AVS 47th International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeM

Paper TF-WeM5
Low Temperature Growth of 2D Pb Islands on Si(111)7x7 Surfaces

Wednesday, October 4, 2000, 9:40 am, Room 203

Session: Modeling of Thin Film Growth
Presenter: C.S. Chang, Academia Sinica, Taiwan, ROC
Authors: C.S. Chang, Academia Sinica, Taiwan, ROC
S.H. Chang, National Tsing Hua University, Taiwan, ROC
W.B. Su, Academia Sinica, Taiwan, ROC
C.M. Wei, Academia Sinica, Taiwan, ROC
L.J. Chen, National Tsing Hua University, Taiwan, ROC
TienT. Tsong, Academia Sinica, Taiwan, ROC
Correspondent: Click to Email
Lead (Pb) is known to grow on Si(111) with the Stranski-Krastanov (SK) mode at room temperature. With the variable temperature scanning tunneling microscopy, we study the low temperature growth of Pb films on the Si(111)-7x7 surface from T ~40 K to 200 K. The islands are formed after the completion of the wetting layer and display peculiar properties that cannot be categorized into any of the conventional growth modes. Their tops are all very flat and even more surprisingly, they prefer to grow into some discrete thicknesses corresponding to 4, 7 and 9 atomic layers. Among them, that equivalent to seven atomic layers is especially dominant. While the stress in heteroepitaxy may be the only dominant factor for a thick film and hence causes the film to form into 3D islands, for a thin film some other effects may be in play to counterbalance the stress. One of such effects is the "quantum size confinement", which could reduce the system energy due to quantization of the confined electrons in the film. Preliminary ab initio calculations seem to support this theory.