Dionízio Moreira M, Venezuela P, Schmidt T M
Instituto de Física, Universidade Federal Fluminense, Campus da Praia Vermelha, Niterói, Rio de Janeiro, CEP 24210-340, Brazil.
Nanotechnology. 2008 Feb 13;19(6):065203. doi: 10.1088/0957-4484/19/6/065203. Epub 2008 Jan 23.
The effects of surface passivation on the electronic and structural properties of InP nanowires have been investigated by first-principles calculations. We compare the properties of nanowires whose surfaces have been passivated in several ways, always by H atoms and OH radicals. Taking as the initial reference nanowires that are fully passivated by H atoms, we find that the exchange of these atoms at the surface by OH radicals is always energetically favorable. A nanowire fully passivated by OH radicals is about 2.5 eV per passivated dangling bond more stable than a nanowire fully passivated by H atoms. However, the energetically most stable passivated surface is predicted to have all In atoms bonded to OH radicals and all P atoms bonded to H atoms. This mixed passivation is 2.66 eV per passivated dangling bond more stable than a nanowire fully passivated by H atoms. Our results show that, in comparison with the fully H-saturated nanowire, the fully OH-saturated nanowire has a smaller energy band gap and localized states near the energy band edges. Also, more interestingly, concerning optical applications, the most stable H+OH passivated nanowire has a well-defined energy band gap, only 10% smaller than the H-saturated nanowire energy gap, and few localized states always close to the valence band maximum.
通过第一性原理计算研究了表面钝化对磷化铟纳米线电子和结构性质的影响。我们比较了通过几种方式进行表面钝化的纳米线的性质，这些方式均是用氢原子和羟基自由基进行钝化。以被氢原子完全钝化的纳米线作为初始参考，我们发现表面的这些原子被羟基自由基取代在能量上总是有利的。被羟基自由基完全钝化的纳米线比被氢原子完全钝化的纳米线每个钝化悬空键约稳定2.5电子伏特。然而，预测能量上最稳定的钝化表面是所有铟原子与羟基自由基键合且所有磷原子与氢原子键合。这种混合钝化比被氢原子完全钝化的纳米线每个钝化悬空键稳定2.66电子伏特。我们的结果表明，与完全氢饱和的纳米线相比，完全羟基饱和的纳米线具有更小的能带隙以及能带边缘附近的局域态。此外，更有趣的是，对于光学应用而言，最稳定的氢加羟基钝化纳米线具有明确的能带隙，仅比氢饱和纳米线的能带隙小10%，并且几乎没有总是靠近价带最大值的局域态。
