Observation of the enhanced tunnel current of NiO thin films in grain boundary by peakforce TUNA

2019 ◽  
Vol 36 (4) ◽  
pp. 160-164
Author(s):  
Yidong Zhang
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Adhesion Force ◽  
Electronic Conductivity ◽  
Tunnel Current ◽  
Band Bending ◽  
Content Type ◽  
Atomic Force ◽  
Tunnel Model ◽  
Nio Thin Film

Purpose The purpose of this paper is to investigate the nanoscale electric performance of NiO thin films in grain boundary and grain face. Design/methodology/approach PeakForce tunnel atomic force is applied to visualize the nanoscale current imaging of the NiO thin film on fluorine tin oxide substrate. Findings The results show that the grain boundary has a significant impact on the nanoscale current of the NiO film. The electronic conductivity and in grain boundary is higher than that of the NiO film in grain face. The width of the conductive zone in the NiO film over grain boundaries is ∼ 60 nm. The tunnel current between the tip and the NiO film is consistent with the Fowler–Nordheim tunnel model. Originality/value The higher tunnel current in grain boundary is probably attributed to the enhanced energy band bending and adhesion force.

Structural and Ferroelectric Properties of Epitaxial PbZr0.52Ti0.48O3 and BaTiO3 Thin Films Prepared on SrRuO3/SrTiO3(100) Substrates

2001 ◽  
Vol 688 ◽  
Author(s):  
J. Rodríguez Contreras ◽  
J. Schubert ◽  
U. Poppe ◽  
O. Trithaveesak ◽  
K. Szot ◽  
...  
Keyword(s):  
Thin Films ◽  
Rutherford Backscattering Spectrometry ◽  
Ferroelectric Properties ◽  
Hysteresis Loops ◽  
Tunnel Current ◽  
Single Crystalline ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Ferroelectric Hysteresis

AbstractWe have prepared single crystalline epitaxial PbZr0.52Ti0.48O3 (PZT) and BaTiO3 (BTO) thin films on single crystalline epitaxial SrRuO3 (SRO) thin films grown on SrTiO3 (100) (STO) substrates. PZT and SRO thin films were grown using high-pressure on-axis sputtering and BTO using pulsed laser deposition (PLD). The film thickness ranged between 12 to 165 nm. Their excellent structural properties, surface smoothness and interface sharpness were demonstrated by X-Ray Diffraction measurements (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and Atomic Force Microscopy (AFM). Rutherford Backscattering Spectrometry and Channeling measurements (RBS/C) were used to analyze stoichiometry and crystalline quality. Ferroelectric hysteresis loops were obtained for all films of a thickness down to 12 nm showing a decrease in the remanent polarization Pr and an increase in the coercive field Ec towards thinner film thicknesses. Furthermore we have prepared tunneling junctions with a PZT or BTO barrier thickness of 3-6 nm. Reproducible bi-stable I-V-curves and bias dependence of the conductance were obtained suggesting an influence of the ferroelectric properties of the barrier material on the tunnel current.

scholarly journals Grain-Boundary-Induced Alignment of Block Copolymer Thin Films

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 103 ◽  
Author(s):  
Steven Gottlieb ◽  
Marta Fernández-Regúlez ◽  
Matteo Lorenzoni ◽  
Laura Evangelio ◽  
Francesc Perez-Murano
Keyword(s):  
Thin Films ◽  
Block Copolymer ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Direct Writing ◽  
Force Microscopy ◽  
Mechanical Removal ◽  
Atomic Force ◽  
Vertically Aligned ◽  
Critical Process

We present and discuss the capability of grain boundaries to induce order in block copolymer thin films between horizontally and vertically assembled block copolymer grains. The system we use as a proof of principle is a thermally annealed 23.4 nm full-pitch lamellar Polystyrene-block-polymethylmetacrylate (PS-b-PMMA) di-block copolymer. In this paper, grain-boundary-induced alignment is achieved by the mechanical removal of the neutral brush layer via atomic force microscopy (AFM). The concept is also confirmed by a mask-less e-beam direct writing process. An elongated grain of vertically aligned lamellae is trapped between two grains of horizontally aligned lamellae. This configuration leads to the formation of 90° twist grain boundaries. The features maintain their orientation on a characteristic length scale, which is described by the material’s correlation length ξ. As a result of an energy minimization process, the block copolymer domains in the vertically aligned grain orient perpendicularly to the grain boundary. The energy-minimizing feature is the grain boundary itself. The width of the manipulated area (e.g., the horizontally aligned grain) does not represent a critical process parameter.

scholarly journals In Situ Imaging of Candida albicans Hyphal Growth via Atomic Force Microscopy

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Arzu Çolak ◽  
Mélanie A. C. Ikeh ◽  
Clarissa J. Nobile ◽  
Mehmet Z. Baykara
Keyword(s):  
Atomic Force Microscopy ◽  
Candida Albicans ◽  
Adhesion Force ◽  
Hyphal Growth ◽  
Antifungal Drugs ◽  
Content Type ◽  
Force Microscopy ◽  
Atomic Force ◽  
Host Tissues

ABSTRACT Candida albicans is an opportunistic fungal pathogen of humans known for its ability to cause a wide range of infections. One major virulence factor of C. albicans is its ability to form hyphae that can invade host tissues and cause disseminated infections. Here, we introduce a method based on atomic force microscopy to investigate C. albicans hyphae in situ on silicone elastomer substrates, focusing on the effects of temperature and antifungal drugs. Hyphal growth rates differ significantly for measurements performed at different physiologically relevant temperatures. Furthermore, it is found that fluconazole is more effective than caspofungin in suppressing hyphal growth. We also investigate the effects of antifungal drugs on the mechanical properties of hyphal cells. An increase in Young’s modulus and a decrease in adhesion force are observed in hyphal cells subjected to caspofungin treatment. Young’s moduli are not significantly affected following treatment with fluconazole; the adhesion force, however, increases. Overall, our results provide a direct means of observing the effects of environmental factors and antifungal drugs on C. albicans hyphal growth and mechanics with high spatial resolution. IMPORTANCE Candida albicans is one of the most common pathogens of humans. One important virulence factor of C. albicans is its ability to form elongated hyphae that can invade host tissues and cause disseminated infections. Here, we show the effect of different physiologically relevant temperatures and common antifungal drugs on the growth and mechanical properties of C. albicans hyphae using atomic force microscopy. We demonstrate that minor temperature fluctuations within the normal range can have profound effects on hyphal cell growth and that different antifungal drugs impact hyphal cell stiffness and adhesion in different ways.

Structural and mechanical properties of a-axis AlN thin films growth using reactive RF magnetron sputtering plasma

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Anis Suhaili Bakri ◽  
Nafarizal Nayan ◽  
Chin Fhong Soon ◽  
Mohd Khairul Ahmad ◽  
Ahmad Shuhaimi Abu Bakar ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Magnetron Sputtering ◽  
Young’S Modulus ◽  
Plasma Deposition ◽  
Young's Modulus ◽  
Rf Magnetron Sputtering ◽  
Content Type ◽  
Sputtering Deposition ◽  
Atomic Force

Purpose This paper aims to report the influence of sputtering plasma deposition time on the structural and mechanical properties of the a-axis oriented aluminium nitride (AlN) thin films. Design/methodology/approach The AlN films were prepared using RF magnetron sputtering plasma on a silicon substrate without any external heating with various deposition times. The films were characterized using X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), atomic force microscope (AFM) and nanoindentation techniques. Findings The XRD results show that the AlN thin films are highly oriented along the (100) AlN plane at various deposition times indicating the a-axis preferred orientation. All the AlN thin films exhibit hexagonal AlN with a wurtzite structure. The hardness and Young’s modulus of AlN thin films with various deposition times were measured using a nanoindenter. The measured hardness of the AlN films on Si was in the range of 14.1 to 14.7 GPa. The surface roughness and the grain size measured using the AFM revealed that both are dependent on the deposition times. Originality/value The novelty of this work lies with a comparison of hardness and Young’s modulus result obtained at different sputtering deposition temperature. This study also provides the relation of AlN thin films’ crystallinity with the hardness of the deposited films.

scholarly journals Nanomechanical Characterization of Bacillus anthracis Spores by Atomic Force Microscopy

2016 ◽  
Vol 82 (10) ◽  
pp. 2988-2999 ◽  
Author(s):  
Alex G. Li ◽  
Larry W. Burggraf ◽  
Yun Xing
Keyword(s):  
Atomic Force Microscopy ◽  
Bacillus Anthracis ◽  
Elevated Temperatures ◽  
Adhesion Force ◽  
Spore Surface ◽  
Content Type ◽  
Force Microscopy ◽  
Nanomechanical Properties ◽  
Atomic Force ◽  
Bacillus Anthracis Spores

ABSTRACTThe study of structures and properties of bacterial spores is important to understanding spore formation and biological responses to environmental stresses. While significant progress has been made over the years in elucidating the multilayer architecture of spores, the mechanical properties of the spore interior are not known. Here, we present a thermal atomic force microscopy (AFM) study of the nanomechanical properties of internal structures ofBacillus anthracisspores. We developed a nanosurgical sectioning method in which a stiff diamond AFM tip was used to cut an individual spore, exposing its internal structure, and a soft AFM tip was used to image and characterize the spore interior on the nanometer scale. We observed that the elastic modulus and adhesion force, including their thermal responses at elevated temperatures, varied significantly in different regions of the spore section. Our AFM images indicated that the peptidoglycan (PG) cortex ofBacillus anthracisspores consisted of rod-like nanometer-sized structures that are oriented in the direction perpendicular to the spore surface. Our findings may shed light on the spore architecture and properties.IMPORTANCEA nanosurgical AFM method was developed that can be used to probe the structure and properties of the spore interior. The previously unknown ultrastructure of the PG cortex ofBacillus anthracisspores was observed to consist of nanometer-sized rod-like structures that are oriented in the direction perpendicular to the spore surface. The variations in the nanomechanical properties of the spore section were largely correlated with its chemical composition. Different components of the spore materials showed different thermal responses at elevated temperatures.

Oxidation kinetics of nanocrystalline Al thin films

2019 ◽  
Vol 66 (5) ◽  
pp. 638-643
Author(s):  
Jinsong Luo ◽  
Ligong Zhang ◽  
Haigui Yang ◽  
Nan Zhang ◽  
Yongfu Zhu ◽  
...  
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Grain Boundary ◽  
Film Thickness ◽  
Silicon Substrate ◽  
Oxidation Kinetics ◽  
Oxidation Rate ◽  
Boundary Diffusion ◽  
Content Type ◽  
Kinetics Of

Purpose This paper aims to study the oxidation kinetics of the nanocrystalline Al ultrathin films. The influence of structure and composition evolution during thermal oxidation will be observed. The reason for the change in the oxidation activation energy on increasing the oxidation temperature will be discussed. Design/methodology/approach Al thin films are deposited on the silicon wafers as substrates by vacuumed thermal evaporation under the base pressure of 2 × 10−4 Pa, where the substrates are not heated. A crystalline quartz sensor is used to monitor the film thickness. The film thickness varies in the range from 30 to 100 nm. To keep the silicon substrate from oxidation during thermal oxidation of the Al film, a 50-nm gold film was deposited on the back side of silicon substrate. Isothermal oxidation studies of the Al film were carried out in air to assess the oxidation kinetics at 400-600°C. Findings The activation energy is positive and low for the low temperature oxidation, but it becomes apparently negative at higher temperatures. The oxide grains are nano-sized, and γ-Al2O3 crystals are formed at above 500°C. In light of the model by Davies, the grain boundary diffusion is believed to be the reason for the logarithmic oxidation rate rule. The negative activation energy at higher temperatures is apparent, which comes from the decline of diffusion paths due to the formation of the γ-Al2O3 crystals. Originality/value It is found that the oxidation kinetics of nanocrystalline Al thin films in air at 400-600°C follows the logarithmic law, and this logarithmic oxidation rate law is related to the grain boundary diffusion. The negative activation energies in the higher temperature range can be attributed to the formation of γ-Al2O3 crystal.

Topography effects in AFM force mapping experiments on xylan-decorated cellulose thin films

Holzforschung ◽  
2016 ◽  
Vol 70 (12) ◽  
pp. 1115-1123 ◽  
Author(s):  
Christian Ganser ◽  
Katrin Niegelhell ◽  
Caterina Czibula ◽  
Angela Chemelli ◽  
Christian Teichert ◽  
...  
Keyword(s):  
Thin Films ◽  
Adhesion Force ◽  
Resonance Spectroscopy ◽  
Phase Imaging ◽  
Adhesion Forces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Multiple Parameter ◽  
Force Mapping ◽  
Imaging Mode

Abstract Xylan-coated cellulose thin films has been investigated by means of atomic force microscopy (AFM) and force mapping experiments. The birch xylan deposition on the film was performed under control by means of a multiple parameter surface plasmon resonance spectroscopy (MP-SPR) under dynamic conditions. The coated films were submitted to AFM in phase imaging mode to force mapping with modified AFM tips (sensitive to hydrophilic OH and hydrophobic CH3 groups) in order to characterize and localize the xylan on the surfaces. At the first glance, a clear difference in the adhesion force between xylan-coated areas and cellulose has been observed. However, these different adhesion forces originate from topography effects, which prevent an unambiguous identification and subsequent localization of the xylan on the cellulosic surfaces.

scholarly journals Evaluation of grain boundaries as percolation pathways in quartz-rich continental crust using Atomic Force Microscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ritabrata Dobe ◽  
Anuja Das ◽  
Rabibrata Mukherjee ◽  
Saibal Gupta
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Boundary ◽  
Continental Crust ◽  
Electron Backscatter Diffraction ◽  
Vital Role ◽  
Force Microscopy ◽  
Atomic Force ◽  
Width Measurements ◽  
Lower Temperature ◽  
Backscatter Diffraction

AbstractHydrous fluids play a vital role in the chemical and rheological evolution of ductile, quartz-bearing continental crust, where fluid percolation pathways are controlled by grain boundary domains. In this study, widths of grain boundary domains in seven quartzite samples metamorphosed under varying crustal conditions were investigated using Atomic Force Microscopy (AFM) which allows comparatively easy, high magnification imaging and precise width measurements. It is observed that dynamic recrystallization at higher metamorphic grades is much more efficient at reducing grain boundary widths than at lower temperature conditions. The concept of force-distance spectroscopy, applied to geological samples for the first time, allows qualitative estimation of variations in the strength of grain boundary domains. The strength of grain boundary domains is inferred to be higher in the high grade quartzites, which is supported by Kernel Average Misorientation (KAM) studies using Electron Backscatter Diffraction (EBSD). The results of the study show that quartzites deformed and metamorphosed at higher grades have narrower channels without pores and an abundance of periodically arranged bridges oriented at right angles to the length of the boundary. We conclude that grain boundary domains in quartz-rich rocks are more resistant to fluid percolation in the granulite rather than the greenschist facies.

Atomic force microscopy of in situ deformed nickel thin films

1999 ◽  
Vol 353 (1-2) ◽  
pp. 194-200 ◽  
Author(s):  
C. Coupeau ◽  
J.F. Naud ◽  
F. Cleymand ◽  
P. Goudeau ◽  
J. Grilhé
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Force Microscopy ◽  
Nickel Thin Films ◽  
Atomic Force
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