Advances in ultrafast scanning tunneling microscopy

Abstract

Time resolved tunnel current was measured over 4 orders of magnitude in separation between tip and sample using an ultrafast scanning tunneling microscope (USTM). These measurements reveal two distinct regimes for tip height dependence of the signal. In addition, we report 900 femtosecond temporal resolution with a sensitivity of 20 mV/√Hz in USTM measurements of voltage pulses on a coplanar transmission line, and we show that the microscope operates as a high impedance probe. © 1996 American Institute of Physics.