Shape and composition of buried PbSe quantum dots determined by scanning tunneling microscopy

Capping of self-assembled semiconductor quantum dots usually alters their shape and composition due to alloying with the matrix material. To determine the structure of capped dots, a method is developed based on the analysis of surface displacements induced by buried dots measured by scanning tunneling microscopy. For self-assembled PbSe dots overgrown with PbTe layers, the buried dots are found to be highly truncated and extended in the lateral direction, and due to intermixing their composition is changed to Pb Se x Te 1 − x , with x Se of only 55%.