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Enhanced Secondary Electron Emission in Nanoscale Thin Metal Containing MgO Film: Laser Irradiation on Creation of F Centers

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journal contribution
posted on 15.09.2011, 00:00 by Hak Ki Yu, Woong-Kwon Kim, Eung Chul Park, Jae Sung Kim, Bon-Woong Koo, Young-Woon Kim, Jae Hwa Ryu, Jong-Lam Lee
A number of oxygen vacancies were found in the MgO film when a nanoscale-metal embedded MgO film (MgO/nanoscale metal film/MgO) was exposed to a pulsed KrF excimer laser. This was due to the interfacial reaction between embedding nanoscale metal and MgO film. In a case of Nb embedding metal, the Nb2O5 crystallites were evidenced to proceed the reaction at the MgO/Nb interface; 5MgO + 2Nb → Nb2O5 + 5Mg + 5VO··. The oxygen vacancies formed the F centers in the MgO bandgap, resulting in high cathodoluminescence intensity at the 431 and 526 nm region, corresponding to F+ and F centers. The F centers in MgO played a role in increasing secondary electron emission coefficient (γ). As several kinds of nanoscale metals for creating F centers (Cr, Ti, V, In, Ta, and Nb) were embedded into MgO film, the γ values were found to be inversely linear with the ΔGf for the formation of metal oxides. The Nb embedded MgO film showed the highest γ value of ∼0.232 compared with normal MgO film (0.034).