Experimental investigation of the sub-Doppler transmission spectroscopy in a thin vapour layer at room temperature

The sub-Doppler transmission spectrum in a thin vapour layer (about 150 μm) was observed at room temperature using the wavelength modulation technology. The absorption signal and its second-order harmonic were detected with an external-cavity diode laser. A sub-Doppler spectrum corresponding to resonant transitions of the caesium D_2 line (6S_{1/2}→6P_{3/2}) was demonstrated. The dependence of the transmission signal on the intensity of the laser was also investigated.     

Sub-Doppler spectroscopy by sub-micron thin Cs vapour layer

A unique extremely thin cell (ETC) with the thickness of Cs atomic vapour layer in the range of 150–300 nm has been developed for the first time. All six hyperfine transitions of D₂ line (852 nm) of Cs, i.e. 6S_1/2(F=3)→6P_3/2(F=2–4) and 6S_1/2(F=4)→6P_3/2(F=3–5) are very well resolved in the transmission and fluorescence spectra, whereas in a cell of usual length they are not resolved due to Doppler broadening. It is demonstrated that a robust and widely used simple laser-diode technique is enough to observe separately atomic hyperfine transitions at the intensity up to 100 mW/cm² thanks to the ETC usage. We report also the first results obtained with the new ETC of 300 nm thickness filled with natural Rb. The usage of ETC allowed us to completely resolve each particular hyperfine transition of both ⁸⁵Rb and ⁸⁷Rb isotopes in D₁ line fluorescence spectrum.     

级联三能级原子薄蒸汽膜的色散特性

从理论上讨论了囚禁于两电介质间的级联三能级系统薄原子蒸汽膜的色散特性.由于腔中慢速原子及泵浦-探测机制的速度选择贡献,色散谱线表现为Dicke窄化的亚多普勒结构及明显的慢光效应,当泵浦光和探测光异侧入射时这种现象更为突出.两个叠加的色散线型,一个对应光学泵浦,另一个对应可能出现的电磁诱致透明.     

Physical properties of ZnSe thin films: Air and vacuum annealing evolution to buffer layer applications

In order to develop high efficiency solar cell device by replacing conventional hazardous CdS window layer by environmental friendly Zn-based buffer layer, ZnSe thin films of thickness 100 nm were grown on glass and ITO substrates employing electron beam evaporation technique followed by air and vacuum annealing at temperature 100 °C, 200 °C and 300 °C. As-grown and annealed films were subjected to characterization tools like XRD, UV-Vis spectrophotometer, SEM, EDS and source meter. Structural results reveal the amorphous phase, SEM images indicate uniform deposition without pin holes and EDS patterns confirm the deposition. Transmittance is observed to be high in visible region and band gap is found to change with temperature of the treatment and I-V measurements demonstrate ohmic nature. On the basis of optimized results, the films annealed at 200 °C in vacuum may be used as buffer layer to develop high efficiency Cd-based and CIGS thin film solar cells.     

Determination of the parameters of a linear-viscoelastic thin layer using the normally-incident ultrasonic waves

This paper proposes a method of simultaneous determination of the four layer parameters (mass density,longitudinal velocity,the thickness and attenuation) of an immersed linear-viscoelastic thin layer by using the normally-incident reflected and transmitted ultrasonic waves.The analytical formula of the layer thickness related to the measured transmitted transfer functions is derived.The two determination steps of the four layer parameters are developed,in which acoustic impedance,time-of-flight and attenuation are first determined by the reflected transfer functions.Using the derived formula,it successively calculates and determines the layer thickness,longitudinal velocity and mass density by the measured transmitted transfer functions.According to the two determination steps,a more feasible and simplified measurement setups is described.It is found that only three signals (the reference waves,the reflected and transmitted waves) need to be recorded in the whole measurement for the determination of the four layer parameters.A study of the stability of the determination method against the experimental noises and the error analysis of the four layer parameters are made.This study lays the theoretical foundation of the practical measurement of a linear-viscoelastic thin layer.     

ZnO：Sb薄膜的光致发光及拉曼特性研究

利用射频磁控溅射法（MS．RF）在玻璃基片上制备了不同掺杂浓度的ZnO：Sb薄膜．借助X射线衍射仪（XRD）、透射光谱、光致发光谱（PL）和拉曼散射光谱（Raman）等手段研究了Sb掺杂浓度对ZnO薄膜的微结构、光致发光和拉曼特性的影响．结果表明：所有样品均呈现ZnO六角纤锌矿结构且具有高度C轴择优取向;在Sb掺杂ZnO薄膜的拉曼光谱中观察到位于532cm^-1的振动模式,结合XRD分析认为此峰归因于Sb替代Zn位且与0成键的局域振动模式（LVMSb--O）;光致发光谱测试发现,仅在ZnO：Sb薄膜中观察到位于3．11eV附近的紫光发射峰,结合拉曼光谱分析认为此峰与XbZn-O复合体缺陷相关．     

Tandem organic light-emitting diode with a molybdenum tri-oxide thin film interconnector layer

A 10-nm-thick molybdenum tri-oxide(MoO3) thin film was used as the interconnector layer in tandem organic lightemitting devices(OLEDs).The tandem OLEDs with two identical emissive units consisting of N,N-bis(naphthalen-1-yl)N,N-bis(phenyl)-benzidine(NPB) /tris(8-hydroxyquinoline) aluminum(Alq3) exhibited current efficiency-current density characteristics superior to the conventional single-unit devices.At 20 mA/cm2,the current efficiency of the tandem OLEDs using the interconnector layers of MoO3 thin film was about 4.0 cd/A,which is about twice that of the corresponding conventional single-unit device(1.8cd/A).The tandem OLED showed a higher power efficiency than the conventional single-unit device for luminance over 1200cd/m2.The experimental results demonstrated that a MoO3 thin film with a proper thickness can be used as an effective interconnector layer in tandem OLEDs.Such an interconnector layer can be easily fabricated by simple thermal evaporation,greatly simplifying the device processing and fabrication processes required by previously reported interconnector layers.A possible explanation was proposed for the carrier generation of the MoO3 interconnector layer.     

Optical bistability of a thin layer of a substance with quasiresonance polarizability components

Optical-bistability conditions for a thin (smaller than the wavelength of the acting laser radiation) surface layer of resonance atoms are calculated with allowance for the influence of the polarizing fields of transitions adjacent to the resonance one and allowed in the electrodipole approximation on the transmissivity of the medium of the layer. It is noted that the change in the threshold bistability characteristics is due to the influence of the self-modulation broadening of the line of the laser field occurring in the thin resonancepolarized layer on the effective level of its absorption. Institute of Applied Optics, National Academy of Sciences of Belarus, 11, Byalynitskii-Birulya Str., Mogilev, 212793, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 661–665, September–October, 1999.     

基于氧化镍背接触缓冲层碲化镉薄膜太阳电池的研究

采用电子束蒸发法制备了NiO薄膜,并对其作为碲化镉薄膜太阳电池背接触缓冲层材料进行了相关研究.NiO缓冲层的加入使得碲化镉太阳电池开路电压显著增大.通过X射线光电子能谱测试得到的NiO/CdTe界面能带图表明NiO和CdTe的能带匹配度很好.NiO是宽禁带P型半导体材料,在电池背接触处形成背场,减少了电子在背表面处的复合,从而提高电池开路电压.通过优化NiO薄膜厚度,制备得到转换效率为12.2%、开路电压为789 mV的碲化镉太阳电池.研究证实NiO是用来制备高转换效率、高稳定性碲化镉薄膜太阳电池的一种极有前景的缓冲层材料.     

基于薄层单元与弹簧单元的滚动直线导轨副动力学建模

针对某大型光机装置中使用的LM型直线导轨-滑块的结合面,采用薄层单元与弹簧单元模拟其接触面,建立了大行程传输结构模拟件的有限元模型。通过模型修正方法,根据模态试验结果对薄层单元弹性模量以及弹簧刚度进行了识别。模型修正后,结构前三阶模态频率计算结果与试验结果最大差别为2.23%,地脉动载荷下各测点位移响应计算结果与试验结果最大差别为7.61%。计算结果与试验结果具有较好的一致性,验证了模型的有效性。     

c轴垂直取向FePt薄膜的磁和磁光性能研究

采用直流磁控溅射的方法在氧化镁(100)单晶基板上生长了一系列c轴垂直取向的FePt薄膜，通过改变沉积时的基板温度，薄膜从Fe，Pt原子无序排列的面心立方结构逐渐变化到有序排列的L1₀相面心四方结构.在此基础上，系统研究了FePt薄膜的化学有序度对磁和磁光性能的影响.随着有序度的增加，FePt薄膜的磁晶各向异性能，以及沿垂直方向的矫顽力、剩磁比均增加，在基板温度高于530 ℃时制备的薄膜中的磁晶各向异性能超过1 J/cm³.同时，还观察到有序FePt合金薄膜的磁光克尔光谱(克尔转角的大小和极值所对应的跃迁光子能量)随化学有序度的显著变化. 关键词： FePt薄膜 化学有序度参数 磁光克尔光谱     

掺杂透明导电半导体薄膜的光电性能研究

掺杂氧化锌透明导电膜(AZO)是一种重要的光电子信息材料，其制备方法有真空蒸镀法、磁控溅射法，化学气相沉积和脉冲激光沉积法等。该文采用溶胶 凝胶（sol gel)工艺在普通玻璃基片上成功地制备出Al3+掺杂型ZnO透明导电薄膜。将这种薄膜在空气和真空中以不同的温度进行了退火处理，并对薄膜进行了XRD分析和光电性能研究。结果表明，所制备的薄膜为钎锌矿型结构，在c轴方向择优生长，真空退火有利于薄膜结晶状况的改善，并使薄膜的载流子浓度大幅度地增加而电阻率下降，并且真空退火对薄膜的透射率影响不大。     

Influence of Ge addition on the optical properties of As40Se50Ge10 thin film probed by spectroscopy techniques

The thin films of As₄₀Se₆₀ and As₄₀Se₅₀Ge₁₀ were prepared on glass substrates by thermal evaporation method with thickness 1000 nm. The prepared films were amorphous in nature which was confirmed through X-ray diffraction. The chemical composition and the surface picture were obtained from energy dispersive X-ray analysis and Scanning Electron Microscopy analysis. The transmission data of the two films were collected in the wavelength range 400–1000 nm. The transmission percentage is found to be decreased whereas the absorption coefficient is increased with the Ge addition. The addition of Ge into As₄₀Se₆₀ is found to increase the refractive index and the extinction coefficient of As₄₀Se₅₀Ge₁₀ thin film. The decrease in optical band gap is explained on the basis of increase in density of states and disorderness due to Ge addition. The optical absorption in the film is due to allowed indirect transition, and the homopolar bond density is increased with Ge addition. The Raman shift observed in the two films clearly supports the optical changes due to Ge addition.     

拉曼光谱法结合薄层层析分析红酵母色素

利用薄层层析色谱法分离红酵母色素,结果显示,红酵母细胞能合成至少三种色素,即β-胡萝卜素、红酵母红素、圆酵母红素;采集三种色素的拉曼光谱,光谱数据经过背景扣除、基线校正、三点平滑等方法预处理,统计不同色素的平均光谱,结果表明三种色素的CC拉曼位移不同,并且β-胡萝卜素的拉曼位移最多,红酵母红素和圆酵母红素的含量较多;定量分析色素特征峰高比值,各色素峰高比值差异不大,峰高比值能用作参数,为深入研究活体细胞内色素的相对含量提供参考。以上结果表明,拉曼光谱法结合薄层层析能够分析红酵母色素,可以提供红酵母色素的丰富信息,是研究色素的有效方法。     

Nonextensive treatment of nucleation and growth in a thin layer

In this study, a generalized method based upon nonextensive statistics is presented for nucleation and growth processes in a thin layer between two interfaces. It is shown that the presented mathematical model, which uses an index called the entropic index that measures the nonextensivity of the physical system, successfully deals with the nucleation and growth processes, and works better than Johnson–Mehl–Avrami–Kolmogorov model. The presented model also contains Austin–Rickett model as a special case.     

太阳电池用本征微晶硅材料的制备及其结构研究

采用VHF-PECVD技术制备了系列不同硅烷浓度和反应气压的微晶硅薄膜.运用拉曼散射光谱和 x射线衍射对制备的材料进行了结构分析.在实验研究的范围内，制备材料的晶化程度随硅烷 浓度的增加而降低.XRD的测试结果表明：制备的微晶硅材料均体现了(220)方向择优.应用在 电池的有源层中，制备出了效率达7.1%的单结微晶硅太阳电池，电池的结构是glass/ZnO/p( μc-Si:H)/i(μc-Si:H)/n(a-Si:H/Al)，没有ZnO背反射电极，有源层的厚度仅为1.2μm. 关键词： 本征微晶硅薄膜 拉曼光谱 x射线衍射     

Optical properties of ultra-thin InN layer embedded in InGaN matrix for light emitters

We theoretically investigate the optical properties of an ultra-thin InN layer embedded in InGaN matrix for light emitters. The peak emission wavelength extends from ultraviolet (374 nm) to green (536 nm) with InN quantum well thickness increasing from 1 monolayer to 2 monolayers, while the overlap of electron-hole wave function remains at a high level (larger than 90%). Increase of In content in InGaN matrix provides a better approach to longer wavelength emission, which only reduces the spontaneous emission rate slightly compared with the case of increasing In content of the conventional InGaN quantum well. Also, the transparency carrier density derived from gain spectrum is of the same order as that in the conventional blue laser diode. Our study provides skillful design on the development of novel structure InN-based light emitting diodes as well as laser diodes.     

原子层沉积HfO2薄膜的激光损伤特性分析

以目前激光惯性约束聚变中应用最广泛的高折射率材料二氧化铪(HfO2)为研究对象,在熔石英基底上分别采用TEMAH和HfCl4前驱体制备了HfO2薄膜,沉积温度分别为100,200和300 ℃。采用椭偏仪和激光量热计对薄膜的光学性能进行了测量分析,采用X射线衍射仪(XRD)对薄膜的微结构进行了测量。最后在小口径激光阈值测量平台上按照1-on-1测量模式对薄膜的损伤阈值进行了测试,并采用扫描电子显微镜（SEM）对损伤形貌进行了分析。研究表明,用同一种前驱体源时,随着沉积温度升高,薄膜折射率增加,吸收增多,损伤阈值降低。在相同温度下,采用有机源制备的薄膜更容易在薄膜内部形成有机残留,导致薄膜吸收增加,损伤阈值降低。采用HfCl4作为前驱体源在100℃制备氧化铪薄膜时,损伤阈值能够达到31.8 J/cm2 (1064 nm,3 ns)。     

Rubbing effect on surface morphology and thermoelectric properties of TTF-TCNQ thin films

Thin films of tetrathiofulvalene-tetracyanoquinodimethane (TTF-TCNQ), a typical organic material of charge transfer salts, were prepared on glass substrates by evaporation using TTF-TCNQ powder. The rubbing effect on the surface morphology and thermoelectric properties was studied. TTF-TCNQ films exhibited a bush-like disordered growth on the as-received glass substrate, whereas those on the rubbed glass substrate had extremely flat surfaces tiled with small rectangular TTF-TCNQ single crystals. Due to the ordered alignment of TTF-TCNQ tiles, improvement in the electrical conductivity and enhancement of the Seebeck coefficient were achieved.     

薄原子蒸汽膜的双光子光谱及Dicke窄化

薄原子蒸汽膜的单光子Dcike窄化吸收光谱可以拓展到双光子情形，以级联三能级系统为例,从理论上得到了亚多普勒结构的双光子吸收光谱，其线型表现出和单光子过程相似的与膜厚和探测光波长的比值(L/λ)相关的周期性.当L/λ=(2n+1)/2(膜厚为半波长的奇数倍)时，吸收谱线窄化现象明显.当L/λ=2n/2(膜厚为半波长的偶数倍)时，单光子情形的谱线窄化现象消失，而双光子情形的谱线仍表现为亚多普勒结构，尤其在异侧入射的情形下，可以获得极窄的双光子谱线结构. 这种结构来自原子与腔壁碰撞的消激发效应和双光子过程的抽运-探测机制的贡献. 关键词： 薄原子蒸汽膜 双光子光谱 Dicke窄化