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Vol. 23, No. 12, pp. 740752, 2002

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Christian L. PETERSEN

Torben M. HANSSENPeter BOGGILDFrancois GREY

1130033 731Capres AS, DTU Bldg.404 east, DK-2800, Lyngby, Denmark

DTU Bldg.345 east, DK-2800, Lyngby, Denmark

2002 3 7

Measurements of Surface Electrical Conductance by Microscopic Four-Point Probes

Shuji HASEGAWA, Ichiro SHIRAKI, Fuhito TANABE, Rei HOBARA,

Taizo KANAGAWA, Takehiro TANIKAWA, Iwao MATSUDA, Christian L. PETERSEN

Torben M. HANSSEN, Peter BOGGILD and Francois GREY

Department of Physics, University of Tokyo, 731 Hongo, Bunkyo-ku, Tokyo 1130033Capres AS, DTU Bldg.404 east, DK-2800, Lyngby, Denmark

Microelectronics Center, Denmark Technical University, Bldg.345 east, DK-2800, Lyngby, Denmark

(Received March 7, 2002)

For in-situ measurements of local electrical conductivity of well-defined crystal surfaces in ultrahigh vacuum, wehave developed two kinds of microscopic four-point probe methods. One is a four-tip STM prober, in which inde-pendently driven four tips of scanning tunneling microscopeSTMare used for four-point probe conductivity measure-ments, whose probe spacing can be changed from 0.5 m to 1 mm. The other one is monolithic micro-four-pointprobes, fabricated on silicon chips, whose probe spacing is fixed around several m. These probes are installed inscanning-electron-microscopyelectron-diffraction chambers, in which the structures of sample surfaces and probe posi-tions are in situ observed. The probe can be positioned precisely on aimed areas on the sample with aid of piezo-actuators. With these machines, the surface sensitivity in conductivity measurements has been greatly enhanced com-pared with macroscopic four-point probe method. Then surface-state conductivity and influence of atomic steps uponconductivity can be directly measured.

E-mail: shuji@phys.s.u-tokyo.ac.jp

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Fig. 633-Ag

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ss ssSFe2L2 h 3

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0.150.0211415SF2 kF SF Fig. 7 d1 m ss1.5103 1 L253 nm

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ing

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747 Christian L. PETERSENTorben M. HANSSENPeter BOGGILDFrancois GREY

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28, 7014 (1983).11) J. Viernow, et al.: Phys. Rev B 57, 2321 (1998).12) S. Hasegawa, et al.: Surf. Sci. 386, 322 (1997).13) W. Moench: Semicon-

ductor Surfaces and Interfaces (Springer, Berlin, 1995)

14) Y. Nakajima, et al.: Phys. Rev. B 56, 6782 (1997); Phys.Rev. B 54, 14134 (1996).

15) X. Tong, et al.: Phys. Rev. B 57, 9015 (1998).16) http:www.capres.com17) T. Ogino: Surf. Sci. 386, 137 (1997).18) N. Sato, et al.: Phys. Rev. B 59, 2035 (1999).19) Y. Hasegawa, et al.: Surf. Sci. 358, 32 (1996).20) S. Heike, et al.: Phys. Rev. Lett. 81, 890 (1998).21) E.H. Sondheimer: Adv. Phys. 1, 1 (1952).22) K. Fuchs: Proc. Cambridge Philos. Soc. 34, 100 (1938).

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