本文選題：GaN + 發(fā)光二極管��； 參考：《太原理工大學(xué)》2015年碩士論文

【摘要】：近年來(lái)，GaN基發(fā)光二極管(light-emitting diodes，LEDs)作為新一代固態(tài)照明光源得到了迅猛的發(fā)展。目前GaN基藍(lán)光LED始終被熱烈討論和研究，人們所研究的熱點(diǎn)為嚴(yán)重的極化效應(yīng)及在大電流注入下的“效率下降”現(xiàn)象，它們都在很大程度上影響了發(fā)光二極管的光電性能。 在三族氮化物中，有源區(qū)的極化效應(yīng)會(huì)產(chǎn)生強(qiáng)大的極化電場(chǎng)，它會(huì)極大地改變LED的能帶結(jié)構(gòu)。尤其是在有源區(qū)的量子阱中，能帶發(fā)生傾斜，電子和空穴分開(kāi)分別局限于量子阱兩側(cè)，使得載流子參與輻射復(fù)合而發(fā)光的機(jī)會(huì)大大減小，因此降低了量子阱的發(fā)光效率。極化效應(yīng)會(huì)使LED的發(fā)光波長(zhǎng)發(fā)生紅移，從而降低通過(guò)光譜所得材料組分的準(zhǔn)確度；極化效應(yīng)還會(huì)增強(qiáng)量子阱結(jié)構(gòu)對(duì)阱寬和壘厚的依賴性。 在高電流注入下，雖然可用于發(fā)光的載流子數(shù)目增加了，但LED的發(fā)光效率并沒(méi)有隨著注入電流的增加有所提高反而呈下降的趨勢(shì)，效率下降問(wèn)題已經(jīng)成為限制LED發(fā)展的一個(gè)瓶頸。許多研究指出，導(dǎo)致效率下降的原因可能是極化效應(yīng)、電子泄露、差的空穴注入、外延缺陷、俄歇復(fù)合等。因此，在高電流注入下，LED的發(fā)光效率受到了極大地限制。 到目前為止，已經(jīng)有很多優(yōu)秀的研究團(tuán)隊(duì)對(duì)如何減小氮化物的極化電場(chǎng)及如何改善在高注入電流下的效率下降現(xiàn)象進(jìn)行研究，期望有效改善LED的光電性能。本論文將繼續(xù)尋找減小極化效應(yīng)及改善效率下降的LED器件結(jié)構(gòu)優(yōu)化設(shè)計(jì)。本論文的研究重點(diǎn)在于如何有效減小InGaN LED的極化效應(yīng)及有效改善效率下降現(xiàn)象，具體的研究?jī)?nèi)容和研究成果主要包括： 1.研究In組分梯度漸變多量子阱(MQW)結(jié)構(gòu)對(duì)InGaN藍(lán)光LED光電性能的影響。模擬結(jié)果表明，In組分梯度漸變MQW結(jié)構(gòu)能夠有效地減小LED有源區(qū)的極化效應(yīng)，使得電子與空穴的波函數(shù)重疊率提高，提高輻射復(fù)合率，從而提高內(nèi)量子效率，所以LED器件的輸出功率大大地增強(qiáng)了。此外，效率下降現(xiàn)象和發(fā)光波長(zhǎng)的穩(wěn)定性也得到了顯著的改善。 2.通過(guò)對(duì)LED中電子阻擋層(EBL)的能帶結(jié)構(gòu)進(jìn)行設(shè)計(jì)，研究新設(shè)計(jì)的EBL對(duì)InGaN/GaN藍(lán)光LED光電性能的影響，并對(duì)新設(shè)計(jì)的EBL結(jié)構(gòu)進(jìn)行系統(tǒng)地優(yōu)化，找出最佳設(shè)計(jì)方案。模擬結(jié)果表明，新設(shè)計(jì)的EBL結(jié)構(gòu)通過(guò)修剪極化，能夠有效減小LB/EBL界面的極化效應(yīng)，增強(qiáng)空穴注入效率和電子束縛能力，從而改善效率下降現(xiàn)象，提高藍(lán)光LED的光電學(xué)性能。 3.通過(guò)對(duì)LED有源區(qū)的壘厚進(jìn)行設(shè)計(jì)，研究不同壘厚設(shè)計(jì)對(duì)LED發(fā)光性能的影響。本文提出了用從n邊到p邊逐漸減小壘厚的結(jié)構(gòu)取代相等壘厚的傳統(tǒng)結(jié)構(gòu)，，在靠近n-GaN層采用較厚的壘用于增加電子傳輸距離，然而在靠近p-GaN層采用較薄的壘用于減小空穴傳輸距離。模擬結(jié)果表明，所提出的結(jié)構(gòu)能夠增強(qiáng)空穴注入且空穴分布更均勻，從而顯著增強(qiáng)InGaN藍(lán)光LED的發(fā)光效率并改善高電流注入下的效率下降現(xiàn)象。
[Abstract]:In recent years, GaN-based light-emitting diodes (LEDs) have been developed rapidly as a new generation of solid-state lighting sources. At present, GaN based blue light LED has always been discussed and studied. The research focus is the serious polarization effect and the phenomenon of "efficiency decline" under the high current injection, which greatly affects the photovoltaic performance of GaN diodes. In three groups of nitride, the polarization effect in the active region will produce a strong polarization electric field, which will greatly change the band structure of LED. Especially in the quantum wells in the active region, the energy band is inclined and the electrons and holes are confined to the two sides of the quantum well respectively, which makes the carrier participate in the radiation recombination and the chance of luminescence is greatly reduced, thus reducing the luminescence efficiency of the quantum well. Polarization effect will make the luminescence wavelength of LED red shift, thus reducing the accuracy of the material components obtained through the spectra, and the polarization effect will also enhance the dependence of the quantum well structure on the well width and barrier thickness. Under high current injection, although the number of carriers available for luminescence increases, the luminescence efficiency of LED does not increase with the increase of injection current. The problem of efficiency decline has become a bottleneck restricting the development of LED. Many studies indicate that the reasons for the decrease in efficiency may be polarization effect, electron leakage, poor hole injection, epitaxial defects, Auger recombination and so on. Therefore, the luminescence efficiency of LED is greatly limited under high current injection. Up to now, many excellent research teams have studied how to reduce the polarized electric field of nitride and how to improve the efficiency decline at high injection current, in order to improve the photoelectric performance of LED effectively. In this thesis, we will continue to search for the optimal design of LED devices which can reduce polarization effect and improve efficiency. This thesis focuses on how to effectively reduce the polarization effect of InGaN LED and effectively improve the phenomenon of efficiency decline. The specific research content and research results mainly include: 1. The effect of in composition gradient gradient multiple quantum well (MQW) structure on the optoelectronic properties of InGaN blue light LED is studied. The simulation results show that the gradient gradient MQW structure of in component can effectively reduce the polarization effect in the active region of LED, increase the overlap rate of wave function between electron and hole, improve the radiation recombination rate and improve the internal quantum efficiency. So the output power of the LED device is greatly enhanced. In addition, the decrease of efficiency and the stability of luminous wavelength are also improved. 2. Through the design of the energy band structure of the electronic barrier layer (EBL) in LED, the influence of the newly designed EBL on the optoelectronic performance of the InGaN/GaN blue-light LED is studied, and the newly designed EBL structure is systematically optimized to find out the best design scheme. The simulation results show that the newly designed EBL structure can effectively reduce the polarization effect of the LB/EBL interface, enhance the hole injection efficiency and the electron binding ability through pruning polarization, thus improve the efficiency decline and improve the optoelectronic properties of the blue-ray LED. 3. By designing the barrier thickness of LED active region, the influence of different barrier thickness design on the luminescence performance of LED is studied. In this paper, we propose to replace the traditional structure with equal barrier thickness by decreasing the barrier thickness from the n-edge to the p-edge, and using the thicker barrier near the n-GaN layer to increase the electron transmission distance. However, a thin barrier is used near the p-GaN layer to reduce the hole propagation distance. The simulation results show that the proposed structure can enhance the hole injection and the hole distribution is more uniform, so the luminescence efficiency of InGaN blue LED can be significantly enhanced and the efficiency decline under high current injection can be improved.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN312.8

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 吳洋;;基于LED的汽車后組合燈關(guān)鍵技術(shù)分析[J];科技創(chuàng)新與應(yīng)用;2012年23期

本文編號(hào)：1805207