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TiO2 chiral sculptured thin films (CSTFs) prepared using glancing angle deposition (GLAD) method based on electron beam evaporation are studied. The relationship between structural parameters and circular Bragg phenomenon (CBP) is investigated. Results demonstrate that, the central wavelength of Bragg regime red-shifts with the increasing pitch of helix, and peak value of selective transmittance will increase after adding more turns to the helix. After annealing, the central wavelength blue-shifts and the peak value rises. Tuning CBP by modulating the deposition parameters and annealing can optimize the performance of circularly polarized devices fabricated from CSTFs. 相似文献
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Fabrication of Ag or Au nanocolumns by oblique angle deposition (OAD) is now prevalent for their surface enhanced Raman scattering (SERS) property and their biosensor application. However, the size, shape, and the density of nanocolumns are not directed in a desired way. To sufficiently realize the growth process controlled by multiple physical factors like deposition angle (a), substrate temperature (T), and deposition rate (F), we develop a three-dimensional (3D) kinetic Monte Carlo (KMC) model for simulating processes of Ag nanocolumnar growth by oblique angle deposition. The dependences of nanocolumnar morphologies on these factors are analyzed. The mimical results reach a reasonable agreement with the experimental morphologies generated bv OAD. 相似文献
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Fabrication of nc-Si/SiO2 structure by thermal oxidation method and its luminescence characteristics
Nano-crystalline silicon/silicon oxide (nc-Si/SiO2) structures have been prepared from amorphous silicon films on both silicon and quartz substrates by using electron-beam evaporation approach and annealing at temperatures about 600 ℃ in air. As a thermal oxidation procedure, the annealing treatment is not only a crystallization process but also an oxidation process. Scanning electron microscopy is employed to characterize the surface morphology of the nc-Si/SiO2 layers. Transmission electron microscopy study shows the sizes of nc-Si grains on the two different substrates. The nc-Si/SiO2 structures exhibit visible luminescence at room temperature as confirmed by photoluminescence spectroscopy. Comparing the photoluminescence spectra of different samples, our results agree with the quantum confinement-luminescence center model. 相似文献
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利用半经典理论,对脉冲光学抽运重水气体产生THz激光信号过程进行分析,对其中抽运光强度与输出THz信号光之间的关系进行了数值计算和求解,结果表明,THz信号出射光强度跟抽运源入射光强度之间不满足简单的线性关系,而是呈现高阶的非线性关系.在工作介质腔长、气压和工作温度一定的条件下,存在最佳抽运光强度,在一定的抽运光强范围内,THz信号出射光强度与抽运源入射光强度的关系呈现近似线性的增长关系,抽运光能量和信号光能量之间的转换效率相对较高,当抽运光强超过一定值时,由于瓶颈效应的发生会导致THz输出信号的逐步减弱,并产生一定的频率调谐范围. 相似文献
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采用超短皮秒脉冲激光激发制备了SnO2:F 玻璃衬底和石英衬底的CdTe多晶薄膜,在室温下测量其稳态和瞬态荧光光谱。结果表明,随着激发功率的增大,其荧光光谱峰逐渐展宽,并发生蓝移。对于退火处理的样品,其荧光光谱伴随主峰旁出现一个肩峰,是Cl 原子与富Cd区存在的空位形成复合体引起的发射。其瞬态荧光光谱寿命呈双指数衰减,即表面效应所引起的慢过程和带边激子态发射的快过程组成。样品退火处理后荧光寿命变长,有利于电子-空穴对在复合发光前分离,提高电子空穴的迁移率,改善其光伏性能。 相似文献