閃鋅礦硫族化合物中的無序雜質(zhì)的電子結(jié)構(gòu)研究
發(fā)布時間：2018-07-23 16:10
【摘要】：閃鋅礦結(jié)構(gòu)硫族化合物半導(dǎo)體具有優(yōu)異的光電性能,吸引了大批研究者的關(guān)注,是半導(dǎo)體器件和太陽能電池領(lǐng)域的重點研究對象。無序分布的雜質(zhì)和缺陷對這類半導(dǎo)體的能帶結(jié)構(gòu)和有效質(zhì)量等電輸運(yùn)性質(zhì)有重要的影響,對其進(jìn)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(jié)構(gòu)光電材料Cu1-x Agx Ga X2(X=S,Se)中的無序摻雜對能帶結(jié)構(gòu)和有效質(zhì)量的影響,其中Cu/Ag原子位置的無序分布使用特殊準(zhǔn)隨機(jī)結(jié)構(gòu)(SQS)方法進(jìn)行模擬。通常情況下,由于交換關(guān)聯(lián)勢的不準(zhǔn)確,第一性原理計算會大幅度低估半導(dǎo)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(jì)地對能帶結(jié)構(gòu)進(jìn)行有效修正。此外,本文中輸運(yùn)性質(zhì)相關(guān)的計算均是基于修正后的能帶結(jié)構(gòu)。我們的研究結(jié)果表明,具有無序黃銅礦結(jié)構(gòu)的硫化物半導(dǎo)體材料和硒化物半導(dǎo)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(dǎo)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(dǎo)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(dǎo)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(dǎo)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(xì)能帶結(jié)構(gòu)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(jìn)一步理解Cu1-x Agx Ga X2(X=S,Se)系列半導(dǎo)體材料的輸運(yùn)性質(zhì),我們計算了該系列合金的有效質(zhì)量(EM),研究得到了EM與無序Ag離子濃度x之間的關(guān)系。最后,對Cu1-x Agx Ga Se2化合物的靜電勢與能帶偏移進(jìn)行了相關(guān)研究,其研究結(jié)果表明Ag離子的摻入將導(dǎo)致半導(dǎo)體的靜電勢降低;構(gòu)成異質(zhì)結(jié)半導(dǎo)體兩側(cè)的半導(dǎo)體原子層數(shù)的測試結(jié)果有:異質(zhì)結(jié)兩邊各取4個周期半導(dǎo)體結(jié)構(gòu)足夠屏蔽異質(zhì)結(jié)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(dǎo)體材料中無序摻雜Ag離子的研究結(jié)果為設(shè)計出高吸收、高遷移率的光電器件提供了一定的理論指導(dǎo)。
[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(xué)位授予單位】：四川師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)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(xué)位授予單位】：四川師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM914.4;TN304.2
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2 嚴(yán)輝,楊巍,宋雪梅,呂廣宏;第一原理方法在材料科學(xué)中的應(yīng)用[J];北京工業(yè)大學(xué)學(xué)報;2004年02期
相關(guān)碩士學(xué)位論文 前1條
1 向君;硫族化合物薄膜太陽能電池材料研究[D];華中科技大學(xué);2013年
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