飞秒激光形成的半导体低维结构与发光

采用飞秒激光辐照硅和硅锗样品,用扫描电子显微镜(SEM)观察样品同,发现样品上产生了某低维结构.用飞秒激光作用产生等离子体相干驻波对硅和硅锗表面的融蚀模型来解释低维结构的形成机制,发现硅的表面周期约为400 nm的光栅结构在波长719 nm处有较强的光致荧光(PL)峰.该光致荧光的发光强度较小,其机制可从激光的脉宽和重复率两个方面来分析.当激光辐照的能量明显超过硅的融蚀阈值时,光栅形状消失,另一种锥状结构开始形成.控制加工条件,可以获得用于衍射和微分束的纳米光栅.     

聚合物前驱体制备氮化硅纳米纤维及其发光

由聚硼硅氮烷前驱体在高温常压下热裂解得到氮化硅纳米纤维,确定了样品结构为α相,讨论了纳米纤维的生长模式属于气-液-固生长机制。在室温下用488nm激光对样品激发,观察到样品有很宽的强光致发光带,并有两个发光中心,这种强的可见光致发光主要来自氮化硅的内禀Si和N的悬键。测量了纳米纤维的室温吸收光谱,得到氮化硅纳米纤维的光学带隙为4．80eV。     

非桥氧空穴发光中心对铁钝化多孔硅光致发光的影响

采用水热腐蚀法制备了铁钝化多孔硅样品,样品光致发光谱的荧光峰位于2.0eV附近,半峰宽约为0.40eV。激发波长从240nm增大到440nm的过程中,荧光峰先红移再蓝移,最后基本稳定,变化曲线呈勺型。通过分析15片发光多孔硅样品的统计结果,发现荧光峰逆转所对应的激发波长位于330nm附近,相应的激发光子能量约为3.8eV。样品光致发光谱随激发波长的勺型变化过程与≡Si—O↑和≡Si—O↑…H—O—Si≡两类非桥氧空穴发光中心共同作用时的发光行为一致。     

120keV的N+注入SiC薄膜的光谱特性研究

文中主要研究了120keV的N⁺注入后SiC薄膜样品的光致发光谱(PL)和傅立叶红外光谱(FTIR)特性.从红外光谱可以看到有明显得碳氮单键、双键、三键等新结构生成.从PL光谱则发现365nm处的发光峰明显增强,这表明N⁺注入使得带隙中深的能级辐射中心复合的效率大幅度提高     

激光辐照和高温氧化硅锗合金的低维结构和发光特性

采用强激光辐照硅锗合金,然后高温氧化的方法,在样品表面生成微米级小孔,用高精度扫描电镜观察孔内结构,发现片状纳米结构的存在。用荧光光谱仪测量其光致荧光谱,对于激光辐照(无高温氧化)的样品,在峰值705 nm处出现较强的光致发光(PL)。高温氧化后,样品在606 nm处出现一尖锐的PL光谱。利用量子受限和纳晶与氧化物的界面态综合模型解释PL光谱的产生。     

双端泵浦的高功率掺Yb3+双包层光纤激光器

 分析了Yb³⁺的能级结构、光谱特性以及激光发射特性。实验研究了中心波长为1 100 nm、输出功率为61.6W、斜率效率为55%的高功率掺Yb³⁺双包层光纤激光器。采用了两个中心波长在915 nm的高功率激光二极管分别从光纤的两端将泵浦光耦合进入光纤，采用45°对波长在（1 100±10） nm的激光高反，对波长在（915±10） nm的泵浦光高透的双色镜将激光输出，实验发现了掺Yb³⁺双包层光纤的合作发光效应。理论分析表明，掺Yb³⁺双包层光纤中合作发光效应是由Yb³⁺对在激光产生过程中的吸收与发射引起的。     

退火氧化生成的硅锗低维结构的光致发光性质

用激光辐照辅助电化学刻蚀的方法加工硅锗薄膜样品,30min后,在样品表面形成了多孔状的结构,该结构在724nm处有很强的光致发光(PL)峰。将该多孔状结构的样品置于高温氧化炉中进行不同时间的退火氧化处理后,发现在不同的退火氧化条件下样品的PL光谱发生了明显的变化。通过分析,作者根据量子受限(QC)和量子限制-发光中心(QCLC)模型,建立了新的量子受限-晶体与氧化物界面态综合模型来解释样品PL发光的变化。     

多孔硅的微结构与发光特性研究

利用原子力显微镜（AFM）和光致荧光（PL）光谱对一系列直流腐蚀和脉冲腐蚀的多孔硅的微结构及发光特性进行了对比研究．表面和侧面的AFM结果表明，多孔硅表面呈“小山”状，有许多小的、突出的硅颗粒．在相同的腐蚀条件（等效）下，脉冲腐蚀的样品表面Si颗粒更加尖锐、突出，侧面的线状结构更明显，多孔硅层更厚．对应的PL谱，脉冲腐蚀的样品发光更强．量子限制效应的理论可以比较成功地解释这个结果 关键词：     

直接Z型CdO-CdS纳米棒阵列的制备及其光电催化性能研究

本文通过简单的水热法制备了一种CdO-CdS一维纳米棒阵列,并系统地研究了材料的结构、形貌及其光电化学性质和产氢活性. 所得纳米棒为直径100至200 nm的六方柱. 通过优化煅烧温度和时间得到了该实验条件下光电催化性能最优的样品. 在0 V vs. Ag/AgCl偏压下,CdO-CdS光电流密度为6.5 mA/cm²,光电催化产氢活性为240 μmol·cm^-2·h^-1,几乎是纯CdS的2倍. 该体系的光电催化性能超过了许多已报道的相似体系. 根据材料结构和光电化学性能表征结果,提出了直接z型光催化机理,该机理可以很好地解释光致载流子的高分离效率和优异的氧化还原性能.     

掺Bi离子锗铌酸盐红外发光玻璃的研究

用高温熔融法制备了Bi₂O₃掺杂的(0.9-x) GeO₂-xNb₂O₅-0.1BaO (含量x为摩尔分数, x=0, 0.04, 0.07, 0.1)系列玻璃. 测定了玻璃样品的差热分析(DTA)曲线、吸收光谱、发射光谱及X射线光电子能谱(XPS). 从DTA曲线分析得到玻璃的结晶起始温度与软化温度之差(T_x-T_g)达200℃以上. 吸收光谱中可观察到位于500, 700, 808和1000 nm处的吸收峰, 并随着Nb₂O₅含量x的增加吸收边带发生红移. 在波长为808 nm激光激发下, 观察到发光中心位于1300 nm处、荧光光谱半高宽约为200 nm的宽带发光. 荧光强度随Bi₂O₃掺杂量δ的增加先增强后减弱, 当掺杂量δ达到约0.01时, 荧光强度达到最强. 随着Nb₂O₅含量x从0.04增加到0.1时, 荧光强度逐步减弱. 样品的XPS峰分别位于159.6和164.7 eV, 它们介于Bi³⁺与Bi⁵⁺的特征结合能之间, 因此Bi³⁺与Bi⁵⁺可能同时存在于玻璃基质中. 从XPS及Bi离子的发光特性推断, 宽带的荧光发射可能起因于Bi⁵⁺. 随着Nb₂O₅含量x的增加, 荧光强度逐步减弱. 分析认为, Nb₂O₅取代GeO₂后形成了NbGe缺陷, 需要低价Bi离子进行电子补偿, 因而抑制了Bi⁵⁺形成, 致使荧光强度减弱.     

Low-dimensional structures formed by irradiation of laser

Some kinds of low-dimensional nanostructures can be formed by irradiation of laser on the pure silicon sample and the SiGe alloy sample. This paper has studied the photoluminescence (PL) of the hole-net structure of silicon and the porous structure of SiGe where the PL intensity at 706nm and 725nm wavelength increases obviously. The effect of intensity-enhancing in the PL peaks cannot be explained within the quantum confinement alone. A mechanism for increasing PL emission in the above structures is proposed, in which the trap states of the interface between SiO₂ and nanocrystal play an important role.     

Optical properties of low-dimensional structures formed by irradiation of laser

Some kinds of low-dimensional nanostructures can be formed by the irradiation of laser on a pure silicon sample and SiGe alloy sample. We have studied the photoluminescence (PL) of the hole-net structure of silicon and the porous structure of SiGe where the PL intensity at 706 nm and 725 nm wavelength increases obviously. The effect of intensity-enhancing in the PL peaks cannot be explained within the quantum confinement alone. We propose a mechanism on the increasing PL emission in the above structures, in which the trap state of the interface between SiO₂ and nanocrystal plays an important role.      

硅表面硅镱键合与量子级联结构的发光

用纳秒强激光脉冲制备了纳米硅和硅表面的硅镱键合结构,检测了纳米硅表面硅镱键合的发光特性,并对这种结构相应的光致发光(PL)和电致发光(EL)的动力学机理进行了研究。观察到纳米硅表面硅镱键合在700nm附近尖锐的强发光峰,结合第一性原理计算认为是硅镱键合在弯曲纳米硅表面的局域态发光;利用纳秒脉冲激光沉积技术(PLD)制备多晶硅薄膜,发现由硅镱界面的失配形成表面的突触,其上的硅镱键合产生带隙中的电子局域态,该局域态发光分布在1250~1650nm波长范围,有增强的EL发光;用PLD方法制备硅镱多层膜量子级联结构,测量到光通信窗口的多个发光峰,并观察到随膜层数增加且发光峰增多。     

Localized electronic states in gaps on hole-net structures of silicon

Hole-net structure silicon is fabricated by laser irradiation and annealing, on which a photoluminescence (PL) band in a the region of 650--750~nm is pinned and its intensity increases obviously after oxidation. It is found that the PL intensity changes with both laser irradiation time and annealing time. Calculations show that some localized states appear in the band gap of the smaller nanocrystal when Si=O bonds or Si--O--Si bonds are passivated on the surface. It is discovered that the density and the number of Si=O bonds or Si--O--Si bonds related to both the irradiation time and the annealing time obviously affect the generation of the localized gap states of hole-net silicon, by which the production of stimulated emission through controlling oxidation time can be explained.     

Laser on porous silicon after oxidation by irradiation and annealing

Stimulated emission has been observed from oxide structure of silicon when optically excited by 514 nm laser. The photoluminescence (PL) pulse has a Lorentzian shape with a full width at half maximum (FWHM) of 0.5-0.6 nm. The twin peaks at 694 nm and 692 nm are dominated by stimulated emission which can be demonstrated by its threshold behavior and transition from sub-threshold to linear evolution in light emission. The gain coefficient from the evolution of the peak-emission intensity as a function of the optically pumped sample length has been measured. The oxide structure was fabricated by laser irradiation and annealing treatment on silicon. A model for explaining the stimulated emission has been proposed in which the trap states of the interface between oxide of silicon and porous nanocrystal play an important role.     

Stimulated photoluminescence emission and trap states in Si/SiO2 interface formed by irradiation of laser

Stimulated photoluminescence （PL） emission has been observed from an oxide structure of silicon when optically excited by a radiation of 514nm laser. Sharp twin peaks at 694 and 692nm are dominated by stimulated emission, which can be demonstrated by its threshold behaviour and linear transition of emission intensity as a function of pump power. The oxide structure is formed by laser irradiation on silicon and its annealing treatment. A model for explaining the stimulated emission is proposed, in which the trap states of the interface between an oxide of silicon and porous nanocrystal play an important role.     

多孔硅量子点的受激辐射：陷阱态的作用

 经激光辐照和高温退火后能够在硅基上生成氧化多孔硅结构。用514 nm的激光泵浦,观测到该多孔硅的受激辐射。当激励强度超过阈值时,在650～750 nm区域有很强的受激发光峰。这些受激发光峰的半高宽小于0.5 nm。激光辐照和高温退火后,在样品上能形成某些特殊的氧化结构。在傅里叶红外光谱分析中,显示有硅氧双键或硅氧桥键在硅表面形成。计算结果表明：当硅氧双键或硅氧桥键形成时,电子的陷阱态出现在纳晶硅的带隙中。价带顶和陷阱态之间的粒子数反转是解释这种受激辐射的关键。     

多孔硅锗的制备及其近红外发光增强

用激光照射辅助电化学刻蚀硅锗合金样品能够形成多种低维纳米结构。在硅锗合金上形成的多孔状结构在波长为725 nm处有很强的光致发光(PL)峰,PL的增强效应不能单独用量子受限模型来解释。我们提出新的模型来解释这种低维纳米结构的PL增强效应。     

Optical properties of silicon microcolumn grown by nanosecond pulsed laser irradiation

We have investigated the optical properties of silicon pillars formed by cumulative nanosecond pulsed excimer laser irradiation of single-crystal silicon in vacuum created under different repetition rates. The changes in optical characteristics of silicon pillar were systematically determined and compared as the number of KrF laser shots was increased from 1 to 15,000.The results show that silicon pillar PL curves exhibit a blue band around 430 nm and an ultraviolet band peaking at 370 nm with the vanishing of the green emission at 530 nm. A correlation between the intensity of the blue PL band and the intensity of the Si-O absorption bands has been exploited to explain such emission, whereas, the origin of the ultraviolet band may be attributed to different types of defects in silicon oxide.     

高质量ZnO微米棒的制备及其光学性质

利用水热法制备ZnO微米棒。醋酸镁[Mg(CH3COO)2.4H2O]、醋酸锌[Zn(CH3COO)2.2H2O]和六次甲基四胺(C6H12N4)以一定比例配置成反应溶液,把反应溶液加热到90℃,反应时间为24h,能够在硅衬底上生长高质量的ZnO微米棒。用扫描电镜(SEM)和X射线衍射仪对ZnO微米棒的晶体结构和表面形貌进行了分析,结果表明,样品为细长条棒状结构,呈现六方纤锌矿结构,长径比可达10∶1,并且在[002]方向择优生长。在样品中并未发现镁离子,它有可能扮演着催化剂的角色。对ZnO微米棒的光致发光性能进行测量,由PL光谱分析可知,样品在384nm处有一个紫外发光峰,半峰全宽为13nm,紫外发光峰强度比可见发光峰强度大的多,样品的质量较好。