Growth and characterization of two- and three-dimensionally ordered quantum dots

Two dimensionally (2D) periodic pit structures are obtained by a lithograph technique on Si (001) substrate. Under proper growth conditions, the pit-pattern can be reserved after a thick Si buffer growth although the depth and the geometrical profiles of the pits are changed. During Ge deposition, GeSi islands preferentially grow at the pit bottoms, resulting in 2D ordered islands. In addition, the size homogeneity of these ordered islands is significantly improved. A kinetic model is proposed to qualitatively explain these results. By growing multilayer GeSi islands separated by thin Si spacers, three-dimensionally ordered islands or island crystal can be realized on pre-patterned substrates. These ordered islands helps to analyze the properties of a single island and island ensemble