Electron trapping in misfit dislocations of MgO thin films

Abstract

Misfit dislocations in a thin MgO/Mo(001) film have been investigated by conductance and light-emission spectroscopy using scanning tunneling microscopy and electron-paramagnetic resonance (EPR) spectroscopy. The line defects exhibit a higher work function than the pristine MgO, being explained by their ability to trap electrons. The electron traps are associated with a nonstoichiometric defect composition in thin oxide films and attractive pockets in the Madelung potential in thicker ones. The latter traps can be reproducibly filled by the adsorption of atomic hydrogen, which gives rise to a free-electronlike signal in EPR spectroscopy.