Electronic Structure and Photoelectric Properties ofZnTe under High Pressure
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摘要: 应用第一性原理平面波赝势计算方法，研究了闪锌矿ZnTe晶体在外界压力下的电子结构和光电性质, 并计算了介电函数和光学吸收系数随压力的变化情况。结果表明：在高压作用下，Te原子和Zn原子的态密度分布都向低能量方向移动，分布范围增大，Te 5p和Zn 3d电子轨道杂化变强。随着压力的增大，直接带隙逐渐增大，而间接带隙逐渐变小。当压力为10.7 GPa时，能带结构从直接带隙转变为间接带隙结构。压力增大，有利于Te 5p与Zn 3d电子间的跃迁，光吸收系数增大，产生更多的电子-空穴对，材料导电能力增强。Abstract: The electrons structure and photoelectric properties of zinc-blende structural ZnTe were investigated under high pressure, using first-principles plane-wave pseudo-potential method.The dielectric function and optical absorption coefficient were also predicted under high pressure.The results show that the distributions of density of states of Te and Zn atoms under high pressure shift towards lower energy direction and cover wider range.High pressure leads to stronger hybridization between Te 5p and Zn 3d electrons.The direct band gap increases gradually with pressure while the indirect band gap decreases.The direct band gap structure becomes an indirect one when the ambient pressure reaches 10.7 GPa.High pressure helps the transitions between Te 5p and Zn 3d electrons.The optical absorption coefficient increases, which leads to more electron-hole pairs and enhances the conductivity.
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图 3 不同压力下Te原子的s和p电子的态密度
Figure 3. Density of states of s and p electrons of Te under different pressures
图 4 不同压力下Zn原子的s和d电子的态密度
Figure 4. Density of states of s and d electrons of Zn under different pressures
表 1 ZnTe在不同压力下的直接带隙和间接带隙
Table 1. Direct and indirect band gaps of ZnTe under different pressures
Pressure/
(GPa)E1/(eV) E2/(eV) Present Calc.[19] Calc.[20] Exp.[18] Present Calc.[19] Exp.[18] 0 1.39 1.28 1.10 2.39 2.45 2.11 3.30 1.0 1.48 1.35 - - 2.44 2.07 - 2.0 1.57 1.42 - - 2.42 2.04 - 3.0 1.66 1.49 - - 2.40 2.00 - 4.0 1.74 1.56 - - 2.39 1.97 - 5.0 1.82 1.63 - - 2.37 1.93 - 6.0 1.89 1.70 - - 2.35 1.90 - 7.0 1.96 1.77 - - 2.32 1.86 - 8.0 2.02 1.84 - - 2.28 1.82 - 9.0 2.08 1.91 - - 2.25 1.79 - 10.0 2.15 1.98 - - 2.21 1.76 - 10.7 2.19 - - - 2.19 - - 11.0 2.21 2.05 - - 2.18 1.72 - 12.0 2.26 2.12 - - 2.15 1.68 - Note:E1 and E2 represent the direct and indirect band gaps，respectively. 
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