This paper describes the possibility of atom/molecule switching devices, Atom Relay Transistor (ART)@footnote 1@ and MOlecular Single Electron Switching transistor (MOSES),@footnote 2@ which would supersede present semiconductor devices beyond their ultimate limitations. ART consists of an atom wire, a switching atom, a switching gate and a reset gate. MOSES devices consist of a conducting molecule and an insulating molecule, the former being the quantum dot and the latter the tunnel barrier. ART and MOSES devices are evaluated on the basis of the five major characteristics necessary for information processing integrated circuit devices,@footnote 1@ and indicated that they are the most promising candidates for the future information processing. Scanning Tunneling Microscope (STM) should be the most probable tool to fabricate these devices. Technology development to realize these atom/molecule devices are described, including Beam Assisted STM (BASTM)@footnote 3@ which enables insulator observation, Needle Formation and Tip Imaging (NFTI)@footnote 4@ which directly evaluates STM tip apex for reliable atom/molecule manipulation, micromachine STM@footnote 5@ which makes possible the direct observation of vacuum tunneling gap. Gallium (Ga) atom wire was successfully fabricated on Si (100)-H surface by removing hydrogen atoms by STM and filling the dangling bond by Ga atoms,@footnote 6@ which is theoretically predicted to be conductive.@footnote 7@ Those technologies should lead to a successful ART/MOSES demonstration.
@FootnoteText@
@footnote 1@Y.Wada, et al., J. Appl. Phys., 74, 7321 (1993).
@footnote 2@Y.Wada, Trans. IEICEJ, OME 93-54, 31 (1994).
@footnote 3@S.Heike, et al., Appl. Phys. Lett., 64, 1100 (1994).
@footnote 4@S.Heike, et al., Japan. J. Appl. Phys., 34, L1061 (1995).
@footnote 5@M.I.Lutwyche et al., Appl. Phys. Lett., 66, 2807 (1995).
@footnote 6@T.Hashizume, et al., Japan. J. Appl. Phys., 35, L1085 (1996).
@footnote 7@S.Watanabe, et al., Phys. Rev. B, 54, 17308 (1997).