Abstract
Au-doped MgO films were prepared by reactive sputtering of individual Mg and Au targets, and the Au doping effect on the electron-induced secondary electron emission (SEE) performance was explored by means of surface analysis, first-principle calculation, and electrical characteristic measurement. The results show that the size enlargement of MgO grains and the reduction of surface work functions induced by Au doping are the main reasons for the increase of the SEE coefficient (δ). Additionally, the superior SEE degradation property of the Au-doped MgO film under continuous electron bombardment results from the improvement of electrical conductivity. Through the optimization of Au doping concentration (x), Au-doped MgO film with an x value of 3.0% was found to have the best SEE performance due to its highest SEE coefficient and longest duration of maintaining a relatively high SEE coefficient; its maximum δ value reached 11.5—an increase of 32.2% in comparison with the undoped one.
Highlights
Since its discovery by Campbell, secondary electron emission (SEE) of solid materials has been widely investigated and applied in various electronic information fields such as space navigation, space instruments, night-vision technology, and microanalysis [1,2,3,4]
Secondary electron emission generally occurs in three steps: (1) production of internal secondary electrons caused by primary electron bombardment; (2) transport of internal secondary electrons towards the material surface; and (3) escape of internal secondary electrons from the material surface
Insulator materials including beryllium oxide, silicon nitride, diamond, and magnesium oxide (MgO) generally exhibit high SEE coefficients (δ) because of their wide band gaps which can help internal secondary electrons reduce collisions with free electrons and have a greater possibility to be emitted from the material surface [5,6,7,8]
Summary
Since its discovery by Campbell, secondary electron emission (SEE) of solid materials has been widely investigated and applied in various electronic information fields such as space navigation, space instruments, night-vision technology, and microanalysis [1,2,3,4] In these fields, solid materials need to have excellent electron-induced SEE performances for achieving the function of electrical signal amplification. Insulator materials including beryllium oxide, silicon nitride, diamond, and magnesium oxide (MgO) generally exhibit high SEE coefficients (δ) because of their wide band gaps which can help internal secondary electrons reduce collisions with free electrons and have a greater possibility to be emitted from the material surface [5,6,7,8]. The effect of Au doping on the surface morphologies, electronic structures, electrical conductivities, and SEE performances of MgO films was analyzed in order to elaborate the SEE mechanism of Au-doped MgO films
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