Growth of Ge QDs-Decorated SiGe Nanocrystals: Toward Integration of Quantum Dots and Mie Resonators in Ultrathin Film for Photodetection and Energy Harvesting
Mansour Aouassa, Mohammed Bouabdellaoui, Walter Batista Pessoa, Isabelle Berbézier, T. Kallel, Thouraya Ettaghzouti, Makram Yahyaoui, K. M. A. Saron, A.K. Aladim, Mohammed Ibrahim, Ibrahim Althobaiti
Abstract
To efficiently integrate SiGe-based Mie resonators and germanium quantum dots into a single-layer structure for ultrathin solar cells and high performance self-powered photodetectors, we introduce an innovative method involving solid-state dewetting and germanium (Ge) condensation within SiGe nanocrystals. This results in the growth of SiGe/SiO 2 -SiGe-SiO 2 core/shells nanocrystals decorated with Ge quantum dots. The process begins with solid-state dewetting, initiating the growth of SiGe core nanocrystals (Mie resonators) from a Ge layer initially deposited via molecular beam epitaxy on an ultrathin silicon-on-insulator (UT-SOI) film. Subsequently, SiO 2 -SiGe-SiO 2 shells form through thermal oxidation, encapsulating the SiGe nanocrystals by germanium condensation. Finally, Ge quantum dots are grown by molecular beam epitaxy (MBE), resulting in concentric core/multishell nanocrystals embellished with minuscule Ge quantum dots. Our original nanostructure, validated via HR-TEM and HAADF analysis, represents a significant breakthrough in the integration of both Ge QDs and SiGe Mie resonators in one ultrathin layer for optoelectronic applications. Remarkably, these engineered nanostructures demonstrate a photovoltaic effect in the visible spectrum. Anticipating significant potential, this distinctive configuration holds promise for fostering advancements in optoelectronics and sensing applications.