Enhanced secondary electron emission properties of sputter-deposited MgO–Au composite film via Cr doping

High and stable secondary electron emission yield (SEY) is essential for thin film materials used for electrical signal amplification in electronic devices. To enhance the secondary electron emission (SEE) capability of MgO–Au composite film, Cr-doped MgO–Au film was prepared by magnetron sputtering and the effect of Cr doping on the SEE properties of MgO–Au film was intensively investigated. It was confirmed that the doped Cr element is distributed through the whole composite film in a form of Cr₂O₃. Compared to the conventional MgO–Au film, the Cr-doped MgO–Au film with a Cr/(Cr + Mg) atomic ratio of 0.71 % achieves a SEY of 7.1 with a 4.4 % rise at the primary electron energy (E_p) of 300 eV and a maximum SEY of 10.9 with a 10.1 % increase at the E_p of 800 eV, and it also has a reduction of 49.2 % in SEE decay rate under continuous electron bombardment. For this novel composite film, the SEY ascension mainly attributes to the MgO grain enlargement and chemical stability enhancement, and the decreased SEE decay rate is associated with the improvements of resistance to electron bombardment and electric conductivity induced by Cr doping.