- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Layer by layer deposition of alternate carbon nanotubes and Ni films for efficient multilayer thin film temperature gauges
摘要： This study reports a novel approach for growing multilayer thin films consisting of alternate layers of carbon nanotubes (CNT) and nickel on Si (1 0 0) substrates and justifies their use in thin film temperature sensors. A low pressure chemical vapor deposition system was employed for synthesizing CNT films, while Ni films were deposited by electrodeposition. Porous-Si was used as substrate to increase adhesion between the layers of the multilayer structure. The structure of the multilayer films and the quality of the CNT grown were analyzed using several characterization methods, including scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray auger electron spectroscopy and Raman spectroscopy. The electrical characteristics were investigated using a van der Pauw setup and the effect of the increasing number of CNT layers in the multilayer structure was studied. The sensitivity of the multilayer film was found to increase with increasing number of CNT layers, despite the decrease of the temperature coefficient of resistance. On the other hand, the initial resistance was found to increase. Results indicated that these multilayer structures are appropriate for fabricating highly sensitive thin film gauges that can detect lower heat fluxes with more accuracy.
关键词： carbon nanotubes,thin film gauges,surface and interface chemistry,porous silicon,adhesion sensing,x-ray photoelectron spectroscopy
更新于2025-09-23 15:22:29
-
Development of flexible, stable, and efficient inverted organic solar cells harvesting light in all directions
摘要： In this work, we designed low-cost, liquid-free, efficient, and highly flexible fiber-shaped inverted structure organic solar cells (FOSCs) over a flexible polyethylene terephthalate (PET) monofilament substrate. We also prepared a graphene–ZnO (G-ZnO) composite, wherein G sheets were compacted into a bunched-up structure through the binding force of Zn atoms with the C atoms of G. This composite was then utilized as a bifunctional layer i.e. electron transport and downconversion spectral in the FOSCs. The FOSCs based on the G-ZnO (D-1) demonstrated a power conversion efficiency (PCE) of 2.13% out of which 4.89% and 5% was retained after 8000 times bending and 120 h storage in ambient environmental conditions, respectively. The non-G-ZnO FOSCs (D-2) demonstrated a PCE of 1.78% and retained 5% and 6% of the initial value after 6000 bends and 48h of storage in ambient environmental conditions, respectively. This better performance of D-1 compared to that of D-2 is due to the interfacial functionalization of G-sheets and ZnO nanoparticles inside the G-ZnO composite. Because of these interfacial chemical bonds, the G sheets were in close contact with each other and attached firmly through the ZnO molecules. As a result, these compacted G layers could serve as a strong barrier resisting the penetration of water molecules inside the device, thereby leading to an improved lifetime for the device. Additionally, the longitudinal and cross linkage of G-sheets could improve the mechanical properties of the G-ZnO composite, which in turn enhanced the flexibility of D-1. Finally, these interface functionalizations could work as linking bridges, providing an additional pathway for the transportation of free charge carriers. Therefore, D-1 demonstrated a higher Jsc by collecting a greater number of charges at the electrode compared to D-2, because the latter lacked similar functionalization.
关键词： Electron transport layer,Mechanical and Environmental stability,G-ZnO interface chemistry,Downconversion spectral,Fiber-shaped OSCs
更新于2025-09-16 10:30:52
-
Engineering the Palladium–WSe <sub/>2</sub> Interface Chemistry for Field Effect Transistors with High Performance Hole Contacts
摘要： Palladium has been widely employed as a hole contact to WSe2 and has enabled, at times, the highest WSe2 transistor performance. However, there are orders of magnitude variation across the literature in Pd–WSe2 contact resistance and ION/IOFF ratios with no true understanding of how to consistently achieve high–performance contacts. In this work, WSe2 transistors with impressive ION/IOFF ratios of 106 and Pd–WSe2 Schottky diodes with near–zero variability are demonstrated utilizing Ohmic–like Pd contacts through deliberate control of the interface chemistry. The increased concentration of a PdSex intermetallic is correlated with an Ohmic band alignment and concomitant defect passivation, which further reduces the contact resistance, variability, and barrier height inhomogeneity. The lowest contact resistance occurs when a 60 minute post metallization anneal at 400 °C in forming gas (FG) is performed. X-ray photoelectron spectroscopy indicates this FG anneal produces 3× the concentration of PdSex and an Ohmic band alignment, in contrast to that detected after annealing in ultra–high vacuum, during which a 0.2 eV hole Schottky barrier forms. Raman spectroscopy and scanning transmission electron microscopy highlight the necessity of the fabrication step to achieve high–performance contacts as no PdSex forms and WSe2 is unperturbed by room temperature Pd deposition. However, at least one WSe2 layer is consumed by the necessary interface reactions that form PdSex requiring strategic exploitation of a sacrificial WSe2 layer during device fabrication. The interface chemistry and structural properties are correlated with Pd–WSe2 diode and transistor performance and the recommended processing steps are provided to enable reliable high–performance contact formation.
关键词： annealing,palladium,WSe2,interface chemistry,X-ray photoelectron spectroscopy,transistor,metal contact
更新于2025-09-09 09:28:46