(AlxGa<subscript>1-x</subscript>)<subscript>2</subscript>O<subscript>3</subscript> 结构、电子和光学性质的 第一性原理研究. (Chinese)

The crystal structure, charge density distribution, band structure, density of states (DOS), and optical properties of Al-doped β-Ga 2 O 3 (i. e. (Al x Ga 1-x ) 2 O 3 ) with different Al concentrations were calculated by the first-principles based on density functional theory. The calculated results for intrinsic and Al-doped β-Ga 2 O 3 with various Al concentrations were compared. The results show that, as the Al concentration increases, both the lattice parameters and bond lengths of (Al x Ga 1-x ) 2 O 3 monotonously decrease, whereas the band gap progressively widens. It is found that an intermediate band exists above the conduction band minimum (CBM), which is mainly composed of Ga 4s and Al 3p orbitals. Al doping enlarges the band gap by introducing impurity energy levels in this intermediate conduction band. Meanwhile, the introduction of Al atoms shifts the density of states to high-energy side by nearly 3 eV, which also leads to an increase of the band gap. According to the optical property calculation results, a significant blue shift for both the imaginary part of the dielectric function and the absorption coefficient are observed after Al doping. This blue shift behavior is generated by the transition from the O 2p states in the valence band maximum (VBM) to the Ga 4s states in the CBM. Moreover, the blue shift is intensified with the increase of Al doping concentration. This investigation can provide ideas and theoretical guidance for the construction of optoelectronic devices based on (Al x Ga 1-x ) 2 O 3 . [ABSTRACT FROM AUTHOR]

本文采用基于密度泛函理论的第一性原理计算了不同Al 掺杂浓度β-Ga 2 O 3 (即(Alx Ga1 - x)2 O3)的晶体结构、电 荷密度分布、能带结构、态密度和光学性质,并对本征β-Ga 2 O 3 和不同Al 掺杂浓度的β-Ga 2 O 3 的计算结果进行了分析 对比。结果表明,随着Al 掺杂浓度的增加,(Al x Ga 1-x ) 2 O 3 的晶格常数和键长均单调减小,而带隙逐渐增大。β-Ga 2 O 3 导带底上方存在主要由Ga 4s 和Al 3p 轨道组成的中间带,Al 掺杂在此中间带引入杂质能级,从而导致带隙增加。同 时,Al 的引入使态密度向高能侧偏移了近3 eV,也导致了带隙的增加。根据光学性质的计算结果,在掺杂Al 后,介电 函数的虚部和吸收系数均观察到明显的蓝移现象。这是由价带顶中的O 2p 态和导带底中的Ga 4s 态之间的跃迁产 生的。并且,随着Al 掺杂浓度的增加,蓝移现象加剧。本文研究可为基于(Al x Ga 1-x ) 2 O 3 光电器件的设计提供思路和 理论指导. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)