激光辐照对热退火金属/掺氟二氧化锡透明导电薄膜光电性能的影响

采用532 nm纳秒脉冲激光对热退火的铝(Al)/掺氟二氧化锡(FTO)、铜(Cu)/FTO和银(Ag)/FTO三种双层复合薄膜表面分别进行处理, 结果显示薄膜样品的光电性能都得到提高.其中, 热退火Ag/FTO薄膜的平均透光率(400–800 nm)增幅最大, 从72.6%提高到80.5%, 主要是由于其表面产生了具有减反增透作用的光栅结构.激光辐照后热退火Ag/FTO薄膜的导电性也略有提高, 其方块电阻从5.6 Ω/sq下降到5.3 Ω/sq, 原因主要是激光辐照的热效应造成的退火作用使薄膜的晶粒尺寸增大, 减少了晶界散射而使载流子迁移率提高.计算结果显示, 激光辐照后热退火Ag/FTO薄膜的品质因子从0.73×10^-2Ω^-1增大为2.16×10^-2Ω^-1, 表明其综合光电性能得到显著提高.激光辐照可同步实现薄膜表面光栅结构的制备和附加退火作用, 这为金属层复合透明导电薄膜光电性能的综合优化提供了新的思路.     

碳化硅薄膜脉冲激光晶化特性研究

采用XeCl准分子激光对非晶碳化硅(a-SiC)薄膜的脉冲激光晶化特性进行了研究.通过原子力显微镜（AFM）和Raman光谱技术对退火前后薄膜样品的形貌、结构及物相特性进行了分析.结果表明，选用合适的激光能量采用激光退火技术能够实现a-SiC薄膜的纳米晶化.退火薄膜中的纳米颗粒大小随着激光能量密度的增加而增大；Raman谱分析结果显示了退火后的薄膜的晶态结构特性并给出了伴随退火过程存在的物相分凝现象.根据以上结果并结合激光退火特性，对a-SiC的脉冲激光晶化机理进行了讨论. 关键词： 激光退火 晶化 碳化硅     

镱铒共掺Al2O3薄膜激光退火研究

讨论了激光退火工艺参量对镱铒共掺Al2O3薄膜表面形貌和退火均匀性的影响。薄膜样品被置放于衰减扩束透镜的3倍焦距位置时,薄膜上8 mm半径区域内近似均匀退火;退火时间为32 s时,表面形貌与退火前基本相同。阈值退火功率为5 W,最佳退火功率为20 W。对相同工艺制备的镱铒共掺Al2O3薄膜分别进行CO2激光退火和热退火处理,光致发光(PL)谱测量表明,前者峰值强度比后者强10倍以上,并且热退火光致发光强度随抽运功率增加出现饱和、下降,而激光退火近似随抽运功率单调线性增强。     

Investigation of the structural and electrical properties of air-annealed ruthenium thin films on 6H–SiC at different temperatures

Ruthenium (Ru) Schottky contacts and thin films on n-type 6H–SiC were fabricated and characterised by physical and electrical methods. The characterisation was done after annealing the samples in air at various temperatures. Rutherford backscattering spectroscopy (RBS) analysis of the thin films indicated the oxidation of Ru after annealing at a temperature of 400 °C, and interdiffusion of Ru and Si at the Ru–6H–SiC interface at 500 °C. XRD analysis of the thin films indicated the formation of RuO₂ and RuSi in Ru–6H–SiC after annealing at a temperature of 600 °C. The formation of the oxide was also corroborated by Raman spectroscopy. The ideality factor of the Schottky barrier diodes (SBD) was seen to generally decrease with annealing temperature. The series resistance increased astronomically after annealing at 700 °C, which was an indication that the SBD had broken down. The failure mechanism of the SBD is attributed to deep inter-diffusions of Ru and Si at the Ru–6H–SiC interface as evidenced by the RBS of the thin films.     

多孔硅衬底上溅射沉积SiC:Tb薄膜的光致发光行为

在多孔硅衬底上用射频溅射法沉积了非晶的SiC:Tb薄膜. 对样品在N2中进行了不同温度的退火处理. 用傅里叶红外变换谱分析了样品的结构.用荧光光谱仪测试了样品的光致发光，在紫外、可见光区域观测到了强的发光峰.发现随着衬底加热温度和样品退火温度的变化，发光峰有明显的强度变化和微弱的蓝移现象.分析了产生这种现象的机理，得出了紫外区域的发光峰是由于氧缺乏中心引起的，而可见区的发光是由于Tb离子产生的. 关键词： 碳化硅 光致发光 氧缺乏中心 多孔硅     

Initial study on the structure and photoluminescence properties of SiC films doped with Al

SiC films doped with aluminum (Al) were prepared by the rf-magnetron sputtering technique on p-Si substrates with a composite target of a single crystalline SiC containing several Al pieces on the surface. The as-deposited films were annealed in the temperature range of 400-800 °C under nitrogen ambient. The thin films have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show that the introduction of Al into films hinders crystalline formation process. And with the increase of annealing temperature, more Si particles are formed in the films, which strongly affect the optical absorption properties. The photoluminescence (PL) spectra of the samples show two peaks at 370 nm and 412 nm. The intensities of the PL peaks are evidently improved after Al doped. We attribute the origin of the two PL peaks to a kind of Si-related defect centres. The obtained results are expected to have important applications in modern optoelectronic devices.     

Structural and photoluminescence properties of silicon nanocrystals embedded in SiC matrix prepared by magnetron sputtering

Si nanocrystals (NCs) embedded in an SiC matrix were prepared by the deposition of Si-rich Si_1?xC_x/SiC nanomultilayer films using magnetron sputtering, subsequently followed by thermal annealing in the range of 800～1200 °C. As the annealing temperature increases to 1000 °C, Si NCs begin to form and SiC NCs also start to emerge at the annealing temperature of 1200 °C. With the increase of annealing temperature, two photoluminescence (PL) peaks have an obvious redshift. The intensity of the low-energy PL peak around 669～742 nm gradually lowers, however the intensity of high-energy PL peak around 601～632 nm enhances. The low-energy PL peak might attribute to dangling bonds in amorphous Si (a-Si) sublayers, and the redshift of this peak might be related to the passivation of Si dangling bonds. Whereas the origin of the high-energy PL peak may be the emergence of Si NCs, the redshift of this peak correlates with the change in the size of Si NCs.     

The structure and optical properties of SiC film on Si (111) substrate with a ZnO buffer layer by RF-magnetron sputtering technique

We have fabricated a multiply layer SiC/ZnO on Si substrates using the RF-magnetron sputtering technique with the targets of a single crystalline SiC and a polycrystalline ZnO. The as-deposited films were annealed in the temperature range of 600–1000 °C under nitrogen ambient. We have observed a strong ultraviolet (UV) emission (370 nm) from the as-deposited SiC/ZnO film and an intense violet emission (412 nm) from the film annealed at high temperature (1000 °C) under nitrogen ambient. The SiC film quality and the PL intensities are considered to be strongly dependent on the crystalline quality of the ZnO buffer layer. With the increase of the annealing temperature, the crystalline quality of the ZnO buffer layer is improved, resulting in the improvement of the SiC film quality and the increase of the PL intensities. The thin films have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) to provide the evidences of photoluminescence (PL). We suggest that the UV emission could be attributed to the nanocrystal silicon particles, that the 395 nm band is related to ZnO buffer layer and has a great relation to the crystalline quality of the ZnO film, and that the violet emission is associated with the emission luminescence from 6H-SiC, which bears on the SiC film quality. The obtained results are expected to have important applications in modern optoelectronic devices.     

Photoluminescence study of Ce-doped silica films

Ce-doped silica films with different Ce concentrations were prepared by ion-beam sputtering and ion implantation. The films containing 1.2 at% Ce were annealed at temperatures from 500 °C to 1200 °C in air ambient, and were annealed in different ambient at 1100 °C. Ce-related photoluminescence was observed in films sensitive to the Ce concentrations, annealing temperatures and the annealing ambient. The peak intensity of the photoluminescence band is approximately linear with Ce concentrations. Also, the photoluminescence intensity is dependent on the annealing temperatures and reaches its highest value after annealing at 700 °C. In addition, the experimental results show that compared with the annealing in an air ambient, the photoluminescence intensity can be enhanced with nitrogen gas. There would be no obvious change for the photoluminescence position or shape.     

退火对ZnO薄膜的结构和光学性质的影响

采用射频磁控溅射法在Si衬底上制备了高c轴择优取向的ZnO薄膜,研究了退火对ZnO薄膜的晶粒尺度和发光光谱的影响。XRD结果显示退火可以改善ZnO薄膜的结构特性,PL谱结果显示退火对ZnO薄膜的发光强度产生很大影响。     

HFCVD法制备纳米晶态SiC及其室温下的光致发光

用热丝化学气相沉积(HFCVD)法以CH4和SiH4作为反应气体在Si衬底上制备了纳米晶态6H-SiC。为减小6H-SiC与Si衬底之间的晶格失配,在HFCVD系统中通过对Si衬底表面碳化处理制备了缓冲层,确立了形成缓冲层的最佳条件。采用扫描电镜、傅里叶红外吸收谱和X射线衍射等分析手段对样品进行了结构和组分分析。结果表明,在较低的衬底温度下所沉积的是晶态纳米SiC,纳米晶粒平均尺寸约为60nm,并在室温下观察到所制备的纳米SiC位于380～420nm范围内的短波可见光。研究和分析了碳化时间对发光峰及红外吸收峰位置的影响。     

Photoluminescence of SiO<Subscript>2</Subscript> layers prepared on β-SiC films and an analysis of their elemental composition

The spectra of pulsed time-resolved photoluminescence of oxidized films prepared through electrochemical oxidation on SiC/Si films are investigated. The elemental composition of the films is analyzed using Rutherford backscattering and nuclear reactions. It is revealed that a certain part of the carbon atoms remain in the oxide. The specific features of the parameters of the spectral bands and their kinetics with time are explained by the presence of carbon uniformly distributed throughout the oxide. The structure of oxides at different oxidation times is examined with the use of electron microscopy. Conclusions are drawn regarding possible photoluminescence centers.     

退火温度对ZnO薄膜结构和发光特性的影响

采用反应射频磁控溅射法在 Si(100)基片上制备了高c轴择优取向的ZnO薄膜，研究了退火温度对ZnO薄膜的晶粒尺度、应力状态、成分和发光光谱的影响，探讨了ZnO薄膜的紫外发光光谱和可见发光光谱与薄膜的微观状态之间的关系.研究结果显示,在600—1000℃退火温度范围内，退火对薄膜的织构取向的影响较小，但薄膜的应力状态和成分有比较明显的变化.室温下光致发光光谱分析发现，薄膜的近紫外光谱特征与薄膜的晶粒尺度和缺陷状态之间存在着明显的对应关系；而近紫外光谱随退火温度升高所呈现的整体峰位红移是各激子峰相对比例变 关键词： ZnO薄膜 退火 光致发光 射频反应磁控溅射 可见光发射     

Effect of post annealing temperature on structural and optical properties of ZnCdO thin films deposited by sol–gel method

Ternary ZnCdO thin films oriented along c-axis have been successfully deposited on p-Si (1 0 0) substrates using sol–gel spin coating route. To optimize most suitable annealing temperature for the Zn_1−xCd_xO thin films; these films with selected cadmium content x = 0.10 were treated at annealing temperatures from 300 °C up to 800 °C in oxygen ambient after deposition. The structural and optical properties of deposited thin films have been characterized by X-ray diffraction, energy dispersive spectroscopy, atomic force microscopy, UV–Vis spectroscopy, and photoluminescence spectra. The results show that the obtained films possess high crystallinity with wurtzite structure. The crystallite size, lattice parameters, lattice strain and stress in the deposited films are determined from X-ray diffraction analysis. The band gap energy increased as a function of annealing temperatures as observed from optical reflectance spectra of samples. The presence of Cd in the deposited films is confirmed by energy dispersive spectrum and it is observed that Cd re-evaporate from the lattice with annealing. The photoluminescence measurements as performed at room temperature did not exhibit any luminescence related to oxygen vacancies defects for lower annealing temperatures, as normally displayed by ZnO films. The green yellow luminescence associated to these defects was observed at higher annealing temperatures (≥700 °C).     

非晶态Nb氧化物纳米薄膜可见光区的光玫发光

在低真空及亚高温(200～300℃)下.通过热氧化法在Si单晶基底上合成了呈准直阵列的椎形结构的氧化铌(NbOx)非晶结构纳米薄膜,薄膜经热处理后室温下在可见光区具有很好的光致发光.实验研究了退火温度与发光强度规律,对铌氧化物纳米薄膜的光致发光(PL)机制进行了初步分析和讨论.变功率光致发光(PL)实验有力地支持了初步讨论结果.     

热处理温度对ZnO∶Al薄膜性能的影响

利用溶胶-凝胶技术在玻璃衬底上制备了ZnO∶Al薄膜,表征了薄膜的结构、光透过和光致发光特性,探讨了热处理温度对薄膜晶体结构和光学性质的影响.结果表明,在热分解温度400 ℃和退火温度600 ℃时,ZnO∶Al薄膜的C轴择优取向明显,透过率较高.在热处理温度400 ℃情况下,激发波长340 nm的光致发光谱中有三个发光中心,紫外发光强度随退火温度的升高先升高后下降,500 ℃时发光强度最强.其它两个发光峰的强度随退火温度的升高而降低甚至消失.激发波长不同,ZnO∶Al薄膜的发光中心和强度均发生变化.     

Effect of post thermal annealing on the structural and optical properties of ZnO thin films prepared from polymer precursor

ZnO thin films were synthesised by a new method which uses polyvinyl alcohol (PVA) as polymer precursor. The films are annealed at different temperatures and for different annealing times. The structural parameters, like grain size, lattice constants, optical band gap, and Urbach energy, depend on the annealing temperature and annealing time. All the films possess tensile strain which relaxes as the annealing temperature and the annealing time increases. The photoluminescence (PL) spectra contain only ultraviolet (UV) peaks at low temperature, but as the annealing temperature and time increase we observe peaks at blue and green regions with variation of the intensities of these peaks with annealing temperature and annealing time.     

Effects of nanostructure on optoelectronic properties of β phase polyoctylfluorene thin film

β phase polyoctylfluorene thin films were obtained by exposure to toluene vapor for various annealing times or dipping into a THF/methanol mixture. The photoluminescence and electroluminescence of PFO thin films decrease with increasing annealing time. Grazing incident X-ray diffraction of the thin films indicates that more and larger β phase crystallites will be generated in thin film exposed for longer time, which will lead to more defects that reduce photoluminescence and electroluminescence. By analyzing the mechanism of formation of β phase, we assume that the defects mainly come from the formation of out-of-plane crystalline structure. The assumption is confirmed by higher photoluminescence of β phase polyoctylfluorene thin film achieved by dipping into a THF/methanol mixture that has less out-of-plane crystalline structure.     

退火温度对低温生长MgxZn1－xO薄膜光学性质的影响

用射频磁控溅射法在80℃衬底温度下制备出Mg_xZn_1-xO(x=0.16)薄膜，用X射线衍射(XRD)、光致发光(PL)和透射谱研究了退火温度对Mg_xZn_1-xO薄膜结构和光学性质的影响.测量结果显示，Mg_xZn_1-xO薄膜为单相六角纤锌矿结构，并且具有沿c轴的择优取向；随着退火温度的升高，(002)XRD峰强度、平均晶粒尺寸和紫外PL峰强度增大，(002)XRD峰半高宽(F 关键词： xZn_1-xO薄膜')" href="#">Mg_xZn_1-xO薄膜 射频磁控溅射 退火     

Studies on the influence of lithium incorporation in the photoluminescence of Y2O3:Eu thin films

Nanostructured europium-doped yttrium oxide thin films with lithium as a co-dopant were prepared using pulsed laser ablation technique. X-ray diffraction studies of the films indicated amorphous nature of the as deposited films and a transformation to crystalline phase with increase of annealing temperature. In this transformation, lithium co-doped films showed early crystallization. Lithium substitution resulted not only in enhancement of photoluminescence at 612 nm, resulting from ⁵D₀-⁷F₂ transition within europium, but also found to reduce the required processing temperature for intense photoemission. The deviation observed in the value of lattice constant of films annealed at different temperatures is found to be sensitive to annealing temperature. In the light of this, the dependence of photoluminescence intensity on the magnitude of lattice imperfection is also discussed. The morphology and transmittance of the films are also found to be sensitive to annealing process and lithium doping.