Fig.11
From: The Design of the Emission Layer for Electron Multipliers
Relationship between the material's best secondary electron emission coefficient and film thickness, a shows the information of Al2O3 (on the silicon wafer, grow xnm-Al2O3), b shows the information of MgO (on the silicon wafer, grow xnm-MgO), c shows the information of Al2O3/MgO (on the silicon wafer, grow xnm-Al2O3, and then grow 9 nm-MgO), and d shows the information of MgO/Al2O3 (on the silicon wafer, grow 35 nm-MgO, and then grow xnm-Al2O3)