title: Thirty per cent contrast in secondary-electron imaging by scanning field-emission microscopy.
abstract: We perform scanning tunnelling microscopy (STM) in a regime where primary electrons are field-emitted from the tip and excite secondary electrons out of the target-the scanning field-emission microscopy regime (SFM). In the SFM mode, a secondary-electron contrast as high as 30% is observed when imaging a monoatomic step between a clean W(110)- and an Fe-covered W(110)-terrace. This is a figure of contrast comparable to STM. The apparent width of the monoatomic step attains the 1nmmark, i.e. it is only marginally worse than the corresponding width observed in STM. The origin of the unexpected strong contrast in SFM is the material dependence of the secondary-electron yield and not the dependence of the transported current on the tip-target distance, typical of STM: accordingly, we expect that a technology combining STM and SFM will highlight complementary aspects of a surface while simultaneously making electrons, selected with nanometre spatial precision, available to a macroscopic environment for further processing.
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: D A
authors.identifier: 0000-0002-7749-4104
authors.initials: DA
authors.lastname: Zanin
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: L G
authors.initials: LG
authors.lastname: De Pietro
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: Q
authors.initials: Q
authors.lastname: Peter
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Kostanyan
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Cabrera
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Vindigni
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: Th
authors.initials: T
authors.lastname: Bähler
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Pescia
authors.affiliation: Laboratory for Solid State Physics , ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: U
authors.initials: U
authors.lastname: Ramsperger
keywords: scanning field-electron microscopy; scanning field-emission microscopy; scanning tunnelling microscopy; secondary-electron imaging