Electron tunneling time measurement by field-emission microscopy

Abstract

Electron-tunneling time has been measured using field-emission microscopy (FEM). The analysis of the FEM images of the dopant samarium ions located inside the calcium fluoride coating onto the silicon nanotip gives the value of the perpendicular momentum distribution of emitted electrons. This distribution is a natural measure of the tunneling time: the more time an electron spends under the barrier, the narrower such a distribution is (Larmor clock experiment). For the barrier height of 1.7 eV and electric-field strength ranging from 0.55 to 0.7 V/nm, the tunneling time ranges from 6 to 8 fs.