【摘要】：隨著藍光LED的廣泛使用,InGaN材料受到越來越廣泛的關(guān)注。它不僅可做為發(fā)光材料,也展現(xiàn)了非常優(yōu)異的光伏特性。由于其能帶可以從0.65eV到3.4eV連續(xù)可調(diào),幾乎覆蓋了整個可見光譜,并且還具有高吸收系數(shù),高遷移率和高抗輻照能力,因此InGaN作為太陽能電池具有巨大潛力。本文對InGaN異質(zhì)結(jié)太陽電池的載流子輸運進行了較系統(tǒng)的研究。第一章主要闡述了InGaN材料應(yīng)用于光伏領(lǐng)域的國內(nèi)外研究進展,以及存在的主要問題和挑戰(zhàn)。還介紹了本文使用的模擬系統(tǒng),以及異質(zhì)結(jié)太陽能電池的基礎(chǔ)知識。第二章主要研究了不同In組分的InGaN/Ga N多量子阱太陽電池響應(yīng)波長遠低于吸收邊的原因。我們發(fā)現(xiàn)低能量光子激發(fā)的載流子所能達到的能級較低,需要越過很高的勢壘才能逃逸出量子阱,當(dāng)激發(fā)光子能量低于一定閾值,產(chǎn)生的載流子只能復(fù)合而對光電流沒有貢獻。載流子逃逸的光子能量閾值與壘厚有關(guān),計算得到了不同壘厚情況下InGaN/Ga N多量子阱太陽電池波長響應(yīng)極限,為InGaN/GaN多量子阱太陽電池的設(shè)計提供了參考。第三章研究了V型坑在In GaN多量子阱太陽能電池中的作用。我們通過數(shù)值模擬的手段發(fā)現(xiàn)了V型坑能夠為載流子提供輸運的通道,從而可以提高轉(zhuǎn)換效率。除此之外,我們對不同位錯密度的V坑進行了討論,發(fā)現(xiàn)V坑形成的越多對電池的提升效果越明顯。第四章研究了溫度對In GaN太陽能電池中載流子運輸?shù)淖饔?我們發(fā)現(xiàn)溫度從室溫升高到360K,光電流的增大隨光源的注入電流的增大而增大,這意味著從量子阱逃逸的載流子總數(shù)也越多。并且通過量子點-量子阱復(fù)合模型很好地解釋了我們的實驗結(jié)果。為了得到更高的效率,我們在第五章對InGaN p-i-n型太陽能電池的異質(zhì)結(jié)界面進行了優(yōu)化,我們發(fā)現(xiàn)用n-ZnO作為電子傳輸層不僅能夠改善晶格失配帶來的極化效應(yīng),而且能夠有效減少界面勢壘,更有利于光生載流子的輸運。同時研究了將p型GaN用p型InGaN代替能夠增加吸收的光子并且改善界面的性質(zhì),能夠?qū)㈦姵氐霓D(zhuǎn)化效率從7%提高到14%。進一步優(yōu)化器件的尺寸可以將效率提高到15%。第六章主要對前面幾章的內(nèi)容進行總結(jié)以及對未來應(yīng)用進行了展望。
[Abstract]:With the wide use of blue LED materials, more and more attention has been paid to InGaN materials. It not only can be used as a luminescent material, but also shows excellent photovoltaic properties. Because its band can be continuously adjustable from 0.65eV to 3.4eV, it covers almost the whole visible spectrum, and also has high absorption coefficient, high mobility and high radiation resistance, so InGaN has great potential as a solar cell. The carrier transport of InGaN heterojunction solar cells is studied systematically in this paper. In the first chapter, the research progress of the application of InGaN materials in photovoltaic field, as well as the main problems and challenges are described. The simulation system used in this paper and the basic knowledge of heterojunction solar cells are also introduced. In chapter 2, the reason why the response wavelength of InGaN/Ga N multiple quantum well solar cells with different In components is far lower than the absorption edge is studied. We find that the carriers excited by low energy photons can reach a lower energy level and need to cross a very high barrier to escape the quantum wells. When the excited photon energy is below a certain threshold, the resulting carriers can only be recombined and have no contribution to the photocurrent. The photon energy threshold of carrier escape is related to the barrier thickness. The wavelength response limits of InGaN/Ga N multiple quantum well solar cells with different barrier thickness are calculated, which provides a reference for the design of InGaN/GaN multiple quantum well solar cells. In chapter 3, the role of V-type pits in In GaN multiple quantum well solar cells is studied. By means of numerical simulation, we find that V-type crater can provide carrier transport channel, which can improve the conversion efficiency. In addition, the V pits with different dislocation densities are discussed, and it is found that the more V pits are formed, the more obvious the lifting effect of the batteries is. In chapter 4, we study the effect of temperature on carrier transport in In GaN solar cells. We find that the temperature increases from room temperature to 360 K, and the increase of photocurrent increases with the increase of the injection current of the light source. This means that the total number of carriers escaping from quantum wells also increases. Our experimental results are well explained by quantum dot-quantum well composite model. In order to achieve higher efficiency, we optimize the heterojunction interface of InGaN p-i-n solar cells in Chapter 5. We find that using n-ZnO as the electron transport layer can not only improve the polarization effect caused by lattice mismatch. Moreover, the interface barrier can be reduced effectively, which is more favorable to the transport of photogenerated carriers. The conversion efficiency of p-type GaN can be improved from 7% to 14% by replacing p-type InGaN with photons absorbed and improving the properties of interface. Further optimization of the device size can improve the efficiency to 15. The sixth chapter summarizes the contents of the previous chapters and prospects for future applications.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM914.4

【參考文獻】

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