溶胶-凝胶法制备ZnO薄膜及其光致发光性质

利用溶胶-凝胶法在石英衬底上制备了ZnO薄膜,通过测量样品的透射谱、X射线衍射谱、扫描电子显微镜(SEM)图像和光致发光谱研究了其结构特征和发光性质.结果表明:在衍射角2θ=34.32°处出现了对应(002)晶面的强衍射峰,ZnO膜呈多晶状态,具有六角纤矿晶体结构和良好的C轴择优取向,薄膜中颗粒的平均粒径为56nm;光致发光呈多发光峰状,有中心波长为378nm的紫带,520nm绿带,446nm附近的蓝带以及发现未见报道过的绿带以后中心波长为586nm和570nm两个弱发射峰.实验结果表明,制备的ZnO薄膜具有发光特性,但内部与深能级发射相关的结构缺陷浓度还是较高,样品中两个低能量光致发光应来源于晶粒间界的缺陷能级,多缺陷能级导致了多发射峰的光致发光谱.     

溶胶-凝胶法制备CaSiO_3:Eu~(3+)Bi~(3+)

采用溶胶-凝胶法制备出了CaSiO_3:Eu~(3+)Bi~(3+),利用DTA样品进行了检测并分析了其反应过程。XRD谱图表明:在CaSiO_3中少量掺杂Eu~(3+)、Bi~(3+)并没有改变其晶体结构。     

溶胶-凝胶法制备氧化锌薄膜的压电行为

"采用溶胶-凝胶技术在单晶硅Si(111)上制备了ZnO压电薄膜,并以扫描电镜、X射线衍射仪(XRD)和原子力显微镜(AFM)进行了表征．XRD衍射实验表明ZnO薄膜随着膜厚的增大,其(002)取向逐渐增强;AFM研究了薄膜的表面形貌、粗糙度与晶粒大小的结果表明,ZnO压电薄膜的粗糙度与晶粒寸随着薄膜厚度的增大而减小．粗糙度为2.188~0.914 nm．利用PFM研究压电系数,发现随着薄膜厚度的增加,(002)生长方向增强,压电系数逐渐增大;当力参数小于薄膜的表面粗糙度时,压电系数测量不准确且在较大幅度     

溶剂对溶胶-凝胶法制备的掺铝氧化锌透明导电薄膜性质的影响

采用溶胶-凝胶法在玻璃基底上制备得到了高透光率,高导电性的掺铝氧化锌薄膜。研究了溶剂对薄膜晶体结构,薄膜厚度,表面形貌,光学性质和电学性质的影响,结果表明:在相同的制备条件下,薄膜的厚度随溶剂沸点的升高而降低;低沸点溶剂制备的薄膜由c轴择优取向的六角纤锌矿结构的晶体构成,且比较致密;所有薄膜可见光区的透光率在85%以上;乙二醇独甲醚为溶剂制备的薄膜电阻率最低,为3.0×1-0 4Ωm。     

用改进的sol-gel法制备锆钛酸铅薄膜及其物相转化的研究

利用改进的solgel法,在Pt/Ti/SiO2/Si衬底上制备了PbZr0.5Ti0.5O3(PZT50/50)薄膜.采用了一种新的方式,从同一前驱体溶液得到了厚度各异的单一退火层.研究了薄膜的结构和性质随单层退火厚度的改变而发生的变化,发现随着单一退火层厚度的降低,薄膜(111)取向的程度增大,同时薄膜的剩余极化和介电常量也逐渐增高.当单一退火层厚度降低到约为40nm时,可得到高度(111)择优取向的PZT薄膜.从薄膜成核机理的基础上讨论了薄膜结构变化的内在因素,认为随单一退火层厚度的增加薄膜由单一的 关键词：     

热解温度对溶胶-凝胶法制备B掺杂ZnO薄膜晶化行为及性能的影响

采用溶胶-凝胶方法制备了B掺杂ZnO(BZO)薄膜,系统研究了热解温度对薄膜的结晶行为和性能的影响. X射线衍射谱表明所有的BZO薄膜均具有六方纤锌矿结构,并沿c轴方向择优生长. 随着热解温度的升高,BZO薄膜的晶粒尺寸和RMS粗糙度增加. BZO薄膜的载流子浓度和载流子迁移率也随着热解温度的升高而增加,其可见光平均透过率均在90%以上.     

Effects of Thickness and Polarization Field on the Photovoltaic Properties of BiFeO3 Thin Films

We study the effects of film thickness on lattice parameters, direct band gap and photovoltaic outputs in the sol-gel derived BiFeO3 thin films. With the change of the film thickness, the great transitions will take place in the preferred orientation and lattice parameters. Furthermore, the photovoltaic outputs are significantly dependent on the film thickness. The results show that the open circuit voltage gradually increases and the short circuit current reciprocally decreases with the increase of film thickness. In particular, we demonstrate for the first time that there are tunable photovoltaic outputs with external electric field polarization switching in the polycrystalline BiFeO3 film, which is critical for the future device applications based on the photovoltaic properties of BiFeO3 films.     

Structural,Optical and Luminescence Properties of ZnO Thin Films Prepared by Sol-Gel Spin-Coating Method: Effect of Precursor Concentration

Transparent zinc oxide(ZnO) thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations(0.3-1.2 M) using zinc acetate dehydrate [Zn(CH_3COO)_2·2H_2O] as precursor and isopropanol and monoethanolamine(MEA) as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.     

Magnetic Properties of Fe2O3 Particles Prepared by Sol-Gel Method

Fe₂O₃ fine particles dispersed in a silica gel have been prepared by a new sol-gel method and characterized. Various samples have been studied by means of Mössbauer spectroscopy for temperatures ranging between 4.2 K and 300 K. The results show that the average particle size and the kinds of Fe₂O₃ phase obtained (α, γ or ε) are strongly dependent of the temperature on the final heat treatment.     

Thickness Dependence of Photoconductance in Strained BiFeO3 Thin Films With Planar Device Geometry

The recent discovery of efficient charge separation in tetragonal–rhombohedral (T‐R) polymorphic phase boundaries (PPBs) in strained BiFeO₃ (BFO) films is of great interest, and also raised a question of whether the PPBs could enhance the performance of BFO‐based planar photodetectors. To address it, we prepare BFO films with thickness ranging from 8 to 90 nm on the LaAlO₃ substrates, in which the BFO evolves from a pure T phase (without PPBs) to a T‐R mixed phase (with PPBs) due to the strain relaxation. Then, we comparatively investigate the photoconductive properties of these BFO films with the planar device geometry. It is found that the photoconductance first increases and then decreases with increasing film thickness. Particularly, the 50‐nm film containing the pure T phase without any detectable PPBs exhibits the highest photoconductance. This unexpected observation can be understood by analyzing the effects of increasing film thickness and associated phase evolution on the photoconduction‐related parameters.     

溶胶-凝胶法制备MgxZn1-xO薄膜的结构及光学特性

用溶胶-凝胶法制备了一系列的Mg_xZn_1-xO(0≤x≤0.3)薄膜,并用X射线衍射(XRD)和光致发光(PL)研究了不同的退火温度和Mg的掺杂含量对Mg_xZn_1-xO薄膜的结构和光学性质的影响.研究表明: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;发现了中间热处理温度为350℃的Mg_xZn_1-xO薄膜退火温度的转折点为700℃,低于这个温度时随退火温度的升高,(002)衍射峰强度增强且掺Mg的薄膜既有紫外光又有绿光发射;800℃退火时,薄膜的(002)衍射峰强度减小,出现了(100)和(101)衍射峰,且掺Mg的薄膜只有紫外发光峰.不同的掺杂浓度对于发光也有影响,低于700℃退火时,ZnO薄膜只出现紫外发光峰,掺Mg的薄膜却出现了紫外和绿光两个发光峰.     

Sm doped BiFeO3 nanofibers for improved photovoltaic devices

Interdigital electrodes, BiFeO₃ and Sm doped BiFeO₃ nanofibers and corresponding photovoltaic devices were obtained by semiconductor technology and electrostatic spinning method. The interdigital electrodes have prefect structure and the nanofibers have uniform morphology both before and after annealing process examined by SEM and AFM, respectively. The ferroelectric and piezoelectric properties of the BiFeO₃ and Sm doped BiFeO₃ nanofibers were demonstrated by PFM. After Sm doping, the BiFeO₃ nanofibers have improved ferroelectricity. Compared with BiFeO₃ nanofiber photovoltaic device, Sm doped BiFeO₃ nanofiber photovoltaic device has improved photovoltaic performance with increased photocurrent and energy conversion efficiency is improved to 1.65 times. The BiFeO₃-based nanofibers are very promising ferroelectric photovoltaic materials for high performance photovoltaic devices.     

IR Reflection of Thin Bi4Ge3O12 Films

The spectra of IR reflection of the systems thin Bi₄Ge₃O₁₂ film–substrate made of molten -SiO₂ quartz in the region 10–1600 cm^–1 at 295 K are investigatedterpretation of fundamental vibrations in the region 10–800 cm^–1 and two phonon processes in the region 800–1600 cm^–1 are considered.     

Gd2O3:Eu3+溶胶-凝胶薄膜发光特性研究

以无机稀土氧化物为原料制备了Gd2O3:Eu3 溶胶-凝胶薄膜,通过对不同Eu3 离子掺杂浓度、不同烧结温度薄膜发光强度的研究,得出Gd2O3薄膜中Eu3 离子的最佳掺杂浓度为10%、最佳热处理工艺为800℃下烧结2h;由薄膜和粉末激发谱的比较发现:薄膜中存在着比粉末更有效的能量传递,从而更有利于高能射线激发发光;首次观察到薄膜经过1000℃烧结2h后发光消失,并通过SEM和XRD的实验分析对这一现象进行了解释。     

MOD法制备Bi4-xLaxTi3O12铁电薄膜及其谱图分析

采用有机金属沉积法(MOD)制备了Bi4Ti3O12(BIT)和Bi3.25La0.75Ti3O12(BLT)前驱体溶液,分别在单晶硅基片上制备了BIT和BLT铁电薄膜.前驱体溶液的干凝胶粉体和铁电薄膜分别用红外光谱(FTIR)、拉曼光谱和环境扫描电镜(ESEM)进行了表征.结果表明600℃时晶粒实现了由焦绿石相向类钙钛矿相结构的完全转变;温度升高,晶粒尺寸增大,薄膜结晶效果得到改善;引入镧使Ti-O和Bi-O键吸收峰位置向低波数频移,高温时频移率较大;500℃热处理时,干凝胶中乙二醇甲醚、乙酰丙酮完全分解,温度超过600℃后,残留的水及硝酸根离子挥发或分解.     

Local Piezoresponse and Thermal Behavior of Ferroelastic Domains in Multiferroic BiFeO3 Thin Films by Scanning Piezo-Thermal Microscopy

A dual probe, i.e., high resolution scanning piezo-thermal microscopy, is developed and employed to characterize the local piezoresponse and thermal behaviors of ferroelastic domains in multiferroic BiFeO3 thin films. Highly in- homogeneous piezoelectric responses are found in the thin film. A remarkably local thermal transformation across ferroelastic domain walls is clearly demonstrated by the quantitative 3w signals related to thermal conductivity. Different polarization oriented ferroelastic domains are found to exhibit different local thermal responses. The underlying mechanism is possibly associated with the inhomogeneous stress distribution across the ferroelastic domain wails, leading to different phonons scattering contributions in the BiFeO3 thin film.     

低温硫化制备ZnS薄膜的物理性质研究

采用磁控溅射方法先在玻璃衬底上室温下沉积Zn金属薄膜,接着先后在200和400 ℃温度下的硫蒸气和氩气流中进行退火,生长出 ZnS 薄膜。薄膜样品的微观结构、物相结构、表面形貌和光学性质分别采用正电子湮没技术 (PAT)、X射线衍射仪 (XRD)、扫描电子显微镜 (SEM)和紫外-可见分光光度计进行表征。该ZnS薄膜在可见光范围具有约80%的高透光率,随着硫化时间的增加,其带隙由3.55 增加到3.57 eV,S/Zn原子比从0.54上升至0.89,薄膜质量明显得到改善,相对于以前报道的真空封装硫化所制备的ZnS薄膜,硫过量问题得到了较好解决。此外,慢正电子湮没多普勒展宽谱对硫化前后薄膜样品中膜层结构缺陷研究表明,硫化后薄膜的S参数明显增大,生成的ZnS 薄膜结构缺陷浓度高于Zn薄膜。     

近空间升华法制备CdS多晶薄膜的研究

系统地研究了近空间升华法(CSS)制备CdS薄膜沉积速率的影响因素。发现CdS薄膜的沉积速率随升华源温度的升高而增大,但随衬底温度和沉积气压的上升而下降。对所制备样品的结构、表面形貌和光谱透过率特性进行了测试,结果表明：(1)不同氧分压下沉积的CdS薄膜沿(103)晶向择优生长。CdCl₂氛围下退火后,(103)晶向的优势得到进一步加强;(2)不同氧分压制备的CdS薄膜致密且粒径均匀,晶粒的大小随着衬底温度的升高而增大,但薄膜的粗糙度也随之增大;(3)随着CdS薄膜厚度的减小,可见光中短波段的透过率有所增大,有利于提高太阳电池的短波光谱响应。并将CSS制备的CdS多晶薄膜用于CdTe太阳电池的制作,获得了10.29%的光电转换效率,初步验证了该制作工艺的可行性。     

溶胶-凝胶法Er_2O_3薄膜的结构和光学特性

针对稀土Er掺杂Si光源中Er离子掺杂浓度低的问题,采用溶胶-凝胶(Sol-gel)法在Si(100)和SiO2/Si(100)基片上旋涂法制备Er2O3光学薄膜,Er离子浓度与以前掺杂方法相比提高了2个数量级.900℃热处理获得单一立方结构的Er2O3薄膜材料.光致发光(PL)特性研究表明在654nm波长的激光泵浦下,Er2O3薄膜材料获得了1.535μm的发光峰,并具有较小的温度猝灭1/5.在SiO2/Si(100)基体上制备的Er2O3薄膜材料的光致发光强度比Si(100)基体上制备的薄膜提高2-3倍.研究结果表明具有强光致发光特性的Er2O3薄膜是一种有前景的硅基光源和放大器材料.     

分子束外延方法生长p型氧化锌薄膜

用等离子辅助分子束外延 (P MBE)的方法 ,在蓝宝石c 平面上外延生长了p型氧化锌薄膜。在实验中采用高纯金属锌作为Zn源、NO作为O源和掺杂源 ,通过射频等离子体激活进行生长。在生长温度 30 0℃ ,NO气体流量为 1.0sccm ,射频功率为 30 0W的条件下 ,获得了重复性很好的p型ZnO ,且载流子浓度最大可达 1.2× 10 19cm-3 ,迁移率为 0 .0 5 35cm2 ·V-1·s-1,电阻率为 9.5Ω·cm。