镜(SEM)结果表明, ZnO纳米棒具有良好的c轴取向性,随着In和Ga共掺杂浓度的增加,纳米棒的直径减小,密度增加。XRD结果表明,In和Ga共掺杂引起ZnO晶格常数增大,导致(002)衍射峰向低角度方向偏移。同时,ZnO的光学性质受到In和Ga共掺杂的影响。与纯ZnO相比, 共掺杂ZnO纳米棒的紫外发射峰都出现轻微红移,这是表面共振和带隙重整效应综合作用的结果。I-V特性曲线表明,随着In和Ga共掺杂浓度的增加,n-ZnO纳米棒/p-GaN异质结具有更好的导电性。     

Ag掺杂ZnO薄膜光催化降解苯酚的试验研究

本文采用溶胶-凝胶法在石英玻璃基底上制备出性能优良的Ag掺杂的纳米ZnO薄膜,并通过XRD、AFM和UV-Vis吸收光谱对薄膜的结构及光吸收特性进行表征.以苯酚为被降解物,进一步研究了不同掺杂浓度对其光催化性能的影响.结果表明,ZnO:Ag摩尔比为30:1的样品催化效果最佳.     

基于直流磁控溅射晶种层的ZnO纳米阵列的制备及性能研究

采用直流反应磁控溅射法制备品种层薄膜,研究O2/Ar气体分压比和退火温度对品种层结构和微观形貌的影响.通过化学水浴沉积,在预制有晶种层的薄膜上制备ZnO纳米阵列结构,研究不同前驱体浓度和预制晶种层对纳米阵列生长的影响.结果表明,当O2/Ar中O2分压减少,薄膜均匀性较差,当Ar分压增加薄膜由于扩散而趋于平整.退火温度增加,晶粒尺寸增大,内应力降低.磁控溅射法预制的晶种层上生长的纳米棒垂直于衬底生长,(002)晶面的衍射峰强最高,说明纳米棒沿c轴择优取向.生长液的浓度对纳米棒的形貌影响显著,随着生长液浓度的升高,ZnO纳米阵列直径增大,顶端趋于平整的六棱柱结构.     

Mg掺杂浓度对MgxZn1-xO薄膜结构和光学性能的影响

通过超声喷雾热解工艺在P型<100>Si衬底上制备了不同Mg掺杂浓度的纳米MgxZN1-xO薄膜.通过扫描电镜(SEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)和光致发光(PL)谱的测试对不同Mg掺杂浓度下薄膜的表面形貌、成分、品体结构和光学性能进行了研究.SEM测试结果表明,低Mg掺杂浓度时,MgxZn1-xO表面平整致密,但随Mg浓度的增加,薄膜表而平整度降低.XRD测试结果表明在低浓度下MgxZn1-xO薄膜足ZnO的纤锌矿结构,而没有出现MgO的分相,ZnO的衍射峰峰强随Mg浓度的增加逐渐减弱.不同Mg掺杂浓度下的光致发光谱图均出现了近带边紫外发射峰和可见光发射峰,其中近带边紫外发射峰随掺杂浓度的增大出现了明显的蓝移.     

Structural and optical properties of Mg‐doped ZnO thin films prepared by a modified Pechini method

ZnO thin films with different Mg doping contents (0%, 3%, 5%, 8%, 10%, respectively) were prepared on quartz glass substrates by a modified Pechini method. XRD patterns reveal that all the thin films possess a polycrystalline hexagonal wurtzite structure. The peak position of (002) plane for Mg‐doped ZnO thin films shifts toward higher angle due to the Mg doping. The crystallite size calculated by Debey‐Scherrer formula is in the range of 32.95–48.92 nm. The SEM images show that Mg‐doped ZnO thin films are composed of dense nanoparticles, and the thickness of Mg‐doped ZnO thin films with Mg doped at 8% is around 140 nm. The transmittance spectra indicate that Mg doping can increase the optical bandgap of ZnO thin films. The band gap is tailored from 3.36 eV to 3.66 eV by changing Mg doping concentration between 3% and 10%. The photoluminescence spectra show that the ultraviolet emission peak of Mg‐doped ZnO thin films shifts toward lower wavelength as Mg doping content increases from 3% to 8%. The green emission peak of Mg‐doped ZnO thin films with Mg doping contents were 3%, 8%, and 10% is attributed to the oxygen vacancies or donor‐acceptor pair. These results prove that Mg‐doped ZnO thin films based on a modified Pechini method have the potential applications in the optoelectronic devices.     

CuInS2量子点敏化ZnO基光阳极的制备与性能研究

采用两步法在导电玻璃(FTO)基板上制备纯氧化锌(ZnO)纳米棒和钇掺杂的氧化锌(ZnO∶Y)纳米棒,采用连续离子层吸附反应法(SILAR)在所制备的ZnO及ZnO∶Y纳米棒上沉积CuInS₂量子点制备ZnO/CuInS₂和ZnO∶Y/CuInS₂光阳极。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电子探针能谱仪(EDS)、紫外-可见分光光度计(UV-Vis)、电流密度-电压(J-V)曲线等技术手段对不同光阳极样品的晶相结构、微观形貌、化学组成、光吸收性能和太阳电池性能进行了表征。实验结果表明:所制备的ZnO纳米棒和ZnO∶Y纳米棒为六方纤锌矿结构。CuInS₂量子点敏化的ZnO纳米棒薄膜的光学带隙从3.22 eV减小为2.98 eV。CuInS₂量子点敏化ZnO∶Y太阳能电池的短路电流密度和光电转换效率比未掺杂的ZnO纳米棒组装的太阳能电池分别提高了6.5%和50.4%。     

Microemulsion synthesis and characterization of aluminum doped ZnO nanorods

Aluminium doped ZnO (AZO) nanorods were synthesized by microemulsion method with different types of surfactants. Scanning electron microscopy observations show that the ZnO nanorods have diameters around about 80 nm and lengths up to several micrometers. The room temperature photoluminescence (PL) spectrum of AZO nanorods exhibited a sharp and strong ultraviolet bandgap at 383 nm and a relatively weaker emission associated with the defect level. AZO nanorods synthesized with sodium benzene sulfonate (SBS) surfactant showed lower resistivity than aluminum doped ZnO nanorods synthesized with dodecyl benzene sulfonic acid sodium salt (DBS) surfactant. Resistivity of AZO nanorods synthesized with SBS surfactant showed 2.8×10³ Ωcm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fabrication of hollow ZnO nanostructures by a CTAB‐assisted chemical bath deposition method

ZnO films consisted of hollow nanostructures were prepared by a CTAB‐assisted chemical bath deposition (CBD) method. ZnO rings, bowls and assemblies of hollow structures were successfully obtained on different substrates. Dense ZnO films consisted of sunken prisms can also be achieved by controlling the concentration of CTAB. The influences of reactant concentrations, types of the substrates and pre‐coated ZnO nanoparticles on the formation of ZnO films were examined. XRD patterns indicated the Wurtzite structure of ZnO and the preferred growth direction is [001]. The role of CTAB in CBD process was discussed and the evolution of different ZnO nanostructures was studied based on the observation of SEM. A plausible crystal growth mechanism was proposed for the formation of ZnO rings and bowls. The investigation of optical properties showed that high concentration of CTAB can improve the ultraviolet emission.     

Grain boundary defects induced room temperature ferromagnetism in V doped ZnO thin films

Vanadium (V) doped ZnO thin films (Zn_1‐xV_x O, where x = 0, 0.05, 0.10) have been grown on sapphire substrates by RF magnetron sputtering to realize room temperature ferromagnetism (RTFM). The grown films have been subjected to X‐ray diffraction (XRD), resonant Raman scattering, photoluminescence (PL) and vibrating sample magnetometer (VSM) measurements to investigate their structural, optical and magnetic properties, respectively. The full width at half maximum of XRD and Raman scattering peaks increases with V ion concentration indicates that the V ions have been substituted on Zn²⁺ ions in the ZnO matrix. The increase in oxygen vacancies with V concentration is evidenced by PL measurements. Rutherford backscattering spectrometry analysis confirms the presence of the V ions in the films. The room temperature VSM measurements reveal the signature of ferromagnetism in V doped ZnO thin films. It has been observed that the grain boundary defects, i.e., oxygen vacancies play a crucial role in inducing RTFM in V doped ZnO films. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of growth temperature on the structure and optical properties of ZnO nanorod arrays grown on ITO substrate

ZnO nanorod arrays have been successfully prepared on ITO substrate by a chemical‐bath deposition method at different growth temperatures. The influence of the growth temperature on the morphology and microstructure of the ZnO nanorods was investigated by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The results showed that the diameter of the ZnO nanorods decreased and the size of the nanocrystals increased with increasing growth temperature. Optical absorption measurements showed the absorption band edge has shifted to a lower‐energy region due to the quantum size effect. Green emission and UV emission bands were observed and they are found to be temperature dependent, which indicates that the deep‐level emission and band‐edge emission of ZnO nanorods is closely related to the rod diameter, and the related mechanism is discussed.     

Synthesis of ZnO films in different solvents and their photocatalytic activities

ZnO thin films have been successfully synthesized via the chemical bath deposition (CBD) method without using any catalysts or templates. The effects of solvents (such as water, ethanol and n‐propanol) on structure and morphology of ZnO thin films have been studied. XRD analysis showed that all ZnO thin films with wurtzite crystal structure were obtained via various solvents. SEM images showed that ZnO thin films prepared in different solvents have different sizes and morphologies. TEM images showed that crystalline ZnO samples prepared in different solvents have different growth habits. Photoluminescence and photocatalysis properties have been investigated at room temperature. ZnO thin films prepared in water showed superior photocatalytic activity in the degradation of rhodamine B (RhB) compared to other samples.     

聚乙烯醇对ZnO纳米棒结构和光学性能的影响

以六水硝酸锌为锌源,聚乙烯醇(PVA)为分散剂,制备了纳米氧化锌(ZnO).利用X射线衍射(XRD)和电子扫描电镜(SEM)对氧化锌的晶体结构、形貌和尺寸进行了表征.利用吸收光谱对氧化锌的吸收率进行了测量.结果表明,所制备的氧化锌属于六方纤锌矿单晶结构,呈棒状结构.通过改变PVA含量,氧化锌纳米棒的长度可以从400nm到2μm可调.吸收光谱表明,随着PVA含量增加,吸收光谱发生红移.讨论了PVA作用下氧化锌纳米棒的形成机理.