The effects of growth interruptions in the GaAsBi/InAs/GaAs quantum dots: The emergence of three-phase nanoparticles

The study investigated the impact of introducing bismuth into the GaAs capping layer (CL) on InAs quantum dots (QDs) to enhance their QD properties. Three different time-temperature routes (TTRs) were examined, as growth interruption (GI) stages are necessary due to the temperature requirements for the growth processes of QDs (510 °C) and GaAsBi CL (370 °C). Two of the TTRs revealed defective regions with bismuth-free nanotracks in the GaAsBi CL, which are linked to the formation of bismuth-rich droplets on the surface. Interestingly, in one of the TTRs, novel icosahedral-type nanoparticles appeared embedded at the first interface, leaving trails behind them. Upon detailed characterization, it was found that these nanoparticles consist of three distinct phases containing rhombohedral Bi, pure Ga, and a new In₄Bi phase that had not been experimentally described before. The long particle trajectories and low temperatures suggest that the NPs remained liquid throughout the growth process, solidifying upon final cooling to room temperature. This work presents a new technique for incorporating plasmonic nanoparticle arrays made of non-noble metals into buried semiconductor layered interfaces, which offers greater flexibility in device design.