原子层沉积毕业论文

从原理上说，ALD是通过化学反应得到生成物，但在沉积反应原理、沉积反应条件的要求和沉积层的质量上都与传统的CVD不同，在传统CVD工艺过程中，化学蒸汽不断通入真空室内，因此该沉积过程是连续的，沉积薄膜的厚度和温度、压力、气体流量以及流动的均匀性、时间等多种因素有关；在ALD工艺过程中，则是将不同的反应前驱物以气体脉冲的形式交替送入反应室中，因此并非一个连续的工艺过程。相对于传统的沉积工艺而言，ALD在膜层的均匀性、阶梯覆盖率以及厚度控制等方面都具有明显的优势。在某些应用中，需要在具有很大长径比的内腔表面镀膜，极限的情况下长径比会达到15甚至20，采用传统的镀膜方法是无法实现的，而原子层沉积技术由于是通过在基底表面形成吸附层，进一步通过反应生成薄膜，因而在这方面具有独特的优势，可以在大长径比的内腔表面形成厚度均匀的薄膜。工作原理图近年来，对于X射线谱段光学薄膜的需求和研究也日益增加。由于材料的光学常数和性能在X射线区随波长的变化非常显著，同时，在X射线多层膜制备过程中，对基底表面粗糙度要求很高，膜层也很薄，难于控制，这些问题目前在光学薄膜的研究中，仍然是研究的难点。由于ALD技术是通过反应前驱物在表面形成化学吸附后，反应生成薄膜，其主要特点是适合沉积厚度很薄的薄膜，而且成膜质量很好，在X射线光学薄膜器件制备方面具有绝对优势。光子晶体是20世纪80年代末提出的新概念和新材料，由于存在光子禁带和光子局域而具有很广泛的应用前景。由于光子晶体是一种人造微结构，自然界里只存在有限几种，因此，光子晶体的制作技术，一直是研究的热点。原子层沉积技术由于可以精确控制膜层，所获得的高度均匀的表面对光子禁带特性有很大影响，为获得高性能光子晶体结构提供了一条灵活有效的途径。

编译 | 未玖

Science , 13 MAY 2022, VOL 376, ISSUE 6594

《科学》 2022年5月13日，第376卷，6594期

物理学 Physics

Quantum gas microscopy of Kardar-Parisi-Zhang superdiffusion

KPZ超扩散的量子气体显微镜

作者：DAVID WEI, ANTONIO RUBIO-ABADAL, BINGTIAN YE, FRANCISCO MACHADO, JACK KEMP, KRITSANA SRAKAEW, ET AL.

链接：

摘要：

Kardar-Parisi-Zhang（KPZ）普适性类描述了大量经典随机模型的粗粒度行为。令人惊讶的是，最近人们推测KPZ普适性也可用于描述一维量子海森堡模型中的自旋输运。

研究组通过多达50个自旋的自旋链畴壁弛豫，在冷原子量子模拟器中实验探测输运来验证这个猜想。他们发现，畴壁弛豫确实由KPZ动力学指数z=3/2控制，KPZ标度的出现需要可积性和非阿贝尔SU(2)对称性。

最后，研究组利用量子气体显微镜实现的单自旋敏感性探测，来测量基于自旋输运统计的可观测数据。该研究结果产生了一个明确的非线性特征，这是KPZ普适性的一个标志。

Abstract：

The Kardar-Parisi-Zhang (KPZ) universality class describes the coarse-grained behavior of a wealth of classical stochastic models. Surprisingly, KPZ universality was recently conjectured to also describe spin transport in the one-dimensional quantum Heisenberg model. We tested this conjecture by experimentally probing transport in a cold-atom quantum simulator via the relaxation of domain walls in spin chains of up to 50 spins. We found that domain-wall relaxation is indeed governed by the KPZ dynamical exponent z = 3/2 and that the occurrence of KPZ scaling requires both integrability and a nonabelian SU(2) symmetry. Finally, we leveraged the single-spin–sensitive detection enabled by the quantum gas microscope to measure an observable based on spin-transport statistics. Our results yield a clear signature of the nonlinearity that is a hallmark of KPZ universality.

Observing emergent hydrodynamics in a long-range quantum magnet

在长程量子磁体中观测新兴流体动力学

作者：M. K. JOSHI, F. KRANZL, A. SCHUCKERT, I. LOVAS, C. MAIER, R. BLATT, ET AL.

链接：

摘要：

确定非平衡量子态的普适性质是现代物理学的一个重大挑战。一个有趣的预测是，经典流体力学普遍出现在任何相互作用的量子系统演化中。

研究组通过实验探测了51个单独控制离子的量子动力学，实现了长程相互作用的自旋链。通过测量无限温度状态下的时空分辨关联函数，他们观测到了整个从正常扩散到反常超扩散的流体动力学普适性类家族，均由Lévy飞行描述。

研究组提取了流体力学理论的输运系数，反映了系统的微观性质。该结果表明，工程量子系统有潜力为量子物质非平衡态的普适性提供关键见解。

Abstract：

Identifying universal properties of nonequilibrium quantum states is a major challenge in modern physics. A fascinating prediction is that classical hydrodynamics emerges universally in the evolution of any interacting quantum system. We experimentally probed the quantum dynamics of 51 inpidually controlled ions, realizing a long-range interacting spin chain. By measuring space-time–resolved correlation functions in an infinite temperature state, we observed a whole family of hydrodynamic universality classes, ranging from normal diffusion to anomalous superdiffusion, that are described by Lévy flights. We extracted the transport coefficients of the hydrodynamic theory, reflecting the microscopic properties of the system. Our observations demonstrate the potential for engineered quantum systems to provide key insights into universal properties of nonequilibrium states of quantum matter.

材料科学 Materials Science

Highly enhanced ferroelectricity in Hf O2 -based ferroelectric thin film by light ion bombardment

轻离子轰击增强HfO2基铁电薄膜的铁电性

作者：SEUNGHUN KANG, WOO-SUNG JANG, ANNA N. MOROZOVSKA, OWOONG KWON, YEONGROK JIN, YOUNG-HOON KIM, et al.

链接：

摘要：

非易失和准同型的后摩尔电子器件的不断发展需要集成铁电材料和半导体材料。与原子层沉积兼容的氧化铪（Hf O2 ）基铁电体的出现开辟了有趣且颇有前景的研究途径。然而，Hf O2 中铁电性的起源和控制途径仍然是个谜。

研究组证明了局部氦（He）注入可以激活这些材料中的铁电性。他们还分析了可能的竞争机制，包括He离子引发的摩尔体积变化、空位再分布、空位生成和空位迁移率的激活。

这些发现既揭示了该系统中铁电性的起源，也为纳米工程二元铁电体开辟了新途径。

Abstract：

Continuous advancement in nonvolatile and morphotropic beyond-Moore electronic devices requires integration of ferroelectric and semiconductor materials. The emergence of hafnium oxide (Hf O2 )–based ferroelectrics that are compatible with atomic-layer deposition has opened interesting and promising avenues of research. However, the origins of ferroelectricity and pathways to controlling it in Hf O2 are still mysterious. We demonstrate that local helium (He) implantation can activate ferroelectricity in these materials. The possible competing mechanisms, including He ion–induced molar volume changes, vacancy redistribution, vacancy generation, and activation of vacancy mobility, are analyzed. These findings both reveal the origins of ferroelectricity in this system and open pathways for nanoengineered binary ferroelectrics

Ultrafast water permeation through nanochannels with a densely fluorous interior surface

内表面致密氟纳米通道可超快渗透水

作者：YOSHIMITSU ITOH, SHUO CHEN, RYOTA HIRAHARA, TAKESHI KONDA, TSUBASA AOKI, TAKUMI UEDA, ET AL.

链接：

摘要：

水通道蛋白的疏水性内表面促进了水在其中的超快渗透。聚四氟乙烯有着致密的氟面，因此具有很强的防水性。

研究组报道了一系列内径为0.9-1.9纳米的含氟低聚酰胺纳米环。这些纳米环在磷脂双层膜中进行超分子聚合，形成含氟纳米通道，其内壁被氟原子密集覆盖。直径最小的纳米通道的水渗透通量比水通道蛋白和碳纳米管的水渗透通量大两个数量级。

该研究所提出的纳米通道具有可忽略的氯离子（C l- ）渗透性，这是由静电负氟内表面提供的强大静电屏障造成的。因此，这种纳米通道有望在脱盐过程中显示出近乎完美的阻盐。

Abstract：

Ultrafast water permeation in aquaporins is promoted by their hydrophobic interior surface. Polytetrafluoroethylene has a dense fluorine surface, leading to its strong water repellence. We report a series of fluorous oligoamide nanorings with interior diameters ranging from 0.9 to 1.9 nanometers. These nanorings undergo supramolecular polymerization in phospholipid bilayer membranes to form fluorous nanochannels, the interior walls of which are densely covered with fluorine atoms. The nanochannel with the smallest diameter exhibits a water permeation flux that is two orders of magnitude greater than those of aquaporins and carbon nanotubes. The proposed nanochannel exhibits negligible chloride ion (C l- ) permeability caused by a powerful electrostatic barrier provided by the electrostatically negative fluorous interior surface. Thus, this nanochannel is expected to show nearly perfect salt reflectance for desalination.

化学 Chemistry

Scalable processing for realizing 21.7%-efficient all-perovskite tandem solar modules

可扩展处理实现21.7%效率的全钙钛矿串联太阳能模块

作者：KE XIAO, YEN-HUNG LIN, MEI ZHANG, ROBERT D. J. OLIVER, XI WANG, ZHOU LIU, ET AL.

链接：

摘要：

将全钙钛矿串联太阳能电池作为模块而非单结结构来制造面临诸多挑战，包括生长高质量的宽禁带钙钛矿，以及减缓互连触点处卤化物和金属互扩散造成的不可逆退化。

研究组展示了使用可扩展制造技术制备高效全钙钛矿串联太阳能模块。通过系统调节无甲基铵1.8eV混合卤化物钙钛矿的铯比，他们提升了大面积刀片涂层薄膜的结晶均匀性。

研究组在互连的子电池间引入导电共形“扩散势垒”，以提高全钙钛矿串联太阳能模块的功率转换效率（PCE）和稳定性。

该串联模块获得了21.7%的认证PCE，孔径面积为20 c m2 ，在模拟1-太阳光照下连续运行500小时后仍保持75%的初始效率。

Abstract：

Challenges in fabricating all-perovskite tandem solar cells as modules rather than as single-junction configurations include growing high-quality wide-bandgap perovskites and mitigating irreversible degradation caused by halide and metal interdiffusion at the interconnecting contacts. We demonstrate efficient all-perovskite tandem solar modules using scalable fabrication techniques. By systematically tuning the cesium ratio of a methylammonium-free 1.8–electron volt mixed-halide perovskite, we improve the homogeneity of crystallization for blade-coated films over large areas. An electrically conductive conformal “diffusion barrier” is introduced between interconnecting subcells to improve the power conversion efficiency (PCE) and stability of all-perovskite tandem solar modules. Our tandem modules achieve a certified PCE of 21.7% with an aperture area of 20 square centimeters and retain 75% of their initial efficiency after 500 hours of continuous operation under simulated 1-sun illumination.

地球科学 Earth Science

High-resolution mapping of losses and gains of Earth’s tidal wetlands

全球潮汐湿地消长的高分辨率绘图

作者：NICHOLAS J. MURRAY, THOMAS A. WORTHINGTON, PETE BUNTING, STEPHANIE DUCE, VALERIE HAGGER, CATHERINE E. LOVELOCK, ET AL.

链接：

摘要：

人们预期潮汐湿地会对全球环境变化做出动态响应，但湿地损失在多大程度上被湿地增加所抵消仍不清楚。

研究组对卫星数据进行了全球分析，以同时监测1999-2019年间三种高度互联的潮间生态系统类型——潮滩、潮沼和红树林的变化。

在全球范围内，13700 k m2 的潮汐湿地已经消失，但被9700 k m2 的湿地增加所抵消后，最终20年间净缩减4000 k m2 。

研究组发现，这些损失和增长中有27%与直接人类活动有关，例如转向农业和恢复失去的湿地。所有其他变化都归因于间接驱动因素，包括沿海过程和气候变化的影响。

Abstract：

Tidal wetlands are expected to respond dynamically to global environmental change, but the extent to which wetland losses have been offset by gains remains poorly understood. We developed a global analysis of satellite data to simultaneously monitor change in three highly interconnected intertidal ecosystem types—tidal flats, tidal marshes, and mangroves—from 1999 to 2019. Globally, 13,700 square kilometers of tidal wetlands have been lost, but these have been substantially offset by gains of 9700 k m2 , leading to a net change of 4000 k m2 over two decades. We found that 27% of these losses and gains were associated with direct human activities such as conversion to agriculture and restoration of lost wetlands. All other changes were attributed to indirect drivers, including the effects of coastal processes and climate change.