平栅型双层膜的场致发射性能研究

通过在平栅型基板上,分别溅射氧化铋薄膜和氧化锡薄膜,形成阴极场发射阵列,并在阴极和栅极之间加载脉冲电流,使阴栅级之间的薄膜形成裂缝,并进行场致发射性能测试,测试结果表明,平栅型双层膜发射器件的开启电压随阳极电压增加而降低.在阳压为3000 V,隔离子高度为500 μm时,平栅型双层膜场发射器件的开启电压为110 V,在栅压为110 V时的发射效率为1;左右,随着栅压的增大,发射效率逐渐减小.该双层膜阴极具有均匀的发射性能、良好的栅控能力以及场发射特性.     

热蒸发法原位生长-维氧化锌纳米材料及其场发射特性研究

利用磁控溅射在ITO电极上沉积氧化锌薄膜,以氧化锌薄膜为种子层,采用热蒸发法合成ZnO一维纳米材料,利用XRD和SEM方法对氧化锌一维纳米材料的微观结构进行分析,测试其场发射性能.结果显示,氧化锌纳米材料为钉子状结构,每个氧化锌纳米钉由几微米大的钉帽和细棒组成,垂直于基底生长.场发射性能研究表明它具有较低的开启场强,高的发射电流和好的稳定性,是一种优良的冷阴极电子发射源.     

退火处理对ZnO薄膜发光特性的影响

用脉冲激光沉积法(PLD)在MgO(100)、α-Al2O3(0001)和MgAl2O4(111)衬底上沉积了ZnO薄膜,测量了它们的发射光谱,观察到430nm的蓝光发射,并研究了退火、衬底和激发波长对ZnO薄膜这一蓝光发射的影响.指出ZnO薄膜中430nm的蓝光发射是由锌填隙原子缺陷能级到价带顶能级间的跃迁以及电子从氧空位浅施主能级到价带顶能级间的跃迁两种机理共同作用的结果.在MgO衬底上沉积的ZnO薄膜在350nm光激发下蓝光发射峰最强.     

钙钛矿太阳能电池中ZnO电子传输层应用进展

ZnO材料作为一种n型无机半导体材料,ZnO具有优异的电子传输特性、较高的透光性、高导电率、常温制备等优点,是钙钛矿太阳能电池中常见的电子传输层材料.本文简单的介绍ZnO的制备方法,详细的介绍了ZnO薄膜在钙钛矿太阳能电池中的应用.     

超声喷雾热解法制备铝掺杂氧化锌薄膜

采用超声喷雾热解法在玻璃衬底上制作了不同浓度Al掺杂的ZnO: Al薄膜(AZO).采用扫描电镜(SEM)、X射线衍射(XRD)、光致发光(PL)、反射光谱(Res)、四探针测试仪等测试了不同Al掺杂浓度下AZO薄膜的表面形貌、晶体结构和光学、电学性能.SEM结果表明低掺杂浓度时AZO表面致密,随着Al浓度的增加薄膜表面孔洞增多,平整度降低.XRD结果表明当nZn/nAl物质的量比为100: 5时, AZO薄膜为c轴择优取向纤锌矿结构.PL谱结果表明不同浓度的Al掺杂AZO薄膜具有近带边紫外发射和深能级发射两个发射峰,且紫外发射峰随着Al3+浓度的增加先蓝移后红移.反射光谱表明所有样品在可见光区的反射率较低..方阻测试结果表明当nZn/nAl为100: 5时,AZO薄膜具有良好的导电性.     

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.     

WO3基电致变色器件的制备及性能研究

本文采用真空热蒸发法,在ITO基底上制备WO3薄膜,之后在空气气氛中对其进行了400℃,1 h的退火处理.SEM测试结果表明,退火后的WO3薄膜变得更为致密平整.将退火后的WO3薄膜,及通过溶胶凝胶法制得的TiO2-CeO2对电极薄膜和PC-PEO-LiClO4凝胶态电解质封装得到电致变色器件,以探索该退火处理对WO3薄膜电致变色性能的影响.结果表明,该WO3基电致变色器件在632.8 nm处的光学调制幅度达56.8;,记忆时间超过24 h,且具有良好的循环稳定性.本研究表明WO3薄膜的后期退火处理对制备高性能WO3基电致变色器件具有重要的意义.     

微锥阵列对碳纳米管薄膜强流脉冲发射的影响

采用酞菁铁高温热解方法,以化学镀铜层为缓冲层,在具有微锥结构阵列的硅基底上制备了CNTs薄膜,并采用二极结构,在20 GW脉冲功率源系统中对其强流脉冲发射特性进行了测试.结果表明:在相同的峰值电场下,CNT薄膜的发射电流峰值随基底微结构单元尺寸的减小而增大,且当脉冲电场的峰值增加时,CNT薄膜的发射电流的峰值增长速度随基底微结构单元尺寸的减小而增大.结合利用有限元分析软件ANSYS模拟计算的微锥阵列结构上表面的电场分布,研究了不同单元尺寸的微锥阵列对碳纳米管薄膜强流脉冲发射能力的影响.     

ZnO∶Er薄膜的结构和发光特性研究

本文研究了用电子束分蒸技术制备的ZnO∶Er薄膜的结构和发光特性.X射线衍射(XRD)谱表明,六角晶体结构的ZnO∶Er薄膜具有强的择优c轴取向(002).在室温下,用阴极射线激发样品,观测到强的蓝光(455nm)发射.本文认为,蓝光发射是ZnO∶Er薄膜中铒离子(Er3+)的激发态4F5/2到基态4I15/2的辐射跃迁.研究薄膜的阴极射线发光强度与电子束流的关系时发现,蓝光发射强度强烈地依赖于电子束流的大小.此外,超过阈值电子束流0.6μA,蓝光发射强度首先迅速增加,然后缓慢地增加,趋于饱和,根据瓶颈效应和稀土发光理论很好地解释了这一实验结果.     

宽带隙化合物半导体Zn1-xMgxO薄膜的制备

利用超声雾化热分解技术,在玻璃衬底上生长出宽带隙的Zn1-xMgxO薄膜.所有样品在可见光范围内的透过率可达到85;以上.X射线衍射的测试结果表明所有样品都具有c轴择优生长特性,并且随薄膜中Mg含量的不同出现规律性变化.光致发光谱表明Mg掺入后ZnO薄膜的紫外发射峰出现了蓝移,实现了对禁带宽度的调节.     

4H-SiC衬底表面SiC薄膜的同质外延生长

以4H-SiC为衬底,在不同衬底温度下进行SiC薄膜的同质外延生长。利用反射式高能电子衍射(RHEED)、扫描电子显微镜(SEM)、拉曼(Raman)等测试手段,对生长样品的结构和结晶质量进行了表征。根据测试结果发现,在衬底温度为1200℃时能够得到质量较高的薄膜,在另外两个温度(1100℃和1300℃)条件下得到的薄膜质量是较差的。     

Study on n-type Doped Electron-Transporting Layers in OLEDs by Electron Spin Resonance

We present an electron spin resonance (ESR) study of Cs₂CO₃ and LiF doped tris(8-hydroxyquinoline) aluminum (Alq₃) thin films. The g values of the Cs₂CO₃ and LiF doped Alq₃ thin films were obtained as 2.0040 and 2.0028, repectively. The g value of the LiF doped film was very close to a theoretically calculated one for an isolated Alq₃ radical anion, while Cs₂CO₃ doped film showed a large g shift. This feature can be explained by large spin-orbit interaction caused by heavy Cs atoms. While doping of Cs₂CO₃ did not showed cathode-metal (Al and Au) dependence, LiF doping required Al as cathode.     

碳化气体引入温度对3C-SiC薄膜生长的影响

通过低压化学气相沉积方法,在Si(100)衬底上生长了高度择优取向的3C-SiC(100)薄膜.SiC(200)峰的摇摆曲线表明SiC薄膜的结晶质量随着丙烷气体引入温度(Tgi)的升高而增加.选区电子衍射像表明高Tgi下生长的薄膜比低Tgi下生长的薄膜具有更好的取向.典型的SiC薄膜高分辨像中观察到了孪晶和层错.表面场发射扫描电镜像表明随着Tgi的升高,SiC薄膜的表明形貌发生了改变.     

The influence of strain and mosaic structure on electrical and optical properties of GaN films on sapphire substrates

Photoluminescence, electron transport measurements, and seven-crystal X-ray diffractometry have been used to analyze high mobility (intentionally silicon-doped) and highly resistive (unintentionally doped) GaN films grown on a-plane (11 0) sapphire substrates. Values of ω/2θ X-ray rocking curve FWHMs were seen which were lower than typically reported for GaN films on sapphire, and this has been attributed to the increased thickness of the analyzed films. Broadening was observed in the tail of the ω/2θ X-ray rocking curve of a Si-doped GaN film relative to that of unintentionally doped films, indicating diffuse scatter of the X-ray beam. Mosaic structure and curvature induced in the sapphire substrate by the subsequently grown GaN film was also observed.     

Electron microscopy studies of epitaxial MgB2 superconducting thin films grown by in situ reactive evaporation

The morphology and chemistry of epitaxial MgB₂ thin films grown using reactive Mg evaporation on different substrates have been characterized by transmission electron microscopy methods. For polycrystalline alumina and sapphire substrates with different surface planes, an MgO transition layer was found at the interface region. No such layer was present for films grown on MgO and 4-H SiC substrates, and none of the MgB₂ films had any detectable oxygen incorporation nor MgO inclusions. High-resolution electron microscopy revealed that the growth orientation of the MgB₂ thin films was closely related to the substrate orientation and the nature of the intermediary layer. Electrical measurements showed that very low resistivities (several μΩ cm at 300 K) and high superconducting transition temperatures (38 to 40 K) could be achieved. The correlation of electrical properties with film microstructure is briefly discussed.     

Effect of AlN doping on the growth morphology of SiC

AlN doped SiC films were deposited on on‐axis Si‐face 4H‐SiC (0001) substrates by the physical vapor transport (PVT) method. Thick film in the range of 20 μm range was grown and morphology was characterized. Films were grown by physical vapor deposition (PVD) in a vertical geometry in the nitrogen atmosphere. We observed that nucleation occurred in the form of discs and growth occurred in hexagonal geometry. The X‐ray studies showed (001) orientation and full width of half maxima (FWHM) was less than 0.1° indicating good crystallinity. We also observed that film deposited on the carbon crucible had long needles with anisotropic growth very similar to that of pure AlN. Some of the needles grew up to sizes of 200 μm in length and 40 to 50 μm in width. It is clear that annealing of SiC‐AlN powder or high temperature physical vapor deposition produces similar crystal structure for producing AlN‐SiC solid solution. SEM studies indicated that facetted hexagons grew on the top of each other and coarsened and merged to form cm size grains on the substrate. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth of GaN films on PLD-deposited TaC substrates

GaN films were grown by metal organic chemical vapor deposition on TaC substrates that were created by pulsed laser deposition of TaC onto (0 0 0 1) SiC substrates at ∼1000 °C. This was done to determine if good quality TaC films could be grown, and if good quality GaN films could be grown on this closely lattice matched to GaN, conductive material. This was done by depositing the TaC on on-axis and 3° or 8° off-axis (0 0 0 1) SiC at temperatures ranging from 950 to 1200 °C, and examining them using X-ray diffraction, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The GaN films were grown on as-deposited TaC films, and films annealed at 1200, 1400, or 1600 °C, and examined using the same techniques. The TaC films were polycrystalline with a slight (1 1 1) texture, and the grains were ∼200 nm in diameter. Films grown on-axis were found to be of higher quality than those grown on off-axis substrates, but the latter could be improved to a comparable quality by annealing them at 1200–1600 °C for 30 min. TaC films deposited at temperatures above 1000 °C were found to react with the SiC. GaN films could be deposited onto the TaC when the surface was nitrided with NH₃ for 3 min at 1100 °C and the low temperature buffer layer was AlN. However, the GaN did not nucleate easily on the TaC film, and the crystallites did not have the desired (0 0 0 1) preferred orientation. They were ∼10 times larger than those typically seen in films grown on SiC or sapphire. Also the etch pit concentration in the GaN films grown on the TaC was more than 2 orders of magnitude less than it was for growth on the SiC.     

Growth and characterization of epitaxial Ti3GeC2 thin films on 4H-SiC(0001)

Epitaxial Ti₃GeC₂ thin films were deposited on 4° off-cut 4H-SiC(0001) using magnetron sputtering from high purity Ti, C, and Ge targets. Scanning electron microscopy and helium ion microscopy show that the Ti₃GeC₂ films grow by lateral step-flow with {112?0} faceting on the SiC surface. Using elastic recoil detection analysis, atomic force microscopy, and X-Ray diffraction the films were found to be substoichiometric in Ge with the presence of small Ge particles at the surface of the film.     

掺杂VO2薄膜的相变机理和研究进展

掺杂VO2薄膜是一种具有相变特性的功能材料,具有广阔的应用前景.本文综述了掺杂VO2薄膜的相变机理、制备方法和应用前景,并指出掺杂VO2薄膜的发展趋势,以期更好地探讨掺杂VO2薄膜的应用研究.     

衬底温度对磁控溅射法制备掺Ta氧化锌薄膜性能的影响

采用射频磁控溅射法,在不同的衬底温度下制备了钽(Ta)掺杂的氧化锌(ZnO)薄膜,采用X射线能谱(EDS)、X射线衍射(XRD)、扫描电镜(SEM)、紫外-可见分光光度计和光致发光(PL)光谱研究了衬底温度对制备的Ta掺杂ZnO薄膜的组分、微观结构、形貌和光学特性的影响.EDS的检测结果表明,Ta元素成功掺入到了ZnO薄膜;XRD图谱表明,掺入的Ta杂质是替代式杂质,没有破坏ZnO的六方晶格结构,随着衬底温度的升高,(002)衍射峰的强度先增大后降低,在400℃时达到最大;SEM测试表明当衬底温度较高时(400℃和500℃),Ta掺杂ZnO薄膜的晶粒明显变大;紫外-可见透过光谱显示,在可见光范围,Ta掺杂ZnO薄膜的平均透光率均高于80;,衬底不加热时制备的Ta掺杂ZnO的透光率最高;制备的Ta掺杂ZnO薄膜的禁带宽度范围为3.34~3.37eV,衬底温度为500℃时制备的Ta掺杂ZnO薄膜的禁带宽度最小,为3.34eV.PL光谱表明衬底温度为500℃时制备的Ta掺杂ZnO薄膜中缺陷较多,这也是造成薄膜禁带宽度变小的原因.