铝诱导纳米硅制备大晶粒多晶硅薄膜的研究

本文以超白玻璃为衬底,利用热丝化学气相沉积和磁控溅射法制备了Glass/nc-Si/Al的叠层结构,然后置于管式退火炉中在H2气氛下进行5h诱导晶化,用XRD、光学显微镜、扫描电镜和拉曼光谱对样品进行了表征.结果表明所有样品都是有(111)择优取向的多晶硅薄膜,在425℃诱导时,多晶硅晶粒尺寸最大达400 μm,但薄膜不连续;随着诱导温度升高到450℃,样品表面已形成了连续的多晶硅薄膜,但晶粒尺寸有所减小;475℃下诱导获得的最大晶粒尺寸约为200μm,此时多晶硅薄膜的结晶质量更好.还从动力学的角度分析了铝诱导纳米硅的晶化机理.     

PECVD法制备不同衬底微晶硅薄膜的研究

采用等离子体增强化学气相沉积(PECVD)法分别在玻璃衬底和p型薄膜硅衬底上制备了微晶硅薄膜。使用拉曼谱仪、紫外-可见分光光度计、傅里叶红外光谱仪等对微晶硅薄膜进行检测,重点研究了硅烷浓度、衬底温度对薄膜沉积速率和晶化率的影响。实验结果表明:两种衬底上薄膜的沉积速率均随硅烷浓度的增大、衬底温度的升高而变大。硅烷浓度对两种衬底的薄膜晶化率影响规律相同,即均随其升高而降低;但两种衬底的衬底温度影响规律存在差别:对玻璃衬底而言,温度升高,样品晶化率减小;而p型薄膜硅衬底则在温度升高时,样品晶化率先增大后减小。此外还发现,晶化率与薄膜光学性能及含氧量存在较密切关联。     

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.     

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℃.     

基于PECVD制备多晶硅薄膜研究

基于PECVD以高纯SiH4为气源研究制备多晶硅薄膜,在衬底温度550℃、射频(13.56MHz)电源功率为20W直接沉积获得多晶硅薄膜.采用X射线衍射仪(XRD) 和场发射扫描电子显微镜(SEM) 对多个样品薄膜的结晶情况及形貌进行分析,薄膜结晶粒取向均为<111>、<220>、<311>晶向.对550℃沉积态薄膜在900℃、1100℃时进行高温退火处理,硅衍射峰明显加强.结果表明,退火温度越高,退火时间越长,得到多晶硅薄膜表面晶粒趋于平坦,择优取向为<111>晶向,晶粒也相对增大.     

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.     

用快速光热退火制备多晶硅薄膜的研究

用等离子体增强型化学气相沉积先得到非晶硅(a-Si:H)薄膜,再用卤钨灯照射的方法对其进行快速光热退火(RPTA),得到了多晶硅薄膜.然后,进行XRD衍射谱、暗电导率和拉曼光谱等的测量.结果发现,a-Si:H薄膜在RPTA退火中,退火温度在750℃以上,晶化时间需要2min,退火温度在650℃以下,晶化时间则需要2.5h;晶化后,晶粒的优先取向是(111)晶向;退火温度850℃时,得到的晶粒最大,暗电导率也最大;退火温度越高,晶化程度越好;退火时间越长,晶粒尺寸越大;光子激励在RPTA退火中起着重要作用.     

Ge覆盖层诱导晶化多晶Si薄膜的晶化特性研究

采用电子束蒸发技术在衬底温度为180℃条件下生长具有Ge覆盖层的非晶Si薄膜,并于500℃、600℃、700℃真空退火5h.采用Raman散射、X射线衍射(XRD)、全自动数字式显微镜等对所制备薄膜的晶化特性进行研究.结果表明,Ge覆盖层具有诱导非晶Si薄膜晶化的作用,且随着退火温度的升高a-Si薄膜晶化越显著.具有Ge覆盖层非晶薄膜经500℃退火5h沿Si(400)方向开始晶化,对应晶粒尺寸约为4.9 nm.将退火温度升高到700℃时,非晶硅薄膜几乎全部晶化,晶化多晶Si薄膜在Si(400)方向表现出很强的择优取向特性,晶粒尺寸高达23.3μm.与相同条件下制备的无Ge覆盖层的非晶Si薄膜相比,晶化温度降低了300℃.     

灯丝温度对热丝CVD法制备p型氢化纳米晶硅薄膜微结构与光电性能的影响

本文采用热丝化学气相沉积法在不同灯丝温度(1650 - 1850℃)下沉积了p型氢化纳米晶硅薄膜,研究了灯丝温度对薄膜微结构、光学性能及电学性能的影响.结果表明,随着灯丝温度的升高,薄膜的晶化率先增大后略微减小,最大值是55.5;.载流子浓度和霍尔迁移率先分别从5×1017 cm-3和0.27 cm2/V·s增加到1.32×1020 cm-3和0.43 cm2/V·s后略微减小,同时电导率从0.02 S/cm显著增加到8.95 S/cm,而电导激活能则从271.5 meV急剧减小至25 meV.     

衬底温度对微晶硅薄膜微结构的影响

采用等离子体化学气相沉积(RF-PECVD)技术,在不同衬底温度Ts下沉积了氢化微晶硅(μc-Si:H)薄膜,并深入研究了衬底温度对微晶硅薄膜微结构的影响.研究结果表明随着衬底温度的升高,表征μc-Si:H 薄膜微结构的晶化率和平均晶粒尺寸均呈现了相似的变化规律,其临界温度点随着硅烷浓度的增加向高温方向移动.该实验结果可通过"表面扩散模型"得到合理解释.     

等离子体增强CVD法沉积的微晶硅薄膜的微结构研究

本文系统研究了PECVD法沉积μc-Si薄膜中衬低温度、氢气稀释率和射频功率等参数对μc-Si薄膜结构特性的影响.表明:随着衬低温度的增加、氢气稀释率的增大、射频功率的提高,薄膜的晶化率增大.沉积薄膜的晶化率最大可达80;,表面粗糙度大约为30nm.通过对反应过程中的能量变化进行了分析,得到反应为放热反应,且非晶结构对沉积参数比较敏感.     

Photocatalytic TiO2 films prepared by chemical vapor deposition at atmosphere pressure

Nanometer semiconductor titanium dioxide thin films have excellent properties of photocatalysitic degeneration. The glass coated TiO₂ films is called self-cleaning glass. In this paper, chemical vapor deposition (CVD) method is employed to deposit TiO₂ films on glass. The effect of spacing between nozzle and glass and the effect of substrate temperature on deposition rate are studied. The crystalline structure at different deposition temperatures is analyzed by XRD and anatase was found. And the microstructure of the TiO₂ films is also determined by SEM. It shows that the size of crystal grain increases with the temperature.     

Transition between amorphous and crystalline phases of SiC deposited on Si substrate using H3SiCH3

This paper presents a study of the transition between amorphous and crystalline phases of SiC films deposited on Si(1 0 0) substrate using H₃SiCH₃ as a single precursor by a conventional low-pressure chemical vapor deposition method in a hot-wall reactor. The microstructure of SiC, characterized by X-ray diffraction and high-resolution transmission electron microscopy, is found to vary with substrate temperature and H₃SiCH₃ pressure. The grain size decreases with increasing MS pressure at a given temperature and also decreases with reducing temperature at a given MS pressure. The deposition rates are exponentially dependent on the substrate temperature with the activation energy of around 2.6 eV. The hydrogen compositional concentration in the deposited SiC films, determined by secondary ion mass spectrometry depth profiling, is only 2.9% in the nanocrystalline SiC but more than 10% in the amorphous SiC, decreasing greatly with increasing deposition temperature. No hydride bonds are detected by Fourier transform infrared spectroscopy measurements. The chemical order of the deposited SiC films improves with increasing deposition temperature.     

Raman study of gallium arsenide thin films

The influence of deposition parameters on the structure of the gallium arsenide thin films was investigated by Raman scattering. The study was based on the analysis of the first-order Raman spectra which allows for a differentiation between the amorphous component and crystallites of various sizes. The amorphous and crystalline volume fractions were calculated from the integrated intensities of the deconvoluted peaks. It was demonstrated that a transition occurs from μ-GaAs to a-GaAs for particular plasma conditions and substrate temperature. As a function of the deposition parameters the entire range from mostly microcrystalline to completely amorphous films can be obtained. These properties were consistent with the results obtained on the same samples by transmission high-energy electron diffraction and conventional transmission electron microscopy.     

Simulation of temperature and gas density field distribution in diamond films growth on silicon wafer by hot filament CVD

In the present study, the temperature and gas density field inside the hot filament chemical vapor deposition (HFCVD) reactor, which play a determinate role on the growth rate and quality of as-deposited diamond films, are simulated using the finite volume method, and the influence of the size and arrangement of filaments and inlets are investigated. Firstly, the correctness of the simulation model is verified by comparing the temperature data obtained from the simulation with that measured in an actual depositing process, and the results show that the error between them is less than 3%. Thereafter, the deposition parameters are optimized using this model as N(filament number)=6, r(filament radius)=0.4 mm, D(filament separation)=16–18 mm, H(substrate–filament distance)=8–9 mm, and 25 inlets. Finally, diamond films are deposited on silicon (100) wafers using above parameters and the results of characterization by SEM and Raman spectrum exhibit that the deposited diamond films appear homogeneous surface with fine-faceted crystals.     

硅基底上生长金刚石层细晶粒的研究

金刚石/硅声表面波基片的金刚石层晶粒的细化有利于传播损耗的降低,本文采用热丝化学气相沉积法进行了硅基体上沉积细晶粒金刚石工艺的初步探索.探讨了基体温度、气压、氩气和甲烷浓度等因素对金刚石细晶粒生长的影响.对相应样品进行了扫描电镜和拉曼散射谱分析.结果表明:在低气压范围,相同氩气浓度,随着气压的降低,甲烷浓度也要相应降低,能保证金刚石结晶质量.同时,降低气压达到一定值后,金刚石晶粒尺寸变小,经测试可达到纳米级.     

Temperature gradient induced phase transitions and morphological changes in diamond thin film

The diamond films were deposited onto a wurtzite gallium nitride (GaN) thin film substrate using hot-filament chemical vapor deposition (HFCVD). During the film deposition a lateral temperature gradient was imposed across the substrate by inclining the substrate. As grown films predominantly showed the hexagonal phase, when no inclination was applied to the substrate. Tilting the substrate with respect to the heating filament by 6° imposed a lateral temperature gradient across the substrate, which induced the formation of a cubic diamond phase. Diamond grains were predominantly oriented in the (100) direction. However, a further increase in the substrate tilt angle to 12°, resulted in grains oriented in the (111) direction. The growth rate and hence the morphology of diamond grains varied along the inclined substrate. The present study focuses on the measurements of dominant phase formation and crystal orientation with varying substrate inclination using orientation-imaging microscopy (OIM). This technique enables direct examination of individual diamond grains and their crystallographic orientation.     

衬底温度对氧化锌薄膜微结构及光学性能的影响

衬底温度是磁控溅射法制备氧化锌薄膜中一个非常重要的工艺指标,探索衬底温度对氧化锌薄膜微结构及光学性能的影响对制备环保型高质量氧化锌紫外屏蔽材料具有重要意义。以质量分数99.99%的氧化锌陶瓷靶为溅射源,利用射频磁控溅射技术在石英衬底上沉积了氧化锌紫外屏蔽薄膜,通过X射线衍射仪、薄膜测厚仪、紫外-可见分光光度计、荧光分光光度计进行测试和表征,研究了不同衬底温度对ZnO薄膜微结构及光学性能的影响。实验结果表明:制备所得薄膜均为六角纤锌矿结构,具有沿(002)晶面择优取向生长的特点,其晶格常数、晶粒尺寸、透过率、光学能隙、可见荧光、结晶质量等都与衬底温度密切相关,当衬底温度为250 ℃,溅射功率160 W,氩气压强0.5 Pa,氩气流速8.3 mL/min,沉积时间60 min时,所得氧化锌薄膜样品取向性最好,晶粒尺寸最大,薄膜结构致密,具有良好的光学性能和结晶质量。     

PECVD低温制备微晶硅薄膜的研究

实验采用等离子体增强化学气相沉积(PECVD)法在玻璃衬底上制备了微晶硅薄膜.研究了氢稀释比、衬底温度、射频功率等因素对薄膜晶化的影响,得出在一定范围内随着衬底温度的升高、射频功率和氢稀释比的增大,薄膜的晶化率得到提高;但进一步提高沉积温度、射频功率反而会使薄膜晶化效果变差,并对晶化硅薄膜低温生长的机理进行了初步的探讨.