CO2作为单一气相碳氧源制备碳掺杂钛氧薄膜的成分结构性能研究

采用单极脉冲反应磁控溅射,以CO2作为单一气相碳源和氧源,通过控制反应气体流量,制备了碳掺杂钛氧(C∶Ti-O)薄膜.通过原子力显微镜,拉曼光谱和X射线光电子能谱对薄膜的表面形貌、结构和成分进行了表征,利用紫外可见-分光光度计得到了薄膜的透射光谱并用Tauc作图法计算薄膜的带隙宽度,用纳米力学系统测试了薄膜的力学性能.结果表明,随着CO2流量的增大,沉积速率呈先增大后减小的趋势.制备的薄膜主要以金红石相存在,并存在少量锐钛矿相和TiO.C的掺入使得C∶Ti-O薄膜的带隙宽度有不同程度的降低,薄膜硬度也有所提高.     

溅射气压对碳硅氧薄膜透过率及光学带隙的影响

采用射频磁控溅射技术在玻璃基底和单晶硅片(100)上制备了碳硅氧(SiOC)薄膜,通过扫描电镜、X射线衍射、拉曼光谱、X射线光电子能谱及紫外可见透射光谱等技术手段对其进行了分析,研究了在不同溅射气压下所制备薄膜的组分、透过率及光学带隙.结果表明:随着溅射气压的增大,薄膜内部sp3键含量、透过率及光学带隙均随之增大,sp3键及其形成的宽带隙σ键对薄膜光学带隙有着较大影响.在溅射气压为3.0 Pa的条件下,薄膜光学带隙为2.67 eV.     

射频反应磁控溅射制备ZnO薄膜的微结构及其光学性能

采用射频反应磁控溅射技术在石英和Si衬底上制备了高度c轴择优取向的ZnO薄膜,样品的氧氩流量比分别为10:40,20:40,30:40,40:40.利用X射线衍射仪、表面轮廓仪、原子力显微镜和紫外-可见分光光度计研究了样品的微结构与光学特性.研究表明:氧氩流量比为30:40的样品结晶质量最好.所制备的ZnO薄膜的可见光平均透射率均大于87;.随着氧氩流量比的增大,薄膜的透射率呈非单调变化,氧氩流量比为30:40的样品在可见光范围的平均透射率可达93;.光学带隙随着氧氩流量比的增大,先增大后减小.与块材ZnO的带隙(3.37 eV)相比,ZnO薄膜的带隙均变窄.     

空气退火对ZnS薄膜结构和光学特性的影响

采用X射线衍射、扫描电子显微镜和光致发光等技术研究了空气退火对ZnS薄膜的结构和光学特性的影响.薄膜在500℃以下退火后结晶质量得到改善,仍呈ZnS立方相结构.退火温度达到550℃时,薄膜中出现ZnO六方相结构.薄膜退火后,大气中的氧掺入薄膜中,出现ZnS-ZnO复合层.随退火温度升高,薄膜晶粒尺寸增大,透过率增加,带隙逐渐接近ZnO带隙.薄膜光致发光结果表明,复合层内ZnS和ZnO绿色发光的叠加替代了来自ZnS缺陷能级间的绿色发光.     

生长气压对分子束外延β-Ga2O3薄膜特性的影响

本文采用分子束外延技术在具有6°斜切角的c面蓝宝石衬底上外延β-Ga₂O₃薄膜,系统研究了生长气压对薄膜特性的影响。X射线衍射谱和表面形貌分析表明,不同生长气压下所外延的薄膜表面平整,均具有(201)择优取向。并且,其结晶质量和生长速率均随生长气压增大而逐渐提高。通过X射线光电子能谱分析发现,生长气压增大使得氧空位的浓度大幅下降,高价态Ga比例增大,最终使得O/Ga原子数之比接近理想Ga₂O₃材料的化学计量比值。利用Tauc公式和乌尔巴赫带尾模型进行计算,结果表明随着生长气压的增大,样品的光学带隙由4.94 eV增加到5.00 eV,乌尔巴赫能量由0.47 eV下降到0.32 eV,证明了生长气压的增大有利于降低薄膜中的缺陷密度,提高薄膜晶体质量。     

氧气流量对射频磁控溅射制备Cu2O薄膜性能的影响

通过磁控溅射方法在玻璃衬底上制备Cu2O薄膜,采用X射线衍射(XRD)、分光光度计、原子力显微镜(AFM)和X射线光电子能谱(XPS)等研究了氧气流量对Cu2O薄膜性能的影响.结果表明:氧气流量为4.2 sccm时,薄膜为单相的Cu2O,具有较高的结晶质量和可见光透过率,光学带隙为2.29 eV,薄膜的导电类型是p型且空穴浓度为2×1016 cm-3.通过XPS能谱分析Cu 2p3/2和O 1s结合能,确定了薄膜中Cu以+1价存在.     

磁控溅射PbSe薄膜厚度对其结构及光学特性的影响

本文利用射频磁控溅射法在200℃的玻璃衬底上沉积了纳米晶PbSe薄膜,薄膜厚度分别为200 nm、250 nm、500 nm及600 nm.利用X射线衍射仪(XRD)、原子力显微镜(AFM)及紫外-可见分光光度计,分别研究了不同厚度PbSe薄膜的晶体结构、表面形貌和光学特性.结果表明:随膜厚增大,PbSe (200)晶面的择优取向显著增强,薄膜的结晶质量逐渐提高.此外,随薄膜厚度增加吸收边发生红移.膜厚为200nm、250 nm时,薄膜的禁带宽度为1.89 eV和1.60 eV;膜厚较大(500 nm及600 nm)时,带隙宽度减小至1.41 eV和1.34 eV,与太阳的光谱辐射更加匹配.因此,我们认为厚度较大的PbSe薄膜更适于用做太阳能电池的吸收层.     

溶胶-凝胶法制备Mg掺杂ZnO薄膜的微结构与光学性质

采用溶胶-凝胶技术在Si(111)和石英玻璃衬底上制备了Mg掺杂ZnO薄膜.用X射线衍射仪(XRD)、原子力显微镜(AFM)、扫描电镜(SEM)和紫外-可见(UV-Vis)分光光度计测试薄膜的微结构、表面形貌和光学性质.结果表明:所得Mg掺杂ZnO薄膜仍为六角纤锌矿型结构,呈c轴方向择优生长,随着退火温度升高,薄膜的晶格常数c由0.5288 nm减小到0.5278 nm,粗糙度从3.8 nm增大到6.5 nm,光学带隙由3.26 eV增大到3.31 eV.     

(111)择优取向ZnS薄膜的制备及特性研究

采用激光分子束外延技术在Al2O3衬底上成功外延生长了ZnS薄膜.用X射线衍射、扫描电子显微镜和光致发光谱表征了衬底温度对薄膜结构、形貌和光学特性的影响.结果表明所生长的ZnS薄膜为闪锌矿,具有(111)择优长向,随衬底温度的升高,X射线衍射峰的半高宽先减小后增大,在衬底温度为300℃时,半高宽最窄.薄膜结构致密,表面不平整度随衬底温度的升高而增大.薄膜的带隙随衬底温度的升高出现蓝移,可见光区域透射率最高达到98;,在360 nm激发波长下,观测到402 nm和468 nm两个发光带,衬底温度为300℃时,发光最强.     

PECVD沉积参数对非晶硅向微晶硅薄膜转化的影响

采用等离子体增强化学气相沉积(PECVD)系统,以硅烷和氢气为反应气源,通过改变射频功率、硅烷浓度来制备氢化硅基薄膜材料.研究了沉积参数的变化对硅基薄膜材料微结构的影响.通过红外吸收谱、紫外可见光谱以及X射线衍射谱对样品材料进行表征.实验结果表明,随着射频功率的增加,薄膜中氢含量也相应地增大,而光学带隙表现出先增大后减小的规律.当硅烷浓度逐渐降低时,薄膜材料的光学带隙相应地降低,并从非晶硅薄膜逐渐向微晶硅薄膜材料转变,且薄膜材料在(111)方向的晶粒尺度达到了10.92 nm.实现了在高沉积压强、大射频功率、低硅烷浓度条件下可以有效优化改善硅基薄膜质量.     

Nanocrystalline TiO2 films studied by optical, XRD and FTIR spectroscopy

We report the deposition of thin titanium dioxide films on Si(1 0 0) and silica glass at low temperatures between 200 and 350 °C by a technique of ultraviolet-assisted injection liquid source chemical vapor deposition (UVILS-CVD) with 222 nm radiation. The composition and optical properties of the films deposited have been studied using a variety of standard characterisation methods. A strong absorption peak around 438 cm⁻¹, corresponding to Ti-O stretching vibration, was observed by Fourier transform infrared spectroscopy for different deposition temperatures. Nanostructured films on Si wafers were observed by atomic force microscopy while X-ray diffraction results showed that crystalline TiO₂ layers could be formed at deposition temperatures as low as 210 °C. The deposition kinetics and influence of the substrate temperature on the film are discussed. The activation energy for this photo-CVD process at temperatures between 200 and 350 °C was found to be 0.435 eV. This is much lower than the value (E_a=5.64 eV) obtained by conventional thermal CVD. The thicknesses of the films grown, from several nanometers to micrometers can be accurately controlled by changing the number of drops introduced by the injection liquid source. Under optimum deposition conditions, refractive index values as high as 2.5 and optical transmittance of between 85% and 90% in the visible region of the spectrum can be obtained.     

Structural relaxation of Al-W amorphous thin films

The pronounced variation of the electrical resistivity of the amorphous Al-W thin films observed during initial heating above room temperature was examined. Both isochronal and isothermal treatments were performed in order to investigate the effects of the film composition, substrate material, and substrate temperature, on the magnitude of the relaxation phenomena. Regarding the isochronal heating, it was observed that the relaxation effects decreased with an increase of the heating rate, and decreased with the aluminum content in the film. The Al₇₈W₂₂ amorphous thin films were subjected to isothermal annealing for 6 h at a temperature of 515 °C. The effects of the substrate material (alumina ceramic, glass and sapphire), and the deposition temperature (LNT, RT, 200 and 400 °C) were examined. The relaxation decreased in a sequence of: alumina ceramic-glass-sapphire substrates, as well as with an increase of the substrate temperature. An assumed dominant role of the aluminum in the effects observed, was tested by the corresponding investigation of Al-Ti and Cu-Ti amorphous thin films.     

Epitaxial growth of ZnO thin films on Si substrates by PLD technique

Epitaxial ZnO thin films have been grown on Si(1 1 1) substrates at temperatures between 550 and 700 °C with an oxygen pressure of 60 Pa by pulsed laser deposition (PLD). A ZnO thin film deposited at 500 °C in no-oxygen ambient was used as a buffer layer for the ZnO growth. In situ reflection high-energy electron diffraction (RHEED) observations show that ZnO thin films directly deposited on Si are of a polycrystalline structure, and the crystallinity is deteriorated with an increase of substrate temperature as reflected by the evolution of RHEED patterns from the mixture of spots and rings to single rings. In contrast, the ZnO films grown on a homo-buffer layer exhibit aligned spotty patterns indicating an epitaxial growth. Among the ZnO thin films with a buffer layer, the film grown at 650 °C shows the best structural quality and the strongest ultraviolet (UV) emission with a full-width at half-maximum (FWHM) of 86 meV. It is found that the ZnO film with a buffer layer has better crystallinity than the film without the buffer layer at the same substrate temperature, while the film without the buffer layer shows a more intense UV emission. Possible reasons and preventive methods are suggested to obtain highly optical quality films.     

沉积时间对Zn(O,S)薄膜性能及Cu2ZnSnSe4薄膜电池的影响

无镉材料Zn(O,S)因其带隙宽且可调节、无毒无害等优点被作为缓冲层材料重点研究,通过化学水浴法制备Zn(O,S)薄膜,研究了沉积时间的不同(20~35 min)对Zn(O,S)薄膜的成分、结构特性、光学性能及形貌的影响.通过XRD测试可知,水浴法制备的Zn(O,S)薄膜为非晶态.通过透反射谱测试可知,薄膜的光学透过率较高(>80;).通过表面形貌测试可知,30 min时Zn(O,S)薄膜为致密均匀的小颗粒.将Zn(O,S)薄膜应用在CZTSe电池中,在30 min时获得较高器件转换效率5.37;.     

沉积氧压对Bi1.5ZnNb1.5O7薄膜的结构和介电特性的影响

采用固相反应法合成具有焦绿石立方结构的Bi1.5ZnNb1.5O7(BZN)陶瓷靶材,采用脉冲激光沉积法在Pt/SiO2/Si(100)基片上制备立方BZN薄膜。研究了沉积氧压的变化对薄膜的结晶性能,微观形貌以及介电性能的影响。结果表明:沉积的BZN薄膜都呈现出立方焦绿石单相结构,但是薄膜的取向随氧压变化而变化。当沉积氧压为10 Pa时,薄膜的(222)晶面拥有最强的择优取向。随着氧压的升高,BZN薄膜的介电常数明显降低。在10 Pa氧压下沉积的BZN薄膜展示出介电可调特性为5%(500 kV/cm)。     

沉积温度对磁控溅射BiFeO3薄膜结构和性能的影响

应用磁控溅射法在以SrRuO3 (SRO)薄膜为缓冲层的Pt/TiO2/SiO2/Si(001)基片上制备了多晶BiFeO3 (BFO)薄膜,构架了SRO/BFO/SRO异质结电容器.采用X射线衍射、铁电测试仪等研究沉积温度对BFO薄膜结构和性能的影响.X射线衍射图谱显示BFO薄膜为多晶结构.在2.5 kHz测试频率下,500℃生长的BFO薄膜呈现比较饱和的电滞回线,2Pr为145μC/cm2,矫顽场Ec为158 kV/cm,漏电流密度约为2.4×104 A/cm2.漏电机制研究表明,在低电场区,SRO/BFO/SRO电容器满足欧姆导电机制,在高电场区,满足普尔-弗兰克导电机理.实验发现:SRO/BFO/SRO电容器经过109翻转后仍具有良好的抗疲劳特性.     

射频磁控溅射氧气流量对制备的Ga2O3∶Cr薄膜光致发光性能的影响

在不同氧气流量下,采用双靶射频磁控共溅射的方法在蓝宝石(α-Al₂O₃)基底上制备得到系列掺Cr的Ga₂O₃(Ga₂O₃∶Cr)薄膜,详细研究了薄膜在900 ℃退火前后的结构和光学性能。结果表明,未退火的Ga₂O₃∶Cr薄膜为非晶结构,其发光主要位于蓝绿波段。经900 ℃退火后,薄膜的结构由非晶变为多晶,且在近红外波段观测到了来源于Cr³⁺掺杂的发光。退火后的薄膜结晶质量和近红外发光均与氧气流量密切相关,而其光学带隙不受氧气流量的影响。在所研究的氧气流量范围,4 mL/min氧气流量下薄膜的近红外发光强度最强,这与此条件下薄膜结晶质量较好以及Cr³⁺替代Ga³⁺的数量较多有关。以上研究成果可为制备高质量Ga₂O₃∶Cr薄膜提供参考。     

MgO(100)衬底上生长BaTi2O5薄膜及其性能研究

利用脉冲激光沉积技术,在MgO(100)衬底上生长了BaTi2O5薄膜,探讨了沉积条件(衬底温度和氧分压)对薄膜结构的影响,并对其介电和光学性能进行了研究.结果表明:随衬底温度和氧分压的改变,BaTi2O5薄膜的物相和结晶取向逐渐变化;适宜的脉冲激光沉积工艺为衬底温度950~1000 K、氧分压12.5 Pa,在该条件下获得了b轴方向择优生长的BaTi2O5薄膜;该薄膜具有较高的居里温度(750 K),介电常数达2000,而且在可见光和红外波长范围内具有较高的透过率.     

Investigation of the structure of thin rhenium films

The phase composition of thin rhenium films as depending on deposition conditions has been studied. In films deposited at a pressure of 10⁻⁵ torr impurity phases with simple cubic and hexagonal lattices were found. In films evaporated at a pressure of 10⁻⁸ torr only an hep phase equilibrium in bulk samples is formed. It has been concluded that in thin rhenium films no transitions to a fcc phase occurs. In the present work the dependence of thin film phase composition was investigated as a function of film thickness (∼5–500 Å), deposition rate (∼0.1–10 Å/sec) and substrate temperatur (∼ 20–450°C). The films were deposited on NaCl single crystals at a pressure of 10⁻⁵ torr (oil diffusion pump evacuation) an 10⁻⁸ torr (“Orbitron”-type pump evacuation). The measurement of film thickness was conducted by the optical interference method.     

制备参数对钙钛氧化物薄膜的微结构和性能影响

利用钛酸丁酯-氯化钙-无水乙醇体系通过溶胶-浸渍提拉法制备了钙钛氧化物薄膜.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)及能谱分析仪(EDS),荧光光谱仪和紫外-可见分光光度计等技术对薄膜的结构,形貌及元素成分和光学性能进行了分析.结果表明:当n(钛酸丁酯)/n(乙醇)为1∶15时,制备得到了光学性质良好(价带较宽)的钙钛氧化物薄膜.随着焙烧温度升高到550℃,薄膜的结晶强度不断增加,薄膜主晶相由CaTiO3相转化为层状结构CaTi2O4(OH)2主晶相,该薄膜呈现多孔结构,从而使光学特性进一步增强.