Study On The Surface Structure Of The Protective Layer Material For Plasma Display Panel

The improvement in the protective layer of the plasma display panel (PDP) is a key factor in improving the PDP performance. MgO thin film is used as traditional PDP protective layer material.It has a sensitive influence on the display performance of PDP directly. How to improve the property of protective layer has been drawing more and more attention in the world. The current theoretical research on MgO dielectric protective layer mainly focus on bulk structure. Numerical simulation on the surface structure of MgO is few, but it has important research value, because the actual preparation of MgO thin films appears different crystalline orientation. In this thesis, first-principle calculations are applied to investigate different orientation surface structures of MgO and calculate corresponding band structure and density of state. Then properties of these surfaces, influence to surface structure of doping and vacancy are analyzed on the whole.Firstly, the electronic structures of (100), (110), (111) and hydrogenated (111) surface are investigated, respectively. Based on the band parameters obtained from the research on the band structure and density of states, the secondary electron emission coefficient y are calculated. The results show that the hydrogenated (111) surface has the largest y value. Especially in the case of Xe ion, some additional secondary electrons still can be emitted.In addition, the excition spectra of (100) and (110) suface are calculated. The results indicate that the absorption spectrum in consideration of the electron hole pairs appear new absorption peaks at low energies and all thses peaks are followed by exction effect.Secondly, the changes in the electronic structures of ideal MgO surfaces and MgO surfaces with V, F color centers are studied. The results show that the MgO surface formed by F color centers can introduce defect levels between the conduction band and valence band and improve y value, thereby reduce the working voltage especially for high xenon content PDP. The effects of doped CaO, SrO and ZnO on the electronic structure of MgO surface and the secondary electron emission are investigated. The results demonstate that MgO surface doped with alkali metal material CaO, SrO or the small band gap oxide ZnO can reduce the width of band gap and enable the use of high-Xe content plasma display to realize a high discharge efficiency.Finally, the double layer structures are tried to be studied. The results show that the double-layer structure can significantly reduce the width of band gap. The interface formed by double-layer structure has an important influence on the strain and band structure of the whole system. There are more electron hole pairs accumulating on the interface and electronic transition is easier, which is benefit to the secondary electron emission.