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N11.18.1

Formation and Properties of Silicon/Silicide/Oxide Nanochains Hideo Kohno1, Yutaka Ohno1, Satoshi Ichikawa2, Tomoki Akita2, Koji Tanaka2, and Seiji Takeda1 1 Department of Physics, Graduate School of Science, Osaka University, 1-16 Machikaneyama, Toyonaka, Osaka 560-0043, JAPAN 2 National Institute of Advanced Industrial Science and Technology (AIST Kansai), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, JAPAN ABSTRACT Silicon/silicide/oxide nanochains, which have an alternate arrangement of silicon/copper silicide composite nanoparticles and oxide nanowires, were fabricated using silicon/oxide nanochains as templates. Photoluminescence was observed at room temperature and considered to be due to recombination of excitons in oxide. Electrostatic potential in the material was also investigated by electron holography. No visible potential bending at the silicon/silicide interface was detected.

INTRODUCTION Self-organized formation of composite nanomaterials with heterointerfaces and their characterization have been attracted much attention in recent years [1-3]. This class of nanostructures sometimes exhibits rich functionalities, and can be a candidate for building blocks of future devices of bottom-up basis. On the one hand, electron holography has been applied to studying Si p-n junction [4], an AlGaN/InGaN/AlGaN diode [5] and Au/TiO2 catalysts [6], and is also considered to be an optimal tool for investigating electrostatic potential and charge distribution in nanomaterials with self-formed heterointerfaces at nanometer-scale. In this paper, we report that more complex hetero-nanostructures can be fabricated by using templates through a self-organized process. Silicon/oxide nanochains [7-14] which have an alternate arrangement of silicon nanocrystallites and oxide wires in one-dimension forming a chain-like structure were used as templates to fabricate silicon/silicide/oxide composite nanomaterials [15]. In addition to the luminescence property, electrostatic potential across a heterointerface was investigated by electron holography.

EXPERIMENTAL DETAILS The templates, silicon/oxide nanochains [7-14], were grown via the well-know vapor-liquidsolid (VLS) process [16, 17]. To make catalytic particles for the VLS growth of the silicon/oxide nanochains, gold about 10 nm thick was deposited on a silicon substrate (n-type, 1014/cm3) and heated to 500 °C for 30 min in an evacuated silica container. Then, the silicon substrate was sealed in a new container and heated to 1200 °C for 2 h for the silicon/oxide nanochain growth. For fabricating silicon/silicide/oxide nanochains [15], the silicon/oxide nanochains were sealed with a small piece of copper in an evacuated silica container and heated to 700 °C for 10 min to infuse copper into silicon/oxide nanochains. Conventional

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transmission electron microscopy (TEM) observations were performed on a 200kV-TEM, JEOL JEM-2010. PL was measured on a TEM, JEOL JEM-2000EX which was equipped with optical measurement system [18, 19] at room temperature. The 514.5nm e