Research Centre of Materials Science, School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081, China.
J Phys Chem A. 2013 Jul 11;117(27):5650-4. doi: 10.1021/jp402876f. Epub 2013 Jun 28.
The first-principles study of Ni-doped InN has been carried out to explore the doping effect of various charge states of Ni on the structural, electronic, magnetic, and optical properties of InN using generalized gradient approximation. Structural properties like lattice parameters, aspect ratios, bond lengths, and formation energies of (In, Ni) N are used to determine the stability of each doped system. The formation energies of (In, Ni)N systems decrease with the increase in charge state of nickel, while the bond lengths show an opposite trend. The DOS diagram shows that the introduction of Ni-d states within the bang gap region reduces the band gap for Ni(1+)- and Ni(2+)-doped InN, while the isolated states are generated in the case of Ni(3+)- and Ni(4+)-doped systems. The Ni(1+)-, Ni(3+)-, and Ni(4+)-doped InN systems are ferromagnetic in nature, whereas the (In, Ni(2+))N depicts spin-glass-like behavior. The best possible magnetization is obtained for (In, Ni(4+))N with a total magnet moment of 2.42 μB per supercell. Because of the presence of nickel impurities, the optical properties of InN have been significantly improved. The pure and Ni(3+)- and Ni(4+)-doped InN systems show nearly the same values of absorption edges (∼0.56 eV), in contrast with the Ni(1+)- and Ni(2+)-doped systems, where these values are 0.37 and 0.51 eV, respectively. The shift in absorption edges of Ni(1+)- and Ni(2+)-doped InN to lower energies and increase in the intensity of absorption and broadening of absorption peaks can be attributed to the pronounced band-gap reduction for these systems. A negligible shift of absorption edges in the case of Ni(3+)- and Ni(4+)- doped InN is the characteristic of isolated charge states introduced around the Fermi level, which inhibit the band gap reduction, and hence the optical properties are not improved as expected. This study demonstrates an important fact that for best possible optical device applications Ni(1+)-doped InN system is excellent, while for better magnetic properties the (In, Ni(4+))N is more suitable.
采用广义梯度近似方法，对 Ni 掺杂 InN 进行了第一性原理研究，以探讨各种电荷态的 Ni 对 InN 的结构、电子、磁性和光学性质的掺杂效应。晶格参数、纵横比、键长和（In，Ni）N 的形成能等结构性质用于确定每个掺杂体系的稳定性。（In，Ni）N 系统的形成能随着镍电荷态的增加而降低，而键长则呈现相反的趋势。DOS 图表明，Ni-d 态在能带隙区域内的引入降低了 Ni(1+)-和 Ni(2+)-掺杂 InN 的能带隙，而在 Ni(3+)-和 Ni(4+)-掺杂体系中则产生了孤立态。Ni(1+)-、Ni(3+)-和 Ni(4+)-掺杂 InN 体系具有铁磁性质，而（In，Ni(2+))N 表现出类自旋玻璃行为。（In，Ni(4+))N 具有最佳的可能磁化强度，每个超胞的总磁矩为 2.42 μB。由于镍杂质的存在，InN 的光学性质得到了显著改善。与 Ni(1+)-和 Ni(2+)-掺杂体系相比，纯 InN 以及 Ni(3+)-和 Ni(4+)-掺杂 InN 系统的吸收边（约 0.56 eV）值几乎相同，而 Ni(1+)-和 Ni(2+)-掺杂体系的吸收边值分别为 0.37 和 0.51 eV。Ni(1+)-和 Ni(2+)-掺杂 InN 的吸收边向低能移动以及吸收强度的增加和吸收峰的展宽可以归因于这些体系的能带隙显著减小。Ni(3+)-和 Ni(4+)-掺杂 InN 吸收边的微小移动是费米能级附近引入的孤立电荷态的特征，这抑制了能带隙的减小，因此光学性质没有得到预期的改善。这项研究表明了一个重要事实，即对于最佳的光学器件应用，Ni(1+)-掺杂 InN 体系是优异的，而对于更好的磁性性质，（In，Ni(4+))N 更合适。
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