Influence of molecular hydrogen on Ge island nucleation on Si(001)

The influence of molecular hydrogen (H-2) on the structural and optical pro perties of self-assembled Ge dots grown on Si(001) has been studied using a tomic force microscopy and photoluminescence spectroscopy (PL). Without hyd rogen, a well known bimodal island size distribution occurs with small {105 } faceted pyramids, and larger multifaceted domes. In the presence of an ad ditional H-2 flow, we observe that a higher density of smaller pyramids and a lower density of domes occurs. Moreover, in the presence of hydrogen, PL investigations have revealed a thicker wetting layer thickness, probably d ue to a reduction of the surface diffusion length. (C) 2000 American Instit ute of Physics. [S0021-8979(00)07822-1].