Electron paramagnetic resonance and scanning tunneling microscopy investigations on the formation of F(+) and F(0) Color centers on the surface of thin MgO(001) films.
The formation of surface color centers (F(S) centers) by electron bombardment of thin MgO(001) films is investigated using electron paramagnetic resonance and low-temperature scanning tunneling microscopy. At low electron doses both techniques indicate the formation of singly occupied color centers (F(S)(+)), whereas at high electron doses the doubly occupied type (F(S)(0)) is dominant. It is suggested that with increasing electron dose F(S)(+) centers are transformed into F(S)(0). Tunneling spectra of individual F(S)(0) centers reveal a large distribution of energetic positions of occupied and unoccupied states, which is caused by local variations of the coordination number of the defects and explains the broad signals usually detected with integrating spectroscopic techniques.
Sterrer
Martin
M
Department of Chemical Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany. sterrer@ fhi-berlin.mpg.de
Fischbach
Esther
E
Heyde
Markus
M
Nilius
Niklas
N
Rust
Hans-Peter
HP
Risse
Thomas
T
Freund
Hans-Joachim
HJ