閃鋅礦硫族化合物中的無序雜質的電子結構研究
發(fā)布時間：2018-07-23 16:10
【摘要】：閃鋅礦結構硫族化合物半導體具有優(yōu)異的光電性能,吸引了大批研究者的關注,是半導體器件和太陽能電池領域的重點研究對象。無序分布的雜質和缺陷對這類半導體的能帶結構和有效質量等電輸運性質有重要的影響,對其進行系統(tǒng)研究具有較大的理論意義與實際意義。本論文采用基于密度泛函理論的第一性原理計算方法研究了黃銅礦結構光電材料Cu1-x Agx Ga X2(X=S,Se)中的無序摻雜對能帶結構和有效質量的影響,其中Cu/Ag原子位置的無序分布使用特殊準隨機結構(SQS)方法進行模擬。通常情況下,由于交換關聯(lián)勢的不準確,第一性原理計算會大幅度低估半導體能隙。本文采用的修正局域密度近似方法(LDA+C)可以相對經(jīng)濟地對能帶結構進行有效修正。此外,本文中輸運性質相關的計算均是基于修正后的能帶結構。我們的研究結果表明,具有無序黃銅礦結構的硫化物半導體材料和硒化物半導體材料均出現(xiàn)了能隙反常現(xiàn)象,即Ag Ga X2(X=S,Se)化合物半導體材料的能隙值大于Cu Ga X2(X=S,Se)的能隙值。Cu1-x Agx Ga Se2系列硒化物半導體合金的能隙值的修正范圍為1.63 e V到1.78 e V;Cu1-x Agx Ga S2系列硫化物半導體材料的能隙值修正范圍為2.33 e V-2.64 e V。此外,硫化物和硒化物系列半導體合金的能隙值都在Ag離子濃度為50%(x=0.5)和100%(x=1.0)時分別出現(xiàn)局域最小值和最大值。并且,通過研究的詳細能帶結構闡釋了在基態(tài)發(fā)生間接躍遷時所需的光子動量。為了進一步理解Cu1-x Agx Ga X2(X=S,Se)系列半導體材料的輸運性質,我們計算了該系列合金的有效質量(EM),研究得到了EM與無序Ag離子濃度x之間的關系。最后,對Cu1-x Agx Ga Se2化合物的靜電勢與能帶偏移進行了相關研究,其研究結果表明Ag離子的摻入將導致半導體的靜電勢降低;構成異質結半導體兩側的半導體原子層數(shù)的測試結果有:異質結兩邊各取4個周期半導體結構足夠屏蔽異質結界面之間的相互影響。本論文通過在Cu Ga X2(X=S,Se)硫族化合物半導體材料中無序摻雜Ag離子的研究結果為設計出高吸收、高遷移率的光電器件提供了一定的理論指導。
[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.
【學位授予單位】：四川師范大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM914.4;TN304.2
本文編號：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.
【學位授予單位】：四川師范大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM914.4;TN304.2
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相關碩士學位論文 前1條
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