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在掺杂量为1.04 at%-1.39 at%的范围内，Ti掺杂ZnO体系吸收光谱分布和电导率的实验结果存在争议均有文献报道，但是，迄今为止，对此未有合理的理论解释. 为了解决存在的争议，本文采用基于密度泛函理论的广义梯度近似平面波超软赝势GGA+U的方法，用第一性原理构建了两种不同掺杂量Zn0.9792Ti0.0208O和Zn0.9722Ti0.0278O超胞模型. 所有模型在几何结构优化的基础上，对能带结构分布、态密度分布和吸收光谱分布进行了计算. 计算结果表明：在本文限定的掺杂量范围内，Ti掺杂量越增加，掺杂体系体积越增加，体系总能量越升高，体系稳定性越下降，形成能越升高，掺杂越难，掺杂体系布居值减小，Ti-O 键长变长，共价键减弱，离子键增强，所有掺杂体系均转化为n型化简并半导体；掺杂体系带隙越变宽，吸收光谱蓝移越显著，电子有效质量越增加，电子浓度越增加，电子迁移率越减小，电子电导率越减小，掺杂体系导电性能越差. 计算结果与实验结果相符合. 对存在的问题进行了合理的理论解释. 对Ti掺杂ZnO光电功能材料的设计和制备有一定的理论指导作用.Nowadays, the studies on absorption spectra and conductivities of Ti doped ZnO systems have presented distinctly different experimental results when the atom fraction of impurity increases in a range from 1.04 at% to 1.39 at% To solve this contradiction, all calculations in this paper are carried out by the CASTEP tool in the Materials Studio software based on the first-principals generalized gradient approximation (GGA) plane wave ultra-soft pseudopotential method of the density functional theory. The supercell geometric structures of ZnO, Zn0.9792Ti0.208O and Zn0.9722Ti0.278O systems are used as the calculation models. For all the geometry optimization models, the band structures, densities of states, electron density differences, population and absorption spectra are calculated by the method of GGA+U. The results show that with the Ti doping amount increasing from 1.04 at% to 1.39 at%, the lattice parameters and also the volume of the doping system increase. The higher the total energy of the doping system, the higher the formation energy of the doping system is, thereby making doping difficult and lower stability of the doping system. The increase of Ti-doping concentration weakens the covalent bond, but strengthens the ionic bond. As the Ti substitutional doping concentration increases, the Mulliken bond populations decrease, but bond lengths of Ti-O increase for the doping system Meanwhile, the higher the Ti doping content, with all the doping systems converted into n-type degenerate semiconductor the wider the band gap of the doping system will be and the more significant the blue shift of absorption spectra of Ti-doped ZnO systems. In this paper the mechanism of band gap widening is reasonably explained. In addition, the higher the Ti doping content, the higher the electronic effective mass of doping systems is The higher the electronic concentration of doping systems, the lower the electronic mobility of doping systems is. The lower the electronic conductivity of doping systems, the worse the doping systems conductivity is. The calculation results of absorption spectrum and conductivity of Ti-doped ZnO system are consistent with the experimental data. And the contradiction between absorption spectrum and conductivity of Ti-doped ZnO system in experiment is explained reasonably by temperature effect. In this paper, the comprehensive optical and electrical properties of Ti-doped ZnO systems are calculated by first-principals GGA+U method. And these results may improve the design and the preparation of photoelectric functional materials for Ti-doped ZnO at quite a low temperature.
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Keywords:
- Ti doped ZnO /
- absorption spectra /
- conductivity /
- first-principals
[1] Salmani E, Benyoussef A, Ez-Zahraouy H, Saidi E H, Mounkachi O 2012 Chin. Phys. B 21 106601
[2] Gao L, Zhang J M 2009 Chin. Phys. B 18 4536
[3] Yao Y H, Cao Q X {2012 Chin. Phys. B 21 124205
[4] Lin Y C, Hsu C Y, Hung S K, Wen D C 2013 Ceram. Int. 39 5795
[5] Zhong Z Y, Zhang T 2013 Mater. Lett. 96 237
[6] Ye Z Y, Lu H L, Geng Y, Gu Y Z, Xie Z Y, Zhang Y, Sun Q Q, Ding S J, Zhang D W 2013 Nano. Res. Lett. 8 1
[7] Zhao W, Zhou Q, Zhang X, Wu X 2014 Appl. Surf. Sci. 305 481
[8] Huang M C, Wang T H, Cheng S H, Lin J C, Lan W H, Wu C C, Chang W S 2014 Nano. Nanotech. Lett. 6 210
[9] Sridhar R, Manoharan C, Ramalingam S, Dhanapandian S, Bououdina M 2014 Spectrochim. Acta Part A 120 297
[10] Lee S, Lee Y, Kim D Y, Kang T W 2013 J. Appl. Phys. 114 064102
[11] Lin J C, Huang M C, Wang T H, Wu J N, Tseng Y T, Peng K C 2015 Mater. Express 5 153
[12] Mahdavi A, Nadjafikhah M, Toomanian M 2015 Solid State Commun. 218 45
[13] Weng Z, Huang Z, Lin W 2012 Physica B 407 743
[14] Xiong Z H, Jiang F Y 2007 J. Phys. Chem. Solids 68 1500
[15] Bergum K, Fjellvg H, Nilsen O 2015 Appl. Surf. Sci. 332 494
[16] Akilan T, Srinivasan N, Saravanan R 2015 Mater. Sci. Semicond. Process. 30 381
[17] Chung J L, Chen J C, Tseng C J 2008 J. Phys. Chem. Solids 69 535
[18] Guo S Q, Hou Q Y, Zhao C W, Mao F 2014 Acta Phys. Sin. 63 107101 (in Chinese) [郭少强, 侯清玉, 赵春旺, 毛斐 2014 63 107101]
[19] Anisimov V V, Zaanen J, Andersen K 1991 Phys. Rev. B 44 943
[20] Mapa M, Thushara K S, Saha B, Chakraborty P, Janet C M, Viswanath R P, Nair C M, Murty K V G K, Gopinath C S 2009 Chem. Mater. 21 2973
[21] Li M, Zhang J, Zhang Y 2012 Chem. Phys. Lett. 527 63
[22] Sun C Q 2003 Prog. Mater. Sci. 48 521
[23] Ju J, Wu X M, Zhuge L J 2012 Int. J. Mod. Phys. B 22 5279
[24] Roth A P, Webb J B, Williams D F 1981 Solid State Commun. 39 1269
[25] Pires R G, Dickstein R M, Titcomb S L, Anderson R L 1990 Cryogenics 30 1064
[26] Erhart P, Albe K, Klein A 2006 J. Phys. Rev. B 73 205203
[27] Ursaki V V, Tiginyanu I M, Zalamai V V, Rusu E V, Emelchenko G A, Masalov V M, Samarov E N 2004 Phys. Rev. B 70 155204
[28] Lu E K, Zhu B S, Luo J S 1998 Semiconductor Physics (Xi'an: Xi'an Jiaotong University Press) p103 (in Chinese) [刘恩科, 朱秉升, 罗晋生1998 半导体物理 (西安: 西安交通大学出版社) 第103 页]
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[1] Salmani E, Benyoussef A, Ez-Zahraouy H, Saidi E H, Mounkachi O 2012 Chin. Phys. B 21 106601
[2] Gao L, Zhang J M 2009 Chin. Phys. B 18 4536
[3] Yao Y H, Cao Q X {2012 Chin. Phys. B 21 124205
[4] Lin Y C, Hsu C Y, Hung S K, Wen D C 2013 Ceram. Int. 39 5795
[5] Zhong Z Y, Zhang T 2013 Mater. Lett. 96 237
[6] Ye Z Y, Lu H L, Geng Y, Gu Y Z, Xie Z Y, Zhang Y, Sun Q Q, Ding S J, Zhang D W 2013 Nano. Res. Lett. 8 1
[7] Zhao W, Zhou Q, Zhang X, Wu X 2014 Appl. Surf. Sci. 305 481
[8] Huang M C, Wang T H, Cheng S H, Lin J C, Lan W H, Wu C C, Chang W S 2014 Nano. Nanotech. Lett. 6 210
[9] Sridhar R, Manoharan C, Ramalingam S, Dhanapandian S, Bououdina M 2014 Spectrochim. Acta Part A 120 297
[10] Lee S, Lee Y, Kim D Y, Kang T W 2013 J. Appl. Phys. 114 064102
[11] Lin J C, Huang M C, Wang T H, Wu J N, Tseng Y T, Peng K C 2015 Mater. Express 5 153
[12] Mahdavi A, Nadjafikhah M, Toomanian M 2015 Solid State Commun. 218 45
[13] Weng Z, Huang Z, Lin W 2012 Physica B 407 743
[14] Xiong Z H, Jiang F Y 2007 J. Phys. Chem. Solids 68 1500
[15] Bergum K, Fjellvg H, Nilsen O 2015 Appl. Surf. Sci. 332 494
[16] Akilan T, Srinivasan N, Saravanan R 2015 Mater. Sci. Semicond. Process. 30 381
[17] Chung J L, Chen J C, Tseng C J 2008 J. Phys. Chem. Solids 69 535
[18] Guo S Q, Hou Q Y, Zhao C W, Mao F 2014 Acta Phys. Sin. 63 107101 (in Chinese) [郭少强, 侯清玉, 赵春旺, 毛斐 2014 63 107101]
[19] Anisimov V V, Zaanen J, Andersen K 1991 Phys. Rev. B 44 943
[20] Mapa M, Thushara K S, Saha B, Chakraborty P, Janet C M, Viswanath R P, Nair C M, Murty K V G K, Gopinath C S 2009 Chem. Mater. 21 2973
[21] Li M, Zhang J, Zhang Y 2012 Chem. Phys. Lett. 527 63
[22] Sun C Q 2003 Prog. Mater. Sci. 48 521
[23] Ju J, Wu X M, Zhuge L J 2012 Int. J. Mod. Phys. B 22 5279
[24] Roth A P, Webb J B, Williams D F 1981 Solid State Commun. 39 1269
[25] Pires R G, Dickstein R M, Titcomb S L, Anderson R L 1990 Cryogenics 30 1064
[26] Erhart P, Albe K, Klein A 2006 J. Phys. Rev. B 73 205203
[27] Ursaki V V, Tiginyanu I M, Zalamai V V, Rusu E V, Emelchenko G A, Masalov V M, Samarov E N 2004 Phys. Rev. B 70 155204
[28] Lu E K, Zhu B S, Luo J S 1998 Semiconductor Physics (Xi'an: Xi'an Jiaotong University Press) p103 (in Chinese) [刘恩科, 朱秉升, 罗晋生1998 半导体物理 (西安: 西安交通大学出版社) 第103 页]
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