EFFECT OF A GRADED INTERFACE ON A CRACK APPROACHING AT AN OBLIQUE ANGLE

Chemical removal of materials from the surface is a fundamental step in micro- and nano-fabrication processes. In conventional plasma etching, etchant molecules are non-directional and perform a uniform etching over the surface. However, using a highly directional obliquely incident beam of etching agent, it can be possible to engineer surfaces in the micro- or nano- scales. Surfaces can be patterned with periodic morphologies like ripples and mounds by controlling parameters including the incidence angle with the surface and sticking coefficient of etching particles. In this study, the dynamic evolution of a rippled morphology has been investigated during oblique angle etching (OAE) using Monte Carlo simulations. Fourier space and roughness analysis were performed on the resulting simulated surfaces. The ripple formation was observed to originate from re-emission and shadowing effects during OAE. Our results show that the ripple wavelength and root-mean-square roughness evolved at a more stable rate with accompanying quasi-periodic ripple formation at higher etching angles (θ > 60°) and at sticking coefficient values (Sc) 0.5 ≤ Sc ≤ 1. On the other hand, smaller etching angle (θ < 60°) and lower sticking coefficient values lead to a rapid formation of wider and deeper ripples. This result of this study can be helpful to develop new surface patterning techniques by etching.

Download Full-text

Simulation Research on the Influence of Basic Airfoil Oblique Angle on the Aerodynamic Characteristics of Forward Swept Airfoil

2020 6th International Conference on Mechanical Engineering and Automation Science (ICMEAS) ◽

10.1109/icmeas51739.2020.00033 ◽

2020 ◽

Author(s):

Zhao Xi-wei ◽

Su Xin-bing ◽

Jiang Wen ◽

Zhang Jun-yi

Keyword(s):

Aerodynamic Characteristics ◽

Oblique Angle ◽

Simulation Research

Download Full-text

Modeling and Experimental Investigations of Nanostructured Ag Thin Films Produced by Oblique-Angle Deposition and Its SERS Performance

Coatings ◽

10.3390/coatings11040458 ◽

2021 ◽

Vol 11 (4) ◽

pp. 458

Author(s):

Datai Hui ◽

Shun Zhou ◽

Changlong Cai ◽

Shigeng Song ◽

Zhentao Wu ◽

...

Keyword(s):

Thin Film ◽

Raman Scattering ◽

Surface Enhanced Raman Scattering ◽

Oblique Angle ◽

Scattering Effects ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering ◽

Simulation Results ◽

Deposition Angle

The growth mechanism of nanocolumnar silver thin film deposited on a smooth silicon substrate using electron beam evaporation process at an oblique angle was simulated with the Kinetic Monte Carlo method. Following the simulated silver nanostructured thin film, a further computational simulation was done using COMSOL for surface-enhanced Raman scattering effects. The simulation results were compared against corresponding experimental results, which demonstrated high agreement between simulation results and experimental data. It was found that as the incident deposition angle increased, the density of the Ag thin film significantly decreased and the surface roughness increased. When the incident deposition angle was at 75° and 85°, the resulting nanocolumnar structure was significantly tilted. For Ag thin films deposited at all investigated angles, surface-enhanced Raman scattering effects were observed. Particularly, the Ag nanocolumns deposited at 85° showed remarkable Surface-enhanced Raman Scattering effects. This was seen in both COMSOL simulations and experimental results: Enhancement factors were 2 × 107 in COMSOL simulation and 3.3 × 105 in the experiment.

Download Full-text