Theoretical study on surface electrical conduction on nanometer scales

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Main results obtained within the term of project are as follows.1.Electrical conduction of Shockley surface statesI studied the electrical conduction of the surface states formed by sp hybridization and clarified the relation between the widths of s and p bands, strength of sp hybridization, and the electrical conductance. This result can be applied to the Shockley surface states of the noble metal surfaces.2.Electrical conduction of dangling-bond statesI clarified the relation between the electrical conduction of the surface states formed in bulk band gaps of semiconductors and the band-gap values.3.Electrical conduction of group-IV semiconductor. (111)2×1 structuresI studied the effect of surface structures, particularly, the existence of buckling on electrical conduction. Furthermore I studied the electrical conduction of double-tip STM and clarified the relation between the effective mass of surface-state bands and the electrical conductance of double-tip STM.4.Surface electrical conduction of silicon nanowiresI studied the inhomogeneous electrical conduction in medium-sized nanowires. I found possibility of electrical conduction through edge states localized at the edges of nanowires.5.Electrical resistance of monatomic steps of Si(111) √3×√3-Ag and the resistance of Bloch wavesI calculated the electrical resistance of a step and explained the results obtained in a recent experiment. I found a new type of step state localized at the edge of the lower terrace of a step. Furthermore I provide a new definition for amplitude and phase of waves including evanescent waves and derived a new formula for the transmission of Bloch waves. I found that the resistance of Bloch waves is separated into two parts : One arises from the difference in Bloch wave numbers and the other from the discontinuity of logarithmic derivatives of the periodic part of Bloch waves.