### Session J20: Focus Session: Electronic and Lattice Properties of Surfaces and Thin Films

11:15 AM–2:15 PM, Tuesday, March 11, 2008
Morial Convention Center Room: 212

Chair: Saw-Wai Hla, Ohio University

Abstract ID: BAPS.2008.MAR.J20.6

### Abstract: J20.00006 : Visualization of 2D subband states formed in Si(111)-$\beta -\surd$3x$\surd$3-Bi surface by STM

12:15 PM–12:27 PM

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#### Authors:

Katsumi Nagaoka
(National Institute for Materials Science)

Shin Yaginuma
(National Institute for Materials Science)

We have investigated electronic subbands formed underneath of Si(111)-$\beta -\surd$3x$\surd$3-Bi ($\beta -\surd$3-Bi) surface by using STM. The $\beta -\surd$3-Bi surface is semiconducting, and the band gap is larger than that of bulk Si. In the dI/dV images, standing waves are found around defects, and the obtained energy dispersion is in good agreement with the free-electron-like model. Apparently, formation of a 2D electronic state is suggested. However, this standing wave is observed only on p-type, but not on n-type Si substrates, and consequently the 2D state is attributed to the subband formed in the depletion layer just below the $\beta -\surd$3-Bi surface. The subband formation is also consistent with the calculation of electronic states inside a potential-well caused by interfacial band bending.