Simultaneous current-, force- and work function measurement with atomic resolution

摘要

The local work function of a surface determines the spatial decay of thecharge density at the Fermi level normal to the surface. Here, we present amethod that enables simultaneous measurements of local work function andtip-sample forces. A combined dynamic scanning tunneling microscope and atomicforce microscope is used to measure the tunneling current between anoscillating tip and the sample in real time as a function of the cantilever'sdeflection. Atomically resolved work function measurements on a silicon(111)-($7\times 7$) surface are presented and related to concurrently recordedtunneling current- and force- measurements.