Alloying of self-organized semiconductor 3D islands

We present a short review of alloying in uncapped self-organized semiconductor heteronanostructures. Our aim is to provide a logical guide through the main concepts proposed in recent scientific debates. In particular, we focus on the issue of mapping the chemical composition within individual germanium quantum dots grown on silicon surfaces, a widely studied model system with high technological potential. We discuss the different experimental results reported so far in the literature, along with the main theories suggested for their rationalization. In particular, we expand on the interplay of competing factors, including thermodynamic considerations, strain relaxation and kinetic limitations. Finally, we propose a possible pathway towards a unifying picture, with the intention to motivate further research on this topic.