Selective epitaxial growth of Ge quantum dots on patterned SiO2/Si(0 0 1) surfaces

We have investigated the formation of Ge quantum dots (QDs) in SiO2/Si(0 0 1) windows prepared either by partial thermal desorption of an ultra-thin oxide layer, or by standard electron beam lithography. Prior to Ge growth, we studied the growth of a silicon buffer. It was shown that the growth of the Si buffer layers evolved towards truncated pyramids whose top area can be controlled via the Si growth time. The number of Ge dots in a window, as well as their position, depends not only on the window dimension but also on the height of the Si buffer layers. Finally, we present some preliminary results on the optical properties of these Ge dots obtained from photoluminescence (PL) and Raman spectroscopies. # 2003 Elsevier B.V. All rights reserved