Photoinduced effects in amorphous semiconductor Ge(S, Se)2 chalcogenide films

The blue shift of optical transmittance edges were observed in amorphous semiconductor Ge(S, Se)2 chalcogenide films with light illumination. The shift in well-annealed films could be recovered by annealing the films near the glass-transition temperature again. The photocrystallization was also observed in amorphous Ge(S,Se)2 films with light illumination by the transmitting electron microscope measurement. The photoinduced phenomina of the amorphous Ge(S,Se)2 films could be applied to designing some new kinds of optical storage materials.     

CuInSe<Subscript>2</Subscript> thin films obtained by pulse-plating electrodeposition technique with novel pulse wave

CuInSe₂ films were electrodeposited onto indium tin oxide (ITO) substrate in constant current mode using bell-like wave modulated square wave in aqueous solution. The films obtained at different pulse frequencies were characterized by scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). UV-Vis-NIR absorption spectro- scopy was used to study the optical properties of these films. The results showed that the chalcopyrite phase CuInSe₂ films with a smooth surface and stoichiometric composition could be obtained at appropriate pulse frequency. The crystallinity of CuInSe₂ films could be further improved after annealing treatment. Despite this, we also found that the films obtained using the pulse-plating electrodeposition technique had a faster deposition rate and better film adhesion ability than that using the traditional CIS elec-trodeposition technique, which is significant to the low-cost CIS thin film solar cell production.     

MoSe2电子结构和光学性质的理论研究

基于密度泛函理论第一性原理,计算了MoSe2的能带结构、态密度和光学性质,再根据相关参数分析了该材料的半导体特性和光学性质.能带结构结果表明MoSe2具有间接带隙宽度为0.853 eV的半导体材料,从态密度图可看出价带由Mo的5s4d价电子和Se的4s4p价电子起主要作用,其它价电子作用较少导带主要是Mo的4d和Se的...     

热处理温度对溶胶-凝胶法制备的Ce_(0.97)Co_(0.03)O_2薄膜结构和光学性能的影响

采用溶胶-凝胶法,在Si(100)衬底上制备了3%Co掺杂CeO2薄膜,研究了不同热处理温度对Ce0.97Co0.03O2薄膜结构和光学性质的影响。X射线衍射(XRD)表明,3%Co掺杂CeO2薄膜为多晶薄膜,且未破坏CeO2原有的结构,随着退火温度的升高,晶粒尺寸逐渐增大。椭偏光谱法研究表明,Ce0.97Co0.03O2薄膜的光学常数(折射率n、消光系数k)随着退火温度增加而增大,光学带隙Eg随退火温度增加而减小,这是薄膜结构随退火温度增加发生变化所致。     

Comparison between P25 and anatase-based TiO<Subscript>2</Subscript> quasi-solid state dye sensitized solar cells

Pure anatase TiO2 films have been made via hydration of titanium isopropoxide using a sol-gel tech-nique, while mixed TiO2 films which contained both anatase and rutile TiO2 were made from commercial P25 powder. Quasi-solid state dye-sensitized solar cells were fabricated with these two kinds of mesoporous films and a comparison study was carried out. The result showed that the open-circuit photovoltages （Voc） for both kinds of cells were essentially the same, whereas the short-circuit photo-currents （1sc） of the anatase-based cells were about 33% higher than that of the P25-based cells. The highest photocurrent intensity of the anatase-based cell was 6.12 mA/cm^2 and that of the P25-based cell was 4.60 mA/cm^2. Under an illumination with the light intensity of 30 mW/cm^2, the corresponding energy conversion efficiency was measured to be 7.07% and 6.89% for anatase-based cells and P25-based cells, respectively.     

Cu2ZnSn(S,Se)4纳米晶薄膜

Cu₂ZnSn(S,Se)₄(CZTSSe)材料因其光吸收系数高,具有理想的带隙,且所含元素丰度高、无毒等特性,非常适合作为太阳能电池的吸收层材料,有望成为低成本和高性能光伏发电的材料之一,引起广泛的关注.介绍了CZTSSe材料的基本物理性质及其纳米晶的生长机制,重点介绍了热注入方法合成CZTSSe纳米晶的过程,概述了目前CZTSSe纳米晶薄膜太阳能电池的现状,最后探讨了CZTSSe薄膜太阳电池中存在的问题及以后的发展方向.     

Bi_(1.6)La_(0.4)Ti_2O_7薄膜的制备及性能研究

采用化学溶液沉积法在ITO基片上制备不同退火温度的掺镧钛酸铋Bi1.6La0.4Ti2O7(BLT)薄膜。研究了其结构、介电性能、漏电流密度与外加电压I-V关系曲线和光学带隙。XRD射线衍射测试结果表明,经500、550、600℃1 h退火后的薄膜的主晶相为烧绿石结构,无杂相生成,600℃时BLT薄膜衍射峰比其他两种温度的强。在1 kHz频率下测得的介电常数、损耗因子分别为114,3%;129,3%;194,6%。BLT薄膜的漏电流密度与外加电压关系曲线表明,BLT薄膜600℃的漏电流比550和500℃稍微减小。通过透射谱分析得到BLT薄膜的光学带隙几乎不受温度影响,均为3.7 eV。这些结果表明制备BLT固溶体薄膜较佳为退火温度600℃,具有较好的性能,在光电器件有良好的应用前景。     

Photoluminescence from Ge-SiO2 thin films and its mechanism

Ge-SiO₂ thin films were deposited on p-type Si substrates using the radio frequency (rf) magnetron sputtering technique with a Ge-SiO₂ composite target. Films were annealed in N₂ ambience for 30 min at 300℃—1000℃ with an interval of 100℃. Through the X-ray diffraction, the average size of Ge nanocrystals (nc-Ge) was determined. They increased from 3.9 to 6.1 nm with increasing annealing temperature in the range of 600℃—1000℃. Under ultraviolet excitation, all samples emit a strong violet band centered at 396 nm. With the formation of nc-Ge, the samples exhibit another emission of orange band with the peak at 580 nm and its intensity increases with the increasing size of nc-Ge. The peak positions of two bands do not shift obviously. Experimental data indicate that the violet band comes from GeO defect and the orange band originates mainly from the luminescence centers at the interface between the nc-Ge and SiO₂ matrix.     

Theoretical study on photophysical property of C60M（CO）5 （M=Cr,Mo and W）

Configurations of three η2 models of transition-metal [60]fullerene derivatives C60M（CO）5（M=Cr, Mo and W） have been optimized at B3LYP/LanL2DZ level. On the basis of the optimized geometrical structures, their electronic spectra and the frequency dependence of third-order nonlinear optical polarizabilities γ in different optical processes of third-harmonic generation （THG）, electric-field-induced second-harmonic generation （EFISHG） and degenerate four-wave mixing （DFWM） are calculated by using TDB3LYP model based on LanL2DZ level coupled with the SOS （sum-over-state） method. The obtained results show that their electronic spectra have a red shift compared with that of [60]fullerene and different transition-metal functional groups added to C60 cage may result in different spectrum properties. For the three studied species, （η^2-C60）Mo（CO）5 has the largest third-order nonlinear optical polarizability.     

Preparation and optical properties of composite thin films with embedded InP nanoparticles

InP nanoparticles embedded in SiO₂ thin films were prepared by radio-frequency magnetron co-sputtering. We analyzed the structure and growth behavior of the composite films under different preparation conditions. X-ray diffraction and Raman spectroscopy analyses indicate that InP nanoparticles have a polycrystalline structure. The average size of InP nanoparticles is in the range of 3–10 nm. The broadening and red shift of the Raman peaks were observed, which can be interpreted by the phonon confinement model. Optical transmission spectra indicate that the optical absorption edges of the films can be modulated in the visible light range. The marked blue shift of the absorption edge with respect to that of bulk InP is explained by the quantum confinement effect. The theoretical values of the blue shift predicted by the effective mass approximation model are different from the experimental results for the InP-SiO₂ system. Analyses indicate that the exciton effective mass of the InP nanoparticles is not constant and is inverse relative to the particles radius, which may be the main reason that results in the discrepancy between the theoretical and the experimental result. We discussed the possible transition of the direct band gap to the indirect band gap for InP nanoparticles embedded in SiO₂ thin films.     

Effect of Mg content on the structural and optical properties of Mg<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>O alloys

Mgx Zn1–x O thin films with x = 0, 0.11, 0.28, 0.44, 0.51, and 0.65 were grown by plasma-assisted molecular beam epitaxy on (0001) sapphire substrates. X-ray diffraction measurement reveals that phase separation of the Mgx Zn1–x O films occurred at x =0.44 and 0.51. Optical absorption spectra show that the absorption edges of the films shift to high-energy side with increasing Mg contents. In resonant Raman spectra, multiple-order Raman peaks originating from ZnO-like longitudinal optical phonons were obser...     

BaAl2S4:Eu溅射靶材合成方法研究

采用放电等离子烧结(SPS)方法和粉末烧结法制备BaAl2S4:Eu溅射靶材,分析了靶材成分和结构特性以及利用靶材制备薄膜的发光特性.实验结果表明,SPS烧结的BaAl2S4:Eu溅射靶材的纯度高,无其它硫化物形成,被氧化的可能性小,靶材致密,气孔少;形成薄膜的PL谱主要是470nm处的蓝光发射.粉末烧结法制备的Ba-Al2S4:Eu溅射靶材的纯度低,靶材被氧化的几率大,气孔多,不致密,呈三维网状结构;在470nm处的蓝光发射峰值相对较弱.放电等离子烧结方法更适合制备BaAl2S4:Eu溅射靶材.     

Zn掺杂锐钛矿TiO2的电子结构及光学性质的研究

采用基于密度泛函理论(DFT)的第一性原理对Zn掺杂锐钛矿TiO_2进行了结构优化,并对掺杂前后的能带结构、电子态密度和吸收光谱进行了计算。研究表明:Zn掺杂锐钛矿TiO_2体系为间接带隙半导体,在价带顶部引入了杂质能级,杂质能级主要由O-2p轨道和Zn-3d轨道贡献,杂质能级的引入增强了TiO_2对可见光区的响应,增大TiO_2的光吸收范围。实验结果表明:Zn掺杂使锐钛矿TiO_2吸收边红移,并能增强TiO_2的光电效应,可用于材料的光阴极保护。     

Sb-Se系和Ge-Sb-Te系相变光盘记录介质微观结构及光学性能研究

利用X射线衍射仪 ,分光光度计对Sb Se系和Ge Sb Te系相变光盘记录介质材料非晶态薄膜相变前后结构的变化 ,光学性能进行了系统的研究 ,X射线衍射分析表明 :SbSe非晶态薄膜退火后有Sb的析晶峰 ,SbSe2 有Se的析晶峰 ,符合化学计量比的Sb2 Se3 全部是Sb2 Se3 的共晶峰 .GeSb2 Te4 非晶态薄膜在热退火过仇逐首先形成fcc亚稳相 ,升高退火温度 ,Fcc相转变为稳定的hex相 ,GeSb4 Te4 非晶态薄膜退火后在发生上述变化的同时 ,还有Sb的析晶峰 .分光光度计测试表明 :Sb Se系非晶态的光稳定性很不理想 ,随着波长的改变 ,反射率变化太快 .对于Ge Sb Te系合金 ,在各种波段处 ,两种合金都有较大的反衬度 ,其非晶态的光稳定性也较理想 ,随着波长的改变 ,反射率变化不大     

TiO2/SiO2/GQDs双层增透膜的制备及其在太阳能板中的应用

采用溶胶-凝胶法制备了SiO₂ 和TiO₂ 纳米溶胶,采用水热法制备了石墨烯量子点（graphene quantum dots,GQDs）。为进一步提高光伏太阳能板的透光率,设计了一种TiO₂/SiO₂/GQDs双层增透膜结构。探究了薄膜的结构、自清洁性能和增透性能,并进一步讨论了GQDs在增透性中的作用。结果表明,SiO₂-TiO₂/TiO₂-GQDs结构的双层薄膜厚度为120 nm时,太阳能板上的光透过率由未涂敷的85%增加至95%。接触角实验和室外耐环境性能实验测试表明,复合膜层接触角为10°,并具有良好的亲水性和耐环境性能。此外,户外实验结果表明,涂覆该薄膜的太阳能电板发电效率提高6%。由此说明双层增透膜可有效地提高太阳能电池板的光能利用率和使用寿命,可高效地利用太阳能。     

Investigation on composite Au /TiO2 nanoparticles (I)

Nanometer sized Au/TiO₂, particles were synthesized by irradiation of a HAuCl₄ solution containing colloidal TiO₂ with light of wavelength (λ) > 330 nm. The absorption maximum attributed to the surface plasmon band of gold was observed at 540 nm, a red shift of about 20 nm from the position in aqueous solution. The Au clusters are situated on the surface of TiO₂ in terms of microcrystallite, which was confirmed by HRTEM, EDS and XRD. The electronic interfaction between the metal and the suport was discussed.     

Preparation and magnetic properties of CoFe2O4/TiO2 composite films

Using （Ti（OC4H9）4） and metal chlorates as starting materials, CoFe2O4/TiO2 composite films were prepared by sol-gel method. The effects of heat treatment temperature and pH of the precursor on microstructure and magnetic properties were studied. The phase structure of the samples was examined by X-ray diffraction. The microstructure was examined by scanning electron microscope, atomic force microscope and polarized microscope. The magnetic property was measured by vibrating sample magnetometer. The results show that the crystals of different phases grow up independently. CoFe2O4 is uniformly embedded into the TiO2 matrix in the prepared composite films, and the growth of composite films is dependent on the heat treatment temperatures and PH of the precursor. The average size of CoFe2O4 crystal is 19 nm in Nanocomposite film prepared when the heat treatment temperature is 800℃ and the pH of the precursor is between 2 and 3. The magnetism of the composite films is enhanced as the heat treatment temperature increases.     

CeO2 thin films grown on biaxially textured nickel (001)

CeO\-2 films have been grown on biaxially textured Ni substrates at various temperatures. The results show that CeO\-2 films without IBAD are dominated by (111) orientation from room temperature to 800℃ while the preferential orientation of CeO\-2 films with IBAD is (001) at lower deposition temperature and (111) at deposition temperature higher than 450℃. CeO\-2 films with better in_plane texture and out_of_plane orientation can be grown at 360℃ with 240 eV ion energy and 200 μA/cm\+2 ion current density.     

Measurement of the absorption spectrum of H2O+ in the visible region

Together with the 74 lines belonging to (0,9,0)- (0,0,0) band, the high-resolution absorption spectrum of H₂O⁺ A²A₁-X²B₁ system was observed in the visible region of 16680 — 17300 cm^-1 using optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy for the first time, which verifies the high sensitivity and high signal to noise ratio (S/N) of this technique.     

Development of high-temperature superconducting filters operating at temperatures above 90 K

This paper represents the development of a high temperature superconducting （HTS） filter, the highest operating temperature of which is up to 93 K. The filter is designed for S band with 4% fractional bandwidth and fabricated using thallium-barium-calcium-copper oxide （TI2Ba2CaCu2O8） thin films. At 93 K, the measurements of the filter show that the insertion loss in the passband is less than 0.22 dB, the return loss is better than 20 dB, and the out-of-band rejection is more than 80 dB. The analysis on the characteristics of the filter operating at different temperatures shows that the filter can work well at temperatures around 90 K. The temperature of 93 K is the highest among the previous reports for HTS filters. The result reported in this paper is significant for HTS filters to be used in the field of microwave communication requiring high sensitivity.