Transport and electrical properties of Si and Ge quantum dots embedded in oxide layers of MOS structures for optoelectronic applications

This study investigates the structural, morphological, and electrical properties of silicon (Si) and germanium (Ge) quantum dots (QDs) embedded within thin SiO₂ layers in Metal–Oxide–Semiconductor (MOS) capacitors for optoelectronic applications. The QDs are formed through solid-state dewetting of ultra-thin amorphous germanium-on-insulator (a-GOI) and amorphous silicon-on-insulator (a-SOI) layers, grown by Molecular Beam Epitaxy (MBE). Morphological and structural analyses are performed using Atomic Force Microscopy (AFM) and High-Resolution Transmission Electron Microscopy (HR-TEM), while electrical properties are examined via Capacitance–Voltage (C–V) and Deep-Level Transient Spectroscopy (DLTS) measurements. The Si and Ge QDs exhibit high density, uniformity, and spherical shapes with tunable sizes and densities, making them promising for optoelectronic applications. Their integration into MOS structures induces a shift in the flat-band voltage and increases the hysteresis in C–V curves, suggesting the creation of switchable charge states. These findings underscore the potential of Si and Ge QDs for enhancing the functionality of advanced optoelectronic devices.