掺硼nc-Si:H薄膜中纳米硅晶粒的择优生长

利用等离子体增强化学气相沉积(PECVD)生长的系列掺硼氢化纳米硅(nc-Si:H)薄膜中纳米硅晶粒(nanocrystallinesilicon,简称nc-Si)有择优生长的趋势。用HRTEM、XRD、Raman等方法研究掺硼nc-Si:H薄膜的微观结构时发现:掺硼nc-Si:H薄膜的XRD只有一个峰,峰位在2θ≈47o,晶面指数为(220),属于金刚石结构。用自由能密度与序参量的关系结合实验参数分析掺硼nc-Si:H薄膜择优生长的原因是:适当的电场作用引起序参量改变,导致薄膜在适当的自由能范围内nc-Si的晶面择优生长。随着掺硼浓度的增加,nc-Si:H薄膜的晶态率降低并逐步非晶化。nc-Si随硅烷的稀释比增加而长大,但晶态率降低。nc-Si随衬底温度升高而长大,晶态率提高。nc-Si随射频功率密度的增大而长大,晶态率增大的趋势平缓。但未发现掺硼浓度、稀释比、衬底温度、射频功率密度的变化引起薄膜中nc-Si晶面的择优生长。     

类金铡石薄膜内应力的测试

采用射频－直流等离子增强化学气相沉积法制备出类金刚石薄膜，用弯曲法测定薄膜的内应力。类金刚石薄膜中存在１－４．７ＧＰａ的压应力，沉积工艺对薄膜的内应力有很大影响，薄膜的内应力随极板负偏压的升高而降低，随Ｃ２Ｈ２气体一的增加而增大。     

溅射条件下对FeSiB薄膜磁性及巨磁阻抗效应的影响

采用射频磁控溅射法,在不同溅射条件下制备了ＦｅＳｉＢ薄膜。研究了溅射条件下对薄膜应力、磁滞回线及磁阻抗效应的影响。结果表明：随着溅射氩气压强的增加,薄膜内应力从压应力变为张应力,磁滞回线的形状随溅射条件下的不同也发生改变。对磁各向异性的变化作了分析和讨论,而面内横向单轴磁各向异性的重要性在磁阻抗效应的实验中充分得到了体现。     

纳米硅薄膜的镜反射红外光谱研究

研究探讨了镜反射红外光谱在纳米材料方面的应用。通过等离子化学气相沉积法(PECVD)，制备本征和掺磷的纳米硅薄膜(nc-Si：H)，利用镜反射红外光谱研究了本征和掺磷的纳米硅薄膜的光谱特征。通过实验，发现这两种薄膜中都存在多氢键合方式，PECVD工艺参数如衬底温度、直流电压和掺杂浓度对薄膜结构具有一定的影响。     

基片与膜厚对硬质薄膜力学性能的影响

采用毫牛力学探针技术的两步压入试验法研究了高速钢和不锈钢基片上不同厚度TiN薄膜的硬度和弹性模量。结果表明：采用同样工艺制备的TiN薄膜，其力学性能随基片类型和膜厚的不同有明显变化。薄膜的硬度和弹性模量随膜厚的增加而提高；基体硬度的提高也使薄膜呈现较高的硬度和模量。分析认为薄膜内应力状态的改变是产生这些现象的主要原因。     

溅射条件对FeSiB薄膜磁性及巨磁阻抗效应的影响

采用射频磁控溅射法,在不同溅射条件下制备了FeSiB薄膜。研究了溅射条件对薄膜应力、磁滞回线及巨磁阻抗效应的影响。结果表明:随着溅射氩气压强的增加,薄膜内应力从压应力变为张应力,磁滞回线的形状随溅射条件的不同也发生改变。对磁各向异性的变化作了分析和讨论,而面内横向单轴磁各向异性的重要性在巨磁阻抗效应的实验中充分得到了体现。     

类金刚石薄膜内应力的测试

采用射频-直流等离子增强化学气相沉积法制备出类金刚石薄膜,用弯曲法测定薄膜的内应力。结果表明,类金刚石薄膜中存在1～4.7GPa的压应力,沉积工艺对薄膜的内应力有很大的影响,薄膜的内应力随极板负偏压的升高而降低,陆C_2H_2气体含量的增加而增大。     

在Si基底上真空蒸发沉积Ag-MgF2复合薄膜的内应力研究

报道了用电子薄膜应力分布测试仪测量了不同温度、不同厚度的Ag-MgF2复合薄膜的内应力变化情况，得到了基底温度(退火温度)在300～400℃范围内薄膜平均应力最小，且处于张应力向压应力转变区城。XRD分析表明，在Ag-MgF2复合薄膜中Ag对复合薄膜内应力的影响大于MgF2。     

氮化硅介质薄膜内应力的实验研究

研究了等离子体增强化学气相沉积氮化硅介质薄膜的内应力。采用钠光平面干涉测量了氮化硅薄膜内应力,通过改变薄膜沉积时的工艺参数,考察了反应气体流量化、沉积温度、射频功率密度等因素对氮化硅薄膜内应力的影响。在此基础上,对氮化硅介质薄膜本征应力的形成机制进行了分析讨论。     

PECVD法沉积氢化非晶硅薄膜内应力的研究

利用等离子体增强化学气相沉积技术在硅基底上沉积了氢化非晶硅(α-Si:H)薄膜,通过纳米压入仪、电子薄膜应力分布仪、傅里叶变换红外光谱仪等表征技术,研究了沉积时的工艺参数(射频功率、沉积温度、工作压强)对薄膜内应力的影响,对薄膜的本征应力、热应力进行分析,并探讨了射频功率对薄膜红外吸收光谱的影响。研究结果表明,提高射频功率能够使薄膜从张应力转变为压应力,且压应力随射频功率的增大而增大;提高工作压强能够使薄膜从压应力转变为张应力;应力随沉积温度的升高而增大;薄膜中氢含量、SiH组态、SiH2组态含量随射频功率的增大而增大。通过优化工艺,得到了沉积具有较小张应力薄膜的工艺参数(射频功率30W,沉积温度250℃,气体流量80cm3/min(标准状态),工作压强67Pa),并将其成功应用于非晶硅薄膜自支撑悬空结构。     

复合光导层液晶光阀的研究

介绍了一种具有柱状结构的a-Si：H／nc—Si复合光导层的液晶光阀，复合光导层是通过热蒸发和等离子体辉光放电沉积方法，采用Al诱导a-Si：H制成的。经过测试，这种柱状结构薄膜具有电导各向异性，其横向电导率小于纵向电导率。用这种薄膜制成的液晶光阀其分辨率达到5001p／inch。     

PECVD非晶SiOx∶H薄膜的Si—O—Si键红外吸收特性研究

用傅里叶红外光谱(FT-IR)测试分析了等离子体化学气相沉积法沉积的非晶SiOx∶H(0≤x≤2.0)薄膜中的Si—O—Si伸缩振动模与氧含量x的关系。Si—O—Si伸缩振动模在1000和1150cm     

Growth characteristics of nanocrystalline silicon films fabricated by using chlorinated precursors at low temperatures

We employed plasma enhanced chemical vapor deposition technique to fabricate nanocrystalline Si films at a low temperature of 250 degrees C by using SiCl4 and H2 as source gases. The evolution of microstructure of the films with deposition periods shows that nanocrystalline Si can be directly grown on amorphous substrate at the initial growth process, which is in contrast to the growth behavior observed in the SiH4/H2 system. Furthermore, it is interesting to find that the area density of nanocrystalline Si as well as grain size can be controlled by modulating the concentration of SiCl4. By decreasing the SiCl4 concentration, the area density of nanocrystalline Si can be enhanced up to 10(11) cm(-2), while the grain size is shown to decrease down to 10 nm. It is suggested that Cl plays an important role in the low-temperature growth of nanocrystalline Si.     

掺Si对MOCVD生长的GaN单晶膜的黄带发射及生长速率的影响

对ＭＯＣＶＤ生长ＧａＮ：Ｓｉ薄膜进行了研究,研究表明随ＳｉＨ４／ＴＭＧａ流量比增大,ＧａＮ：Ｓｉ单晶膜的电子浓度增大,迁移率下降,Ｘ射线双晶衍射峰半高宽增加,同时这发射强度得到了大大的提高,并报导了随ＳｉＨ４／ＴＭＧａ流量比增大,ＧａＮ：Ｓｉ的生长速率降低的现象,研究结果还表明,预反应对ＧａＮ：Ｓｉ单晶膜黄带发射影响很大,预反应的减小可以使黄带受到抑制。     

Stress and crystallization of plasma enhanced chemical vapour deposition nanocrystalline silicon films

Nanocrystalline Si films were prepared with a RF-PECVD system using different SiH4/H2 ratios, plasma powers, substrate temperatures and annealing conditions. The film's intrinsic stress was characterized in relation to the crystallization fraction. Results show that an increasing H2 gas ratio, plasma power or substrate temperature can shift the growth mechanism across a transition point, past which nanocrystalline Si is dominant in the film structure. The film's intrinsic stress normally peaks during this transition region. Different mechanisms of stress formation and relaxation during film growth were discussed, including ion bombardment effects, hydrogen induced bond-reconstruction and nanocomposite effects (nanocrystals embedded in an amorphous Si matrix). A three-parameter schematic plot has been proposed which is based on the results obtained. The film structure and stress are presented in relation to SiH4 gas ratio, plasma power and temperature.     

Deposition of amorphous hydrogenated carbon films on Si and PMMA by pulsed direct-current plasma CVD

A pulse-modulated direct-current methane plasma is used to deposit amorphous hydrogenated carbon (a-C:H) films on Si and polymethyl methacrylate (PMMA) substrates. The structure and mechanical properties of the films are examined by applying a negative pulse bias voltage of 0.5 to 3 kV to the substrate at a pulse bias period of 100 to 200 μs. The deposition rate on both Si and PMMA increases with increasing the net input power, independent of the pulse period. The Raman spectra demonstrate that the films on Si are diamond-like carbon (DLC), while those on PMMA are polymer-like or soft amorphous carbon because of higher crystallinity of the sp² phase and lower nanoscale hardness. The residual compressive stress of the films on PMMA is constantly low ranging from 0 to 2 GPa due exclusively to high flexibility of PMMA, which causes the easy relief of the stress and thus the density decrease in the films.     

热丝CVD法低温制备的多晶硅薄膜质量对衬底依赖性的研究

以SiH4和H2作为反应气体,采用HWCVD的方法分别在石英玻璃、AZO、Si（100）和Si（111）衬底上制备了多晶硅薄膜。利用X射线衍射（XRD）,拉曼（Raman）光谱和傅里叶红外（FT-IR）吸收光谱研究了不同衬底对多晶硅薄膜的择优取向、晶化率和应力的影响,用SEM观察了多晶硅薄膜的表面形貌。研究发现在4种衬底上生长的多晶硅薄膜均为（111）择优取向。单晶硅片对多晶硅薄膜有很强的诱导作用,并且Si（111）的诱导作用优于Si（100）的诱导作用。AZO对多晶硅薄膜生长也有一定的诱导作用。通过计算薄膜晶态比,得到除以石英为衬底的样品外,其它3种样品的晶态比均在90%以上,尤其以单晶硅片为衬底的样品更高。石英玻璃、AZO和Si（100）上生长的多晶硅薄膜中均存在压应力。     

电感耦合等离子体CVD室温制备的硅薄膜的结构研究

用内置式单圈电感耦合等离子体化学气相沉积(ICP-CVD)方法在室温下制备Si薄膜.用傅里叶红外吸收光谱、喇曼光谱、原子力显微镜和分光椭圆偏振谱等测量分析表明,即使在室温下用ICP-CVD也获得了有纳米结晶相的Si薄膜,样品结构与源气体SiH4浓度密切相关.实验结果预示着在高电子密度的ICP-CVD过程中,活性原子集团的形成以及薄膜的生长机理与传统的等离子体CVD过程不同.     

残余应力对SrRuO3薄膜磁学及电输运性能的影响

采用射频磁控溅射法在单晶SrTiO₃ (STO)衬底和硅(Si)衬底上制备出不同取向的SrRuO₃ (SRO)薄膜, 对薄膜的残余应力进行了分析, 并研究了应力对不同取向SRO薄膜磁学性能与电输运特性的影响。根据X射线衍射(XRD)结果分析可知, Si基SRO薄膜为多晶单轴取向薄膜, 且应力来源主要为热失配拉应力; STO基SRO薄膜为外延薄膜, 其应力主要为热失配压应力和外延压应力; 磁学性能测试表明, (001)取向SRO薄膜比(110)取向薄膜拥有更高的居里温度T_C; 压应力提高了(001)取向SRO薄膜的T_C, 却降低了(110)取向薄膜的T_C。电阻性能测试表明, 对于在同种类型衬底上沉积的SRO薄膜, (001)取向的薄膜的剩余表面电阻比(RRR)高于(110)取向的薄膜。另外, 拉应力引起了薄膜微结构的无序度增加, 弱化了表面电阻率的温度依赖性, 提高了金属绝缘体转变温度(T_MI)。     

Influence of RF power on structural optical and electrical properties of hydrogenated nano-crystalline silicon (<Emphasis Type="Italic">nc</Emphasis>-Si:H) thin films deposited by PE-CVD

We report synthesis of hydrogenated nanocrystalline silicon (nc-Si:H) thin films by using conventional plasma enhanced chemical vapor deposition (PE-CVD) system from gas mixture of pure silane (SiH₄) and hydrogen (H₂). We investigated the effect of RF power on structural, optical and electrical properties using various characterization techniques including Raman spectroscopy, FTIR spectroscopy, UV–visible spectroscopy etc. Low angle XRD and Raman spectroscopy analysis revealed that the RF power in PE-CVD is a critical process parameter to induce nanocrystallization in Si:H films. The FTIR spectroscopy analysis results indicate that with increase in RF power the predominant hydrogen bonding in films shifts from Si–H to Si–H₂ and (Si–H₂)_n bonded species bonded species. However, the bonded hydrogen content didn’t show particular trend with change in RF power. The UV–visible spectroscopy analysis shows that the band tail width (E₀₄–E_Tauc) with increase in RF power. The defect density and Urbach energy also increases with increase in RF power. The highest dark conductivity (and lowest charge carrier activation energy) was obtained for the film deposited at RF power of 125 W indicating that 125 W is optimized RF power of our PE-CVD unit. At this optimized RF power nc-Si:H films with crystallite size ~3.7 nm having good degree of crystallinity (~86.7 %) and high band gap (E_Tauc ~ 2.01 eV and E₀₄ ~ 2.58 eV) were obtained with a low hydrogen content (6.2 at.%) at moderately high deposition rate (0.24 nm/s).