Surface electronic transport on silicon: donor- and acceptor-type adsorbates on Si(111)-√3×√3-Ag substrate

Surface electronic structure ofK- andCs-induced21×<

“…Three reconstructions have been found when adding K atoms on Ag/ Si͑111͒ ͱ 3 ϫ ͱ 3 at room temperature (RT), i.e., a ͱ 21 ϫ ͱ 21, a 6ϫ 6, and a 2 ͱ 3 ϫ 2 ͱ 3 phase. 8 In the case of Cs, a ͱ 21ϫ ͱ 21 and a 6 ϫ 6 phase have been observed at RT. An interesting property of the various ͱ 21ϫ ͱ 21 -͑Ag, Au, Cu, K, Cs͒ phases is that they all show an anomalously high surface conductance compared to the initial ͱ 3 ϫ ͱ 3 surface.…”

“…An interesting property of the various ͱ 21ϫ ͱ 21 -͑Ag, Au, Cu, K, Cs͒ phases is that they all show an anomalously high surface conductance compared to the initial ͱ 3 ϫ ͱ 3 surface. 8 The high surface conductance has been explained in terms of two metallic bands on the Au-induced ͱ 21ϫ ͱ 21 surface. 9 However, a detailed investigation of our photoemission data shows that there is only one metallic band on the ͱ 21ϫ ͱ 21 surface.…”

Fermi surfaces of surface states on Si(111)-Ag, Au

“…Recent reports include the effects of charge density waves [1][2][3], a two-dimensional plasmon in a metallic surface-state band [4], increased surface conductivity via adatom doping [5], and metallic umklapp bands arising from a discommensurate overlayer [6]. In particular, surface conductivity is receiving increased interest with the arrival of sophisticated micro-probes, such as 4-point STM probes [7][8][9][10][11].…”

(C6H5)5C60HatPhillips1, O’Shea2, Birkett3 et al. 2005Phys. Rev. B

“…38 A shift of the Si 2p core-level to higher BE, in a simple band bending picture, would be consistent with a charge transfer from the adsorbed fullerenes to the underlying substrate-a somewhat surprising result given the propensity for charge transfer in the opposite direction for a very wide range of fullerene-surface systems. As noted above, the electrical transport data of Hasegawa et al 36 have been interpreted in terms of charge transfer from the S 1 surface state band-a charge transfer that was suggested not to promote band bending. Importantly, however, in our recent experiments to probe Si 2p core-level shifts for the 1 ML C 60 u Ag: Si͑111͒-͑ ͱ 3 ϫ ͱ 3͒R30°system, 39 the Ag: Si͑111͒ -͑ ͱ 3 ϫ ͱ 3͒R30°surface was annealed prior to fullerene deposition so as to remove all excess Ag.…”

“…Hasegawa et al 36 have proposed that C 60 acts as an electron acceptor when adsorbed on the Ag: Si͑111͒-͑ ͱ 3 ϫ ͱ 3͒R30°reconstruction, compensating conduction electrons in the S 1 surface-state band 32,37 of the substrate but, significantly, not promoting additional band bending. This scenario is consistent with the apparent lack of a Si 2p binding energy shift in the data published by LeLay et al 35 However, as LeLay et al do not explicitly comment on the binding energy of the Si 2p core-level, and in order to provide a direct comparison to the Si 2p data recorded for ϳ1 ML coverage of ͑C 6 H 5 ͒ 5 C 60 H on Ag:Si͑111͒-͑ ͱ 3 ϫ ͱ 3͒R30°, we have revisited the C 60 on Ag: Si͑111͒-͑ ͱ 3 ϫ ͱ 3͒R30°system and studied the shift of the Si 2p core-level due to adsorption of the "parent" fullerene.…”