闪锌矿硫族化合物中的无序杂质的电子结构研究
发布时间：2018-07-23 16:10
【摘要】：闪锌矿结构硫族化合物半导体具有优异的光电性能,吸引了大批研究者的关注,是半导体器件和太阳能电池领域的重点研究对象。无序分布的杂质和缺陷对这类半导体的能带结构和有效质量等电输运性质有重要的影响,对其进行系统研究具有较大的理论意义与实际意义。本论文采用基于密度泛函理论的第一性原理计算方法研究了黄铜矿结构光电材料Cu1-x Agx Ga X2(X=S,Se)中的无序掺杂对能带结构和有效质量的影响,其中Cu/Ag原子位置的无序分布使用特殊准随机结构(SQS)方法进行模拟。通常情况下,由于交换关联势的不准确,第一性原理计算会大幅度低估半导体能隙。本文采用的修正局域密度近似方法(LDA+C)可以相对经济地对能带结构进行有效修正。此外,本文中输运性质相关的计算均是基于修正后的能带结构。我们的研究结果表明,具有无序黄铜矿结构的硫化物半导体材料和硒化物半导体材料均出现了能隙反常现象,即Ag Ga X2(X=S,Se)化合物半导体材料的能隙值大于Cu Ga X2(X=S,Se)的能隙值。Cu1-x Agx Ga Se2系列硒化物半导体合金的能隙值的修正范围为1.63 e V到1.78 e V;Cu1-x Agx Ga S2系列硫化物半导体材料的能隙值修正范围为2.33 e V-2.64 e V。此外,硫化物和硒化物系列半导体合金的能隙值都在Ag离子浓度为50%(x=0.5)和100%(x=1.0)时分别出现局域最小值和最大值。并且,通过研究的详细能带结构阐释了在基态发生间接跃迁时所需的光子动量。为了进一步理解Cu1-x Agx Ga X2(X=S,Se)系列半导体材料的输运性质,我们计算了该系列合金的有效质量(EM),研究得到了EM与无序Ag离子浓度x之间的关系。最后,对Cu1-x Agx Ga Se2化合物的静电势与能带偏移进行了相关研究,其研究结果表明Ag离子的掺入将导致半导体的静电势降低;构成异质结半导体两侧的半导体原子层数的测试结果有:异质结两边各取4个周期半导体结构足够屏蔽异质结界面之间的相互影响。本论文通过在Cu Ga X2(X=S,Se)硫族化合物半导体材料中无序掺杂Ag离子的研究结果为设计出高吸收、高迁移率的光电器件提供了一定的理论指导。
[Abstract]:Sphalerite structured sulfur compound semiconductors have attracted a great deal of attention due to their excellent optoelectronic properties and have been the focus of research in the field of semiconductor devices and solar cells. The disordered distribution of impurities and defects have an important influence on the energy band structure and effective mass isoelectric transport properties of this kind of semiconductors. It is of great theoretical and practical significance to study them systematically. In this paper, the influence of disordered doping on the band structure and effective mass of chalcopyrite structure photovoltaic material Cu1-x Agx Ga X2 (XSX se) has been studied by using the first-principle calculation method based on density functional theory (DFT). The disordered distribution of Cu/Ag atoms is simulated by a special quasi-random structure (SQS) method. In general, due to the inaccuracy of the exchange correlation potential, the first principle calculation will greatly underestimate the semiconductor energy gap. The modified local density approximation (LDA C), which is used in this paper, can effectively modify the band structure relatively economically. In addition, the calculation of transport properties in this paper is based on the modified band structure. Our results show that both sulfide semiconductor materials and selenide semiconductor materials with disordered chalcopyrite structure exhibit abnormal energy gap phenomena. That is, the energy gap value of Ag Ga x 2 (X Si Si se) compound semiconductor material is larger than that of Cu Ga X 2 (X Si Si se). The correction range of energy gap number of Cu 1-x Agx Ga Se2 series selenide semiconductor alloy is from 1. 63 EV to 1. 78 e V, Cu 1 x Agx Ga S 2 series sulfide semiconductors. The correction range of energy gap value is 2.33 e V-2.64 EV. In addition, the band gap values of sulfides and selenide series semiconductors show local minimum and maximum values at Ag concentration of 50% (x ~ (0.5) and 100% (x ~ (1.0), respectively. Furthermore, the photon momentum required for the indirect transition of the ground state is explained by the detailed band structure studied. In order to further understand the transport properties of Cu1-x Agx Ga X2 (XSZ se) series semiconductors, we have calculated the relationship between EM and the concentration of disordered Ag ions x in the effective mass (EM), study of this series of alloys. Finally, the electrostatic potential and band shift of Cu1-x Agx Ga Se2 compounds are studied. The results show that the doping of Ag ions leads to the decrease of electrostatic potential of semiconductors. The measurement results of the number of semiconductor atomic layers on both sides of the heterojunction semiconductor are as follows: four periodic semiconductor structures on each side of the heterojunction are sufficient to shield the interaction between the heterojunction surfaces. In this thesis, the results of disordered doping of Ag ions in Cu Ga X2 (XSN se) sulfur compound semiconductor materials provide theoretical guidance for the design of high absorption and high mobility photovoltaic devices.
【学位授予单位】：四川师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM914.4;TN304.2
本文编号：2139936
[Abstract]:Sphalerite structured sulfur compound semiconductors have attracted a great deal of attention due to their excellent optoelectronic properties and have been the focus of research in the field of semiconductor devices and solar cells. The disordered distribution of impurities and defects have an important influence on the energy band structure and effective mass isoelectric transport properties of this kind of semiconductors. It is of great theoretical and practical significance to study them systematically. In this paper, the influence of disordered doping on the band structure and effective mass of chalcopyrite structure photovoltaic material Cu1-x Agx Ga X2 (XSX se) has been studied by using the first-principle calculation method based on density functional theory (DFT). The disordered distribution of Cu/Ag atoms is simulated by a special quasi-random structure (SQS) method. In general, due to the inaccuracy of the exchange correlation potential, the first principle calculation will greatly underestimate the semiconductor energy gap. The modified local density approximation (LDA C), which is used in this paper, can effectively modify the band structure relatively economically. In addition, the calculation of transport properties in this paper is based on the modified band structure. Our results show that both sulfide semiconductor materials and selenide semiconductor materials with disordered chalcopyrite structure exhibit abnormal energy gap phenomena. That is, the energy gap value of Ag Ga x 2 (X Si Si se) compound semiconductor material is larger than that of Cu Ga X 2 (X Si Si se). The correction range of energy gap number of Cu 1-x Agx Ga Se2 series selenide semiconductor alloy is from 1. 63 EV to 1. 78 e V, Cu 1 x Agx Ga S 2 series sulfide semiconductors. The correction range of energy gap value is 2.33 e V-2.64 EV. In addition, the band gap values of sulfides and selenide series semiconductors show local minimum and maximum values at Ag concentration of 50% (x ~ (0.5) and 100% (x ~ (1.0), respectively. Furthermore, the photon momentum required for the indirect transition of the ground state is explained by the detailed band structure studied. In order to further understand the transport properties of Cu1-x Agx Ga X2 (XSZ se) series semiconductors, we have calculated the relationship between EM and the concentration of disordered Ag ions x in the effective mass (EM), study of this series of alloys. Finally, the electrostatic potential and band shift of Cu1-x Agx Ga Se2 compounds are studied. The results show that the doping of Ag ions leads to the decrease of electrostatic potential of semiconductors. The measurement results of the number of semiconductor atomic layers on both sides of the heterojunction semiconductor are as follows: four periodic semiconductor structures on each side of the heterojunction are sufficient to shield the interaction between the heterojunction surfaces. In this thesis, the results of disordered doping of Ag ions in Cu Ga X2 (XSN se) sulfur compound semiconductor materials provide theoretical guidance for the design of high absorption and high mobility photovoltaic devices.
【学位授予单位】：四川师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM914.4;TN304.2
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