Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/91748
標題: Ab-initio Study on Cr2+0.25Zn0.75Te, V2+0.25Zn0.75Te, and Mn2+0.25Zn0.75Te Femtosecond Laser and its Electro-Optical Characteristics
利用第一原理計算探討Cr2+0.25Zn0.75Te、V2+0.25Zn0.75Te及Mn2+0.25Zn0.75Te 飛秒雷射與電光特性
作者: Bang-Wun Lin
林榜文
關鍵字: first-principles
ZnTe
band structure
density of state
第一原理計算
碲化鋅
能帶結構
部份態密度
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摘要: In this study, the band structure and partial density of state (PDOS) of ZnTe, Cr2+0.25Zn0.75Te, V2+0.25Zn0.75Te, and Mn2+0.25Zn0.75Te were analysed by performing first-principles calculations based on density functional theory. The ZnTe band gap of 1.23 eV and the valence band energy level E0 of -1.35 eV appeared Te-5p orbital dominated in the PDOS, and the conduction band energy level E1 of -0.13 eV appeared Zn-3d and Te-5p dominated. Regarding Cr2+0.25Zn0.75Te, V2+0.25Zn0.75Te, and Mn2+0.25Zn0.75Te, the energy levels of the band gaps were 0.49 eV, 0.25 eV, and 0.68 eV, respectively, and the defect levels |-2>, |-1>, |0>, and |1> appeared to be Cr-3d, V-3d, Mn-3d, and Te-5p orbital dominated in the PDOS. We observed narrowing of the transition metal doped in the ZnTe system band gap, then generated the defect level. The property of the band structure was half metal. Degeneracy analysis was performed on the ZnTe band structures. Cr1+0.25Zn0.75Te and Cr2+0.25Zn0.75Te exhibited the same energy levels and wave function degeneracy phenomena, Cr1+0.125Zn0.875Te and Cr2+0.125Zn0.875Te exhibited nondegenerate phenomena that appeared split, and Cr1+0.03Zn0.97Te and Cr2+0.03Zn0.97Te exhibited enhanced nondegenerate phenomena.
本論文係以第一原理(First-principles)計算基於密度泛函理論(Density functional theory, DFT)對ZnTe與Cr2+0.25Zn0.75Te、V2+0.25Zn0.75Te及Mn2+0.25Zn0.75Te進行能帶結構與部分態密度(Partial Density of State, PDOS)進行研究,並透過能階分析了解ZnTe之元素的軌道貢獻。ZnTe的能隙值為1.23 eV而價電帶能階E0在-1.35 eV由PDOS顯示Te-5p軌道主導,導電帶能階E1在-0.13 eV顯示為Zn-3d與Te-5p軌道所主導, Cr2+0.25Zn0.75Te、V2+0.25Zn0.75Te及Mn2+0.25Zn0.75Te能隙值為0.49 eV、0.25 eV及0.68 eV,而Cr2+0.25Zn0.75Te、V2+0.25Zn0.75Te及Mn2+0.25Zn0.75Te結構,三者的缺陷能階|-2>、|-1>及|0>與導電帶能階|1>都由Cr-3d、V-3d及Mn-3d軌道與Te-5p軌道所主導。可得知過渡金屬摻雜於ZnTe中使能隙變窄產生缺陷能階提供電子躍遷而能帶結構方面價電帶跨越費米能階會呈現半金屬特性。ZnTe簡併分析以能帶結構圖觀察,Cr1+0.25Zn0.75Te與Cr2+0.25Zn0.75Te波函數具有相同能量而發生簡併現象,Cr1+0.125Zn0.875Te與Cr2+0.125Zn0.875Te能級產生分裂出現非簡併現象,而Cr1+0.03Zn0.97Te與Cr2+0.03Zn0.97Te的非簡併現象更為劇烈。
URI: http://hdl.handle.net/11455/91748
文章公開時間: 2017-10-31
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