ABSTRACT for APS March 1999 Centennial Meeting

TITLE:  Atomic and Electronic Structure of GaSe Bilayer Grown on Si(111)

AUTHORS:  Shuang Meng, Brett R. Schroeder, Aaron Bostwick, and Marjorie A.
Olmstead

ABSTRACT:

We have found that initial nucleation of GaSe on Si(111)7$\times$7 results
in formation of a pseudomorphic bilayer, which passivates the substrate
dangling bonds and serves as the interface for further film growth.
Component-resolved x-ray photoelectron diffraction and low-energy electron
diffraction show this bilayer is oriented in a single domain, with the
Ga-Se bond aligned with the substrate Si-Si bond. The bonding is between
Ga and Si and leaves Se lone-pair states on the surface. This makes the
resultant surface highly resistant to contamination, and additional GaSe
does not stick for T$_{substrate}\ge$550$^{\circ}$C. Angle-resolved
ultraviolet photoemission spectroscopy shows the electronic structure is
quite similar to that of Si(111):As, which has a similar lone-pair state.
However, additional surface states are found for Si(111):GaSe. * Supported
by NSF DMR9801302