气相沉积法制备聚酰亚胺薄膜的热环化研究

采用两种单体同时蒸发沉积聚合方法制备得到聚酰亚胺（PI）薄膜。对不同温度下和不同恒温时间的聚酰胺酸（PAA）薄膜进行了红外分析,将300 ℃恒温3 h以上的薄膜脱膜,用白光干涉仪测量了PI薄膜热环化前后表面质量。采用热重分析仪在不同升温速率条件下对薄膜进行了分析。结果表明,在热环化过程中,随着温度增加亚胺化程度逐渐增加。在300 ℃时随着恒温时间增加亚胺化程度逐渐增加,恒温3 h以上薄膜亚胺化较为完全,可以获得完整且不易破损的自支撑薄膜。在热环化过程中,升温速率较低时薄膜的亚胺化程度在低温区转化率提高,过量单体蒸发更完全,故一般选择较小的升温速率,约10 ℃/min甚至更低。采用上述热环化工艺得到了亚胺化程度较高且不易破损的PI薄膜,其表面均方根粗糙度为9.8 nm。     

衬底温度对PLD制备的Mo薄膜结构及表面形貌的影响

 运用脉冲激光沉积(PLD)技术在Si(100)基片上沉积了金属Mo薄膜。在激光重复频率2 Hz,能量密度5.2 J/cm²,本底真空10^－6 Pa的条件下,研究Mo薄膜的结构和表面形貌,讨论了衬底温度对薄膜形貌与结构的影响。原子力显微镜(AFM)图像和X射线小角衍射(XRD)分析表明,薄膜表面平整、光滑,均方根粗糙度小于2 nm。沉积温度对Mo薄膜结构和表面形貌影响较大,在373~573 K范围内随着温度升高,薄膜粗糙度变小,结晶程度变好。     

电子束蒸发氧化锆薄膜的粗糙度和光散射特性

利用电子束蒸发工艺，以Ag层为衬底，沉积了中心波长为632.8nm的氧化锆(ZrO₂)薄膜，膜层厚度在80—480nm范围内变化.研究了不同厚度样品的粗糙度变化规律和表面散射特性.结果发现，随着膜层厚度的逐渐增加，其表面均方根(RMS)粗糙度和总积分散射(TIS)均呈现出先减小后增大的趋势.利用非相关表面粗糙度的散射模型对样品的TIS特性进行了理论计算，所得结果与测量结果相一致. 关键词： 氧化锆 表面粗糙度 标量散射 电子束蒸发     

不同衬底温度下PLD法制备的氧化锌薄膜的特性

利用GCR-170型脉冲激光器Nd:YAG的三次谐波(355nm),以蓝宝石Al2O3(0001)为衬底,在不同温度下采用脉冲激光沉积法制备了ZnO薄膜.通过原子力显微镜、Raman谱、光致发光谱、红外透射谱、霍尔效应和表面粗糙度分析仪对制备的ZnO薄膜进行了测试.分析了在不同衬底温度下薄膜的表面形貌、光学特性,同时进行了薄膜结构和厚度的测试.研究表明:衬底温度对ZnO薄膜的表面形貌、光学特性、结构特性都是重要的工艺参量,尤其在500℃时沉积的ZnO薄膜致密均匀,并表现出较强的紫外发射峰.     

Fe/Al混合膜的PLD法制备及表面分析

 采用脉冲激光气相沉积（PLD）技术制备了Fe/Al混合膜，测量了该混合膜的光电子能谱（XPS），并采用原子力显微镜（AFM）、扫描电子显微镜（SEM）对Fe/Al混合膜作了表面分析。结果表明：Fe/Al混合膜的表面粗糙度对衬底温度有明显的依赖性， 随着衬底温度的升高，薄膜的表面逐渐变得平滑，膜层变得致密，在200 ℃衬底温度下制得了均方根（rms）粗糙度为0.154 nm、具有原子尺度光滑性的Fe/Al混合膜， 膜中Fe和Al分布比较均匀，其成分比约为1∶3，同时XPS分析也表明Fe/Al混合膜暴露在空气中后表面形成了Al₂O₃和FeO氧化层。     

NaF薄膜的脉冲激光沉积法制备与结构研究

 采用脉冲激光沉积(PLD)方法在Si(100)衬底上制备了NaF薄膜。在激光重复频率2 Hz，能量密度3 J/cm²，本底真空度5×10^-5 Pa的条件下，研究衬底温度对薄膜沉积速率及结构的影响。台阶仪分析表明：薄膜的沉积速率随衬底温度增加呈指数函数增加，算出NaF薄膜的反应激活能为48.67 kJ/mol。原子力显微镜分析表明：薄膜致密而光滑，均方根粗糙度为0.553 nm。扫描电镜截面微观形貌分析表明：薄膜呈现柱状结构。X射线衍射分析表明：NaF薄膜为面心立方晶体结构，并具有显著的择优取向；当衬底温度约为400 ℃时，平均晶粒尺寸最大(129.6 nm)，晶格微应变最小(0.225%)。     

膜厚对直流磁控溅射Nb薄膜微结构的影响

 采用直流磁控溅射方法制备膜厚为50, 100, 200, 400, 600 nm的Nb薄膜,对薄膜的沉积速率、表面形貌、晶体结构进行了研究,并对其应力和择优取向进行了详细的分析。原子力显微镜图像显示Nb膜表面光滑、致密,均方根粗糙度达到0.1 nm量级。X射线小角衍射给出了薄膜的晶格结构、晶粒尺寸和应力情况。分析表明薄膜为多晶体心立方结构(bcc),在(110)晶面方向存在明显的择优取向,且随着薄膜厚度增大而增强。Nb膜应力先随薄膜厚度增大而增大,在200 nm时达到最大值(为1.015 1 GPa),后随薄膜厚度的增大有所减小。     

退火温度对溅射铝膜结构与电性能的影响

 采用直流磁控溅射方法成功地制备了Al膜,研究了退火温度对Al膜表面形貌、晶体结构、应力、择优取向及反射率的影响。研究表明：不同退火温度的薄膜晶粒排布致密而光滑,均方根粗糙度小。XRD测试表明：不同温度退火的铝膜均成多晶状态,晶体结构为面心立方,退火温度升高到400 ℃时,Al膜的应力最小达0.78 GPa,薄膜平均晶粒尺寸由18.3 nm增加到25.9 nm;随着退火温度的升高,(200)晶面择优取向特性变好。薄膜紫外-红外反射率随着退火温度的升高而增大。     

原子力显微镜在PLD法制备ZnO薄膜表征中的应用

利用脉冲激光沉积(PLD)法在氧压为16 Pa、衬底温度为400~700 ℃时,在单晶Si(100) 衬底上制备ZnO薄膜,并通过原子力显微镜(AFM)、X射线衍射(XRD)谱和光致发光谱对制得的薄膜样品进行表面形貌、结构特性和发光性质研究。其中通过原子力显微镜对样品的二维、三维以及剖面线图进行了分析。结果表明衬底温度700 ℃时得到的薄膜样品表面较均匀致密,晶粒生长较充分,结晶质量较高,相对发光强度高。控制氧压为5.7 Pa,在衬底温度为600 ℃,沉积时间分别为10,20,45 min制备ZnO薄膜样品;利用原子力显微镜对样品进行表面形貌观察,得知只有沉积时间足够长才能使薄膜表面晶粒充分生长。     

二氧化锆薄膜表面粗糙度的研究

采用电子束蒸发工艺,利用泰勒霍普森相关相干表面轮廓粗糙度仪,研究了不同基底粗糙度、不同二氧化锆薄膜厚度以及不同的离子束辅助能量下所沉积的二氧化锆薄膜的表面粗糙度。结果表明：随着基底表面粗糙度的增加,二氧化锆薄膜表面粗糙度呈现出先缓慢增加,当基底的粗糙度大于10nm后呈现快速增加的趋势;随着二氧化锆薄膜厚度的增加,其表面均方根粗糙度（RMS）先减小后增大;随着辅助沉积离子能量的增加,其表面粗糙度呈现出先减小后增加的趋势。     

Morphological and optical properties of silicon thin films by PLD

Silicon thin films have been prepared on sapphire substrates by pulsed laser deposition (PLD) technique. The films were deposited in vacuum from a silicon target at a base pressure of 10⁻⁶ mbar in the temperature range from 400 to 800 °C. A Q-switched Nd:YAG laser (1064 nm, 5 ns duration, 10 Hz) at a constant energy density of 2 J × cm⁻² has been used. The influence of the substrate temperature on the structural, morphological and optical properties of the Si thin films was investigated.Spectral ellipsometry and atomic force microscopy (AFM) were used to study the thickness and the surface roughness of the deposited films. Surface roughness values measured by AFM and ellipsometry show the same tendency of increasing roughness with increased deposition temperature.     

Epitaxial growth and structural characterization of Pb(Fe1/2Nb1/2)O3 thin films

We have grown lead iron niobate thin films with composition Pb(Fe_1/2Nb_1/2)O₃ (PFN) on (0 0 1) SrTiO₃ substrates by pulsed laser deposition. The influence of the deposition conditions on the phase purity was studied. Due to similar thermodynamic stability spaces, a pyrochlore phase often coexists with the PFN perovskite phase. By optimizing the kinetic parameters, we succeeded in identifying a deposition window which resulted in epitaxial perovskite-phase PFN thin films with no identifiable trace of impurity phases appearing in the X-ray diffractograms. PFN films having thicknesses between 20 and 200 nm were smooth and epitaxially oriented with the substrate and as demonstrated by RHEED streaks which were aligned with the substrate axes. X-ray diffraction showed that the films were completely c-axis oriented and of excellent crystalline quality with low mosaicity (X-ray rocking curve FWHM?0.09°). The surface roughness of thin films was also investigated by atomic force microscopy. The root-mean-square roughness varies between 0.9 nm for 50-nm-thick films to 16 nm for 100-nm-thick films. We also observe a correlation between grain size, surface roughness and film thickness.     

Radio-frequency assisted pulsed laser deposition of nanostructured WOx films

The synthesis of tungsten oxide films with large surface area is promising for gas sensing applications. Thin WO_x films were obtained by radio-frequency assisted pulsed laser deposition (RF-PLD). A tungsten target was ablated at 700 and 900 Pa in reactive oxygen, or in a 50% mixed oxygen-helium atmosphere at the same total pressure values. Corning glass was used as substrate, at temperatures including 673, 773 and 873 K. Other deposition parameters such as laser fluence (4.5 J cm⁻²), laser wavelength (355 nm), radiofrequency power (150 W), target to substrate distance (4 cm), laser spot area (0.7 mm²), and number of laser shots (12,000) were kept fixed. The sensitivity on the deposition conditions of morphology, nanostructure, bond coordination, and roughness of the obtained films were analyzed by scanning and transmission electron microscopy, micro-Raman spectroscopy, and atomic force microscopy.     

二氧化钛薄膜表面粗糙度研究

为了探究二氧化钛(TiO₂)薄膜表面粗糙度的影响因素, 利用离子束辅助沉积电子束热蒸发技术对不同基底粗糙度以及相同基底粗糙度的K9玻璃完成二氧化钛(TiO₂)光学薄膜的沉积。采用TalySurf CCI非接触式表面轮廓仪分别对镀制前基底表面粗糙度和镀制后薄膜表面粗糙度进行测量。实验表明, TiO₂薄膜表面粗糙度随着基底表面的增大而增大, 但始终小于基底表面粗糙度, 说明TiO₂薄膜具有平滑基地表面粗糙的作用; 随着沉积速率的增大, 薄膜表面粗糙度先降低后趋于平缓; 对于粗糙度为2 nm的基底, 离子束能量大小的改变影响不大, 薄膜表面粗糙度均在1.5 nm左右; 随着膜层厚度的增大, 薄膜表面粗糙度先下降后升高。     

ITO/Au/ITO multilayer thin films for transparent conducting electrode applications

Transparent and conducting ITO/Au/ITO multilayered films were deposited without intentional substrate heating on polycarbonate (PC) substrate using a magnetron sputtering process. The thickness of ITO, Au and ITO metal films in the multilayered structure was constant at 50, 10 and 40 nm, respectively.Although the substrate temperature was kept constant at 70 °C, ITO/Au/ITO films were polycrystalline with an (1 1 0) X-ray diffraction peak, while single ITO films were amorphous. Surface roughness analysis indicated ITO films had a higher average roughness of 1.76 nm, than the ITO/Au/ITO film roughness of 0.51 nm. The optoelectrical properties of the ITO/Au/ITO films were dependent on the Au thin film, which affected the ITO film crystallinity. ITO/Au/ITO films on PC substrates were developed with a resistivity as low as 5.6 × 10⁻⁵ Ω cm and a high optical transmittance of 71.7%.     

Crystalline and photoluminescence characteristics of YVO4:Sm thin films grown by pulsed laser deposition under oxygen pressure

YVO₄:Sm³⁺ films were deposited on Al₂O₃ (0 0 0 1) substrates at various oxygen pressures changing from 13.3 to 46.6 Pa by using the pulsed laser deposition method. The crystallinity and surface morphology of these films were investigated by means of X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The XRD pattern confirmed that YVO₄:Sm³⁺ film has zircon structure and the AFM study revealed that the films consist of homogeneous grains ranging from 100 to 400 nm. The room temperature photoluminescence (PL) spectra showed that the emitted radiation was dominated by a reddish-orange emission peak at 602 nm radiating from the transition of (⁴G_5/2→⁶H_7/2). The crystallinity, surface morphology, and photoluminescence spectra of thin-film phosphors were highly dependent on the deposition conditions, in particular, the substrate temperature. The surface roughness and photoluminescence intensity of these films showed similar behavior as a function of oxygen pressure.     

Structural and surface analysis of thin-film ZnTe formed with pulsed-laser deposition

Nanosecond pulses of a Nd:YAG laser have been employed to deposit thin-film zinc telluride (ZnTe) on silicon (Si) and glass without heating these substrates. We present and discuss the structural and surface properties of films deposited at 1064 nm and 532 nm. X-ray diffraction and analysis of the surface roughness with atomic force microscopy reveal that the material texture and surface morphology depend on the ablation laser line used rather than on the substrate. The observations contribute to improved understanding of pulsed-laser deposition and provide tools to optimize the optoelectronic and photonic properties of ZnTe thin-films as well as their incorporation into Si-based technologies in order to fabricate cost-effective and functional optoelectronic devices and all-optical laser digitizer.