Growth and Characterization of SiGe/SiO₂ Core/Shell Nanocrystals on Insulators

In this study, we report the growth and characterization of high-quality SiGe/SiO2 core–shell nanocrystals on an insulator. Our approach involves the solid-state dewetting of a germanium (Ge) film deposited via molecular beam epitaxy on an ultrathin silicon-on-insulator film. The resulting nanocrystals exhibit exceptional uniformity, a well-defined hemispherical shape, and distinct crystallographic facets, as confirmed by rigorous analyses using advanced techniques, such as high-resolution transmission electron microscopy and energy-dispersive spectrometry. Furthermore, we successfully integrated these SiGe/SiO2 core/shell nanocrystals into a metal–insulator–semiconductor (MIS) structure. Through current–voltage and impedance spectroscopies, we determine the transport and electrical properties of this integrated system. Our measurements reveal the formation of a Schottky diode with high rectifying behavior. Importantly, impedance measurements allow us to elucidate the equivalent circuit of this MIS structure, highlighting the significant influence of the SiGe/SiO2 core–shell nanocrystals on the electrical transport phenomena within the MIS architecture. These findings represent a significant advancement in the fabrication and characterization of SiGe/SiO2 core/shell nanocrystals for MIS devices, opening up exciting possibilities for their applications in photovoltaics and photodetection.