Since the establishment of techniques for surface conductivity measurement by microscopic four-point probes (M4PP) [1-5] with four-tip scanning tunneling microscope (4T-STM) and monolithic four-point probes, electronic transport through single-atomic layers and self-assembled atomic/nano wires on semiconductor crystals has attracted considerable interests for atomic-scale low-dimensional transport physics. The conductivity can be measured at a region as small as 20 nm [6]. It has been revealed that the instability and atomic-scale defects intrinsic to such nano-scale structures play decisive roles in transport inducing carrier localization and hopping conduction. I will introduce and summarize the following several topics in the talk. Recent advancements with metal-coated carbon nanotube tips in 4T-STM are also introduced [7].
(2) Resistance caused by monatomic steps on surface [9].
(3) Non-metallic conduction of metallic Au wires [10]
(4) Conductance of individual silicide nano-wires and carbon nanotubes [6,11,12].
[1] T. Kanagawa, et al., Phys. Rev. Lett. 91, 036805 (2003).
[2] T. Tanikawa, et al., e-J. Surf. Sci. Nanotech. 1, 50 (2003)[http://dx.doi.org/10.1380/ejssnt.2003.50]
[3] S. Hasegawa, et al., J. Phys.: Condens. Matter 14, 8379 (2002).
[4] S. Hasegawa, et al., Surf. Rev. Lett. 10, 963 (2002).
[5] R. Hobara, et al., Rev. Sci. Instr. 78 (2007), in press.
[6] S. Yoshimoto, et al., Nano Letters 7 (May, 2007), in press.
[7] Y. Murata, et al., Jpn. J. Appl. Phys. 44, 5336 (2005);
S. Yosimodo, et al., ibid. 44, L1563 (2005);
H. Konishi, et al., Rev. Sci. Instr. 78 , 013703 (2007).
[8] T. Tanikawa, et al., Phys. Rev. Lett. 93, 016801 (2004).
[9] I. Matsuda, et al., Phys. Rev. Lett. 93, 236801 (2004).
[10] H. Okino, et al., Phys. Rev. B 70, 113404 (2004).
[11] H. Okino, et al., Appl. Phys. Lett., submitted.
[12] R. Hobara, et al., Jpn. J. Appl. Phys. 43, L1081 (2004).
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