MOCVD法生长ZnO薄膜的结构及光学特性

采用MOCVD方法在c Al2 O3衬底上生长出了具有单一c轴取向的ZnO薄膜 ,采用X射线衍射 (XRD)、Raman散射、X射线光电子能谱 (XPS)及光致发光 (PL)谱等方法对ZnO薄膜的结构及光学特性进行分析测试。XRD分析只观察到ZnO薄膜 (0 0 0 2 )衍射峰 ,其FWHM数值为 0 1 84°。Raman散射谱中 ,4 35 32cm- 1 处喇曼峰为ZnO的E2 (high)振动模 ,A1 (LO)振动模位于 5 75 32cm- 1 处。XPS分析表明 :ZnO薄膜表面易吸附游离态氧 ,刻蚀后ZnO薄膜O1s光电子能谱峰位于 5 30 2eV ,更接近Zn—O键中O1s电子结合能 (5 30 4eV)。PL谱中 ,在3 2 8eV处观察到了自由激子发射峰 ,而深能级跃迁峰位于 2 5 5eV ,二者峰强比值为 4 0∶1 ,表明生长的ZnO薄膜具有较高的光学质量     

薄膜光学 薄膜光学理论与膜系设计

O484．1 2006065221表面覆盖退火对ZnO薄膜光学性质的影响=Effect of surface-covered annealing on optical properties of ZnO films grown by MOCVD[刊,英]/王立(南昌大学教育部发光材料与器件工程研究中心,江西,南昌(330047)),蒲勇…//半导体学报．—2006．27(3)．—409-412研究了暴露在空气中退火和表面覆盖蓝宝石基板退火对MOCVD生长的ZnO薄膜光学性质的影响,研究发现,暴露在空气中退火虽可以去除薄膜中的氢杂质,并在低温光致发光(PL)谱中观察到与氢相关的束缚激子峰消失,但是退火后样品室温PL谱中可观察到很强的可见光     

非掺杂ZnO薄膜中紫外与绿色发光中心

用直流反应溅射方法在硅衬底上淀积了ZnO薄膜,测量它们的光致发光(PL)光谱,观察到两个发光峰,峰值能量分别为3.18(紫外峰,UV)和2.38eV(绿峰).样品用不同温度分别在氧气、氮气和空气中热处理后,测量了PL光谱中绿峰和紫外峰强度随热处理温度和气氛的变化,同时比较了用FP-LMT方法计算的ZnO中几种本征缺陷的能级位置.根据实验和能级计算的结果,推测出ZnO薄膜中的紫外峰与ZnO带边激子跃迁有关,而绿色发光主要来源于导带底到氧错位缺陷(O_Zn)能级的跃迁,而不是通常认为的氧空 关键词： ZnO薄膜 热处理 光致发光光谱 缺陷能级     

镉掺杂氧化锌纳米花的制备及其光催化活性

以氯化锌、氯化镉、氢氧化钠为原料,采用水热法合成Cd掺杂纳米花状ZnO光催化剂,并通过该样品对罗丹明B水溶液的降解来研究其光催化活性。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能量色散谱(EDS)、光致发光谱(PL)及紫外-可见分光光度计(UV-Vis)等测试手段对材料物性进行表征。实验结果表明:当掺杂Cd2+时,样品形貌发生变化、粒径减小;掺杂Cd2+后的ZnO的吸收边和紫外峰对比于纯ZnO均发生红移,禁带宽度由3.24 eV减小到3.16 eV。通过光催化实验分析可知,掺杂后纳米ZnO光催化剂对罗丹明B水溶液的降解率有所提高,光照3 h其降解率高达98%,说明与纯ZnO相比,Cd掺杂ZnO纳米花具有更高的光催化活性。     

掺AlZnO纳米线阵列的光致发光特性研究

采用化学气相沉积方法，以金做催化剂，在Si (100)衬底上制备了掺AlZnO纳米线阵列.扫描电子显微镜(SEM)表征发现ZnO纳米线的直径在30nm左右.X射线衍射(XRD)图谱上只存在ZnO的(002)衍射峰，说明ZnO纳米线沿c轴择优取向.掺AlZnO纳米线阵列的室温光致发光(PL)谱中出现了3个带边激子发射峰：373nm，375nm，389nm.运用激子理论推算出掺AlZnO纳米线的禁带宽度为3.343eV ，束缚激子结合能为0.156eV；纯ZnO纳米线阵列PL谱中3个带边激子发射 关键词： 光致发光 化学气相沉积(CVD) 激子 ZnO纳米线阵列     

氢稀释制备的非晶碳膜的绿光和蓝光发射

在电容耦合式PECVD系统中,以CH4和H2为气源,通过控制H2的流量制备了一系列氢化非晶碳膜（a-C:H)样品。利用傅里叶变换红外光谱（FTIR）、光致发光谱（PL）和吸收谱对a-C:H膜的结构及光学性质进行了研究。结果表明：氢稀释可以在一定程度上减少碳的sp^2团簇的形成,增大它的光学带隙,并改变薄的微结构。与此同时,光致发光峰随郑 光学带隙的增大而蓝移;当光学带隙增大2．72eV时,出现了2．4eV（绿光）和2．97eV(蓝光）组成的发光峰。     

氢等离子体气氛中退火多孔硅的表面和光荧光特性

用电化学腐蚀法制备了多孔硅(PS),在氢等离子体气氛中不同温度下对多孔硅样品进行了退火处理,并进行了光致发光(PL)谱和原子力显微镜(AFM)表面形貌的测量。不同退火温度给PS表面形态带来较大变化,也影响了其PL谱特性。在退火的样品中观察到的PL谱高效蓝光和紫光谱带,我们认为主要源于量子限制发光峰和非平衡载流子被带隙中浅杂质能级所俘获而引起的辐射复合所产生的。在420—450℃退火处理的多孔硅的PL谱上观察到了一个未见诸于报道的紫光新谱带(3．24eV,382nm),其发光机理有待于进一步研究。     

ZnO：V薄膜后退火处理前后的微结构与发光特性

利用溶胶-凝胶(Sol-gel)法在单晶硅(100)衬底上分别制备了ZnO:V薄膜和纯ZnO薄膜。为进一步研究后退火对ZnO:V薄膜结构和发光性质的影响,在两段式快速退火后又在800℃下进行了后退火处理。X射线衍射的结果表明:后退火处理前,钒(V)的掺入使ZnO结晶质量变差,而800℃退火处理后,从ZnO的衍射峰中可以看出,相对于无V杂样品其结晶质量变好。扫描电子显微镜形貌图中可以看出制备的样品薄膜颗粒大小均匀,薄膜致密度较高。光致发光(PL)谱的研究表明:ZnO:V薄膜在800℃退火处理后,紫外和绿带发光峰均增强,但紫外发光峰增强得更多;与同样条件下制备的纯ZnO薄膜的PL谱比较,发现V掺杂后样品的紫外激子复合发光峰的强度明显增强且峰位发生蓝移,而缺陷引起的绿带发光峰的强度降低。     

ZnO∶V薄膜后退火处理前后的微结构与发光特性

利用溶胶-凝胶(Sol-gel)法在单晶硅(100)衬底上分别制备了ZnO∶V薄膜和纯ZnO薄膜。为进一步研究后退火对ZnO∶V薄膜结构和发光性质的影响,在两段式快速退火后又在800℃下进行了后退火处理。X射线衍射的结果表明:后退火处理前,钒(V)的掺入使ZnO结晶质量变差,而800℃退火处理后,从ZnO的衍射峰中可以看出,相对于无V杂样品其结晶质量变好。扫描电子显微镜形貌图中可以看出制备的样品薄膜颗粒大小均匀,薄膜致密度较高。光致发光(PL)谱的研究表明:ZnO∶V薄膜在800℃退火处理后,紫外和绿带发光峰均增强,但紫外发光峰增强得更多;与同样条件下制备的纯ZnO薄膜的PL谱比较,发现V掺杂后样品的紫外激子复合发光峰的强度明显增强且峰位发生蓝移,而缺陷引起的绿带发光峰的强度降低。     

Cu掺杂氧化锌薄膜的发光特性研究

通过射频反应溅射法在Si（111）衬底上制备了不同Cu掺杂量的ZnO薄膜.室温下测量了样品的光致发光（PL）谱，所有样品的PL谱中均观察到435?nm左右的蓝光发光带，该发光带的强度与Cu掺杂量和溅射功率有关.当溅射功率为150?W，Cu掺杂量为2.5%时，ZnO薄膜的PL谱中出现了较强的蓝光双峰，而溅射功率为100?W，Cu掺杂量为1.5%时，出现了位于437nm（2.84eV）处较强的蓝光峰，后者的取向性较好.还研究了掺杂量和溅射功率对发光特性的影响，并对样品的蓝光发光机制进行了探讨. 关键词： ZnO薄膜 Cu掺杂 光致发光谱 射频反应共溅射     

Influence of Al-doping on the structure and optical properties of ZnO films

Al-doped ZnO (ZnO:Al) thin films with c-axis preferred orientation were deposited on glass substrates using the radio frequency reactive magnetron sputtering technique. The effect of Al concentrations on the microstructure and the luminescence properties of the ZnO:Al thin films were studied by atomic force microscopy (AFM), X-ray diffraction (XRD), and fluorescence spectrophotometer. The results showed that the crystallization of the films was promoted by appropriate Al concentrations; the photoluminescence spectra (PL) of the samples were measured at room temperature. Strong blue peak located at 437 nm (2.84 eV) and two weak green peaks located at about 492 nm (2.53 eV) and 524 nm (2.37 eV) were observed from the PL spectra of the four samples. The origin of these emissions was discussed. In addition, absorption and transmittance properties of the samples were researched by UV spectrophotometer; the UV absorption edge shifted to a shorter wavelength first as Al was incorporated, and then to a longer wavelength with the increasing Al concentrations. The optical band gaps calculated based on the quantum confinement model are in good agreement with the experimental values.     

纳米ZnO薄膜可见发射机制研究

利用溶胶－凝胶法 （Sol-Gel）制备了纳米ZnO薄膜，获得了高强的近紫外发射室温下测量了样品的光致发光谱(PL )、吸收谱(ABS)、X射线衍射谱(XRD).X射线衍射(XRD)的结果表明：纳米ZnO薄膜呈多晶态，具有六角纤锌矿结构和良好的C轴取向；发现随退火温度升高，（002）衍射峰强度显著增强，衍射峰的半高宽（FWHM）减小、纳米颗粒的粒径增大.由吸收谱(ABS)给出了样品室温下带隙宽度为3.30 eV.在PL谱中观察到二个荧光发射带，一个是中心波长位于392 nm附近强而尖的紫带，另一个是519 nm附近弱而宽的绿带研究了不同退火温度样品的光致发光峰值强度的变化关系，发现随退火温度升高，紫带峰值强度增强、绿带峰值强度减弱，均近似呈线性变化.证实了纳米ZnO薄膜绿光发射主要来自氧空位(Vo)形成的浅施主能级与锌空位(VZn)形成的浅受主能级之间的复合，或氧空位(Vo)形成的深施主能级上的电子至价带顶的跃迁；紫带来自于导带中的电子与价带中的空位形成的激子复合.     

稀土Tb3+掺杂纳米ZnO的发光性质

ZnO是一种优良的直接宽带隙半导体发光材料(Eg=3.4 eV),具有优异的晶格、光学和电学性质,稀土离子掺杂浓度和热处理温度对ZnO∶Re3 纳米晶发光强度、峰位变化等光学性质具有重要影响.利用溶胶-凝胶法(Sol-Gel),在不同退火温度下,制备了不同浓度的ZnO∶Tb3 纳米晶.室温下,测量了样品的X射线衍射谱(XRD)、光致发光谱(PL)和激发谱(PLE).观察到纳米ZnO基质在520 nm附近宽的绿光可见发射和稀土Tb3 在485,544,584和620 nm附近的特征发射.通过ZnO基质可见发射强度和稀土Tb3 特征发射强度随Tb3 掺杂浓度、退火温度的变化关系,获得了5D4→7F5跃迁的绿色主发射峰最强的样品制备工艺参数,其退火温度为600℃、掺杂浓度为4 at%;给出了稀土Tb3 的激发态5D4→7F6(485 nm),5D4→7F5(544 nm)和5D4→7F4(584 nm)的发射机制;证实了稀土Tb3 与纳米ZnO基质之间存在双向能量传递.     

射频磁控溅射法制备ZnO薄膜的发光特性

利用射频磁控溅射法在硅衬底上制备出具有（002）择优取向的氧化锌薄膜，用波长为300nm的光激发，观察到在446nm处有一强的光致发光峰，它来自于氧空位浅施主能级上的电子到价带上的跃迁。并讨论了发光峰与氧压的关系以及退火对它的影响，且给出了解释。     

低能Co离子注入单晶ZnO的光致发光特性

采用离子注入法研究了Co离子注入ZnO晶体的光致发光效应。 对离子注入后的样品在Ar气保护下进行退火处理, 退火温度为700 ℃, 退火时间为10 min, 在其光致发光谱中观察到了406和370 nm的紫光发射峰。 对比了Co, Cu离子分别注入的ZnO晶体的光致发光谱, 观测到二者的光致发光谱类似。 同时, 研究了Co离子注入剂量对样品发光性质的影响, 结果表明随注入剂量的增加绿色发光中心逐渐向低能边偏移, 分析认为绿色发光中心的偏移与离子注入后ZnO晶体的禁带宽度发生改变相关。 In this paper, ion implantation techniques were used to study the photoluminescence(PL) of the Co implanted crystal ZnO. After Co ion implanted, the samples were annealed at 700 ℃ for 10 min in Ar gas flow. It was observed violet emission peak of 406 and 370 nm in the PL spectrum. The PL spectra of the ZnO crystal samples which were implanted by Co ions and Cu ions, respectively, have been compared and observed that the PL spectrum of the Co implanted ZnO is similar to that of the Cu implanted ZnO. We studied the influence of implantation dose on the PL of the Co implanted ZnO and found that the green luminescence centre shifted with increasing of implantation dose. It is concluded that the shift of the green luminescence centre is related to the change of ZnO band gap which was caused by ion implantation.     

Hydrogen passivation effect on the yellow-green emission band and bound exciton in n - ZnO

Photoluminescence (PL) measurements performed on as-grown, hydrogenated, and annealed n-type ZnO bulk samples investigated the origins of their yellow (2.10 eV) and green (2.43 eV) emission bands. After hydrogenation, the defect-related peak at 2.10 eV was no longer present in the room temperature PL spectrum, the peak intensity at 2.43 eV was unchanged, and the intensity of the emission peak at 3.27 eV increased significantly. These results indicate that yellow band emission is due to oxygen vacancies, as the emission peak at 2.10 eV disappears when hydrogen atoms passivate these vacancies. The emission peak at 2.43 eV originates from complexes between oxygen vacancies and other crystal defects. We discuss the shallow donor impurities arising due to these hydrogen atoms in the ZnO bulk sample.     

退火对多晶ZnO薄膜结构与发光特性的影响

用射频反应溅射法在Si（111）衬底上制备了C轴取向的多晶ZnO薄膜，通过不同温度的退火处理，研究了退火对多晶ZnO薄膜结构和发光特性的影响.由x射线衍射得知，随退火温度的升高，晶粒逐渐变大，薄膜中压应力由大变小至出现张应力.光致发光测量发现，样品在430nm附近有一光致发光峰, 峰的强度随退火温度升高而减弱，联合样品电阻率随退火温度升高而逐渐变大的测量及能级图，推测出ZnO薄膜中的蓝光发射主要来源于锌填隙原子缺陷能级与价带顶能级间的跃迁. 关键词： ZnO薄膜 退火 光致发光 射频反应溅射     

氧分压对PLD制备ZnO薄膜结构和发光性质的影响

采用脉冲激光沉积(PLD)技术,在Si(100)衬底上制备出高度c轴取向的ZnO薄膜。通过X射线衍射(XRD)谱,扫描电镜(SEM)和室温光致发光(PL)光谱的测量,研究了生长气氛压强的改变对薄膜结构和光致发光的影响。实验结果表明,当氧压从10Pa升高到100Pa时ZnO(002)衍射峰的半峰全宽(FWHM)增大。可以认为这是由于较高的氧压下,到达衬底表面的离子动能减小。这样部分离子没有足够的能量迁移到生长较快的(002)面,c轴取向变差,导致(002)衍射峰的强度降低,半峰全宽增大。随着氧压增大,紫外发光强度增强。这可能是氧压变大,薄膜的化学配比升高,说明化学配比对UV发光的影响要大于薄膜微结构的影响。改变氧气压强对薄膜的表面形貌也有较大的影响。     

Temperature dependence of excitonic luminescence from nanocrystalline ZnO films

The properties of the excitonic luminescence for nanocrystalline ZnO thin films are investigated by using the dependence of excitonic photoluminescence (PL) spectra on temperature. The ZnO thin films are prepared by thermal oxidation of ZnS films prepared by low-pressure metalorganic chemical vapor deposition (LP-MOCVD) technique. The X-ray diffraction (XRD) indicates that ZnO thin films have a polycrystalline hexagonal wurtzite structure with a preferred (0 0 2) orientation. A strong ultraviolet (UV) emission peak at 3.26 eV is observed, while the deep-level emission band is barely observable at room temperature. The strength of the exciton-longitudinal-optical (LO) phonon coupling is deduced from the temperature dependence of the full-width at half-maximum (FWHM) of the fundamental excitonic peak, decrease in exciton-longitudinal-optical (LO) phonon coupling strength is due to the quantum confinement effect.     

Investigation of the luminescence properties of ZnO tetrapods and clusters grown on Si substrates

ZnO nanostructures are formed on Si substrates using Zn powder without catalyst. The substrate temperature was controlled from 450 to 600 °C, and the variation of structural and optical properties was investigated. From all samples both ZnO tetrapods and clusters were observed. Among them, no significant dispersion was observed from the ZnO tetrapods. However, ZnO clusters show considerable change in density and size. From the energy dispersive X-ray spectroscopy (EDX) results, atomic composition difference was observed. The clusters have considerable O-deficiencies, while tetrapods have almost stoichiometric composition. From all samples, strong luminescence, UV emission at 3.21 eV and green emission at 2.5 eV, were observed at room temperature. Cathodoluminescence measurements showed that the UV emission is closely related with tetrapods and the green emission is dominated from the clusters.