固化温度对纳米微结构制备的影响

在100℃、150℃、200℃和270℃下固化得到四种聚酰亚胺薄膜,随着固化温度的提高,聚酰亚胺薄膜的残留溶剂量减少,表面粗糙度增大、玻璃化转变温度显著提高.采用波长355nm的紫外脉冲激光,在四种聚酰亚胺薄膜表面成功制备了纳米微条纹结构,观察到微结构的形成分为孵化期和自增长期.随着固化温度的提高,条纹形成的孵化期明显延长.在34 mJ/cm2激光强度下,100℃固化的聚酰亚胺薄膜表面200个脉冲后就能够观察到比较清晰的条纹结构;而150℃和200℃下固化得到的聚酰亚胺薄膜在此时只能观察得到孵化期的不规则结构,在300个脉冲以后才能形成较稳定的条纹结构;而270℃下固化得到的聚酰亚胺薄膜在700个脉冲以后才能观察到清晰条纹结构的形成.随着固化温度的提高,薄膜承受高能量激光的能力增强.当激光强度在22 mJ/cm2～98 mJ/cm2之间时,能够在100℃固化的聚酰亚胺薄膜得到微条纹结构,当激光强度大于98 mJ/cm2时,100℃固化的聚酰亚胺薄膜表面的结构完全被破坏,但仍能够在固化温度大于150℃的薄膜表面得到微条纹结构,并且随着激光能量的增大,条纹周期下降.(PH4)     

用于制作衍射变色图形的激光干涉打标系统

研制出一种用于在光滑表面制作衍射变色图形的双光束干涉打标系统。采用分束器将高功率脉冲激光分成两束,并聚焦成双光束干涉光场,直接对工件表面进行单脉冲刻蚀,形成周期性微光栅结构。改变干涉光场的取向和干涉光之间的夹角,实现下一次刻蚀,最终实现大面积打标不同取向和不同空频的微光栅构成的衍射变色图形。在不同角度入射光照射下,衍射变色图形产生不同亮度的衍射变色效果。激光波长527nm,单脉冲能量1.0mJ@20ns,打标材料有不锈钢、氧化铬薄膜等,给出了激光干涉打标的实验结果。     

激光能量对脉冲激光沉积法制备ZnO薄膜性能的影响

脉冲激光沉积技术(PLD)易于获得高质量的氧化物薄膜已成为一种重要的制备ZnO薄膜的技术.采用脉冲激光沉积(PLD)(KrF准分子激光器:波长248 nm,频率5 Hz,脉冲宽度20 ns)方法在氧气气氛中以高纯Zn(99.999%)为靶材、在单晶硅和石英衬底表而成功生长了ZnO薄膜.通过X射线衍射仪、表面轮廓仪、荧光光谱仪、紫外可见分光光度计对合成薄膜材料的晶体结构、厚度、光学性质等进行了研究,分析了激光能量变化对其性能的影响.实验结果表明我们使用PLD法可以制备出(002)结晶取向和透过率高于75%的ZnO薄膜,激光能量为450 mJ的ZnO薄膜的发射性能较好,但激光能量的增加不能改善薄膜的透光率.     

可用于可穿戴设备的透明非晶硅薄膜太阳能电池的研究

一种可用于可穿戴设备屏幕表面的透明非晶硅薄膜太阳能电池,采用激光刻蚀高密度微纳光通道阵列、TCO薄膜作为透明导电背电极,并减薄I层厚度来提升光线透过率。实验表明随着光刻密度增加或I层厚度的减少,光电转换效率会降低,光线透过率会增加,当I层厚度300nm,光刻孔隙直径30m,阵列间隔55m以内时,可获得50%以上的透过率（最高59%）和2.5%以上的光电转化效率（最高3%）。     

基于类金刚石沉积的短脉宽XeCl激光设计及脉宽分析

在气体配比HCl:Xe:He=0.12％:1％:98.88％实现了大功率短脉冲XeCl准分子激光器,以纳米异质结构、微观量子阱、表面微小尺度薄膜沉积,镀制金刚石薄膜、半导体薄膜、巨磁薄膜,及外延生长及后续的光刻、激光与物质的相互作用、等离子体研究为目的,设计了高能量、短脉宽脉冲放电激励的XeCl准分子激光器新型结构,完成了脉冲波形测试。试验结果表明:激光脉宽最短13ns,单脉冲能量450mJ,矩形光斑大小2cm×1cm,束散角3mrad,最高重复频率5 Hz。验证了激光器结构、动力学速率方程、总结出了饱和增益、脉宽规律。产生的短脉宽激光热融蚀效应小,类金钢石材料对基底形成了良好的等离子溅射羽辉。     

中红外量子级联激光器偏振合束实验研究

合束是实现量子级联激光器高功率输出的关键技术,基于激光的偏振特性,研究了偏振合束的实验原理及实验方法。使用线栅偏振片和中波半波片组成偏振合束装置,对两路4.05 μm量子级联激光器进行偏振合束,测试了中波半波片对4.05 μm激光的透过率以及中波线栅偏振片对4.05 μm激光透射率和反射率与入射角的关系,通过实验研究,当透射路光束和反射路光束与线栅偏振片的夹角为30°时,透射路的透射率为81%,反射路反射率为91%,其光束合束效率达到约86%,并使用光束质量分析仪对合束之后的光束质量进行测试分析。结果表明:两路光束通过该合束装置合束之后,在保证合束效率的条件下,具有较好的光束质量。     

氧化多孔硅周期性波导光栅耦合器的实验研究

报道了用两束相干激光在HF溶液中的多孔Si(PS)表面上干涉形成光强周期分布,通过光溶解得到了孔隙率周期变化的结构,从而制备出氧化PS周期性波导光栅。实现了辐射模与波导中传输模之间的耦合,并由外部入射光波或衍射光的方向确定了波导层的有效折射率。     

GaAs外延薄膜的As缺位研究

研制太赫兹量子级联激光器的核心是制备以GaAs为代表的量子阱超晶格,在制备GaAs为代表的量子阱超晶格过程中,需要解决As缺位等基础性物理问题。采用激光分子束外延技术制备了GaAs外延薄膜,研究了实验参数对GaAs薄膜性能,特别是As缺位的影响。在线RHEED测试结果表明,GaAs可以实现外延生长。原位XPS和UPS等测试研究结果表明,激光分子束外延技术制备GaAs外延薄膜过程中存在As缺位问题,激光能量对GaAs薄膜中As含量具有明显的影响,要获得理想成分比的GaAs外延薄膜,需要较高的脉冲激光能量(600 mJ)。     

硅薄膜太阳电池抗反射微纳结构研究

在硅薄膜太阳电池中,灵活的光学设计可以实现表层的零反射损耗,增大吸收层中光的透射率,从而提高薄膜太阳电池的光收集能力。在薄膜太阳电池吸收层表面设计了矩形介质光栅。利用严格耦合波理论和模态传输理论研究了光栅结构参数对反射率的影响。考虑到AM1.5 G太阳能光谱和a-Si的吸收光谱,光栅参数进一步优化。由于微加工的误差,使得矩形光栅变成梯形光栅,必然会影响硅薄膜太阳电池表面反射率。研究结果表明,长周期光栅同样可以实现低反射率,在工艺上也容易实现。采用梯形光栅可进一步降低表面反射率,并且在太阳光入射角为-40°~+40°的范围内保持在6%以下。     

ITO薄膜电极激光损伤形貌的多重分形研究

液晶光学器件中液晶分子的转动由施加在ITO薄膜电极间的电场来控制,ITO晶体结构中空穴和自由电子与强激光的相互作用,使ITO薄膜电极成为液晶光学器件结构中激光损伤的薄弱环节.为探索ITO薄膜电极的激光损伤机制,使用原子力显微镜(AFM)对厚度约为10nm的ITO薄膜的表面形貌进行了测量.采用多重分形理论,定量分析了薄膜表面粗糙度及微孔洞分布情况,对薄膜在脉冲宽度为10ns,能量分别为50mJ、lOOmJ、200mJ激光辐照下所获得薄膜的表面粗糙度分布情况进行比较分析,结果显示,随着激光功率的增加,多重分形谱的谱宽△a呈增大趋势,且△f为负值,表明ITO.薄膜表面粗糙度增大并形成微孔洞缺陷.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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