C掺杂锐钛矿相TiO_2吸收光谱的第一性原理研究

The first-principles study of absorption spectrum of C-doped anatase TiO_2

运用第一性原理,对C掺杂锐钛矿相TiO2的电子结构进行了研究,从能带结构理论解释了C掺杂TiO2吸收光谱的一些实验现象.发现在C掺杂后的锐钛矿相TiO2的禁带宽度增大,并且在带隙中出现了杂质能级,这些杂质能级主要是由C2p轨道上的电子构成的,它们之间是独立的,正是这些独立的杂质能级使TiO2掺杂后可以发生可见光响应.价带上的电子可以吸收一定能量的光子跃迁到杂质能级,而杂质能级上的电子也可以吸收一定能量的光子跃迁到导带,所以从理论上可以计算出掺杂后的TiO2在可见光范围内存在两个吸收边,与实验中所得到的现象相一致.

We have performed first-principle calculations of electronic band structure of C-doped anatase TiO2,and explained some experimental phenormena of C-doped TiO2＇s absorption spectrum.The results indicated that the band gap broaders and some new bands appears in the band gap.These new bands result from C 2p orbitals,they are separated,and their existance explains the visible light response.The electrons in the valence band can be excited to the new states and subsequently excited to the conduction band,leading to existence of two absorption edges.Theoretical result are in agreement with the experimental result.