Influence of the substrate temperature on the microstructure and electron-induced secondary electron emission properties of MgO/Au composite film

Highlights: • MgO/Au film was prepared by magnetron sputtering of individual Mg and Au targets. • A higher substrate temperature (T_s) is conducive to the growth of MgO grains. • The surface roughness firstly rises and then decreases with T_s increasing. • The increase of T_s greatly enhances the SEE coefficient of the composite film. - Abstract: The influence of the substrate temperature (T_s) on the microstructure and electron-induced secondary electron emission (SEE) properties of MgO/Au composite film prepared by reactive magnetron sputtering was investigated in order to improve the SEE performance of this composite film. During the deposition of MgO/Au film, a relatively high T_s is conducive to the growth of MgO grains and causes the formation of some large aggregated gold particles on which MgO grains cover in the composite film. In terms of the SEE properties of MgO/Au film, the increase of T_s brings about a significant improvement of SEE coefficient (δ), while it also leads to a slightly accelerated SEE degradation under the continuous electron bombardment due to a faster surface charging. The MgO/Au film prepared at T_s of 773 K has a δ value of 4.9 at a primary electron energy of 200 eV and the maximum δ value of 11.5.