Theoretical Investigation on Electronic Structure, Optical Properties and Electrical Properties of Zinc Oxide under High Pressure
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摘要: 基于密度泛函理论从头计算法, 研究了500 GPa外压力条件下纤锌矿结构ZnO氧化物的晶格结构、电子结构、光学性质和导电性能。计算分析结果表明，在500 GPa外压力下，ZnO氧化物的晶格对称性保持不变，晶格参数减小，Zn—O键长和O—Zn—O键角均减小，但不同方向上材料的可压缩性不同；ZnO氧化物的带隙类型仍为直接带隙，其宽度增加到1.65 eV；费米能级附近的能级数量减少，态密度降低，电子在不同能量区域的局域化趋势明显；ZnO氧化物的光吸收向高能量范围扩展，低能量光学吸收降低，高能量光吸收增强。分析结果表明，500 GPa的外压力下，ZnO氧化物费米能级附近的载流子浓度、有效质量和迁移速率均降低，其电性能降低。Abstract: In the present work, we investigated the crystal structure, electronic structure, optical properties and electrical properties of the wurtzite type ZnO oxide at exoteric pressures of 500 GPa based on the density functional theory ab-initio calculations framework. The results show that the lattice of ZnO is decreased at 500 GPa and, at the same time, the Zn—O bond length and the O—Zn—O bond angle are decreased while, however, the compressibility varies in different crystal directions and the symmetry remains the same. The band gap is direct at 500 GPa with the band gap value rising to 1.65 eV. The number of the energy bands decreases and so does the density of states. An obvious localization effect of the electrons is observed at 500 GPa. The absorption peaks move towards the high energy region, and the absorption decreases for low energy photon and increases for the high energy photon. The results from our analysis show that the density, effective mass and the mobility of the carriers near Fermi level decrease under 500 GPa, leading to a reduced performance of their electrical properties.
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Key words:
- ZnO oxide /
- high pressure effects /
- optical properties /
- electrical properties
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图 2 ZnO氧化物键长和键角示意图
Figure 2. Schematic of the bond length and bond angle for ZnO oxides
图 3 500 GPa压力下ZnO氧化物的键长和键角
Figure 3. Bond lengths and bond angles for ZnO oxides under 500 GPa pressure
图 4 计算所得无压力下和500 GPa压力下ZnO氧化物的能带结构
Figure 4. Calculated band structures for ZnO oxides under 0 and 500 GPa pressure
图 5 计算所得无压力和500 GPa压力下ZnO氧化物的态密度
Figure 5. Calculated density of states for ZnO oxides under 0 and 500 GPa pressure
图 6 计算所得无压力和500 GPa压力下ZnO氧化物的分态密度
Figure 6. Calculated partial density of states for ZnO oxides under 0 and 500 GPa pressure
图 7 计算所得无压力和500 GPa压力下ZnO氧化物的介电函数
Figure 7. Calculated dielectric functions for ZnO oxides under 0 and 500 GPa pressure
表 1 不同压力条件下ZnO的晶格参数
Table 1. Lattice parameters of ZnO at different pressures
Pressure/
(GPa)a/(nm) b/(nm) c/(nm) 0 0.330 98 0.330 98 0.530 54 500 0.220 38 0.220 38 0.535 18 Pressure/
(GPa)α/(°) β/(°) γ/(°) Space
group0
50090 90 120 P63mc 
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