Structure of the Ba-induced Si(111)- (3 x 2) reconstruction.
The Ba/Si(111) surface, previously known as a 3 x 1 phase, is found to have a 3 x 2 periodicity and a semiconducting band gap. The substrate reconstructs into the honeycomb chain-channel (HCC) structure with Ba atoms in the channel, as in the alkali-metal-induced Si(111)-(3 x 1). However, the metal coverage is determined to be 1/6 monolayers, half the alkali-metal coverage. We propose that the structure and the metal coverage determined for the Ba adsorbate is universal for other alkaline-earth-metal adsorbates. With the alkali-metal-induced 3 x 1 case, our results lead to a rule that one donated electron per 3 x 1 surface unit is necessary to stabilize the HCC reconstruction of Si.
Lee
G
G
Materials Evaluation Center, Korea Research Institute of Standards and Science, Taejon 305-600, Korea. glee@kriss.re.kr
Hong
S
S
Kim
H
H
Shin
D
D
Koo
J Y
JY
Lee
H I
HI
Moon
D W
DW