Sol-gel法制备ZnO:Cd薄膜及性能研究

采用Sol-gel法使用旋转涂覆技术在Si(100)基片上生长了ZnO:Cd薄膜.XRD结果表明:ZnO:Cd薄膜具有与ZnO一样的六角纤锌矿结构,随热处理温度的升高,(002)衍射峰强度逐增,FWHM减小,并沿c轴择优取向生长;透射光谱实验表明:以石英为基底,适度掺镉可降低薄膜的禁带宽度Eg,特别是在800℃、8?条件下,Eg=2.80eV,与纯ZnO的禁带宽度3.30eV相比,明显降低了光学禁带;光致发光谱(PL)实验表明:在吸收边附近均有较强的紫外发射峰,且随热处理温度升高呈规律的变化;电阻率测定表明:掺镉使薄膜导电性增强.     

热处理温度对溶胶-凝胶法制备ZnO薄膜晶体结构和发光特性的影响

采用溶胶-凝胶(Sol-Gel)旋涂法在Si(100)衬底上制备ZnO薄膜,利用X射线衍射(XRD)、光致发光谱(PL)、扫描电子显微镜(SEM)等手段分析制得的ZnO薄膜的晶体结构和发光特性。着重考察了热分解温度对ZnO薄膜晶体结构和发光特性的影响。结果表明,溶胶-凝胶旋涂法制备的ZnO薄膜样品厚度约为220nm,属六方纤锌矿结构,其c轴取向度与热分解温度有很大关系;ZnO薄膜在室温下均有较强的紫外带边发射峰,且紫外带边发射峰与样品c轴取向度没有直接关系,与缺陷有关的可见发射带很弱。     

衬底温度对PLD法制备ZnO薄膜结构及发光特性的影响

在60Pa的高氧压气氛中,用脉冲激光沉积法以Si(111)为衬底在不同温度下制备了ZnO薄膜.RHEED和XRD结果表明,所有样品都是c轴高度择优取向的多晶ZnO薄膜.随衬底温度的升高,ZnO薄膜(002)衍射峰的半高宽不断减小,从0.227～0.185°.对(002)衍射峰的2θ值分析表明,650℃下生长的ZnO薄膜几乎处于无应力的状态,而在较低或较高温度下生长的薄膜中都存在着一定程度的c轴压应力.室温PL谱测试说明在650℃生长的ZnO薄膜具有最强的紫外发射峰和最窄的UV峰半高宽(83meV).在700℃得到的样品PL谱中,检测到一个位于3.25eV处的低能发射峰.经分析,该峰可能是来自于施主-受主对(DAP)的跃迁.     

氧氩比对磁控溅射ZnO薄膜结构及光致发光性能的影响

采用射频反应磁控溅射法以不同的氧氩比在玻璃衬底上制备了ZnO薄膜,并对薄膜进行了退火处理;利用X射线衍射仪（XRD）和原子力显微镜（AFM）分别对薄膜的物相组成和表面形貌进行了分析,利用荧光分光光度计对ZnO薄膜的室温光致发光（PL）谱进行了测试。结果表明：当氧氩气体积比为7∶5时,所制备的ZnO薄膜晶粒细小均匀,薄膜结晶质量最好;ZnO薄膜具有紫光、蓝光和绿光三个发光峰,随着氧氩比的增加,蓝光的发射强度增强,而紫光和绿光的发射强度先增强后减弱,当氧氩气体积比为7∶5时紫光和绿光的发射强度最强。     

ZnO薄膜中与Zn原子缺陷相关的发光特性研究

ZnO薄膜中可见光的发射与缺陷有关,为了研究ZnO薄膜中与Zn原子缺陷相关的发光特性,将不同Zn缓冲层厚度的ZnO薄膜沉积在Si衬底上,且所有样品在400℃下真空中退火1 h,采用X射线衍射谱(XRD)、吸收谱和光致发光谱(PL)表征了样品的晶体结构和光学特性。结果表明,随着Zn缓冲层溅射时间的增加,ZnO薄膜中的紫光峰向长波段发生了红移,且所有的发光峰强度逐渐增加;缓冲层和真空中退火都使得样品中有过量的Zn原子缺陷出现,薄膜中所有的发光峰与Zn原子缺陷相关。     

Cu掺杂ZnO的光致发光光谱

ZnO是宽禁带半导体,室温下禁带宽度为3.37eV,激子束缚能高达60meV,是制备光电器件的优选材料。然而,p型掺杂仍是亟待解决的问题。ⅠB元素Cu被认为在ZnO中产生受主能级,可以实现ZnO的p型掺杂。综述了各种制备方法、制备条件和激发条件下得到的Cu掺杂ZnO薄膜、纳米线和纳米棒的光致发光谱和机理,总结出Cu掺杂ZnO光致发光谱的带边发射会因为Cu的掺杂强度降低,或出现发射中心红移等现象。可见光区域由于Cu掺杂会产生新的蓝光、绿光和橙光发射峰,蓝光发射峰可能与Cu2+-Cu+跃迁或VZn和Zni有关;绿光发射峰可能与Cu杂质或VO-VZn跃迁有关,Cu掺杂还可能引入非辐射复合的点缺陷中心;橙光发射峰则可能由于Cu杂质受主能级向深施主能级跃迁而产生。     

ZnO:Cd纳米棒薄膜的制备及其光学氢敏性质研究

采用磁控溅射法在透明玻璃基底上制备50nm厚的ZnO种子层,利用水热法在ZnO种子层上生长厚度大约为1 000nm左右的ZnO:Cd纳米棒薄膜,通过SEM,XRD对其形态和晶体结构进行分析。结果表明:该薄膜是由沿C轴方向生长,呈六角纤锌矿结构的ZnO:Cd纳米棒阵列组成,并研究了薄膜型光学气敏传感器对氢气的光学敏感特性,结果表明:当工作温度为室温时,ZnO:Cd纳米棒薄膜器件对浓度为500×10~(-6)的氢气表现出明显的光学敏感特性,且具有良好的可重复性。     

直流磁控溅射ZnO薄膜的结构和室温PL谱研究

ZnO是一种新型的宽带化合化半导体材料 ,对短波长的光电子器件如UV探测器 ,LED和LD有着巨大的潜在应用。本实验研究采用直流反应磁控溅射法在硅衬底上沉积C轴择优取向的ZnO晶体薄膜 ,薄膜呈柱状结构 ,晶粒大小约为 10 0nm ,晶粒内为结晶性能完整的单晶 ,但晶粒在C轴方向存在较大的张应力。ZnO薄膜在He Cd激光器激发下有较强的紫外荧光发射 ,应力引起ZnO禁带宽度向长波方向移动 ,提高衬底温度有利于降低应力和抑制深能级的绿光发射     

丝网印刷纳米ZnO薄膜阴极场致发射的研究

鉴于化学气相沉积生长方法成本高且很难制备出大面积均匀的纳米ZnO薄膜,采用成本低的丝网印刷方法制备了大面积纳米ZnO阴极薄膜.测试研究了分散、热烧结、退火处理对ZnO薄膜的场致发射特性的影响,提出了低成本丝网印刷制备大面积ZnO薄膜阴极热烧结和退火处理的工艺,根据样品的形貌、发射特性和均匀稳定发光的阳极可以判断,最高温度843K的热烧结和823K、10min的退火处理适实用于制作大面积纳米ZnO薄膜场致发射阴极.     

RF溅射稀土掺杂ZnO薄膜的结构与发光特性

通过射频磁控溅射技术在Si(111)衬底上制备了未掺杂和La、Nd掺杂ZnO薄膜.XRD分析表明,ZnO薄膜具有c轴择优生长,La、Nd掺杂ZnO薄膜为纳米多晶薄膜.AFM观测,La、Nd掺杂ZnO薄膜表面形貌较为粗糙.从薄膜的室温光致光谱中看到,所有薄膜都出现了395 nm的强紫光峰和495 nm的弱绿光峰,La掺杂ZnO薄膜的峰强度增大,Nd掺杂ZnO薄膜的峰强度减弱,分析了掺杂引起PL峰强度变化的原因.     

Optical characterization of ZnO thin films deposited by Sol-gel method

In this paper, ZnO thin film is deposited on Pt/TiO₂/SiO₂/Si substrate using the sol-gel method and the effect of annealing temperature on the structural morphology and optical properties of ZnO thin films is investigated. The ZnO thin films are crystallized by the heat treatment at over 400°C. The ZnO thin film annealed at 600°C exhibits the greatest c-axis orientation and the Full-Width-Half-Maximum (FWHM) of X-ray peak is 0.4360°. A dense ZnO thin film is deposited by the growth of uniform grains with the increase of annealing temperature but when the annealing temperature increases to 700°C, the surface morphology of ZnO thin film becomes worse by the aggregation of ZnO particles. In the results of surface morphology of ZnO thin film using atomic force microscope (AFM), the surface roughness of ZnO thin film annealed at 600°C is smallest, that is, approximately 1.048 nm. For the PL characteristics of ZnO thin film, it is observed that ZnO thin film annealed at 600°C exhibits the greatest UV (ultraviolet) exciton emission at approximately 378 nm, and the smallest visible emission at approximately 510 nm among ZnO thin films annealed at various temperatures. It is deduced that ZnO thin film annealed at 600°C is formed most stoichiometrically, since the visible emission at approximately 510 nm comes from either oxygen vacancies or impurities.     

Relationship between ultraviolet emission and electron concentration of ZnO thin films

ZnO thin films were deposited on (0001) Al₂O₃ substrates depending on oxygen partial pressure by pulsed laser deposition. Optical properties of ZnO were investigated by photoluminescence (PL). The relationship between PL and electron concentration has been investigated. Origin of the dominant ultraviolet (UV) emission in ZnO thin film measured at room temperature was identified as a free electron-neutral-acceptor transition (eA⁰) through temperature dependence of PL measurement. The UV emission intensity at room temperature is related to variation of electron concentration because a free-electron-neutral-acceptor transition (eA⁰) as origin of UV emission at room temperature is related to impurity concentration of ZnO.     

[101]取向Li掺杂ZnO薄膜光学性能的研究

采用射频磁控溅射法在玻璃衬底上制备了[101]取向的Li:ZnO薄膜, 研究了该薄膜的光学性能随热处理温度变化的规律. 结果表明, 399nm的发光峰是由Li的杂质能级引起; 与[002]取向的薄膜相比, 未经热处理的[101]薄膜其光学带隙大, 且出现了380nm附近的带边发射(NBE) 峰; 在560～580℃热处理下, 其晶胞变小、光学带隙变窄、360nm 左右的带间发光峰红移; 当热处理温度升至610℃时, 薄膜中再次出现380nm的NBE峰.     

The characteristics of ZnO deposited on PPC plastic substrate

In this paper, we report the deposition of ZnO thin film on poly propylene carbonate (PPC) plastic substrate by sputtering technique. The structural, optical and electrical properties of the ZnO thin film were investigated. The ZnO thin film deposited on PPC plastic has a smooth surface morphology as revealed by scanning electron microscopy (SEM). X-ray diffraction (XRD) measurement shows that the ZnO thin film has preferential orientation along the c-axis with strong peak observed at 2θ? = 34.25^o, while the photoluminescence (PL) spectrum shows strong UV emission peak at 385 nm. Spectrophotometry measurements reveal that transmission values of the film are low at wavelength shorter than 380 nm. Current-voltage measurements show that the dark- and photocurrents were found to be 6.11 and 89.3 μA, respectively, under dark and illuminated conditions at 5 V.     

Co-emission of UV, violet and green photoluminescence of ZnO/TiO2 thin film

ZnO/TiO₂ thin films were fabricated on quartz glass substrates by E-beam evaporation. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectra, optical transmittance and photoluminescence. XRD analysis indicates that the TiO₂ buffer layer can increase the preferential orientation along the (002) plane of the ZnO film. PL measurements suggest that co-emission of strong UV peak at 378 nm, violet peak at 423 nm and weak green luminescence at 544 nm is observed in the ZnO/TiO₂ thin film. The violet luminescence emission at 423 nm is attributed to the interface trap in the ZnO film grain boundaries.     

Novel synthesis of aligned Zinc oxide nanorods on a glass substrate by sonicated sol-gel immersion

For the first time, aligned ZnO nanorod structured thin films have been synthesized on a glass substrate, which had been coated with an Al-doped ZnO thin film, using the sonicated sol-gel immersion method. These nanorods were found to have an average diameter of 100 nm and an average length of 500 nm, with hexagonal wurtzite phase grew preferentially along the c-axis direction. A sharp ultra-violet (UV) emission centred at 383 nm corresponding to the free exciton recombination was observed in a room temperature photoluminescence (PL) spectrum. The prepared ZnO nanorod structured thin film is transparent in the visible region with an average transmittance of 78% in the 400-800 nm wavelength range and high absorbance properties in the UV region (< 400 nm). The results indicate that the prepared ZnO nanorods are suitable for ultra-violet photoconductive sensor applications.     

Stable p-type conductivity and enhanced photoconductivity from nitrogen-doped annealed ZnO thin film

We report on the growth of p-type ZnO thin films with improved stability on various substrates and study the photoconductive property of the p-type ZnO films. The nitrogen doped ZnO (N:ZnO) thin films were grown on Si, quartz and alumina substrates by radio frequency magnetron sputtering followed by thermal annealing. Structural studies show that the N:ZnO films possess high crystallinity with c-axis orientation. The as-grown films possess higher lattice constants compared to the undoped films. Besides the high crystallinity, the Raman spectra show clear evidence of nitrogen incorporation in the doped ZnO lattice. A strong UV photoluminescence emission at ~ 380 nm is observed from all the N:ZnO thin films. Prior to post-deposition annealing, p-type conductivity was found to be unstable at room temperature. Post-growth annealing of N:ZnO film on Si substrate shows a relatively stable p-type ZnO with room temperature resistivity of 0.2 Ω cm, Hall mobility of 58 cm²/V s and hole concentration of 1.95 × 10¹⁷ cm^− 3. A homo-junction p-n diode fabricated on the annealed p-type ZnO layer showed rectification behavior in the current-voltage characteristics demonstrating the p-type conduction of the doped layer. Doped ZnO films (annealed) show more than two orders of magnitude enhancement in the photoconductivity as compared to that of the undoped film. The transient photoconductivity measurement with UV light illumination on the doped ZnO film shows a slow photoresponse with bi-exponential growth and bi-exponential decay behaviors. Mechanism of improved photoconductivity and slow photoresponse is discussed based on high mobility of carriers and photodesorption of oxygen molecules in the N:ZnO film, respectively.     

Mn掺杂对ZnO薄膜结构和光学性质的影响

利用脉冲激光淀积的方法在Si衬底上生长出了c轴高度取向的ZnO和Zn0.9Mn（0.1）O薄膜.光致发光结果显示了Mn的掺杂引起了薄膜的带边发射蓝移,强度减弱,紫光发射几乎消失,但绿光发射增强.利用X射线衍射,X射线吸收精细结构和X射线光电子能谱等实验技术对Mn掺杂的ZnO薄膜的结构及其对光学性质影响进行了研究.结果表明：Mn掺入到ZnO薄膜中形成了Zn0.9Mn0.1O合金薄膜,Mn以＋2价的价态存在,这就导致了掺Mn以后的薄膜带隙变大,在发光谱中表现为带边发射的蓝移.同时由于掺入的Mn与薄膜中的填隙Zn反应,导致薄膜的结晶性变差,薄膜中的填隙Zn减少,O空位增多,引起带边发射和紫光发射减弱,绿光发射增强.     

脉冲磁控溅射制备硼掺杂氧化锌纳米薄膜的光学特性研究

采用脉冲磁控溅射法制备硼掺杂氧化锌（ZnO：B）纳米薄膜,研究了其结构和光学特性,经XRD分析,ZnO：B为多晶纳米薄膜,具有六方钎锌矿结构,薄膜沿着c轴取向择优生长。薄膜在可见光和近红外光谱区的透光性很好,其中在可见光区的平均透光率可达84％以上,而在近红外区的透光率随着波长增加而逐渐降低至45％。在可见光区,ZnO：B纳米薄膜的光学常数随波长的变化很小且数值基本趋于恒定,而在紫外区,光学常数随波长的变化很明显,并且在367nm和397nm附近存在两个紫外发光峰。     

Blue fluorescence of decorated nano zinc oxide/polystyrene hybrid thin film prepared by pulsed laser ablation

Decorated nano ZnO/PS organic sol was successively produced by pulsed laser ablation at the interface of ZnO ZnO target submerged in the flowing liquid of butyl acetate solution of PS which contained salicylic acid, then decorated nano ZnO/PS hybrid thin film was obtained. It is found that decorated nano ZnO/PS hybrid thin film radiates intense blue light under ultraviolet radiation and has a broad emission band centered at 448 nm in the emission fluorescence spectrum. TEM shows that the size of the nano ZnO particles distributes between 10 nm and 15 nm. TG-DSC reveals that the heat resistance of decorated nano ZnO/PS hybrid thin film increases.