Si掺杂金红石TiO2光学特性的第一性原理研究

TiO2是一种重要的n型金属氧化物半导体功能材料。近年来的实验与理论研究表明，运用杂质掺入来减小TiO2禁带宽度是提高其活性的一种有效办法。本文运用基于局域密度泛函和赝势的第一性原理方法，从理论上研究了Si掺杂金红石相TiO2的电子结构和光学特性。通过能带结构、态密度及电荷布居的分析发现，Si原子的引入使Si-Ti的键长发生明显的变化，近邻氧原子有靠近硅原子的趋势而近邻钛原子有远离硅原子的趋势。半导体禁带宽度没有明显变化，但是禁带中产生了一个杂质能级，该杂质能级主要是由Si的3p电子和Ti的3d电子杂化引起的。因此，Si掺杂能使材料的宏观特性表现为电子激发能量减小，材料活性增强，响应可见光范围达到480nm左右。

Study of the Optical Properties of Si-doped Rutile TiO2 by First-principles Theory

TiO2 has been known as an n-type metallic oxide semiconductor and an important inorganic function material. In recent years many theories and experiment researches have reported that in order to decrease the gap, to improve the activity, nonmetallic impurities doping TiO2 is one of the effective methods. The optical properties and electronic properties of Si-doped futile TiO2 are investigated by first-principles pseudopotcutial calculations based on density-functional theory （DFT） in this paper. In analyzing band structures, densities of states and charge populations, it is found that there is an obvious change of electrical populations. Si-Ti bond lengths vary longer and Si-O bond lengths become shorter. It is discovered that the nearby oxygen atom has the trend of closing to the silicon atom and the nearby titanium atom has the trend of keeping off the silicon atom. Theoretical results show that the band gap of TiO2 remains few changes and a defect level appears about 2.59 eV above the top of value band in the gap, which result from hybridizing Si 3p states with Ti 3d states. It is concluded that the electronic excitation energy decreases and the 480 nm light can be responded due to the defect level.