Germanium impact on dewetting behavior of silicon-on-insulator

• Published in: Vacuum 2024-07, Vol.225, p.113168, Article 113168
• Main Authors: Aouassa, Mansour, Bouabdellaoui, Mohammed, Pessoa, Walter Batista, Berbezier, Isabelle, Kallel, Tarak, Ettaghzouti, Thouraya, Yahyaoui, Makram, Saron, K.M.A., Aladim, A.K., Ibrahim, Mohammed, Althobaiti, Ibrahim
• Format: Article
• Language: English
• Subjects: Dewetting engineering; Germanium-silicon; Molecular beam epitaxy (MBE); Nanocrystals; Selective growth and solar cells
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2024.113168

The solid-state dewetting of silicon and germanium thin films is crucial for growing high-performance photoactive layers and crafting Mie resonator-based antireflective coatings, which are essential components for highly sensitive photodetectors and third-generation solar cells. This study illustrates the feasibility of engineering the composition and organization of SiGe nanocrystal on an insulator by combining solid-state dewetting of ultra-thin silicon-on-insulator films (SOI) with epitaxial growth of germanium (Ge). Commencing with an exploration into the dewetting kinetics of conventional SOI, the investigation pivots towards controlling nanocrystal composition through germanium growth on SOI during the dewetting process. When germanium is deposited on SOI, solid-state dewetting prompts the formation of both Ge-rich and Si-rich nanocrystals on the same substrate. The manipulation of these nanocrystals' distribution and morphological anisotropy can be achieved by modulating the thickness of germanium deposited on the SOI substrate. Furthermore, the research demonstrates the potential transition from SOI dewetting to Ge/SOI dewetting within a single experiment, resulting in the emergence of Si-rich nanocrystals encircled by Ge-rich counterparts. These experimental findings furnish crucial insights into comprehending the dewetting mechanisms of Ge/SOI thin films, thereby paving the way for scalable and sample-specific methodologies in growing photonic nanostructures reliant on SiGe nanocrystals via solid-state dewetting. •Introducing a novel method by combining SOI dewetting and epitaxial growth of Ge for engineering SiGe nanocrystals on an insulator.•Epitaxial growth of Ge on SOI significantly accelerates dewetting kinetics, leading to the formation of denser, spherical, and disordered Ge-rich nanocrystals.•Observing a morphological anisotropy depends on the thickness of the Ge deposited on SOI; however, this anisotropy disappears for a Ge thickness equal to or greater than 5 nm.•Demonstrating a transition from SOI dewetting to Ge/SOI dewetting within the same experiment, resulting in Si-rich nanocrystals encircled by Ge-rich counterparts.•Utilizing cutting-edge techniques (SEM, AFM, TEM, Raman spectroscopy) to unveil valuable insights into the dewetting mechanisms of Ge/SOI thin films. Additionally, paving the way for selective growth of Si and SiGe nanocrystals on a single substrate, promising advancements in photonics and optoelectronics.