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Staff profile

Overview

Mogtaba Mekki

PGR Student

Affiliations
Affiliation
PGR Student in the Department of Physics

Biography

I am a Ph.D. student studying dynamical non-equilibrium processes, particularly self-organized pattern formation, on solid surfaces induced by irradiation with energetic ions. I employ both experimental and numerical studies to understand the evolution of these structures with the ultimate aim of being able to quantitatively predict pattern formation under specific conditions.

Research Activity:

Sputtering  a solid surface with an ion beam of relatively low energy (order of a few kilo electron volts) can result not only in surface kinetic roughening [1] but also in the self-organization of ordered quasi-periodic nanostructures [2], such as ripples, dots, and holes under appropriate conditions, as shown in the figure below.

My Ph.D. project focuses on investigating the mechanism underlying ion bombardment induced self-organized nanoscale periodic ripples on monoatomic solid surfaces with fixed experimentally accessible parameters of low ion beam energy, large incidence angle and room temperature. These characterization studies explore and answer key questions about the driving forces behind ripple generation. Linear and nonlinear behaviours are investigated using both experimental approaches and deterministic solutions of a continuum equation which describes the evolution of surface morphology (a special case of Makeev-Cuerno-Barabási (MCB) continuum equation [3]). Experiments are conducted by erosion solid monatomic surfaces with inert gas ions under vacuum conditions. The resulting surfaces are then imaged by Atomic Force Microscopy and the associated micrographs analysed to obtain key parameters associated with surface morphology such as interface width and the wavelength of quasi-periodic features. The continuum equation is evaluated in Fourier space using a custom-written solver on a High-Performance Computing cluster.

Amplification rate factor Rk and the images

The outcomes of this project will enhance theoretical understanding of non-equilibrium surface patterning, ultimately aiming to quantitatively predict the wavelength of quasi-periodic structures and tune their structural coherence for potential applications in diverse fields such as anti-reflective surfaces, optoelectronics, and data storage.

References:

[1] Bernd Rauschenbach. Low-Energy Ion Irradiation of Materials: Fundamentals and Application. Volume 324: Springer Nature. 2022; DOI: 10.1007/978-3-030-97277-6.

[2] Wai Lun Chan, Eric Chason. Making waves: Kinetic processes controlling surface evolution during low energy ion sputtering. Applied Physics Reviews. 2007;101(12): p. 1-46; DOI: 10.1063/1.2749198.

[3] Maxim A. Makeev, Rodolfo Cuerno, Albert-László Barabási. Morphology of ion-sputtered surfaces. Nuclear Instruments and Methods in Physics Research B. 2002;197(3-4): p. 185–227; DOI: 10.1016/S0168-583X(02)01436-2.