Self-assembly of epitaxially grown Ge/Si quantum dots enhanced by As ion implantation

Ge/Si islands, grown using molecular-beam epitaxy on a Si/Si0.5Ge0.5 buffer structure modified with in situ ion implantation of 1 keV As+, are investi gated by transmission electron microscopy (TEM), photoluminiscence (PL), an d Raman spectroscopy. Vertically correlated Ge islands are observed by TEM as a result of the implantation. A 0.8 mum PL peak is detected from the lay ers of self-assembled Ge quantum dots. A nonhomogeneous distribution of str ain around the Ge/Si islands is deduced from the Raman scattering data. Thi s strain is assumed to be responsible for the PL emission. (C) 2001 America n Institute of Physics.