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1.
本文对在抛光铜衬底上通过填隙法制备的高质量石墨烯薄膜进行了详细研究。在电化学机械抛光后的铜衬底上制备石墨烯晶畴,降低了晶畴的成核密度。利用光学显微镜和扫描电子显微镜对抛光铜衬底和未抛光铜衬底上制备的石墨烯晶畴进行测试,测试结果表明,铜衬底的表面形态对于降低石墨烯的成核密度,增大石墨烯晶畴的尺寸起到了至关重要的作用。利用拉曼面扫描证明了所制备的石墨烯晶畴为单层、均匀的石墨烯晶畴。然后,通过填隙法在抛光铜衬底上制备出由大尺寸单层的六边形石墨烯晶畴组成的石墨烯连续薄膜,并且通过流程示意图解释了填隙法制备高质量石墨烯薄膜的过程。本文所提出的在抛光铜衬底上通过填隙法制备石墨烯薄膜的技术,能够有效提高石墨烯薄膜的质量,进而有效改善石墨烯基电子器件的性能。 相似文献
2.
本文报导以固态聚苯乙烯为碳源,经机械抛光和电化学抛光双重处理的铜箔为衬底,用CVID法进行石墨烯可控生长的研究结果.用光学显微镜、原子力显微镜、拉曼光谱、光透射谱、扫描隧道显微镜和场发射扫描电镜对生长的石墨烯进行了表征.研究发现经过抛光处理的铜箔由于其平整的表面和很低的表面粗糙度,在其上生长的石墨烯缺陷少,结晶质量高.而未经抛光处理的铜箔在石墨烯生长过程中,铜箔不平整的表面台阶会破坏其上生长的石墨烯的微观结构,在生长的石墨烯二维结构中产生高密度晶界和缺陷.还在双重抛光处理的铜箔上实现了石墨烯的层数可控生长,结果表明固态碳源聚苯乙烯的量为15 mg时可生长出单层石墨烯,通过控制固态源重量得到了1~5层大面积石墨烯. 相似文献
3.
In 2Se 3二维层状材料具有优异的光电、热电和铁电特性。目前In 2Se 3二维层状材料大部分通过对化学气相输运(CVT)法制备的块体In 2Se 3进行机械剥离获得,CVT法制备工艺复杂、制备时间长、成本高,与之相比,布里奇曼(B-S)法具有制备工艺简单、制备效率高、成本低的优势。为此,本文对CVT法和B-S法制备的块体In 2Se 3分别进行了机械剥离,并转移到SiO 2/Si(111)基底,获得了相应的二维层状In 2Se 3样品。同时利用原子力显微镜(AFM)、激光拉曼和X射线衍射(XRD)对两样品进行表面形貌、晶格振动谱和结晶质量的测量,发现用B-S法制备、剥离的样品具有与CVT法制备、剥离样品几乎相同的表面原子级平整度和单晶结晶质量。本文为高质量二维层状In 2Se 3材料的获得提供了更为经济实用的途径。 相似文献
4.
采用溶胶-凝胶法在Pt/Ti/SiO 2/Si衬底上成功制备了BiFe 1-xZn xO 3(BFZO)(x=0、2%、4%、6%)(摩尔分数)薄膜,并系统研究了Zn掺杂对BiFeO 3(BFO)薄膜结构、表面形貌、漏电流密度、铁电及铁磁性能的影响。XRD图谱显示,所有样品均为钙钛矿结构,无其他杂质相引入。扫描电子显微镜(SEM)测试表明,当Zn掺杂量(x)为4%时,BFZO薄膜表现出均匀的细晶粒和更高的密度,有助于改善漏电流密度。漏电流密度曲线表明,在300 kV/cm的电场下,BiFe 0.96Zn 0.04O 3薄膜的漏电流密度(J)最低为1.56×10 -6 A/cm 2,比纯BFO薄膜的低3个数量级。同时,BiFe 0.96Zn 0.04O 3薄膜在室温下表现出较大的剩余极化(2P r=20.91μC... 相似文献
5.
二维(2D)石墨烯具有原子层厚度,在电子器件中展示出突破摩尔定律限制的巨大潜力。目前,化学气相沉积(CVD)是一种广泛应用于石墨烯生长的方法,满足低成本、大面积生产和易于控制层数的需求。然而,由于催化金属(例如Cu)衬底一般为多晶特性,导致CVD法生长的石墨烯晶体质量相对较差。为此,通过高温退火工艺制备了Cu (111)单晶衬底,使石墨烯的初始成核过程得到了很好的控制,从而实现了厘米尺寸的高质量单晶石墨烯的制备。根据二者的晶格匹配关系,Cu (111)衬底为石墨烯生长提供了唯一的成核取向,相邻石墨烯成核岛的边界能够缝合到一起。单晶石墨烯具有高电导率,相较于原始多晶Cu上生长的石墨烯(1 415.7Ω·sq -1),其平均薄层电阻低至607.5Ω·sq -1。高温退火能够清洁铜箔,从而获得表面粗糙度较低的洁净石墨烯。将石墨烯用于场效应晶体管(FET),器件的最大开关比为145.5,载流子迁移率为2.31×10 3 cm 2·V -1·s -1。基于以上结果,相信本工作中... 相似文献
6.
利用高频感应加热化学气相沉积(HFCVD)工艺,以H2稀释的SiH4作为反应气体源,分别在n-(111)Si衬底上常规热生长的SiO2层、织构的SiO2层和纳米晶粒多晶Si薄膜表面上,制备了具有均匀分布的大晶粒多晶Si膜.采用扫描电子显微镜(SEM)和X射线衍射(XRD)等检测手段,测量和分析了沉积膜层的表面形貌、晶粒尺寸、密度分布与择优取向等结构特征.结果表明,多晶Si膜中Si晶粒的尺寸大小和密度分布不仅与衬底温度、SiH4浓度与反应气压等工艺参数有关,而且强烈依赖于衬底的表面状态.本实验获得的最好的薄膜中,Si晶粒平均尺寸约为2.3 μm,密度分布约为3.8×107/cm2.对薄膜的沉积机理分析表明,衬底表面上Si原子基团的吸附、迁移、成核与融合等热力学过程支配着大晶粒多晶Si膜的生长. 相似文献
7.
采用射频(RF)磁控溅射法在石英衬底上制备了MoS 2薄膜。通过正交试验研究了溅射时间、溅射温度、氩气流量和溅射功率对MoS 2薄膜结构的影响。通过XRD、Raman、XPS、EDS和SEM对MoS 2薄膜的结晶度、薄膜厚度和表面形貌进行分析,得到了制备MoS 2薄膜的最佳工艺参数。发现溅射温度较高或较低结晶度都很差,在较低的溅射温度下样品的XRD衍射峰不明显。而当温度为250℃时,样品的XRD衍射峰较多,结晶度较好。根据正交试验法得出溅射温度对MoS 2的结晶效果起着至关重要的作用,其次是氩气流量。当溅射温度为250℃,氩气流量为6 mL/min,溅射时间为30 min,溅射功率为300 W或400 W时,MoS 2膜的结晶度较好。在这个条件下制备的膜较厚,但为以后的实验指明了方向。保持溅射温度、溅射功率和氩气流量不变,通过减少时间成功制备了厚度为58.9 nm的薄膜。 相似文献
8.
利用等离子增强原子层沉积技术(PEALD)在 c面蓝宝石衬底上制备了氧化镓(Ga 2O 3)薄膜,研究了退火气氛( v(N 2)∶ v(O 2)=1∶1(体积比)、空气和N 2)及退火时间对Ga 2O 3薄膜晶体结构、表面形貌和光学性质的影响。研究结果表明,退火前的氧化镓处于亚稳态,不同退火气氛下退火后晶体结构发生明显改变,而且退火气氛中N 2比例增加有利于Ga 2O 3重结晶。在N 2气氛下退火达到30 min,薄膜结构已由亚稳态转变成择优取向的β-Ga 2O 3。而且表面形貌分析表明,退火30 min后表面形貌开始趋于稳定,表面晶粒密度不再增加。另外实验样品在 400~800 nm的平均透射率几乎是100%,且光吸收边陡峭。采用N 2气氛退火,对于富氧环境下沉积的Ga 2O 3更利于薄膜表面原子迁移,以及择优取向Ga 2O 3重结晶。 相似文献
9.
本文使用两步法,通过控制PbI 2(DMSO)溶液的浓度制备了不同厚度的有机-无机杂化钙钛矿(MAPbI 3)光吸收层薄膜,并组装了大面积基于碳电极且无空穴传输层的钙钛矿太阳能电池。对不同厚度MAPbI 3光吸收层薄膜的晶相、光吸收性质、表面形貌、元素组成进行分析,并进一步测试了基于MAPbI 3薄膜制备的钙钛矿太阳能电池的光伏性能。结果表明,MAPbI 3光吸收层薄膜厚度与PbI 2(DMSO)浓度呈正相关关系,浓度为1.3 mol/L的PbI 2溶液制备的MAPbI 3薄膜厚度约为350 nm,具有较好的结晶度和光吸收强度,且薄膜表面致密平整,无明显缺陷,基于350 nm MAPbI 3光吸收层的钙钛矿太阳能电池获得了8.48%的光电转换效率。 相似文献
10.
利用高频感应加热化学气相沉积工艺,以H2稀释的SiH4作为反应气体源,在未抛光的粗糙石英衬底上直接沉积制备了具有均匀分布的大晶粒多晶Si膜.采用扫描电子显微镜、X射线衍射和可见-紫外分光光度计等检测手段,测量和分析了沉积膜层的表面形貌、晶粒尺寸、择优取向与光反射等特性.结果表明,多晶Si膜中Si晶粒的尺寸大小和密度分布不仅与工艺参数有关,而且强烈依赖于衬底的表面状况.1000℃下沉积薄膜的平均晶粒尺寸为~3μm,择优取向为<111>晶向.反射谱测量表明,920℃下制备薄膜的反射率比1000℃下制备的更低,最低值达18.4;,这应归功于前者具有更大的表面粗糙度. 相似文献
11.
We investigated the dependence of the Y 2O 3 film growth on Si surface at initial growth stage. The reflection high-energy electron diffraction, X-ray scattering, and atomic force microscopy showed that the film crystallinity and morphology strongly depended on whether Si surface contained O or not. In particular, the films grown on oxidized surfaces revealed significant improvement in crystallinity and surface smoothness. A well-ordered atomic structure of Y 2O 3 film was formed on 1.5 nm thick SiO 2 layer with the surface and interfacial roughness markedly enhanced, compared with the film grown on the clean Si surfaces. The epitaxial film on the oxidized Si surface exhibited extremely small mosaic structures at interface, while the film on the clean Si surface displayed an island-like growth with large mosaic structures. The nucleation sites for Y 2O 3 were provided by the reaction between SiO 2 and Y at the initial growth stage. The SiO 2 layer known to hinder crystal growth is found to enhance the nucleation of Y 2O 3, and provides a stable buffer layer against the silicide formation. Thus, the formation of the initial SiO 2 layer is the key to the high-quality epitaxial growth of Y 2O 3 on Si. 相似文献
12.
Thin films of crystalline lithium niobate (LN) grown on Si(1 0 0) and SiO 2 substrates by electron cyclotron resonance plasma sputtering exhibit distinct interfacial structures that strongly affect the orientation of respective films. Growth at 460–600 °C on the Si(1 0 0) surface produced columnar domains of LiNbO 3 with well-oriented c-axes, i.e., normal to the surface. When the SiO 2 substrate was similarly exposed to plasma at temperatures above 500 °C, however, increased diffusion of Li and Nb atoms into the SiO 2 film was seen and this led to an LN–SiO 2 alloy interface in which crystal-axis orientations were randomized. This problem was solved by solid-phase crystallization of the deposited film of amorphous LN; the degree of c-axis orientation was then immune to the choice of substrate material. 相似文献
13.
The structure and thermal stability of ZrO 2 films grown on Si (1 0 0) substrates by metalorganic chemical vapor deposition have been studied by high-resolution transmission electron microscopy, selected area electron diffraction and X-ray energy dispersive spectroscopy. As-deposited films consist of tetragonal ZrO 2 nanocrystallites and an amorphous Zr silicate interfacial layer. After annealing at 850°C, some monoclinic phase is formed, and the grain size is increased. Annealing a 6 nm thick film at 850°C in O 2 revealed that the growth of the interfacial layer is at the expense of the ZrO 2 layer. In a 3.0 nm thick Zr silicate interfacial layer, there is a 0.9 nm Zr-free SiO 2 region right above the Si substrate. These observations suggest that oxygen reacted with the Si substrate to grow SiO 2, and SiO 2 reacted with ZrO 2 to form a Zr silicate interfacial layer during the deposition and annealing. Oxygen diffusion through the tetragonal ZrO 2 phase was found to be relatively easier than through the monoclinic phase. 相似文献
14.
The comparison of the results of chemical composition, crystal structure, electronic properties and infrared photoconductivity investigations of PbTe/Si and PbTe/SiO 2/Si heterostructures doped with Ga atoms by two different techniques is presented in this work. One of these techniques is principally based on the vapour-phase doping procedure of PbTe/Si and PbTe/SiO 2/Si heterostructures, which were previously formed by the modified “hot wall” technique. The second method of PbTe(Ga)/Si and PbTe(Ga)/SiO 2/Si heterostructure preparation is based upon the fabrication of lead telluride films, which have been doped with Ga atoms in the layer condensation process directly. The lattice parameter and charge carrier density evolutions with the Ga impurity concentration show principally the different character of PbTe(Ga)/Si films prepared by these techniques. It has been proposed that complicated amphoteric (donor or acceptor) behaviour of Ga atoms may be explained by different mechanisms of substitution or implantation of impurity atoms in the crystal structure of lead telluride. 相似文献
15.
作为宽禁带半导体材料的一员,结构稳定的β-Ga 2O 3具有比SiC和GaN更宽的禁带宽度和更高的巴利加优值,近年来受到科研人员的广泛关注。本文采用射频(RF)磁控溅射法在 C面蓝宝石衬底上生长β-Ga 2O 3薄膜,探究溅射过程中衬底加热温度的影响。溅射完成后通过高温退火处理提升薄膜质量,研究衬底加热温度和后退火温度对氧化镓薄膜晶体结构和表面形貌的影响。利用X射线衍射(XRD)、原子力显微镜(AFM)等测试手段对β-Ga 2O 3薄膜晶体结构、表面形貌等进行分析表征。实验结果表明,随着衬底加热温度的升高,β-Ga 2O 3薄膜表面粗糙度逐渐降低,薄膜晶体质量得到显著提升;在氧气气氛中进行后退火,合适的后退火温度有利于氧化镓薄膜重新结晶、增大晶粒尺寸,能够有效修复薄膜的表面态和点缺陷,对于改善薄膜晶体质量有明显优势。 相似文献
16.
Deposition of sub-monolayer silicon on SiO 2/Si(1 0 0) greatly facilitates nucleation in subsequent thermal chemical vapor deposition (CVD) of silicon nanoparticles. Sub-monolayer seeding is accomplished using silicon atoms generated via disilane decomposition over a hot tungsten filament. The hot-wire process is nonselective towards deposition on silicon and SiO 2, is insensitive to surface temperature below 825 K, and gives controlled coverages well below 1 ML. Thermal CVD of nanoparticles at 1×10 −4 Torr disilane and temperatures ranging from 825 to 925 K was studied over SiO 2/Si(1 0 0) surfaces that had been subjected to predeposition of Si or were bare. Seeding of the SiO 2 surface with as little as 0.01 ML is shown to double the nanoparticle density at 825 K, and densities are increased twenty fold at 875 K after seeding the surface with 30% of a monolayer. 相似文献
17.
Effects of SiO 2 additive on sodium perborate tetrahydrate crystallization (via chemical reaction of NaBO 2 and H 2O 2) has been studied in a MSMPR-type reaction crystallizer. CSD and microscopic observations are used to evaluate the secondary nucleation behaviour. Secondary nucleation rate decreases in case of SiO 2 addition of up to 200 ppm. Higher SiO 2 content results in higher primary nucleation rates. Abrasion resistance increases with the amount of SiO 2 additive. 相似文献
18.
In this paper the technological and scientific aspects of radiation-related charge trapping in thin SiO 2 films are reviewed. These films are amorphous in nature and are thermally grown on single crystal silicon substrates serving as the insulating layer in metal-oxide-semiconductor (MOS) capacitors and transistors. The structure and operation of these devices are reviewed with special emphasis on the effect of charges trapped in the oxide. The technical importance of understanding the interaction of ionizing radiation with thin SiO 2 films is illustrated with two practical examples. The first involves the operation of MOS transistors in environments where ionizing radiation is present, leading to an accumulation of positive space charge in the oxide. The second deals with process-induced defects generated by radiation encountered during the fabrication of devices by processes such as electron beam lithography or electron gun metallization. Unannealed traps of this type capture hot electrons producedin the substrate during the operation of the MOS transistor. In both these examples, the charging of the oxide results in instabilities which degrade operation. Its sensitivity to charge trapped in the insulator makes the MOS system an ideal vehicle for scientific study of these phenomena. The basic techniques for characterizing the density, capture cross-sections, and location are briefly discussed and applied to the problem of radiation-induced defects in thin SiO2 films. Ionizing radiation is shown to interact with the SiO2 in two modes. In the first it supplies carriers to fill pre-existing hole traps at the interfaces. In the second it creates electron and hole traps in the bulk of the thin film. These latter defects are in a neutral state after irradiation and are detectable only when either electrons or holes are subsequently injected into the oxide. The capture cross-sections, trap densities and location of these centers in the film are presented. The annealing treatments required to remove these traps from aluminium and polysilicon gate devices are also discussed. The number traps produced by an incident 25 KV electron beam is found to depend weakly on the dosage. A dipolar defect, produced by the ionizing radiation, seems to explain the behavior of the neutral centers. 相似文献
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