退火温度对电子束沉积Ag/TiO2薄膜光学性质和光催化性能的影响

研究了退火温度对电子束制备Ag/TiO₂薄膜光学 性质和光催化性能的影响。在石英玻璃、硅片 上沉积了Ag/TiO₂复合薄膜,在空气氛围下,进行了400℃, 500℃的退火一小时.用紫外-可见分光光度 计、X射线衍射仪(XRD) 、原子力显微镜(AFM)对沉积和退火后的薄膜分别进行光学、结构、 形貌分析。结 果表明:300℃下制备的Ag/TiO₂复合薄膜为无定形结构,400℃以上薄呈多晶态。吸光度和表面粗糙度 随退火温度的增加而增大,薄膜的光学带隙随退火温度的增加而减小。锐钛矿相表现出了更 好的光催化性能。     

不同深宽比GaAs衬底的Al22O3/HfO2复合薄膜材料原子层沉积及能谱分析

利用热原子层沉积（Atomic Layer Deposition, ALD）技术在不同深宽比GaAs衬底上进行了Al2₂O₃/HfO₂复合薄膜的沉积。通过对其表面和能谱进行分析发现,沉积温度对复合薄膜的摩尔比具有较大的影响。随着深宽比的增大,其沉积表面和沟槽内会出现残留物;随着ALD沉积温度的上升,其沉积表面和沟槽内的残留物减少,摩尔比趋向均匀。当深宽比为2.2并利用150 ℃的低沉积温度时,表面及底面基本无残留物。但当深宽比为4.25时,150 ℃沉积明显有大量残留物。只有当温度升高到300 ℃时,表面和沟槽里复合薄膜的残留物才被明显消除。ALD技术可以实现各种器件结构的全方位钝化,这是其他化学气相沉积法无法比拟的。     

脉冲激光沉积Er:LiNbO3薄膜及1.54μm光致发光的研究

利用脉冲激光沉积(PLD)技术,通过双靶(Er₃O₂/LiNbO₃)交替与脉冲激光作用,在SiO ₂/Si 衬底上制备了c-轴择优取向的Er掺杂LiNbO₃(Er:LiNbO₃)薄 膜。用X射线衍射(XRD)、 场发射扫描电子显微镜(FESEM)、台阶仪及光致发光(PL)光 谱对制备的掺杂薄膜进行了表征。研究了衬底温度、O₂压及沉积时间对Er:LiNbO₃薄膜 结晶、表面形貌及 PL性能的影响。结果发现,衬底温度低于300℃时制备的Er:LiNbO 3薄膜为非晶膜,随衬底温度升高,薄膜出 现(006)衍射峰,并且其强度随衬底温度升高而增大;O₂压变化对 利用双靶沉积获得的Er:LiNbO₃薄膜择优 取向及(006)衍射峰强度影响不明显;沉积时间越长Er:LiNbO₃薄膜 中Er³⁺浓度越大,但结晶择优取向 变差;利用532nm波长激光泵浦,室温下,在1537nm波长处测得很强的光致荧光峰,而且沉积时间越长谱峰越尖锐强 度越大。     

退火温度对银-二氧化硅核壳(Ag@SiO2/TiO2)薄膜结构，光学特性以及光催化性能的影响

局部表面等离子共振广泛应用于光催化和太阳能 电池等领域。采用电子束和热沉积技 术,在融石英和Si片上制备了Ag@SiO₂/TiO₂薄膜。在300 ℃,400 ℃,500 ℃,600 ℃ 温度下,薄膜在空气氛围下退火2h。采用拉曼光谱仪,紫外-可见分光光度 计(UV-Vis)等手段对微结构,光学性能等特性进行了表征。利用能谱仪测定了元素成分及含 量。考察了薄膜在水溶液中降解甲基橙的光催化活性。结果表明:Ag@SiO₂/TiO₂薄膜具有优 异的光催化性能。测试结果表明:在250℃下制备的TiO₂薄膜为无定形结构;在本实验条 件下,随着退火温度的升高,薄膜呈锐钛矿结构;锐钛矿相表现出了更好的光催化性能。     

退火Cu2O薄膜的结构及光学特性

采用射频(RF)磁控溅射单质金属铜(Cu)靶, 在O₂和Ar的混合气氛下制备了Cu₂O薄 膜,并在N₂气氛下对预沉积的Cu₂O薄膜进行快速光热退火(RTA)处理,研究了 衬底温度及退火温度对Cu₂O 薄膜的生长行为、物相结构、表面形貌及光学性能的影响。结果表明,衬底温度在300℃以 下预沉积的Cu₂O薄膜 为非晶薄膜,退火处理对Cu₂O薄膜的结晶行为有明显影响,在N₂气氛下对Cu₂O薄膜进 行退火处理不影响薄膜的物 相结构;预沉积和退火Cu₂O薄膜在650nm以下波长范围内均有较强 吸收,吸收强度随退火温度的增加而增强,薄 膜在400nm以下波长范围内出现两个由缺陷引起的中间带(IB)吸收行 为,快速热退火处理不能减少或消除薄膜沉积 过程中形成的缺陷态;退火处理影响薄膜的光学带隙Eg,预沉 积薄膜经600℃退火处理,E_g值增大了 0.26eV。     

Ag含量对TiO2薄膜光学性能和光催化性能影响

为了研究Ag含量对光催化效率的影响,采用电子 束沉积方法制备了Ag-TiO₂光催化剂,分别用X射 线衍射仪(XRD),紫外－可见光谱仪(UV-Vis),电子扫描显微镜(SEM),原子力显微镜 (AFM),X射线电子能谱 仪(XPS)等手段对晶体结构,光学性能和薄膜形貌以及元素价态元素组成等进行了表征.利用 太阳光,以甲基 橙(MO)为模型,分析了不同Ag含量薄膜的光催化效率.结果显示:Ag是以Ag⁰存在,Ag均匀而 牢固的分布在 TiO₂材料上;在300℃温度下,所形成的薄膜为无定形结构;沉积适 量的银,可以提高纳米二氧化钛光催化活性。     

脉冲激光沉积法制备的单层MoS2薄膜变温光响应研究

报导了在c-Al₂O₃衬底上用脉冲激光沉积法制备MoS₂薄膜,并测试了其不同温度下的光响应。通过拉曼散射光谱和X射线衍射光谱证明了所制备的二硫化钼为纯2H相。通过X光电子能谱证明了所制备的二硫化钼硫钼原子比为1.92：1,在Mo元素的3d核心能级谱中存在红移和蓝移,说明薄膜中存在氧化和硫缺陷。此外,通过拉曼和光致发光分布图,证明了薄膜具有良好的均一性。在不同层数的二硫化钼样品中,单层二硫化钼样品具有最强的光响应,达到3 mAW^-1。单层二硫化钼的变温光响应实验表明,在室温附近,温度升高会提高二硫化钼的光响应强度和响应时间。     

渠道火花烧蚀法制备In2O3∶Mo透明导电薄膜

采用渠道火花烧蚀技术在普通玻璃基板上制备了掺钼氧化铟In₂O₃∶Mo透明导电薄膜，研究了烧蚀时氧气压强对薄膜光电性能的影响. 在基板温度Ts=350℃时，薄膜的电阻率和载流子浓度随氧气压强增大分别呈凹形和凸形的变化趋势. 薄膜电阻率最小值是4.8e-4Ω·cm，载流子浓度为7.1e20cm^-3. 载流子迁移率最高可达49.6cm²/ (V·s) . 可见光区域平均透射率大于87%以上，由紫外光电子谱分析得到薄膜的表面功函数为4.6eV. X射线衍射分析表明，薄膜结晶性良好并在（222）晶面择优取向生长. 原子力显微镜观察薄膜样品表面得到方均根粗糙度为0.72nm,平均粗糙度为0.44nm，峰谷最大差值为15.4nm.     

银纳米颗粒修饰TiO2薄膜的结构,光学及光催化性能

采用电子束沉积技术在石英玻璃、硅片基板上沉积了TiO₂薄膜,利用热蒸发技术在TiO₂薄膜表面沉积了不同厚度的Ag膜,研究了Ag膜厚度对TiO₂薄膜结构、形貌、光学和光催化 性能的影响。利 用紫外-可见分光光度计(UV-VIS)、X射线衍射仪(XRD)、冷场发射电子显微镜(SEM)对沉积 后的薄膜分别 进行光学、结构、形貌分析。利用能谱仪测定了元素成分及含量。用光催化降解亚甲基橙(M O)的速率评 价了合成的Ag-TiO₂的光催化性能。结果表明:Ag纳米粒子在TiO₂表面均匀分布;制备 的Ag修饰多孔TiO₂纳米薄膜具有优异的光催化性能。测试结果表明:在250 ℃下制备的T iO₂薄膜为无定形结构;随着Ag膜厚度 的增加,样品的光催化活性提高。当Ag膜厚度为3.7 nm时,光催化活 性最高;与纯TiO₂相比,Ag-TiO₂具有更高的光催化活性。     

磁控溅射法制备LiTaO3薄膜及其结晶性能研究

用射频磁控溅射法在Pt/Ti/SiO₂/Si(100)基片上沉积了LiTaO₃薄膜,并在氧气气氛中不同温度下进行退火。采用SEM、XRD、XPS等表征方法分析了薄膜的结晶性能、各元素化学价态和元素原子百分比。结果表明,经700℃退火处理1h得到的薄膜结晶性能最好,在(104)晶向上具有强烈的择优取向性。薄膜退火温度的升高导致薄膜中Li空位缺陷和O空位缺陷减少。研究表明,薄膜中O/Li的原子比对结晶性能有着非常明显的影响,原子值越接近晶体化学计量比,结晶性能越好。     

Atomic layer deposition of high capacitance density Ta2O5-ZrO2 based dielectrics for metal-insulator-metal structures

We have investigated electrical properties of laminated atomic layer deposited films: ZrO₂-Ta₂O₅, ZrO₂-Nb₂O₅-Ta₂O₅, ZrO₂-Ta_xNb_1−xO₅ and Ta₂O₅-Zr_xNb_yO_z. Even though the capacitances of laminates were often higher compared to films of constituent materials with similar thickness, considerably higher charge storage factors, Q, were achieved only when tetragonal ZrO₂ was stabilized in ZrO₂-Ta₂O₅ laminate and when the laminate thickness exceeded 50 nm. The decreased Q values in the case of most laminates were the result of increased leakage currents. In the case of thinner films only Ta₂O₅-Zr_xNb_yO_z stack possessed capacitance density and Q value higher than reference HfO₂. Concerning the conduction mechanisms, in the case of thinner films, the Ta₂O₅ or Ta_xNb_1−xO₅ apparently controlled the leakage either by Richardson-Schottky emission or Poole-Frenkel effect.     

原子层沉积方法制备低温多层Al2O3/TiO2复合封装薄膜的研究

原子层沉积(ALD)方法可以制备出高质量薄膜,被认为是可应用于柔性有机电致发光器件(OLED)最有发展前景的薄膜封装技术之一。本文采用原子层沉积(ALD)技术,在低温(80℃)下,研究了Al₂O₃及TiO₂薄膜的生长规律,通过钙膜水汽透过率(WVTR)、薄膜接触角测试等手段,研究了不同堆叠结构的多层Al₂O₃/TiO₂复合封装薄膜的水汽阻隔特性,其中5 nm/5 nm×8 dyads(重复堆叠次数)的Al₂O₃/TiO₂叠层结构薄膜的WVTR达到2.1×10^-5 g/m²/day。采用优化后的Al₂O₃/TiO₂叠层结构薄膜对OLED器件进行封装,实验发现封装后的OLED器件在高温高湿条件下展现了较好的寿命特性。     

Top gate ZnO-Al2O3 thin film transistors fabricated using a chemical bath deposition technique

ZnO thin films were prepared by a simple chemical bath deposition technique using an inorganic solution mixture of ZnCl₂ and NH₃ on glass substrates and then were used as the active material in thin film transistors (TFTs). The TFTs were fabricated in a top gate coplanar electrode structure with high-k Al₂O₃ as the gate insulator and Al as the source, drain and gate electrodes. The TFTs were annealed in air at 500 ℃ for 1 h. The TFTs with a 50 μm channel length exhibited a high field-effect mobility of 0.45 cm²/(V·s) and a low threshold voltage of 1.8 V. The sub-threshold swing and drain current ON-OFF ratio were found to be 0.6 V/dec and 10⁶, respectively.     

Chemical nature of the passivation layer depending on the oxidizing agent in Gd2O3/GeO2/Ge stacks grown by molecular beam deposition

In Ge-based metal oxide semiconductor technology, the insertion of a passivation layer seems to be crucial in unpinning the Fermi level at the interface and in reducing the amount of interface defects. GeO₂ was obtained by atomic oxygen (AO), molecular oxygen or ozone chemisorption. Atomic or molecular oxygen was used in the deposition of Gd₂O₃. Gd₂O₃ thin films were grown by molecular beam deposition directly on (1 0 0) Ge or on a GeO₂ interlayer. The chemical nature of the Gd₂O₃/Ge interface was characterized by time-of-flight secondary ion mass spectrometry depth profiles. Without GeO₂ layer Gd and Ge interdiffusion is observed and the concomitant formation of GeOGd bonds is also supported by X-ray photoelectron spectroscopy energy shift at the Ge 3d peak and by a singularity in the interface defect energy distribution at ∼0.48 eV. Further, depending on the GeO₂ formation process, the profile shape of Ge and O related secondary ions at the GeO₂/Ge interface can be related with a defective Ge region close to the GeO₂/Ge. In particular, considering the ratio between Ge and GeO₂ related secondary ion signals, the interlayer passivated using AO turns out to be comparatively enriched in Ge, while the use of ozone for GeO₂ formation leads to a Ge deficient layer.     

Dielectric deposition process for Cu/SiO2 integration in a dual damascene interconnection architecture

A challenge to integrate Cu in device interconnections is to avoid Cu diffusion into silicon active zone that could seriously damage device performance, and into interlevel dielectric that could induce shorts or degrade dielectric performance. This paper relates the integration of Cu-CVD with SiO₂. Structures studied are SiO₂ deposited on Cu-CVD, and SiO₂/SiN/Cu structure: a thin SiN layer is deposited on Cu before SiO₂ to act as diffusion barrier and as an etch stop during the interconnect structure patterning. Both SiO₂ and SiN dielectric processes are made in plasma-enhanced chemical vapor deposition processes, from SiH₄ precursor with addition of, respectively, N₂O or NH₃. Cu contamination is shown to occur during the dielectric deposition onto Cu, and is enhanced by the fluorine presence in the deposition chamber. Deposition processes were evaluated in order to lower Cu contamination in the dielectric bulk. On an other hand, a noticeable degradation in Cu layer resistance was evidenced after dielectric deposition due to copper contamination during the dielectric deposition process. This issue can be addressed by the optimization of the dielectric deposition process.     

Effects of surface passivation during atomic layer deposition of Al2O3 on In0.53Ga0.47As substrates

In this work we investigate the effect of different III-V surface passivation strategies during atomic layer deposition of Al₂O₃. X-ray photoelectron spectroscopy indicates that bare As-decapped and sulfur passivated In_0.53Ga_0.47As present residual oxides on the surface just before the beginning of the Al₂O₃ deposition while the insertion of a Ge interface passivation layer results in an almost oxide free Ge/III-V interface. The study of the initial growth regimes, by means of in situ spectroscopic ellipsometry, shows that the growth of Al₂O₃ on Ge leads to an enhanced initial growth accompanied by the formation of Ge-O-Al species thus affecting the final electrical properties of the stack. Alternatively, deposition on decapped and S-passivated In_0.53Ga_0.47As results in a more controlled growth process. The sulfur passivation leads to a better electrical response of the capacitor that can be associated to a lower oxide/semiconductor interface trap density.     

Diffusion barrier properties of TaNx films prepared by plasma enhanced atomic layer deposition from PDMAT with N2 or NH3 plasma

Carbon free TaN_x films were deposited by plasma enhanced atomic layer deposition (PEALD) using a combination of pentakis(dimethylamino)Ta (PDMAT) and either N₂ or NH₃ plasma. Good linearity and saturation behavior were observed for the TaN_x films grown with NH₃ plasma while non-ideal saturation features were observed for the films grown with N₂ plasma. The thermal stability of the TaN_x films could be improved by reducing the pressure of the reactants and by increasing the plasma exposure time. The TaN_x films deposited using N₂ plasma exhibit better diffusion barrier properties than the films deposited using NH₃ plasma.     

TaCN growth with PDMAT and H2/Ar plasma by plasma enhanced atomic layer deposition

TaCN films were deposited using atomic layer deposition (ALD) using PDMAT and H₂/Ar plasma. Calculations based on density functional theory (DFT) indicate a high energy barrier and a low reaction energy for reducing the +5 Ta oxidation state in the PDMAT precursor by using pure H radicals. Through the assistance of Ar radicals, low resistivity of TaCN films of 230 μΩ cm could be deposited by using H₂/Ar plasma. By employing in situ X-ray diffraction during annealing, the activation energy for Cu diffusion through the TaCN barrier was evaluated at 1.6 eV.     

Si/Al2O3/ZnO:Al capacitor arrays formed in electrochemically etched porous Si by atomic layer deposition

High surface area Si/Al₂O₃/ZnO:Al capacitors were formed in electrochemically etched porous silicon. The Al₂O₃ dielectric and the ZnO:Al top electrode were deposited by atomic layer deposition in high aspect ratio porous Si. A single capacitor with a typical area of about 1 mm² consisted of about 10⁵ pores. Effective capacitance densities were between 2.0 and 2.5 μF/cm², i.e., approximately 30 times higher than for a planar capacitor prepared under identical conditions, illustrating the effect of the enhanced surface area in the porous structure.