均匀设计法研究PZT铁电薄膜制备工艺的优化

应用射频磁控溅射工艺在Pt/Ti/SiO2/Si衬底上制备具有钙钛矿结构的PZT铁电薄膜。对影响PZT薄膜性能、形貌的工作气压、基片温度、氧/氩 氧之比、溅射功率、退火温度5个主要因素进行分析,在其允许范围和精度内设置5个水平,并根据均匀设计理论对该5因素及5水平进行均匀设计。不同温度下退火之后测定了PZT薄膜的厚度、SEM表面形貌、电容、介电损耗、电滞回线(包括矫顽场强、饱和极化强度、剩余极化强度)等。最后对响应结果进行多元二次线性回归,得出了回归方程。探讨达到最优化薄膜特性所需要的工艺条件。     

Highly (1 0 0)-oriented Pb(Zr0.20Ti0.80)O3/(Pb1−xLax)Ti1−x/4O3 multilayered thin films prepared by RF magnetron sputtering

The Pb(Zr_0.20Ti_0.80)O₃/(Pb_1−xLa_x)Ti_1−x/4O₃ (x = 0, 0.10, 0.15, 0.20) (PZT/PLT_x) multilayered thin films were in situ deposited on the Pt(1 1 1)/Ti/SiO₂/Si(1 0 0) substrates by RF magnetron sputtering technique with a PbO_x buffer layer. With this method, all PZT/PLT_x multilayered thin films possess highly (1 0 0) orientation. The PbO_x buffer layer leads to the (1 0 0) orientation of the multilayered thin films. The effect of the La content in PLT_x layers on the dielectric and ferroelectric properties of the PZT multilayered thin films was systematically investigated. The enhanced dielectric and ferroelectric properties are observed in the PZT/PLT_x (x = 0.15) multilayered thin films. The dielectric constant reaches maximum value of 365 at 1 KHz for x = 0.15 with a low loss tangent of 0.0301. Along with enhanced dielectric properties, the multilayered thin films also exhibit large remnant polarization value of 2P_r = 76.5 μC/cm², and low coercive field of 2E_c = 238 KV/cm.     

Vapor Phase Growth of Centimeter-Sized Band Gap Engineered Cesium Lead Halide Perovskite Single-Crystal Thin Films with Color-tunable Stimulated Emission

Single crystal metal halide perovskites thin films are considered to be a promising optical, optoelectronic materials with extraordinary performance due to their low defect densities. However, it is still difficult to achieve large-scale perovskite single-crystal thin films (SCTFs) with tunable bandgap by vapor-phase deposition method. Herein, the synthesis of CsPbCl_3(1–x)Br_3x SCTFs with centimeter size (1 cm × 1 cm) via vapor-phase deposition is reported. The Br composition of CsPbCl_3(1–x)Br_3x SCTFs can be gradually tuned from x = 0 to x = 1, leading the corresponding bandgap to change from 2.29 to 2.91 eV. Additionally, an low-threshold (≈23.9 µJ cm⁻²) amplified spontaneous emission is achieved based on CsPbCl_3(1–x)Br_3x SCTFs at room temperature, and the wavelength is tuned from 432 to 547 nm by varying the Cl/Br ratio. Importantly, the high-quality CsPbCl_3(1–x)Br_3x SCTFs are ideal optical gain medium with high gain up to 1369.8 ± 101.2 cm⁻¹. This study not only provides a versatile method to fabricate high quality CsPbCl_3(1–x)Br_3x SCTFs with different Cl/Br ratio, but also paves the way for further research of color-tunable perovskite lasing.     

Piezoelectric Sensors Operating at Very High Temperatures and in Extreme Environments Made of Flexible Ultrawide-Bandgap Single-Crystalline AlN Thin Films

Extreme environments are often faced in energy, transportation, aerospace, and defense applications and pose a technical challenge in sensing. Piezoelectric sensor based on single-crystalline AlN transducers is developed to address this challenge. The pressure sensor shows high sensitivities of 0.4–0.5 mV per psi up to 900 °C and output voltages from 73.3 to 143.2 mV for input gas pressure range of 50 to 200 psi at 800 °C. The sensitivity and output voltage also exhibit the dependence on temperature due to two origins. A decrease in elastic modulus (Young's modulus) of the diaphragm slightly enhances the sensitivity and the generation of free carriers degrades the voltage output beyond 800 °C, which also matches with theoretical estimation. The performance characteristics of the sensor are also compared with polycrystalline AlN and single-crystalline GaN thin films to investigate the importance of single crystallinity on the piezoelectric effect and bandgap energy-related free carrier generation in piezoelectric devices for high-temperature operation. The operation of the sensor at 900 °C is amongst the highest for pressure sensors and the inherent properties of AlN including chemical and thermal stability and radiation resistance indicate this approach offers a new solution for sensing in extreme environments.     

Investigation of LSPR Coupling Effects toward the Rational Design of CsxWO3–δ Based Solar NIR Filtering Coatings

The optical range of localized surface plasmon resonance (LSPR) is extended into the infrared region, thanks to the development of highly doped semiconductor nanocrystals. Particularly, the near-infrared (NIR) range holds a significant interest in managing solar radiation. However, practical applications necessitate the arrangement of particles, which is known to possibly impact their optical properties through LSPR coupling effects. How such coupling modifies the LSPR response in semiconductor hosts remains largely unexplored. In this study, a protocol for producing composite coatings composed of cesium-doped tungsten bronze nanocrystals embedded in a silica matrix is presented. Achieving individual dispersion of nanocrystals is made possible through careful selection of a surface polyglycerol ligand exchange. This allows to tune the interparticle distance by adjusting the nanocrystal volume fraction in the composite. The findings demonstrate that LSPR coupling effects significantly influence the LSPR intensity of nanocrystals in the composite when the nanocrystal-to-nanocrystal distance matches their size. Beyond elucidating the LSPR coupling effect, this study provides insights into the potential use of Cs-HTB nanocrystals for solar control applications. Through the optimization of morphology and film structure, remarkable selectivity is obtained in terms of maintaining good transparency in the visible range while achieving high absorption in the NIR.     

自还原体系银导电墨水的制备与低温印制导电图形的研究

总结了开发一种简便快捷的可印制在挠性基板上于低温条件实现烧结形成高导电性线路的自还原型银导电墨水的制备方法。该导电墨水通过混合二乙醇胺溶液和银氨溶液制备得到。印制在塑料基材上后,在75℃下固化形成导电线路。这是因为在碱性环境与高于50℃的温度下,二乙醇胺可分解生成甲醛并自发地与银氨溶液发生反应。随后还原出银原子并让其吸附在基材上形成银薄膜。用该方法印制得到的银线其导电率可达到金属银导电率的20％,通过继续改进可应用于各种印制电子技术中。     

LaNiO3薄膜热稳定性的研究

LaNiO3导电金属氧化物薄膜在现代应用科学研究中作为电极和过渡阻挡层倍受青睐，它具有很好的导电特性和稳定性。该文采用射频溅射法制备了具有(100)择优取向的赝立方结构LaNiO3-x薄膜，并进行了原位热处理。实验结果表明，在265℃的处理条件下，LaNiO3薄膜表现出不稳定性，晶格中的氧在2h内失去了2.7％。氧的损失对品格结构没有明显影响，但薄膜的导电性能明显下降，折射率和消光系数也具有相同幅度的下降。对薄膜的应用具有一定的影响。该文从LaNiO3薄膜的导电机理方面对实验现象给出了分析和解释。     

基片温度对氧化钒薄膜结构与电性能的影响

以V2O5粉末为原料采用真空蒸发法结合真空退火还原法在玻璃基片上制备VOx薄膜，调节不同的基片温度获得几组薄膜。运用X-射线衍射(XRD)分析和扫描电子显微镜(SEM)分析发现随着基片温度的不同，薄膜成分、物相以及表面形貌有明显差异。在基片温度为200℃时所得薄膜的电阻温度系数(TCR)达到-0．03／℃，并发现基片温度越高，薄膜在室温附近的电阻率越低，电阻温度系数绝对值也越小。     

p-Si薄膜生长的ECR-CVD等离子体系统的结构设计

提出了一种生长p-Si薄膜的ECR-PECVD等离子体系统。系统采用永磁铁和线圈相结合，改善反应室磁场的均匀性；微波窗口设计成多层结构．避免窗口污染；衬底托架移动和旋转利于改善生长膜的均匀性。