采用固相晶化和准分子激光晶化制备结晶硅薄膜的对比

为制备高质量的结晶硅薄膜,以工业玻璃为衬底,利用等离子体增强化学气相沉积工艺制备了非晶硅(α-Si)薄膜,然后分别通过固相晶化和准分子激光晶化两种工艺制备结晶硅(nc-Si)薄膜,采用激光显微拉曼光谱仪、X射线衍射仪和扫描电子显微镜等对两类结晶硅薄膜的结晶率、结晶质量和表面形貌等进行了对比分析。结果表明:采用固相晶化得到的结晶硅薄膜的结晶率约为70%,采用准分子激光晶化得到的结晶率则可达90%;当激光拉曼测试条件变化时,两种结晶硅薄膜的结晶率几乎不变,均处于稳定的晶态结构;采用准分子激光晶化制备的结晶硅薄膜显示出微弱的Si(111)结晶峰位,并具有较大的晶粒尺寸和规则的晶界分布。     

用于飞秒激光制备光纤光栅的相位掩模研制

利用严格耦合波理论分析了用于520 nm波长飞秒激光制备光纤光栅的相位掩模的衍射特性,当相位掩模是矩形槽形时,占宽比在0.32~0.43之间,槽形深度在0.57~0.67μm之间时,能够保证零级衍射效率抑制在2%以内,同时±1级的衍射效率大于35%。在此基础上,利用全息光刻-离子束刻蚀技术,制作了用于520 nm波长飞秒激光的周期为1067 nm、有效面积大于40 mm×30 mm的相位掩模。实际制作的相位掩模是梯形槽形,槽深是0.665μm,分析了梯形槽形中梯形角对衍射效率的影响。实验测量表明,该相位掩模的零级衍射效率小于2%,±1级衍射效率大于40%,满足飞秒激光制作光纤光栅的需要。     

二元光学元件的制作技术与进展

综述了二元光学元件的常用制作工艺技术,包括台阶刻蚀法、薄膜沉积法、直接写入法、准分子激光加工法和灰阶掩模法。分析了这些方法的优缺点,并对其制作技术的发展进行了评述。     

基于大晶粒MA0.7FA0.3PbI3的薄膜光探测器

为了研究大晶粒高质量钙钛矿薄膜对光探测器的影响,制备了晶粒尺寸超过2 μm的MA_0.7FA_0.3PbI₃薄膜,并基于该薄膜制备了光电导型的光探测器（MCP-PD）。基于该薄膜的光探测器在532 nm和3 V偏置电压下获得了高响应度（0.905 A/W）和探测度（3.18×10¹² Jones）。在相似性能条件下,基于大晶粒尺寸薄膜制备的MCP-PD还表现出较快的响应速度。实验结果表明,大晶粒尺寸的薄膜降低了晶界对载流子传输的阻碍,提升了光探测器的响应度、探测度及响应速度。     

半导体材料激光退火技术研究(一)

1 α-Si薄膜激光退火 多晶硅薄膜是制造高迁移率薄膜半导体（TFT）的材料,TFT又是制造平面显示屏的关键元件。因而如何使非晶硅（α-Si）转变成为多晶硅就成为微电子器件制造中的重要工序。但是,现在使用的多晶硅薄膜都有高密度晶粒边界,显微组织的完整性相当差。用此种材料制造的TFT装置质量都低于用单晶硅薄膜,不能获得高性能和质量均匀稳定的TFT。使用传统加热退火虽能改善组织,提高性能,但必须用昂贵的石英基体。激光退火则可将廉价的玻璃基体上的非晶硅薄膜转化成多晶硅薄膜,而不会损伤玻璃,因此,具有广阔的应用前景。     

用于强激光系统的光栅偏振器

针对强激光系统中常用的1 053nm激光器进行了偏振光栅结构的优化设计。利用严格耦合波理论分析了光栅偏振器的衍射特性及消光比,分析显示偏振光栅周期为600nm,占宽比为0.535~0.55,槽形深度为1 395nm~1 420nm时,可保证其在1 053nm波长下,透射率高于95%,消光比大于1 500。基于分析结果,利用全息光刻技术制作了高质量光刻胶光栅掩模,并采用倾斜转动的离子束刻蚀结合反应离子束刻蚀的方法对该光刻胶光栅掩模进行图形转移,制作了底部占宽比为0.54,槽形深度为1 400nm的光栅偏振器。实验测量显示其透射率为92.9%,消光比达到160。与其他制作光栅偏振器方法相比,采用单光刻胶光栅掩模结合倾斜转动的离子束刻蚀工艺,不但简化了制作工艺,而且具有激光损伤阈值高、成本低的优点。由于该技术可制作大面积光栅,特别利于在强激光系统中应用。     

氩气对金刚石膜碳价键、粒径和表面形貌的影响

为调整微钻表面金刚石薄膜的晶粒尺寸和粗糙度以满足PCB板钻孔的工况要求,调节氩气和氢气流量比,采用热丝化学气相沉积法,以甲烷、氢气及氩气为气源在硅基体上沉积出一系列金刚石薄膜。利用拉曼光谱仪、X射线衍射仪(XRD)、扫描电子显微镜(SEM)及原子力显微镜(AFM),分别表征不同氩气流量下制备的金刚石薄膜的碳价键结构、晶面取向、晶粒尺寸和表面粗糙度。结果表明:随着氩气流量增大,金刚石薄膜中的石墨含量呈升高趋势,薄膜趋向(111)晶面择优生长,晶粒尺寸从微米级(1. 27μm)细化至纳米级,薄膜粗糙度先升高后降低,最低为65 nm。研究表明,存在最优的氩气流量使得制备的薄膜具有适宜的结构特点,如碳价键含量高、(111)晶面取向度高、晶粒尺寸小和粗糙度低,可满足PCB板超细钻孔的要求。     

串联光伏电池非晶硅薄膜的Nd3+∶YAG激光辅助掺杂与同时毛化

对结合激光辅助掺杂和毛化方法合成的光伏电池用Sb掺杂非晶硅薄膜进行了研究.首先,用阈值通量为460mJ/cm2的激光照射镀有200～300 nm厚Sb的非晶硅薄膜进行施主扩散.为激活施主,样品用230mJ/cm2的低激光通量再一次进行处理.进行施主激光扩散和活化时,激光光斑的重叠度达到光斑大小的90％,因此随后诱发了薄...     

光纤激光诱导背面干法刻蚀制备二元衍射光学元件

为了降低激光直接辐照透明介电材料的表面加工粗糙度和激光能量密度刻蚀阈值,提高微光学元件的产出率,介绍了一种用固体介质作吸收层,激光直接作用在透明光学材料上进行微纳加工的激光诱导背面干法刻蚀工艺。首先,选用95氧化铝陶瓷作固体材料辅助吸收层,应用中心波长为1 064 nm的掺镱光纤激光器,在3.2 mm厚的熔融石英玻璃表面刻蚀了亚微米尺度的二维周期性光栅结构。然后,对刻蚀参数进行拟合并探讨了激光能量密度对刻蚀参数的影响。最后,观察该二元光学元件的衍射花样图形并讨论其衍射特性。实验制备了槽深为4.2 μm,槽底均方根粗糙度小于40 nm,光栅常数为25 μm的二维微透射光栅,其刻蚀阈值低于7.66 J/cm²。结果表明,应用该工艺制备二维透射光栅,降低了激光刻蚀透明材料的密度阈值及加工结构的表面粗糙度。     

应用L-MBE方法制备ZnO薄膜的结构和光学特性

用激光分子束外延(Laser Molecular Beam Epitaxy,L-MBE)设备在p型Si(111)衬底上制备了不同衬底温度和不同氧压的ZnO薄膜,用X射线衍射仪(XRD)和原子力显微镜(AFM)分别对薄膜的结构和形貌进行了分析,用He-Cd激光(325nm)激发的光致发光测试系统对薄膜进行了荧光光谱分析。研究发现,在衬底温度为400℃,氧压1Pa左右所制备的ZnO薄膜表面比较均匀致密,晶粒生长较充分,有较高的结晶质量和发光强度。ZnO薄膜的近带边发射与薄膜的结晶质量和化学配比均有关系。     

用于热机械微纳加工的掺Al多晶硅加热器

针对热机械式微纳米结构的加工,提出了一种以掺Al多晶硅为材料,集成于微悬臂梁上的加热器.采用Al诱导退火晶化(AIC)方法,在750 K对Al/a-Si∶H复合薄膜低温晶化18 h,制备出掺Al多晶硅.通过低温退火,使复合薄膜的拉曼特征峰由478 cm-1移至520 cm-1,完成由非晶硅向多晶硅的转变;由四探针仪测得...     

串联光伏电池非晶硅薄膜的Nd~(3+):YAG激光辅助掺杂与同时毛化(英文)

对结合激光辅助掺杂和毛化方法合成的光伏电池用Sb掺杂非晶硅薄膜进行了研究。首先,用阈值通量为460mJ/cm2的激光照射镀有200～300nm厚Sb的非晶硅薄膜进行施主扩散。为激活施主,样品用230mJ/cm2的低激光通量再一次进行处理。进行施主激光扩散和活化时,激光光斑的重叠度达到光斑大小的90%,因此随后诱发了薄膜表面的毛化。多晶毛化峰由扫描电子显微镜、喇曼光谱、原子力显微镜等多种表征手段进行了验证,处理后的样品其正面和背面的拉曼光谱均出现了521cm-1的晶体峰值。样品的n型特征得到了Hall效应测试的证实,同时证明了掺杂的有效性。表面毛化粗糙度达到450nm,并且观测到了光电导和吸收光谱的增强,这些均证实了样品光伏性质的改善。     

基于辐射压力控制的微型元件的加工与检测

We have been developing new fabrication tools based on optical radiation pressur e and related phenomena to develop aflexible and accurate microfabrication tec hnology. In this paper, the laser trapping probe for the nano-CMM for assessment, in addition to micromachining technique using a small particle controlled by optical radiation pressure and laser aggregation technique are discussed. As the positional detection probe for the nano-CMM, an optically trapped silica particle with 8 mm diameter in forced oscillation state is used. A probe sphere retains a stable position when applied with trapping force by Nd:YAG laser light formed an nu lar and is forced to oscillate by the driving force changed by modulating the in tensity of LD emission. Experintal results show that this vibrational microprobe h as the possibility to achieve positional sensing accuracy of less than 25 nm. As a new micromachining technique, nano-removal process using an optically trapped micro-grain is proposed. The laser trapping force enables not only to stably trap the diamond grain with asymmetrical shape but also to freely control the positi on with spinning. Using this micro machining tool, the machining experiments of h ydrocarbon film are performed. AFM observation confirmed that the fine groove wi th depths of about 3～4 nm can be fabricated. As an additive process based on ra diation pressure, a laser microstructure fabrication using laser agglomeration p h enomena of colloidal particles aided by radiation pressure is investigated. By c ontrolling laser beam scanning in slurry containing KOH solution and SiO₂ par ticles with a diameter of 140 nm, colloidal particles are aggregated and adhered firmly to a silicon wafer substrate. Using this laser agglomerating process, two-dimensional grid microstructures at the pitch of 5 mm can be fabricated.     

Femtosecond laser-induced simultaneous surface texturing and crystallization of a-Si:H thin film: morphology study

Hydrogenated amorphous silicon (a-Si:H) thin films have been considered for use in solar cell applications because of their significantly reduced cost compared with crystalline bulk silicon; however, their overall efficiency and stability are less than that of their bulk crystalline counterparts. Limited work has been performed on solving the efficiency and stability issues of a-Si:H simultaneously. Surface texturing and crystallization on a-Si:H thin film can be achieved through one-step femtosecond laser processing, which can potentially alleviate the disadvantages of a-Si:H in solar cell applications. In this study, submicrometer conical and pillar-shaped spikes are fabricated by irradiating a-Si:H thin films deposited on glass substrates with hundreds of 800 nm-wavelength, 130 fs-duration laser pulses in air, and water environments, respectively. The formation mechanisms for the surface spikes are discussed, and the differences in the surface feature characteristics are also presented and explained within the context of the different processing environments. The effect of laser processing on light absorption and crystallinity will be studied later.     

Nanoscale Line Segment Fabrication Using Super‐Resolution Near‐Field Photolithography

This study proposed a method to combine near‐field photolithography (NFP) with thermally induced super‐resolution, and conducted simulation and analysis on nanoscale line segment fabrication. A theoretical model of optical metal film was used to calculate the transmittance of indium film during line segment fabrication. A theoretical heat transfer model was employed to analyze the exposure power density on the surface of the photoresist after laser beams penetrated the indium film. This study divided the photoresist into finite nodes. Through a simulation combining an exposure energy density formula, an exposure model, and a developmental model, we derived the theoretical width and profile of the line segment fabricated using super‐resolution NFP. The widths of the derived line segments were 88 nm for photoresist with indium coating and 130 nm without. The indium film accounted for a reduction in width of 32%. SCANNING 34: 284–294, 2012. © 2012 Wiley Periodicals, Inc.     

TiO2薄膜电极光电转换性能的影响因素

采用溶胶-凝胶法在玻璃基体表面制备了不同粒径的TiO2薄膜和纳米SnO2/TiO2复合薄膜,将它们与不同对电极进行了光电转换性能测试.结果表明:氧化物薄膜电极经染料敏化、薄膜颗粒细化及薄膜复合化都有利于提高电极的光电转换性能.用汞溴红敏化后,粒径为25 nm的TiO2薄膜的光电转换性能提高了847倍;粒径为25 nm的TiO2薄膜的光电转换性能是粒径为136 nm的TiO2薄膜的5倍;粒径为25 nm的TiO2薄膜经粒径为27 nm的SnO2薄膜复合后,其光电转换性能提高了7.7%.     

EFFECT OF SURFACE ENERGY ON THE GROWTH OF DIAMOND-LIKE CARBON/AMORPHOUS SILICON FILMS ON VARIOUS SUBSTRATES

Diamond-like carbon/amorphous silicon bilayer films were deposited on SiO₂, Ge, and Ta₂O₅ substrates using a pulsed filtered cathodic arc (PFCA) system. Amorphous silicon (a-Si) layer was firstly deposited on three substrates using DC magnetron sputtering, then diamond-like carbon (DLC) film was deposited on a-Si layer via pulsed filtered cathodic arc. The thicknesses of a-Si layer and DLC film as monitored by in-situ ellipsometry during the film deposition were 7 and 10 nm, respectively. The surface energy of SiO₂, Ge, and Ta₂O₅ substrates was determined by measuring the contact angle of water on these substrates. It was found that the contact angles of water on SiO₂, Ge, and Ta₂O₅ substrates were 53°, 63°, and 75°, respectively. This result indicates that SiO₂ has the highest surface energy while Ta₂O₅ has the lowest surface energy. The thickness of the a-Si layer and DLC film was determined from the cross-section transmission electron microscopy (TEM) images. The thinnest a-Si layer of 5.64 nm was obtained from SiO₂ substrate which has the highest surface energy. The thickest a-Si layer of 6.97 nm was obtained from Ta₂O₅ corresponding to the lowest surface energy. This study shows that the thickness of the growth film strongly depends on the surface energy of the substrate. However, the DLC films deposited on each a-Si layer of three substrates have the same thickness approximately of 9.9 nm, because all of them were deposited on a-Si layers having the same surface energy.     

Growth of low resistivity and high transparency boron-doped zinc oxide film by pulse laser deposition

0.5 wt% boron-doped zinc oxide (BZO) films were fabricated by utilizing pulse laser deposition under different growth temperature ranged from 250 to 450 °C. The effect of the growth temperature on the structural, optical, and electrical properties was investigated and discussed. The crystal structure and orientation of BZO thin films were examined by X-ray diffraction. All of the BZO films under various growth temperatures had strong c-axis (002)-preferred orientation. Optical transparency was high (>80%) over a wide spectral range from 400 nm to 700 nm, and the optical bandgap value of BZO are found to be in the range from 3.18 to 3.47eV. According to the experimental data, the resistivity of the BZO film was optimized at ~1.13 × 10⁻³ Ω-cm and significantly influenced by the growth temperature.