Kita Masao, Suzuki Issei, Ohashi Naoki, Omata Takahisa
Department of Mechanical Engineering, National Institute of Technology, Toyama College , 13 Hongo-machi, Toyama, 939-8630, Japan.
Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University , 2-1 Yamada-oka, Suita, 565-0871, Japan.
Inorg Chem. 2017 Nov 20;56(22):14277-14283. doi: 10.1021/acs.inorgchem.7b02379. Epub 2017 Oct 30.
The quaternary I-II-IV-O semiconductor, CuZnGeO, with a wurtz-kesterite structure and 1.4 eV energy band gap has been synthesized for the first time via ion exchange of precursor NaZnGeO. Its crystal structure was refined by Rietveld analysis, and the structural distortion was quantitatively evaluated based on the cation tetrahedral tilting and angle distortion indexes. The tetrahedral distortion in CuZnGeO was smaller than in AgZnGeO but larger than in β-CuGaO, suggesting an indirect band gap of CuZnGeO. Density functional theory calculations using the functional of the local density approximation with corrections for on-site Coulomb interactions indicated that CuZnGeO is an indirect semiconductor as expected from its structural feature. However, the energy difference between the direct and indirect band gaps is very small, suggesting that CuZnGeO shows strong light absorption near the band edge.
首次通过前驱体NaZnGeO的离子交换合成了具有纤锌矿-凯斯特石结构且能带隙为1.4 eV的四元I-II-IV-O半导体CuZnGeO。通过Rietveld分析对其晶体结构进行了精修，并基于阳离子四面体倾斜和角度畸变指数对结构畸变进行了定量评估。CuZnGeO中的四面体畸变小于AgZnGeO中的，但大于β-CuGaO中的，这表明CuZnGeO具有间接带隙。使用具有局域密度近似泛函并对在位库仑相互作用进行校正的密度泛函理论计算表明，正如从其结构特征所预期的那样，CuZnGeO是一种间接半导体。然而，直接带隙和间接带隙之间的能量差非常小，这表明CuZnGeO在带边附近表现出强烈的光吸收。
