PHOTOLUMINESCENCE STUDY OF THE CROSSOVER FROM 2-DIMENSIONAL TO 3-DIMENSIONAL GROWTH FOR GE ON SI(100)

Narrow Ge layers embedded in Si are investigated using photoluminescen ce (PL) spectroscopy. With increasing layer thickness a growth mode ch angeover from two-dimensional (2D) strained-layer growth to three dime nsional Stranski-Krastanov growth is observed. Additional PL lines tha t are redshifted with respect to the PL signal of the 2D strained laye rs are attributed to islands forced by three-dimensional growth. The o ccurrence of these new lines is accompanied by a blueshift of the PL o f the 2D layers, indicating a strong Ge diffusion from the 2D layers t owards the islands. (C) 1995 American Institute of Physics.