0079983c

1. UW-Madison MRSEC IRG 1 Nanostructured Materials and Interfaces Surface Science of Si and Si/Ge at the Atomic LevelDe Pablo DMR-0079983 The earliest stages of Si-Ge interaction during the deposition of Ge on Si are fundamental to the evolution of growth. We have discovered numerous new phenomena in these interactions, in particular those that are a consequence of strain. In collaboration with researchers at Tohoku, Tokyo, and Tsukuba, we have, for example, determined the strain-stabilized atomic structure for the (105) surface of Ge, which makes up the facets of Ge “hut” clusters, correcting the longstanding model proposed by Mo and Lagally. Most recently, the structure and stability of the hydrogen terminated (105) surface of Ge deposited on Si(105) substrates has been investigated by combining scanning tunneling microscopy (STM), electron energy loss spectroscopy, and theory. The studies reveal that Si incorporation into the surface Ge layer of hydrogen-terminated Ge/Si(105) drastically destabilizes the surface. The STM images obtained on this surface are well explained by the new, rebonded-step structure model mentioned above. Figure. Simulated STM images of the hydrogen-terminated Ge(105)/Si(105) surface. Sample bias voltage is set at (left) -1.0 V and (right) +1.0 V from the edge of the valence and conduction bands. Rectangles superimposed in these images show the 1× 2 unit cell of the surface structure with a size of 10.86 Å × 13.84 Å. “Hydrogen-Induced Instability of the Ge(105) Surface”,Y. Fujikawa, T. Nagao, Y. Yamada-Takamura, T. Sakurai,T. Hashimoto, Y. Morikawa, and K. Terakura, and M. G. Lagally, Phys. Rev. Letters, in press.