AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS-WeP

Paper SS-WeP17
Investigation of Sulfur-terminated GaAs(001) Surfaces by Selective Atoms Sublimed Method

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: S. Tsukamoto, National Research Institute for Metals, Japan
Authors: S. Tsukamoto, National Research Institute for Metals, Japan
T. Ohno, National Research Institute for Metals, Japan
N. Koguchi, National Research Institute for Metals, Japan
Correspondent: Click to Email
Recently, a novel S-termination method has been developed by exposure to S vapor in molecular beam epitaxy system, observing not diffused (2x1), commonly reported, but clear (2x6) reconstruction by reflection high-energy electron diffraction and scanning tunneling microscopy(STM).@footnote 1@ Then, we found that the separations, 0.19 - 0.28 nm, between S atoms of S dimers by STM well agreed with the first-principles pseudopotential calculated result, 0.237nm, with the condition of one electron transferred from each S dimer.@footnote 2@ However, the (2x6) structure is still not clear. In this paper, we study the detail of this (2x6) by the investigation of the structural change by a selective atoms sublimed method which uses the thermal desorption of selective S-S dimer from the (2x6). The calculated maps of the charge-density contours of the S-S structures show that the center of the charge-density is as same as the poison of the S atom in the case with the transfer of one electron. On the other hand, in the case without the transfer, the center of the charge-density is about 0.05nm far from the position of the S atom. Therefore, if the charge-density balance is destroied by the thermal desorption, the observed S-S bond length by STM will be drastically changed. The (2x6) structure turns into the (2x3) structure at around 520°C releasing about 20% surface sulfur atoms, which amount consist with the central dimer pairs of the (2x6) structure, however, without interdiffussion and with keeping the same S-S bond length. In addition, the Ga small clusters appeared on this (2x3) surface. It seems that these Ga clusters kept the charge-density balance of the (2x3) structure, keeping the same S-S bond length. @FootnoteText@ @footnote 1@S.Tsukamoto and N.Koguchi, Jpn.J.Appl.Phys., 33 (1994) L1185; Appl.Phys.Lett., 65 (1994) 2199; J.Cryst.Growth., 150 (1995) 33. @footnote 2@S.Tsukamoto, T.Ohno, and N.Koguchi, J.Cryst.Growth., 175/176 (1997) 1303.