- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Phase Intergrowth and Structural Defects in Organic Metal Halide Ruddlesden–Popper Thin Films
摘要： Organic metal halide Ruddlesden?Popper layered perovskite phases combine the excellent optoelectronic properties of three-dimensional, bulk hybrid perovskites with superior material stability under ambient conditions. However, the thin film structure of these layered perovskites is still poorly understood, as phase purity is typically determined solely by specular X-ray diffraction. The thin film structure of these Ruddlesden?Popper phases was examined by increasingly local characterization techniques. From the comparison of grazing-incidence wide-angle X-ray scattering patterns of cast films to expected scattering from single-crystal structures, significant in-plane disorder was observed. Spatially localized photoluminescence measurements show that films do not phase separate on the micrometer scale. Selected area electron diffraction measurements show the intergrowth of different phases within the same thin film, consistent with previous observations seen in epitaxially grown Ruddlesden?Popper complex oxides. Despite the presence of phase impurities that would typically be detrimental for device performance, fits to photothermal deflection spectroscopy measurements show relatively low Urbach energies of 33 meV for (C4H9NH3)2(CH3NH3)2Pb3I10 and 32 meV for (C4H9NH3)2(CH3NH3)3Pb4I13, indicating that the electronic properties are insensitive to the phase impurities.
关键词： phase intergrowth,structural defects,Ruddlesden?Popper,thin films,Organic metal halide,perovskite
更新于2025-09-09 09:28:46
-
Growth of tr6-CaSi <sub/>2</sub> thin films on Si(111) substrates
摘要： Uniform and high-quality tr6-CaSi2 films were successfully grown via the co-deposition of Ca and Si on a Si(111) substrate. Using reactive Ca deposition, the films tended to form mixed phases of orthorhombic CaSi and two trigonal CaSi2 (three-layer repeat: tr3-CaSi2; six-layer repeat: tr6-CaSi2) structures at low substrate temperatures below 580 °C. A tr6-CaSi2 film was formed when the substrate temperature and thickness of the deposited Ca were controlled. By supplying an external source of Si along with Ca deposition, the formation of CaSi and tr3-CaSi2 was suppressed, and single-phase tr6-CaSi2 was obtained.
关键词： co-deposition,thin films,molecular beam epitaxy,Si(111) substrates,tr6-CaSi2
更新于2025-09-09 09:28:46
-
Asymmetric Resistive Switching Dynamics in BaTiO <sub/>3</sub> Tunnel Junctions
摘要： The resistive switching associated with polarization reversal is studied in detail in ferroelectric BaTiO3 tunnel junctions, with focus on the dynamics of the ferroelectric domain switching. It is observed that the transition between the high-resistance state (HRS) and the low-resistance state (LRS) is largely asymmetric being smooth from LRS to HRS, but proceeds via avalanches in the HRS-to-LRS transitions. It is shown that this distinct behavior is related to the presence of an imprint field in the junction and has important consequences on the junction’s performance.
关键词： ferroelectric tunnel junctions,ferroelectric dynamics,neuromorphic computing,BaTiO3 films,memristors
更新于2025-09-09 09:28:46
-
Investigation of sintering kinetics and morphological evolution of silver films from nano-dispersion
摘要： The present study aimed at investigating the sintering kinetics and the mechanism of achieving uniform film morphology from silver nano-dispersion through evaporation of the solvent. A tuned time elapse between drop casting of silver dispersion and the annealing (dwell-time) acted as the decision maker in engineering the morphology: ring stain (infinite dwell-time), uniform deposit (variable dwell-time) and dot formation (zero dwell-time). Three distinct dwell-times (10, 20 and 30 min) are chosen for the study at different temperatures (120 to 250 °C) and the conclusion is derived based on the profile of the deposit. The frozen morphology that resulted from the evaporation goes through the debonding of surfactant with simultaneous sintering to minimize the surface energy. A linear isothermal sintering model comprising initial grain size, grain growth parameter, annealing time and fractional porosity helps to predict the grain size post-annealing. Theoretical predictions of grain sizes are well matched with experimental ones. The grain growth parameter which shows an upward trend with the annealing temperature is mainly due to a reduction in the porosity and the increase in the fraction of solid–solid interface which shows betterment in the percolation paths available for the movement of carriers.
关键词： sintering kinetics,dwell-time,silver films,nano-dispersion,morphological evolution
更新于2025-09-09 09:28:46
-
Optical characterisation of amorphous Se–Te–Sn thin films
摘要： Optical characterization of Sn doped Se–Te thin films has been carried out. The characterization has been carried out using transmission spectra in range 500–2500 nm. Bulk samples were prepared using melt quenching technique and thin films were deposited using thermal evaporation. XRD analysis was used to confirm the amorphous nature of prepared samples. Optical constants such as refractive index and extinction coefficient have been determined using Swanepoel’s method. Variation of refractive index with wavelength has been analysed using single effective oscillator model. Optical band gap of the deposited films was calculated using Tauc plots. The observed properties have been explained using the chemical bond approach.
关键词： Tauc plots,Swanepoel’s method,melt quenching technique,thermal evaporation,Se–Te–Sn thin films,Optical characterization
更新于2025-09-09 09:28:46
-
Morphology and Structure Properties of Boron-doped Diamond Films Prepared by Hot Cathode Direct Current Plasma Chemical Vapor Deposition
摘要： Boron-doped diamond (BDD) films were deposited by hot cathode direct current plasma chemical vapor deposition (HCDC-PCVD) according to various mixture ratios of CH4/H2/B(OCH3)3 gas. The Raman performances and surface morphologies of the BDD films were then characterized by Raman spectroscopy and scanning electron microscopy (SEM). Results indicated that the flow rate of B(OCH3)3 had marked effects on the growth characteristics of the produced boron-doped diamond films. The presence and concentration of the doped boron atoms significantly altered both the surface morphologies and structures of the diamond films. With increasing flow rate of B(OCH3)3, the crystal grain surfaces became smooth as visible under SEM. The B-doping levels in these films increased from 1.75 × 1019 cm-3 to a maximum of 2.4 × 1021 cm-3, estimated from the Raman spectra.
关键词： structural properties,boron-doped diamond (BDD) films,hot cathode direct current PCVD (HCDC-PCVD)
更新于2025-09-09 09:28:46
-
Progresses in Chemical Sensor || Air-Suspended Silicon Micro-Bridge Structures for Metal Oxide- Based Gas Sensing
摘要： Maintaining specific temperature is a key parameter for most of the gas sensing materials, particularly for metal oxide-based thin film layers, to operate them more efficiently to detect different gaseous (or vapor) species at ppm and ppb concentration levels. For field applications, battery-operated micro-gas-sensors, power dissipation and the required temperature stability are to be maintained with a close tolerance for better signal stability and also to analyze the generated data from the sensing element. This chapter mainly focuses on several metal oxide films to highlight the base temperature and its creation on silicon-based platforms. Air-suspended structures are highlighted, and a comparison is drawn between simple and MEMS-based structures from the power dissipation point of view. Ease of fabrication and operation limitations are explained with fabrication issues.
关键词： Platinum resistance thermometer,Gas sensing devices,Platinum micro-heater,Surface micromachining,MEMS,Metal oxide thin films
更新于2025-09-09 09:28:46
-
X-ray Diffraction Line Profile Analysis of Undoped and Se-Doped SnS Thin Films Using Scherrer’s, Williamson–Hall and Size–Strain Plot Methods
摘要： An electrochemical route has been employed to prepare undoped and Se-doped SnS thin films. Six samples including undoped and Se-doped SnS thin films were deposited on the fluorine-doped tin oxide glass substrate. An aqueous solution containing 2 mM SnCl2 and 16 mM Na2S2O3 was used in the electrolyte. Different Se-doped SnS samples were prepared by adding the various amounts of 4 mM SeO2 solution into the electrolyte. The applied potential (E), time of deposition process (t), pH, and bath temperature (T) were kept at -1 V, 30 min, 2.1, and 60°C, respectively. After the completion of the deposition process, x-ray diffraction (XRD) and transmission electron microscopy (TEM) were utilized to characterize the deposited thin films. XRD patterns clearly showed that the synthesized undoped and Se-doped SnS thin films were crystallized in the orthorhombic structure. Using Scherrer’s method, the crystallite size of deposited thin films is calculated. In addition, the crystallite size and lattice strain have been estimated using the modified form of the Williamson–Hall (W–H) method containing a uniform deformation model, a uniform deformation stress model, a uniform deformation energy density model, and by the size–strain plot method (SSP). The shape of SnS crystals was spherical in TEM images. The results showed that there was a good agreement in the particle size obtained from the W–H method and the SSP method with TEM images.
关键词： thin films,Se-doped SnS,size–strain plot method,Line profile analysis,Williamson–Hall method
更新于2025-09-09 09:28:46
-
Nano- and Microfabrication for Industrial and Biomedical Applications || Basic technologies for microsystems
摘要： This chapter introduces the reader the processes used to manufacture microelectronics. A silicon wafer is coated with a resist, most usually by wet deposition. Vapor deposition is also used, but high vacuum conditions are needed. The resist is a photosensitive polymer, which either cross-links or is destroyed under ultra violet (UV) light. Photolithography illuminates this resist through a pattern. The pattern is designed by computer-aided design (CAD), and copied onto a mask of borosilicate. Silicon is machined by wet chemical etching (which has precision limitations, but relatively low cost), or dry etching processes, in which its surface is bombarded with ions. Alternatively, the Bosch process uses gasses heated under low pressure to a plasma state to etch the surface. A great deal of research is under way to investigate other techniques and materials for use in microsystems. Examples include the use of powder blasting and laser ablation as etching techniques, and single-crystal (SC) quartz, amorphous glass, and thermoplastic polymers as alternatives to silicon. Thick resist lithography and locally controlled photopolymerization are techniques that could be used to create microscale features in these polymers. Since recent developments in industrial, biological, and biomedical applications particularly embrace replication technology as a means to pattern multiple parts from a master pattern or even use it for stamping biomolecular features onto a surface for the design and development of novel biological assays, it is time to introduce soft-lithography among the basic microsystems technologies together with a set of nanolithographies presented in Chapter 4.
关键词： soft-lithography,silicon micromachining,thin films,microsystems,nanolithography,photolithography
更新于2025-09-09 09:28:46
-
Multilevel resistance switching behavior in PbTiO3/Nb:SrTiO3(100) heterostructure films grown by hydrothermal epitaxy
摘要： Epitaxial PbTiO3 films with a smooth and dense surface were fabricated by a promising hydrothermal synthesis on an Nb:SrTiO3(100) substrate. The resulting coated substrate was used to fabricate a Pt/PbTiO3/Nb:SrTiO3 heterostructure device. The device exhibited a multilevel storage capacity with an appropriate ROFF/RON ratio and excellent endurance and retention. An electric conduction analysis indicated that the resistive switching behavior of the device was attributed to the trap controlled space-charge-limited current conduction that was caused by the oxygen vacancies in the PbTiO3 hydrothermal films. The modulation of the Pt/PbTiO3 Schottky-like junction depletion under an applied electric field is thought to be responsible for the resistive switching behavior of the device in the carrier injection-trapped/detrapped process.
关键词： Hydrothermal epitaxy,Multilevel resistive switching behavior,PbTiO3 films
更新于2025-09-09 09:28:46