衬底温度对nc-Si∶H薄膜微结构和氢键合特征的影响

采用射频等离子体增强型化学气相沉积(RF-PECVD)技术,以H2和SiH4作为反应气体源,在不同的衬底温度下沉积了nc-Si∶H薄膜.采用Raman散射、X射线衍射、红外吸收等技术分析了薄膜的微结构和氢键合特征.结果表明,随衬底温度的升高,nc-Si∶H薄膜的沉积速率不断增大,晶化率和晶粒尺寸增加,纳米硅颗粒呈现出Si(111)晶面的择优生长趋势.键合特性显示,薄膜中的氢含量随衬底温度升高而逐渐减小,薄膜均匀性先增大后减小.     

H2流量对直流磁控溅射制备a-Si∶H薄膜微观结构及光学性能的影响

采用直流磁控溅射法在不同H2流量的条件下制备了a-Si∶H薄膜,研究了H2流量对薄膜微观结构以及光学性能的影响.结果表明:随H2流量的增加,a-Si∶H薄膜的沉积速率有所下降,但其原子排列的有序度上升,并出现了细小的纳米晶粒,使得薄膜的无序结构得到了一定改善.同时,薄膜的光学性能也表现出明显变化,其中透过率持续上升,而光学带隙则呈现出先增大后减小的趋势.最终得到制备a-Si∶H薄膜的最优H2流量为15 sccm.     

衬底温度对含硅量子点的SiCx薄膜结构及其光学特性的影响

采用磁控共溅射沉积法,以Si靶和SiC靶为靶材,单晶Si(100)和石英为衬底,在不同衬底温度下沉积了富硅SiCx薄膜.在氮气氛下于1100 ℃退火,得到包含硅量子点的SiCx薄膜.采用傅立叶变换红外吸收光谱、拉曼光谱、掠入射X射线衍射和吸收谱对退火后的SiCx薄膜进行了表征.结果表明:当衬底温度从室温(25℃)升至300℃时,薄膜的晶化率增至71.3;,硅量子点尺寸增至8.9 nm,而光学带隙则减至2.42 eV;随着衬底温度进一步升高,薄膜的晶化率降至63.1;,硅量子点尺寸减小至7.3 nm,而光学带隙却增加至2.57 eV;当衬底温度从室温(25℃)升至400℃时,薄膜的吸收系数呈先增大后减小趋势.在本实验条件下,最佳衬底温度为300℃.     

氨气流量对富硅SiNx薄膜结构及其光学特性的影响

采用等离子体增强化学气相沉积技术,以NH3、SiH4和N2为反应气体制备富硅-氮化硅薄膜.在优化了其它沉积参数条件下,研究氨气流量对富硅-氮化硅薄膜的结构和光学性质的影响.利用傅立叶变换红外光谱、紫外可见光谱和X射线衍射谱分析了薄膜的键合情况、带隙结构.结果表明,随着NH3流量的增大,薄膜中的Si-N键和N-H键增强,Si-H键减小并向高波数方向移动,薄膜逐渐由非晶SiNx相向小晶粒Si3 N4相转变.同时随着NH3流量的增大,薄膜的光学带隙逐渐展宽,微观结构的有序度降低.XRD图谱分析表明薄膜内的平均晶粒尺寸也随着氨气流量的增加而在逐渐增大.结合以上结果分析,适当增加NH3流量有助于薄膜由非晶SiNx向包含小晶粒的Si3 N4转变.     

硼掺杂对μc-Si:H薄膜微结构和光电性能的影响

采用射频等离子增强化学气相沉积(RF-PECVD)法制备了掺硼氢化微晶硅(μc-Si:H)薄膜,研究了硼掺杂对薄膜的结晶状况、沉积速率、暗电导率和光学带隙的影响.拉曼光谱、扫描电子显微镜、分光光度计和电导率测试结果表明:当掺硼比(B2H6/SiH4)由0.1;增加到0.75;时,硅膜的晶化率逐渐降低,并由微晶向非晶过渡;沉积速率随掺硼比的增加线性增大;暗电导率先升高后下降,当掺硼比为0.5;时,暗电导率最大;光学带隙随掺硼比的增加逐渐减小.     

氧化硅中纳米晶硅薄膜的低温沉积及其键合特性研究

以Ar和H2为溅射气体,采用Si和SiO2双靶活性溅射技术实现了镶嵌纳米晶硅(nc-Si)的富硅氧化硅(SiOx)薄膜的300℃低温生长,并分析了氢气掺入对薄膜微观结构及键合特性的影响.结果表明,氢气流量比的增加导致纳米硅粒子尺寸增加,而生长速率逐渐减小.薄膜中Si-O键合结构以Si(O4)键为主,随H2流量比的增加,Si-O4-nSin(n=0,1)键密度减小,Si-O4-nSin(n=2,3)和SiH2键密度持续增加,而所对应Si-H键密度呈现先减小后增加趋势,该结果可解释为等离子体内氢原子对反应前驱物中氧的去除效应增强和氢原子与表面氧的解吸附反应几率的增加.     

沉积压力对磁控溅射纳米硅薄膜结构和性能影响

采用射频(RF)磁控溅射方法在玻璃衬底上制备了氢化纳米硅薄膜,研究了沉积压力(4～9 Pa)对薄膜结构和性能的影响.利用XRD、SEM、紫外-可见光分光光度计、傅立叶红外吸收光谱仪(FT-IR)及四探针电阻测试仪等对薄膜结构和性能进行了表征.结果表明:随着沉积压力的提高,薄膜结晶程度逐渐变差,晶粒尺寸降低;薄膜光学带隙在2.04～2.3 eV之间,且随着沉积压力的提高而增加;薄膜具有SiH、SiO、SiH2和SiH3振动吸收峰, 随着沉积压力的增加,SiH、SiH2振动吸收峰向高波数移动,薄膜方块电阻在132～96 Ω/□,且随着沉积压力的升高而降低.     

热丝化学气相沉积微晶硅薄膜结构及性质研究

采用热丝化学气相沉积(HWCVD)技术,以钨丝作为热丝,在不同热丝温度和氢稀释度下,分别在玻璃和单晶硅片衬底上沉积微晶硅(μc-Si∶H)薄膜材料.对所制备的微晶硅薄膜材料使用XRD、傅里叶变换红外吸收光谱、透射谱等进行结构与性能的表征分析.结果表明,随着热丝温度升高,氢稀释度变大,薄膜呈现明显的(220)择优生长取向,晶粒尺寸逐渐增大,光学吸收边出现红移,光学带隙逐渐变小.通过优化沉积参数,在热丝温度为1577℃、氢稀释浓度为95.2;、衬底温度为350℃,沉积速率为0.6 nm/s和沉积气压8 Pa条件下,制备的微晶硅薄膜呈现出了(220)方向的高度择优生长取向,平均晶粒尺寸为146 nm,光学带隙约为1.5 eV,光电导率σ.为3.2×10-6Ω-1·cm-1,暗电导率σrd为8.6×10-7 Ω-1·cm-1,表明制备的材料是优质微晶硅薄膜材料.     

6H-SiC衬底上多晶Si薄膜热壁CVD间隔生长与结构表征

在热壁LPCVD系统中利用间隔生长法在6H-SiC衬底上淀积Si薄膜,采用XRD、SEM、激光共聚焦显微镜和拉曼光谱对Si薄膜的表面形貌和结构进行表征.结果表明:相比于连续生长法,用间隔法制备Si薄膜的速率有所降低,但表面粗糙度有所减小,同时晶粒尺寸也增大.XRD测试结果表明:间隔法可以控制薄膜生长的择优取向.Raman光谱测试结果表明:采用间隔法且断源时间控制在30 s时,生长温度900℃,H2∶ SiH4 =400∶20 sccm时生长Si薄膜的Raman半峰宽最小.     

射频功率对富硅-氮化硅薄膜结构及性质影响

采用等离子体增强化学气相沉积法,以SiH4、NH3和N2为反应气源,通过改变射频功率制备富硅-氮化硅薄膜材料.利用傅里叶变换红外吸收光谱,紫外-可见光透射光谱,扫描电镜等对薄膜材料结构与性质进行表征.实验表明,随着射频功率的逐渐增加,薄膜光学带隙缓慢减小、有序度增加,薄膜材料中的Si-H键、N-H键缓慢减小,Si-N键增多.分析结果发现,适量的增加射频功率有利于提高样品反应速率,使薄膜有序度增加,致密性增强,提高薄膜质量,但过高的射频功率会使薄膜质量变差.     

Fabrication of Er doped oxyfluoride-silicate glass film by pulsed laser deposition for planar amplifier

Pulsed laser deposition (PLD) technique has been employed to fabricate glassy films based on the Er³⁺ doped oxyfluoride lead-silicate glasses. Glassy films have been produced at temperatures between 300 and 400 °C with O₂ pressures ranging from 25 to 175 mTorr. The film microstructure appears to be determined mainly by substrate temperature. The film refractive index increases with higher temperatures and lower O₂ pressures. The photoluminescence intensity of Er³⁺ ions and lifetime are very much dependent on the film microstructure and defects. Fewer fabrication defects and less porous films produce stronger fluorescence intensity and longer lifetime of Er³⁺ ions. At an optimized temperature and O₂ pressure, the Er photoluminescence properties of the film can be reproduced and are very close to those of target glass. Consequently the work reported here suggested a good candidate for further investigation as a thin film material for EDWA.     

In‐situ measurements of mass transport rate in vapour growth of hexamethylenetetramine crystal layers

This paper refers to the implementation of a remote optical imaging system suitable for in‐situ mass transport rate measurements in the growth of crystalline layers when grown in closed cylindrical ampoules by a physical vapour transport (PVT) technique. By means of this system, the measurements are carried out by taking photographs, at regular time intervals, of the source material volume as it reduces itself because of mass transfer. After storing the photographs, in real time, in a PC, a suitable software allows to estimate the mass transport rate during the growth process. The authors report here on the detailed setting up of such system when aimed at measuring the growth rate, as it varies with time, of hexamethylenetetramine (HMT, urotropine) crystal layers. A presentation and discussion of the results of these measurements have previously been reported. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of hydrogen on SiO2 thick film deposited by PECVD and FHD for silica optical waveguide

Silicon dioxide (SiO₂) thick films have been deposited by plasma enhanced chemical vapor deposition (PECVD) and flame hydrolysis deposition (FHD). PECVD SiO₂ films were obtained at low temperatures (<350 °C) by the decomposition of the appropriate mixture of (SiH₄+N₂O) gases under suitable rf power and N₂O/SiH₄ ratio. For low N₂O/SiH₄ ratio, a refractive index(n) value close to 1.50 is obtained. The deposition rate increased with the increase of rf power. FHD SiO₂ films were produced by the flame hydrolysis reaction of halide materials such as SiCl₄, POCl₃ and BCl₃ in an oxy‐hydrogen torch. The porous SiO₂ layer, under the POCl₃/BCl₃ ratio deposition condition, has to be consolidated by annealing at around 1300 °C.     

化学气相沉积法制备二维过渡金属硫族化合物研究进展

二维过渡金属硫族化合物(TMDs)是继石墨烯之后的新型二维材料,由于其自身的独特物理化学性质在半导体、光电材料、能源储存和催化制氢等方面备受瞩目。化学气相沉积(CVD)是目前适合实现大规模制备二维材料的工艺之一,制备过程中参数的高度可控性使其具有很大优势。本文综述了近期通过CVD制备TMDs的研究进展,探讨了在CVD制备工艺中各种参数对产物生长和最终形貌的影响,包括前驱体、温度、衬底、辅助剂、压力和载气流量等。列举了一些改进的CVD制备工艺,并对其特点进行了总结。最后讨论了目前CVD制备TMDs所面临的挑战并对其发展前景进行展望。     

气相输运沉积制备化合物薄膜材料的研究进展

相比用于制备晶体材料的化学气相输运(Chemical Vapor Transport,CVT)方法,近空间气相输运沉积(Close-spaced Vapor Transport Deposition,CSVT)及气相输运沉积(Vapor Transport Deposition,VTD)方法不为人们所熟知.近几年来,气相输运沉积逐渐应用于锑基薄膜(Sb2 Se3、Sb2 S3及Sb2(Se,S)3)、锡基薄膜(SnS、SnS2)及铋基薄膜(Bi2 Se3、Bi2 Te3)等材料的制备,有可能成为一种重要的材料制备方法.本文综述了气相输运沉积用于化合物薄膜制备的研究进展,对其特点进行分析,并对其发展趋势进行了展望.     

The pentacene films on the glass/ITO surface: structure and optical properties

Abstract

The structure, morphology and optical transmittance spectra of pentacene films on the (glass/ITO) surface were studied. The films were grown by two methods - the thermal vacuum deposition (TVD) and pulsed laser deposition (PLD). The electron diffraction pattern from thermally deposited pentacene films confirms their polycrystalline structure while the diffraction pattern of PLD-coated layers has a diffusion character. The results obtained showed that layers deposited by the TVD method has an optical spectrum that is characteristic for the pentacene film in contrary to the layers deposited by the PLD method. It is found a sensitivity of the optical transmittance of pentacene films to the ammonia action, which may be used for development the optical gas sensor.     

Light structured deposition (2): Material optical functionality

Aspherical refractive optical elements have been fabricated by an original light-assisted approach for deposition of semiconducting alloys. The fabrication of axicons by this method is reported for the case of an As–S binary glass alloy. The influence of both light intensity and exposure time on the deposit thickness profile is also presented.     

KTiOAsO4 Thin Films Prepared by Pulsed Laser Deposition

A pulsed Nd:YAG Laser was used to evaporate solid targets of KTiOAsO₄ (KTA) at power densities of 0.6 to 2.0x10⁹ W/cm². KTA thin films were deposited on glass, Si (100). After proper annealing treatment, single phase, (orthorh-ombic) polycrystalline KTA thin films were obtained. Some propitious of these thin films were also examined.     

纳米金刚石场发射阴极制备及性能研究

为了提高阴极场发射的均匀性与稳定性,探索了一种电泳沉积纳米金刚石场发射的阴极工艺.在这个工艺中,研制了特定比例的纳米金刚石电泳液,在抛光的金属钛衬底上通过电泳沉积了纳米金刚石场发射阴极.用扫描电子显微镜和拉曼光谱观察了涂层的形貌和结构,并测试了制备的涂层阴极的场发射特性.实验结果表明,在钛片上沉积的金刚石涂层薄而均匀.采用电泳方法制备场发射阴极具有简单易行,成本低廉以及可大面积制作等优势,可在平板显示器中得到广泛应用.