Secondary electron emission enhancement of MgO-Au composite film by SiO₂ doping in MgO surface layer

The secondary electron emission (SEE) properties of MgO-Au composite film deposited by magnetron sputtering was improved by SiO2 doping with a Si/Mg ratio of 14 % in its MgO surface layer. Compared to the conventional electronic material MgO/(MgO-Au) film, the SiO2-doped MgO/(MgO-Au) film achieved a secondary electron yield (SEY) of 7.69 with an increase of 9.2 % at the primary electron energy (Ep) of 300 eV and the maximum SEY of 11.4 eV with an increase of 12.9 % at the Ep of 700 eV, and it kept relatively high SEY consistently under the continuous bombardment of the incident electrons with the Ep of 200 eV. This SEE enhancement is attributed to the reductions of both the band gap and work function of MgO crystal as well as the grain enlargement and surface roughness decrease of MgO surface layer induced by SiO2 doping. This scheme of SiO2 doping in the MgO surface layer of MgO-Au film provides a new idea for the preparation of high performance MgO-based SEE material.