Characterizing interface structure between crystalline and ion bombarded silicon by transmission electron microscopy and molecular dynamics simulations

• Published in: Applied surface science 2021-02, Vol.540, p.148278, Article 148278
• Main Authors: Rumyantsev, Alexander V., Borgardt, Nikolay I., Prikhodko, Alexander S., Chaplygin, Yuri A.
• Format: Article
• Language: English
• Subjects: Focused ion beam; Irradiation damage; Molecular dynamics; Silicon; Transmission electron microscopy
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.148278

[Display omitted] •Estimating the width of crystalline-amorphous interface transition region using high resolution images.•Molecular dynamics (MD) modeling of the irradiation process.•Simulation of high-resolution images closely matching the experimental ones.•Introduction of the displacement order parameter.•Evaluating the interface transition region width from the calculated atomic positions. Application of ion beams in modern technology requires quantifying disorder induced by the collisions of energetic species and substrate atoms. For studying the structure of the transition region between crystalline silicon and amorphous layer Si(001) substrate was bombarded by gallium ions with the energy of 5 keV. The transition region width and amorphous layer thickness were evaluated using cross-correlation analysis of high- resolution electron microscopy (HRTEM) images taken from cross-section specimens. Performed molecular dynamics simulations allowed obtaining atom positions in amorphized material, which provided close agreement between the simulated and experimental HRTEM images. Analysis of calculated atomic arrangements realized by employing an introduced displacement order parameter enabled finding the interface transition region width and amorphous layer thickness which agreed satisfactorily with the values estimated from HRTEM images. This agreement gives evidence that MD simulation can be applied for reliable prediction and quantification of the disordered region extension in the ion bombarded material. The obtained amorphous layer thickness is also consistent with the results established utilizing the critical point defect density model applied to Monte Carlo simulations.