环境气体对激光烧蚀制备纳米Si晶粒平均尺寸的影响

采用脉冲激光烧蚀装置,在不同环境气体下,沉积制备了含有纳米Si晶粒的薄膜.利用扫描电子显微镜(SEM)观察样品的表面形貌,并对晶粒尺寸进行统计分析,发现不同环境气体下,纳米Si晶粒平均尺寸均随衬底与靶的距离增加有着先增大后减小的规律;通过分析比较,同等条件下Ne气环境下制备的纳米Si晶粒平均尺寸最小.     

WO3/Si纳米晶薄膜的脉冲准分子激光沉积及结构分析

采用脉冲准分子激光大面积扫描沉积技术,在Ｓｉ（１１１）单晶衬底上沉积了 ＷＯ_ｘ薄膜．采用Ｘ射线衍射（ＸＲＤ）、喇曼光谱（ＲＳ）、付里叶红外光谱（ＦＴ－ＩＲ）及透射电镜扫描附件（ＳＴＥＭ）对不同条件下沉积的样品进行了结构分析．结果表明,氧分压和沉积温度是决定薄膜结构和成份的主要参数．在沉积温度３００℃以上及２０Ｐａ氧压下得到了三斜相纳米晶ＷＯ_３薄膜．     

WO3/Si纳米晶薄膜的脉冲准分子激光沉积及结构分析

采用脉冲准分子激光大面积扫描沉积技术，在Si(111)单晶衬底上沉积了WOx薄膜，采用X射线衍射（XRD）、喇曼光谱（RS），付里叶红外光谱（FT－IR）及透射电镜扫描附件（STEM）对不同条件下沉积的样品进行了结构分析，结果表明，氧分压和沉积温度是决定薄膜结构和成份的主要参数，在沉积温度300℃以上及20Pa氧压下得到了三斜相纳米晶WO3薄膜。     

脉冲激光烧蚀过程中阻尼系数的角度分布

采用脉冲激光烧蚀(PLA)技术,在半圆环衬底上制备了含有纳米晶粒的硅(Si)晶薄膜。分析了纳米Si晶粒尺寸和阻尼系数随角度和压强的变化关系。使用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和拉曼光谱仪(Raman)对其表面形貌和结构进行了表征。结果表明,在压强一定的情况下,纳米Si晶粒的尺寸和阻尼系数均相对于轴向呈对称分布,并随着偏离轴向角度的增加而减小;同时随着压强增大,晶粒尺寸和阻尼系数在各个角度处的值均增大。     

脉冲激光制备硅基超薄PtSi薄膜

用脉冲激光沉制备了纳米级Pt/Si异质层,对激光退火形成超薄PtSi薄膜进行了研究,对于Pt、Si互扩散反应形成Pt2Si和PtSi的过程利用XPS进行了测试分析,通过XPS和AFM等分析测试手段对不同参数激光退火形成的PtSi薄膜的结构特性进行观测。我们获得了均匀的、超薄边疆的PtSi层且具有平滑的PtSi/Si界面。     

氮对纳米硅氮薄膜晶化的影响

在电容式耦合等离子体化学气相沉积系统中，用高氢稀释硅烷和氮气为反应气氛制备纳米硅氮（ｎｃ－ＳｉＮｘ２Ｈ）薄膜，结果表明，当Ｎ２／ＳｉＨ４气体流量比（Ｘｎ）从Ｉ增加为４时，薄膜的晶态率从５８％降至１４％，晶粒尺寸从１０ｎｍ降至５ｎｍ，Ｎ／Ｓｉ含量比从０．０３增至０．１２，当Ｘｎ≥５，则生成非晶硅氮（ａ－ＳｉｕＮｘ２Ｈ）薄膜，当Ｘｎ从１增加为１０时，薄膜暗电导率从１０＾－５（Ωｃｍ）＾－１降至１０＾－     

Si（111）基片上Mg2Si薄膜的脉冲激光沉积

采用脉冲激光沉积方法在Si(111)基片上制备了Mg2Si薄膜。研究了激光能量密度、退火气氛及压强、退火温度、退火时间等工艺条件对Mg2Si薄膜生长的影响。用X射线衍射仪分析了Mg2Si薄膜的物相,用原子力显微镜、高分辨场发射扫描电镜表征了薄膜的形貌。实验结果表明:在激光能量密度为2.36 J/cm2,Si(111)基片上室温、真空(真空度10-6Pa)条件下沉积,在Ar气压强为10 Pa,500℃,30 min条件下原位退火得到了纯相、结构均匀、表面平整、厚度约为900 nm的Mg2Si多晶薄膜。     

氧压对脉冲激光沉积LaNiO_3薄膜结构和电学性能的影响

通过改变氧分压,利用脉冲激光沉积方法在Si(100)衬底上制备了系列LaNiO3导电氧化物薄膜;经XRD测试研究发现,通过调控氧压,可获得具有高(100)取向薄膜,且氧压对薄膜结晶性有很大影响,在氧分压为7.5Pa时获得结晶性最好的薄膜。经XRF分析表明,La、Ni元素化学成分计量比随氧压增大而减小。经四探针法测试,薄膜电阻率最小为2.03×10-4Ω.cm,表现出了良好的金属导电性。经SEM和AFM分析表明,薄膜晶粒为柱状晶,排列均匀致密,薄膜表面均匀,粗糙度较小,表明LaNiO3薄膜可以用作一种良好的铁电薄膜底电极材料。     

脉冲激光沉积NiZn铁氧体薄膜的微观结构和磁性

采用脉冲激光沉积（PLD）技术，分别在单晶硅基片和玻璃基片上沉积了NiZn铁氧体多晶薄膜，薄膜为单相尖晶石结构，在两种基片上都呈现出一定的（400）晶面的择优取向，但在硅基片上择优生长更显著；随着基片温度t的升高，薄膜晶粒尺寸逐渐增大；在t=500℃附近饱和磁化强度Ms出现最小值，而矫顽力Hc出现最大值；对薄膜进行退火处理。可使细小晶粒长大和内应力减小，对改善较低温度条件下制备的薄膜的软磁特性具有明显作用。     

脉冲激光沉积NiZn铁氧体薄膜的微观结构和磁性

采用脉冲激光沉积 (PLD)技术 ,分别在单晶硅基片和玻璃基片上沉积了NiZn铁氧体多晶薄膜 ,薄膜为单相尖晶石结构 ,在两种基片上都呈现出一定的 ( 4 0 0 )晶面的择优取向 ,但在硅基片上择优生长更显著 ;随着基片温度t的升高 ,薄膜晶粒尺寸逐渐增大 ;在t=5 0 0℃附近饱和磁化强度Ms 出现最小值 ,而矫顽力Hc 出现最大值 ;对薄膜进行退火处理 ,可使细小晶粒长大和内应力减小 ,对改善较低温度条件下制备的薄膜的软磁特性具有明显作用     

Luminescence hydrogenated nanoamorphous Si films fabricated by reactive pulsed laser ablation

Hydrogenated nanoamorphous Si (na-Si:H) films have been fabricated by reactive pulsed laser ablation technique with hydrogen as reactive gas. It is found that the hydrogen pressure has a great effect on both the structure and photoluminescence (PL) properties of the films. Increasing the hydrogen pressure leads to a structural transition of the films from amphorous Si to na-Si:H, and the PL center wavelength of the na-Si:H films is varied with the hydrogen pressure. The PL decay times of the na-Si:H films are in the nanosecond scale and are shorter on the high energy side of their PL spectrum. The results demonstrate that the na-Si:H films are promising candidates for visible, tunable and high-performance light-emitting devices.     

Microstructure and optical characterization of nanometric silicon films prepared by pulsed laser ablation

The effect of laser energy density, during pulsed laser ablation, on the microstructure and optical properties of silicon films has been investigated using techniques such as atomic force microscopy, scanning electron microscopy, X-ray diffraction, and UV–visible absorption/transmission spectroscopy. The thickness of prepared films increases with increase in laser energy density. The crystallite size and hence the crystallinity of prepared films have been estimated by X-ray diffraction and found to be dependent on laser energy density. The transmittance of films changes with laser energy density. The absorption coefficient of films has been found to be?>10⁴?cm^?1 in wavelength region 450–1100?nm. The band gap of silicon films has been determined as 2.27, 2.11, and 1.90?eV corresponding to laser energy density of 1.5, 2.5, and 3.5?J?cm^?2, respectively.     

Preparation of large-area high-quality YBCO thin films by pulsed laser deposition with Si heater and composite scanning of laser and target

We report on the successful preparation of large-area high-quality YBa₂Cu₃O₇ superconducting thin films by pulsed excimer laser ablation with a Si heater and composite scanning of laser beam and target. The Si heater, composite scanning of laser beam and target, and experiment results are described. The temperature variation of the Si heater was < ±0.5% in a 45×40 mm² area of 900–1000 °C. Films were deposited on LaAlO₃ substrates 35 mm in diameter. The thin films exhibited a thickness variation of ±2.5%; the superconducting properties wereT _c0=91×0.5 K andJ _c= (3.3±0.7)×10⁶ A/cm² at 77 K and zero magnetic field.     

Random lasing in a dye-doped polymer thin film waveguide deposited on a Si surface microstructured by femtosecond laser ablation

Random laser action with ~8 nm of bandwidth from a special waveguide structure is reported. The waveguide structure is composed of a layer of rhodamine 6G-doped PMMA film and a silicon substrate with a microstructured surface induced by a femtosecond laser. The silicon substrate featured two-dimensional island-like microstructures with average sizes ranging from 0.8 μm to 3 μm and average heights at about 0.7 μm. A red-shift of laser peak positions and decrease of threshold were observed with decreasing size of silicon surface microstructures. The spectra at different probe directions were also measured, and the results reveal that the waveguide laser action is strongly confined within ±10° from the direction of the edge. The lasing modes emitted from the edge of the waveguide are found to be mainly transverse electric-polarized. Our experiments demonstrate a promising method to achieve waveguide random lasers.     

脉冲激光沉积制备立方AlN薄膜的研究

采用脉冲激光沉积(PLD)方法,在SrTiO3(100)衬底上在650℃、10Pa N2条件下成功制备了立方结构的AlN薄膜.高能电子衍射(RHEED)及X射线衍射(XRD)分析表明立方AlN和SrTiO3的外延关系为AlN[100]∥SrTiO3[100]和AlN(200)∥SrTiO3(100).其AlN(200)衍射峰的摇摆曲线半高宽(FWHM)为0.44°,说明薄膜结晶性能良好.原子力显微镜(AFM)表明外延的立方AlN薄膜表面具有原子级平整度,其表面均方根粗糙度(RMS)为0.674nm.通过X光电子能谱(XPS)分析AlN薄膜表面成分,结果表明AlN薄膜表面没有被氧化.     

PLD法制备ZnO/Si异质结的I-V特性研究

用脉冲激光沉积法分别在不同电阻率的p型和n型Si( 100)衬底上制备了不掺杂ZnO薄膜,相应制成n-ZnO/p-Si和n-ZnO/n-Si异质结器件.利用X射线衍射和原子力显微镜对ZnO薄膜进行的结构和形貌测试表明,薄膜结晶情况良好,具有高度的c轴择优取向,表面颗粒大小、分布均匀.对器件的I-V特性测试表明,在无光条件下,制备的n-ZnO/p-Si异质结漏电流很低,而n-ZnO/n-Si同型异质结漏电流要稍大一些;随衬底电阻率的增大,上述器件的阈值电压变小;器件在光照下的漏电流明显比无光条件下的要大.     

Effect of interface on mid-infrared photothermal response of MoS2 thin film grown by pulsed laser deposition

This study reports on the mid-infrared (mid-IR) photothermal response of multilayer MoS2 thin films grown on crystalline (p-type silicon and c-axisoriented single crystal sapphire) and amorphous (Si/SiO2 and Si/SiN) substrates by pulsed laser deposition (PLD).The photothermal response of the MoS2 films is measured as the changes in the resistance of the MoS2 films when irradiated with a mid-IR (7 to 8.2 μm) source.We show that enhancing the temperature coefficient of resistance (TCR) of the MoS2 thin films is possible by controlling the film-substrate interface through a proper choice of substrate and growth conditions.The thin films grown by PLD are characterized using X-ray diffraction,Raman,atomic force microscopy,X-ray photoelectron microscopy,and transmission electron microscopy.The high-resolution transmission electron microscopy (HRTEM) images show that the MoS2 films grow on sapphire substrates in a layer-by-layer manner with misfit dislocations.The layer growth morphology is disrupted when the films are grown on substrates with a diamond cubic structure (e.g.,silicon) because of twin growth formation.The growth morphology on amorphous substrates,such as Si/SiO2 or Si/SiN,is very different.The PLD-grown MoS2 films on silicon show higher TCR (-2.9％ K-1 at 296 K),higher mid-IR sensitivity (△R/R =5.2％),and higher responsivity (8.7 V·W-1) compared to both the PLD-grown films on other substrates and the mechanically exfoliated MoS2 flakes transferred to different substrates.     

脉冲激光法原位制备纳米二氧化硅杂化聚苯胺研究

用脉冲激光轰击法连续制备聚苯胺原位修饰的纳米二氧化硅,通过溶剂转换的方法,制备得到聚苯胺/纳米二氧化硅杂化薄膜材料,用标准四探针电性能测试,TEM、UV-Vis、TG、XRD、XPS等手段对其进行表征,探讨了纳米二氧化硅的加入对聚苯胺热、电方面产生的影响,结果表明,用本方法制备的纳米二氧化硅具有较小粒径,不团聚,能较好地分散于聚苯胺中与之形成杂化材料,纳米二氧化硅与聚苯胺分子链存在强烈的相互作用,破坏了聚苯胺的规整堆积,导致其热分解温度下降,导电载流子的浓度及迁移率减少,电导率值下降,而抗氧化性有所提高。     

Properties of amorphous Si thin film anodes prepared by pulsed laser deposition

Amorphous Si (a-Si) thin film anodes were prepared by pulsed laser deposition (PLD) at room temperature. Structures and properties of the thin films were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and electrochemical measurements. Galvanostatic charge/discharge tests of half cells using lithium counter electrode were conducted at a constant current density of 100 μA/cm² in different voltage windows. Cyclic voltammetry (CV) was obtained between 0 and 1.5 V at various scan rates from 0.1 to 2 mV/s. The apparent diffusion coefficient (D_Li) calculated from the CV measurements was about ∼10⁻¹³ cm²/s. The Si thin film anode was also successfully coupled with LiCoO₂ thin film cathode. The a-Si/LiCoO₂ full cell showed stable cycle performance between 1 and 4 V.