INHOMOGENEOUS GROWTH OF CAF2 ADLAYERS ON SI(111) AT INTERMEDIATE TEMPERATURES

The growth morphology of CaF2 adlayers deposited in the temperature ra nge 500-650 degrees C on Si(111) samples with 0.9 degrees miscut in [1 1 (2) over bar] direction has been studied by atomic force microscopy (AFM). After transferring the samples from the MBE chamber to ambient air we found an inhomogeneous film morphology: on one hand there are s mooth islands wetting substrate terraces and on the other hand differe nt substrate terraces show small clusters, The cluster formation is at tributed to the reaction of the first unstable CaF2 layer after contac t with ambient air while the smooth areas consist of thickness stabili zed CaF2 islands. The smooth islands grow preferentially in the [1 (1) over bar 0] direction since the substrate steps block the growth in [ 11 (2) over bar] direction. (C) 1998 Elsevier Science B.V.