金属诱导非晶硅薄膜低温晶化

介绍了一种非晶硅 (a- Si)薄膜低温晶化的新工艺 :金属诱导非晶硅薄膜低温晶化。研究了各种 a- Si/金属双层膜退火后的晶化情况。利用 X射线衍射分析了结晶硅膜的结构 ,通过光学显微镜观察了 Al诱导 a- Si薄膜晶化后的表面形貌 ,并初步探讨了金属诱导非晶硅薄膜低温晶化的机理     

Deterministic Nucleation for Halide Perovskite Thin Films with Large and Uniform Grains

Halide perovskite materials have come to the forefront of optoelectronics recently owing to their excellent light absorbing and emitting properties. Despite their excellent properties there are still problems that need to be overcome such as short operating lifetimes, and an observed hysteresis behavior in their current–voltage characteristics. It is found that these challenges could be overcome by developing a deterministic nucleation process using gold as a nucleation promoter to control the grain size of the perovskite layer. It is shown that this deterministic nucleation process can be expanded across multiple perovskite systems and can be used to achieve extremely uniform and large grain sizes within the perovskite layer. These large perovskite grains exhibit enhanced stability compared to current state‐of‐the‐art nanocrystalline films, and exhibit no hysteresis in their I–V characteristics which is key if commercialization of perovskites is to be realized.     

Tailoring of Ligand-Off Nanoparticles Inks for Thin p-Type Oxide Overlayers Formation with Maintaining Intact Halide Perovskite

In n-i-p halide perovskite solar cells (HPSCs), the development of p-type oxides is one of the most noteworthy approaches as hole transport materials (HTMs) for long-term stability and mass production. However, the deposition of oxide HTMs through a solution process over the perovskite layer without damage to the perovskite layer remains a major challenge. Here, the colloidal dispersion of ligand-off NiO nanoparticles (NPs) to form the HTM overlayer on perovskite using appropriate solvents that do not damage the underlying perovskite layer is reported. Monodispersed NiO NPs are synthesized using oleylamine (OLA) ligands via the solvothermal method, and the OLA ligands are then removed to form ligand-off NiO NPs. Based on the Hansen solubility theory, appropriate mixed solvents are found for both the dispersion of NiO NPs without ligands and coating without perovskite damage. The colloidal dispersion form a compact and uniform NiO NPs layer of 30 nm thickness on the perovskite layer, allowing n-SnO₂/Halide/p-NiO HPSCs to be successfully fabricated. The HPSC shows a record power conversion efficiency under one sun illumination for an n-i-p oxide/halide/oxide structure and excellent thermal stability maintaining 98% of the initial efficiency for 580 h under 85 °C and 10% relative humidity condition.     

Exotic Structural and Optoelectronic Properties of Layered Halide Double Perovskite Polymorphs

Discovering new types of layered perovskites has great importance for designing novel optoelectronic devices. In this article, combining first-principle calculations with global structure searching, it is found that Rb₄SnSb₂Br₁₂, a typical halide double perovskite, can unexpectedly possess fertile low formation-energy polymorphs holding van de Walls (vdW) layered structures. Consequently, these polymorphs can be effectively classified into 12 types according to their local octahedral motifs, exhibiting a wide range of bandgap covering the visible spectrum. Interestingly, the structure-dependent bandgap in these polymorphs can be well understood by developing a simple machine learning model. Moreover, as a layered system, the optoelectronic properties of Rb₄SnSb₂Br₁₂ can be effectively tuned by the layer thickness, and both type-I and type-II band alignment can be achieved in single-compound Rb₄SnSb₂Br₁₂ heterojunctions. Finally, it is suggested that the Sn-moderate condition can be considered to grow intrinsic p-type Rb₄SnSb₂Br₁₂ with lower defect density. Those findings not only provide a promising material system for designing the vdW tandem solar cell, but also offer a new opportunity to achieve exotic optoelectronic applications in a single-phase layered perovskite compound.     

非晶GaN薄膜的空间电荷限制电流特性

采用直流磁控溅射技术制备了Si衬底上的非晶GaN薄膜. GaN肖特基二极管伏安曲线不能简单地用包含串联电阻和复合电流效应的热电子发射理论来解释，其他电流输运机制（空间电荷限制电流）起主要作用. 分析数据得到平衡时的电子浓度为1.1E4cm-3和位于EC-0.363eV的陷阱能级. 测量空间电荷限制电流可以用来研究宽带隙化合物非晶半导体GaN的深能级性质.     

非晶氧化钛薄膜的电学特性研究

室温下,通过采用直流反应磁控溅射法在覆盖有氮化硅薄膜的单晶硅衬底上生长了厚度约为100nm的氧化钛薄膜。掠入射X射线衍射分析结果表明在室温下,不同氧分压下生长的氧化钛薄膜均具有非晶结构。分别采用场发射扫描电子显微镜、X射线光电子能谱对薄膜的表面和断面形貌以及薄膜的组分进行了分析和表征。对薄膜的电学特性测试发现非晶氧化钛薄膜在293～373K的温度范围内主要依靠热激发至扩展态中的电子导电。     

非晶YBCO薄膜热释电红外探测器

介绍了非晶YBCO薄膜用作非制冷热释电红外探测器材料。它在室温下显示出强的热释电行为,并且容易在室温下采用射频磁控溅射法沉积,制备工艺与CMOS工艺相兼容,是 一种很有潜力的热释电探测器材料。并介绍了非晶YBCO热释电薄膜的研究现状,阐述了该薄膜及其探测器的制备技术和研究动向。     

Defect Passivation via the Incorporation of Tetrapropylammonium Cation Leading to Stability Enhancement in Lead Halide Perovskite

Improving the performances of photovoltaic (PV) devices by suppressing nonradiative energy losses through surface defect passivation and enhancing the stability to the level of standard PV represents one critical challenge for perovskite solar cells. Here, reported are the advantages of introducing a tetrapropylammonium (TPA⁺) cation that combines two key functionalities, namely surface passivation of CH₃NH₃PbI₃ nanocrystals through strong ionic interaction with the surface and bulk passivation via formation of a type I heterostructure that acts as a recombination barrier. As a result, nonencapsulated perovskite devices with only 2 mol% of TPA⁺ achieve power conversion efficiencies over 18.5% with higher V_OC under air mass 1.5G conditions. The devices fabricated retain more than 85% of their initial performances for over 1500 h under ambient conditions (55% RH ± 5%). Furthermore, devices with TPA⁺ also exhibit excellent operational stability by retaining over 85% of the initial performance after 250 h at maximum power point under 1 sun illumination. The effect of incorporation of TPA⁺ on the structural and optoelectronic properties is studied by X‐ray diffraction, ultraviolet–visible absorption spectroscopy, ultraviolet photon–electron spectroscopy, time‐resolved photoluminescence, and scanning electron microscopy imaging. Atomic‐level passivation upon addition of TPA⁺ is elucidated employing 2D solid‐state NMR spectroscopy.     

浴铜灵有机分子材料对钙钛矿薄膜表面的钝化作用

采用2,9-二甲基-4,7-二苯基-1,10-邻二氮杂菲(浴铜灵,缩写:BCP)有机小分子作为钙钛矿薄膜与电子传输层之间的界面修饰层,从而使得反型结构的钙钛矿太阳电池性能得到显著改善。通过扫描电子显微镜研究发现:BCP分子可在钙钛矿薄膜样品表面的晶界间充分填充,推测其抑制了界面缺陷态的产生。进一步研究器件内部界面电荷的累积,并结合交流阻抗谱的分析,证实经BCP钝化的钙钛矿太阳电池中界面电荷的累积减少,光生载流子的复合被抑制,电池的光电转换效率由原来的15.7%提升到了17.4%。     

Ultra-Stable and Sensitive Ultraviolet Photodetectors Based on Monocrystalline Perovskite Thin Films

The detection of ultraviolet (UV) radiation with effective performance and robust stability is essential to practical applications. Metal halide single-crystal perovskites (ABX₃) are promising next-generation materials for UV detection. The device performance of all-inorganic CsPbCl₃ photodetectors (PDs) is still limited by inner imperfection of crystals grown in solution. Here wafer-scale single-crystal CsPbCl₃ thin films are successfully grown by vapor-phase epitaxy method, and the as-constructed PDs under UV light illumination exhibit an ultralow dark current of 7.18 pA, ultrahigh ON/OFF ratio of ≈5.22 × 10⁵, competitive responsivity of 32.8 A W⁻¹, external quantum efficiency of 10867% and specific detectivity of 4.22 × 10¹² Jones. More importantly, they feature superb long-term stability toward moisture and oxygen within twenty-one months, good temperature tolerances at low and high temperatures. The ability of the photodetector arrays for excellent UV light imaging is further demonstrated.     

Semimetallicity and Negative Differential Resistance from Hybrid Halide Perovskite Nanowires

In the rapidly progressing field of organometal halide perovskites, the dimensional reduction can open up new opportunities for device applications. Herein, taking the recently synthesized trimethylsulfonium lead triiodide (CH₃)₃SPbI₃ perovskite as a representative example, first‐principles calculations are carried out and the nanostructuring and device application of halide perovskite nanowires are studied. It is found that the 1D (CH₃)₃SPbI₃ structure is structurally stable, and the electronic structures of higher‐dimensional forms are robustly determined at the 1D level. Remarkably, due to the face‐sharing [PbI₆] octahedral atomic structure, the organic ligand‐removed 1D PbI₃ frameworks are also found to be stable. Moreover, the PbI₃ columns avoid the Peierls distortion and assume a semimetallic character, contradicting the conventional assumption of semiconducting metal‐halogen inorganic frameworks. Adopting the bundled nanowire junctions consisting of (CH₃)₃SPbI₃ channels with sub‐5 nm dimensions sandwiched between PbI₃ electrodes, high current densities and large room‐temperature negative differential resistance (NDR) are finally obtained. It will be emphasized that the NDR originates from the combination of the near‐Ohmic character of PbI₃‐(CH₃)₃SPbI₃ contacts and a novel NDR mechanism that involves the quantum‐mechanical hybridization between channel and electrode states. This work demonstrates the great potential of low‐dimensional hybrid perovskites toward advanced electronic devices beyond actively pursued photonic applications.     

Barrier Properties of Amorphous Binary Ta-Ni Thin Films for Cu Interconnection

Highly thermally stable amorphous Ta _x Ni_1–x (x = 0.25 and 0.75) thin films were deposited on Si and Si/SiO₂ substrate by magnetron dc sputtering, and the performance of films (20-nm thick) as barriers for copper (Cu) interconnection was evaluated. The failure behaviors of the films were elucidated using a four-point probe, x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Auger emission spectrometry (AES). A highly (111) textured Cu film could be obtained when Cu was deposited on Si/Ta_0.25Ni_0.75 and Si/SiO₂/Ta_0.25Ni_0.75 substrates. The failure temperatures of Si/Ta_0.25Ni_0.75/Cu- and Si/Ta_0.75Ni_0.25/Cu-stacked films were 550°C and 600°C, respectively. Failure of the studied films initiated the penetration of Cu into the Si/Ta _x Ni_1–x interface and triggered the partial dissociation of the Ta _x Ni_1–x barrier layer, forming Cu₃Si precipitates, Ni-silicide and Ta-silicide. Increasing the Ta content enhanced the microstructural and thermal stability of the stacked films, markedly improving barrier properties. The experimental findings demonstrated that the barrier characteristic of Ta_0.75Ni_0.25 was substantially superior to that of Ta_0.25Ni_0.75.     

Compositionally Modulated Magnetic Epitaxial Spinel/Perovskite Nanocomposite Thin Films

There is great interest in self‐assembled oxide vertical nanocomposite films consisting of epitaxial spinel pillars in a single crystal perovskite matrix, due to their tunable electronic, magnetic, and multiferroic properties. Varying the composition or geometry of the pillars in the out‐of‐plane direction has not been previously reported but can provide new routes to tailoring their properties in three dimensions. In this work, ferrimagnetic epitaxial CoFe₂O₄, MgFe₂O₄, or NiFe₂O₄ spinel nanopillars with an out‐of‐plane modulation in their composition and shape are grown in a BiFeO₃ matrix on a (001) SrTiO₃ substrate using pulsed laser deposition. Changing the pillar composition during growth produces a homogeneous pillar composition due to cation interdiffusion, but this can be suppressed using a sufficiently thick blocking layer of BiFeO₃ to produce bi‐pillar films containing for example a layer of magnetically hard CoFe₂O₄ pillars and a layer of magnetically soft MgFe₂O₄ pillars, which form in different locations. A thinner blocking layer enables contact between the top of the CoFe₂O₄ and the bottom of the MgFe₂O₄ which leads to correlated growth of the MgFe₂O₄ pillars directly above the CoFe₂O₄ pillars and provides a path for interdiffusion. The magnetic hysteresis of the nanocomposites is related to the pillar structure.     

ZnO纳米颗粒薄膜的制备及其光学特性

采用化学回流法制备了3种不同粒径的ZnO纳米颗粒,然后旋涂在ITO玻璃衬底上,形成样品a、b和c3种ZnO纳米颗粒薄膜.场发射扫描电子显微镜(FESEM)结果显示,3种样品晶粒都呈颗粒形状,形成的薄膜较平整,平均晶粒尺寸分别为(φ)5 nm、(φ)25 nm和(φ)40 nm.X线衍射(XRD)结果表明,ZnO纳米颗粒为多晶六方晶系纤锌矿结构.样品a、b在可见光区有很少的光吸收,在紫外光区有很强的吸收,而由于纳米颗粒的直径较大,样品c在紫外和可见光区都存在很强的吸收.室温下的光致发光谱表明,样品a有一个近带边(NBE)紫外发射峰和蓝光发射峰,样品b、c出现一很宽的深能级缺陷相关的可见光发光带,这说明3种薄膜都存在大量的本征缺陷.     

层状钙钛矿铁电薄膜的结构及性能研究

介绍了ＳｒＢｉ２Ｔａ２Ｏ９系列层状钙钛矿铁电薄膜的结构、性能、制备方法以及研究进展。     

The Impact of X-Ray Radiation on Chemical and Optical Properties of Triple-Cation Lead Halide Perovskite: from the Surface to the Bulk

Understanding the effects of X-rays on halide perovskite thin films is critical for accurate and reliable characterization of this class of materials, as well as their use in detection systems. In this study, advanced optical imaging techniques are employed, both spectrally and temporally resolved, coupled with chemical characterizations to obtain a comprehensive picture of the degradation mechanism occurring in the material during photoemission spectroscopy measurements. Two main degradation pathways are identified through the use of local correlative physico-chemical analysis. The first one, at low X-Ray fluence, shows minor changes of the surface chemistry and composition associated with the formation of electronic defects. Moreover, a second degradation route occurring at higher fluence leads to the evaporation of the organic cations and the formation of an iodine-poor perovskite. Based on the local variation of the optoelectronic properties, a kinetic model describing the different mechanisms is proposed. These findings provide valuable insight on the impact of X-rays on the perovskite layers during investigations using X-ray based techniques. More generally, a deep understanding of the interaction mechanism of X-rays with perovskite thin films is essential for the development of perovskite-based X-ray detectors and solar for space applications.     

Electrical Property Enhancement in Orientation-Modulated Perovskite La-Doped SrTiO3 Thermoelectric Thin Films

Thermoelectric oxide thin films are promising in chip cooling. The issues on the orientation of thin films are essential as they are related to the structures, morphologies, and thermoelectric properties. In this regard, the orientation modulation is conducted on La-doped SrTiO₃ thin films on (LaAlO₃)_0.3(Sr₂TaAlO₆)_0.7 (LSAT) single crystal substrates. Layer-by-layer growth mode is found in (001)- and (110)- oriented thin films, resulting in few grain boundaries (GBs). In (111)-oriented films, island growth mode leads to columnar grain boundaries that build up potential barriers for electrons to be strongly scattered and filtered, suppressing electron mobility and increasing effective mass. In addition, the GBs serve as oxygen vacancy diffusion paths when annealing, causing increased carrier concentration and lattice contraction. The weighted mobility of 71.9 cm² V⁻¹ s⁻¹ and electrical conductivity of ≈600 S cm⁻¹ are realized in the (001)-oriented film at room temperature. Ultimately, outstanding power factor values of ≈569 µW m⁻¹ K⁻² (room temperature) and ≈791 µW m⁻¹ K⁻² (573 K) are successfully achieved, outperforming those in polycrystalline ceramics and (111)-oriented films. This study systematically investigates the influence of grain boundaries and orientations on SrTiO₃-based thermoelectric films, which lays a solid foundation for improving thermoelectric performance in other oxide thin films.     

In掺杂对ZnO薄膜结构及光学特性的影响

通过射频反应溅射法在硅衬底上制备了具有ｃ轴择优取向和小晶格失配的In掺杂ZnO薄膜．在室温下测量样品的光致发光（PL）光谱,观察到波长位于415nm（3.02eV）和430nm（2.88eV）附近的蓝紫发光双峰．研究了不同In掺杂量对ZnO薄膜的结构和发光特性的影响．当In片面积为靶总面积的3%时,样品具有高度的ｃ轴择优取向和较小的晶格失配（0.16%）;同时在PL谱中观察到波长位于415nm（3.02eV）和433nm（2.86eV）处的强蓝紫光双峰．     

富硅氮化硅薄膜的制备及其发光特性

采用射频磁控反应溅射法制备了氮化硅薄膜.利用X射线衍射谱(XRD)、红外光谱(IR)、能谱(EDS)和光致发光谱(PL),通过与氮气中和空气中退火薄膜比较,对原沉积薄膜进行了成分与结构和发光特性研究.研究发现原沉积薄膜是部分晶化的富硅氮化硅薄膜,薄膜中晶态氮化硅颗粒的平均粒径为33 nm;在氮气中退火后,纳米颗粒增大;在空气中退火后,薄膜被氧化,晶态颗粒消失.在4.67 eV的光激发下,原沉积薄膜中观测到7个强的PL峰,其峰位分别为3.39,3.24,3.05,2.82,2.61,2.37和2.11 eV.在氮气和空气中退火后, PL峰位和强度有变化.对其光致发光机制进行了探讨, 认为硅悬挂键≡Si,氮悬挂键=N,硅错键≡Si-Si≡以及与氧有关的缺陷在富硅氮化硅薄膜高强度荧光发射中起主导作用.     

Insights into Fullerene Passivation of SnO2 Electron Transport Layers in Perovskite Solar Cells

Interfaces between the photoactive and charge transport layers are crucial for the performance of perovskite solar cells. Surface passivation of SnO₂ as electron transport layer (ETL) by fullerene derivatives is known to improve the performance of n–i–p devices, yet organic passivation layers are susceptible to removal during perovskite deposition. Understanding the nature of the passivation is important for further optimization of SnO₂ ETLs. X‐ray photoelectron spectroscopy depth profiling is a convenient tool to monitor the fullerene concentration in passivation layers at a SnO₂ interface. Through a comparative study using [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) and [6,6]‐phenyl‐C₆₁‐butyric acid (PCBA) passivation layers, a direct correlation is established between the formation of interfacial chemical bonds and the retention of passivating fullerene molecules at the SnO₂ interface that effectively reduces the number of defects and enhances electron mobility. Devices with only a PCBA‐monolayer‐passivated SnO₂ ETL exhibit significantly improved performance and reproducibility, achieving an efficiency of 18.8%. Investigating thick and solvent‐resistant C₆₀ and PCBM‐dimer layers demonstrates that the charge transport in the ETL is only improved by chemisorption of the fullerene at the SnO₂ surface.