Electron-induced secondary electron emission of Zn-doped MgO/Au composite film

An MgO/Au composite film with a 1.8 at% Zn-doped MgO surface layer prepared by reactive magnetron sputtering exhibited a superior electron-induced secondary electron emission (SEE) performance, and it had a SEE coefficient of 5.4 with an increase of 9.3% and a similar SEE degradation rate in comparison with an undoped composite film under primary electron bombardment of 200 eV. The mechanism for this SEE coefficient increase is tightly related to the reduced work function of Zn-doped MgO crystal analyzed by first-principles calculations and the enlarged MgO grains as well as the decreased surface roughness of Zn-doped MgO/Au film observed by morphological characterizations. In addition, for the Zn-doped MgO/Au film its improved electrical conductivity induced by Zn doping results in a similar SEE degradation rate even though it emits secondary electrons with the higher coefficient all the time under continuous electron bombardment compared with the undoped film.