Atomic resolution noncontact atomic force/scanning tunneling microscopy using a 1 MHz quartz resonator

A 1 MHz quartz length extension resonator is used as a force sensor for a noncontact atomic force/scanning tunneling microscope (AFM/STM). A tungsten probe tip glued onto the end of the quartz rod enables the detection of tunneling currents for STM observation. Au surface was observed in both AFM and STM modes. The resolution difference is discussed in terms of the insulating oxide layer on the tip. We also demonstrate the AFM/STM observation of the Si(111)-7x7 surface with atomic resolution in an ultrahigh vacuum. (C) 2003 American Institute of Physics.