Browsing by Author "Hiraki, Akio"

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    Formation of silicon oxide over gold layers on silicon substrates
    (Journal of Applied Physics, 2003) Hiraki, Akio; Lugujjo, Eriabu; Mayer, J. W.
    When a single‐crystal substrate of silicon is covered with evaporated gold and heated at relatively low temperatures (100–300°C) in an oxidizing atmosphere, a silicon‐dioxide layer is readily formed over the gold layer. The mechanism and factors controlling this low‐temperature oxide formation have been investigated using backscattering of 2‐MeV He+ ions. The oxide layer is nonuniform in thickness and the initial growth of this layer is proportional to (time)1/2. Both oxidizing ambient and orientation of the substrate influence the growth rate, and the amount of gold determines the final thickness of oxide. A model is proposed to explain the oxide‐growth mechanism.
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    Low-Temperature Migration of Silicon in Metal Films on Silicon Substrates Studied by Backscattering Techniques
    (Journal of Vacuum Science and Technology, 2000) Hiraki, Akio; Lugujjo, Eriabu
    The backscattering method using 2-MeV4He+ ions is employed to obtain microscopic information about solid-solid reaction of Si with thin layers (200∼4000 Å) of Au, Ag, and Al which are vacuum evaporated onto Si crystal substrates. The interesting observation is the migration of Si atoms into these metal films at temperatures (for example, 150°C in Au, 400°C in Ag) well below their eutectic points (375°C for Au and 850°C for Ag). This phenomenon also indicates that at these low temperatures the dislodgment of Si atoms from tightly bound Si crystal does occur. Our experiments clarify that the origin of this effect is the interaction of Si with metals at the interface.