本文關(guān)鍵詞： AlGaN 多量子阱 深紫外 LED 數(shù)值模擬 Crosslight APSYS 發(fā)光效率　出處：《華中科技大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：近些年,伴隨高亮度藍(lán)光發(fā)光二極管的研究不斷走向成熟,研究學(xué)者們逐漸將研究的重點(diǎn)向高Al組份的AlGaN基深紫外發(fā)光二極管轉(zhuǎn)移。AlGaN基深紫外LED(light emitting diode)在殺菌消毒、生化探測(cè)、安全通訊,紫外固化、白光固態(tài)照明,能源以及軍事探測(cè)等領(lǐng)域都有廣闊的應(yīng)用前景。目前外延生長(zhǎng)高Al組份AlGaN基深紫外LED仍然十分困難,導(dǎo)致其發(fā)光效率非常低。不僅如此,隨著工作電流的增加,其輸出效率也會(huì)急速降低,這些都限制了其大規(guī)模的應(yīng)用。因此,提高AlGaN基深紫外LED的發(fā)光性能、獲得高效的深紫外LED極其重要。本論文首先簡(jiǎn)要敘述了AlGaN基深紫外LED研究背景與發(fā)展概況,器件的工作原理和相關(guān)物理特性以及Crosslight公司的半導(dǎo)體器件仿真軟件APSYS。然后,詳細(xì)介紹了利用APSYS軟件自帶的模型對(duì)AlGaN基深紫外LED量子阱結(jié)構(gòu)和P型區(qū)電子阻擋層的設(shè)計(jì)和優(yōu)化,提出了兩類(lèi)新型器件結(jié)構(gòu),并分別對(duì)兩種結(jié)構(gòu)的AlGaN基深紫外LED的光電特性進(jìn)行了模擬研究:(1)分別對(duì)兩層和三層階梯型(staggered)量子阱的AlGaN基深紫外LED結(jié)構(gòu)進(jìn)行了仿真。通過(guò)對(duì)發(fā)光性能、能帶結(jié)構(gòu)、載流子分布以及輻射復(fù)合效率等特性進(jìn)行分析,得出staggered量子阱的采用一方面增加了電子和空穴的波函數(shù)重疊率,另一方面使得有源區(qū)電子和空穴的濃度增加,輻射復(fù)合增強(qiáng),極大地改善了器件中普遍存在的效率陡降問(wèn)題,提升了發(fā)光效率,模擬結(jié)果證明三層staggered量子阱結(jié)構(gòu)的發(fā)光性能更優(yōu)于兩層。(2)研究了三種新型的三角形電子阻擋層(組分遞增型、倒V型和V型)取代傳統(tǒng)的AlGaN電子阻擋層對(duì)AlGaN基深紫外LED發(fā)光性能的影響。通過(guò)深入分析三角形電子阻擋層(EBL,electron blocking layer)提高發(fā)光效率的不同物理機(jī)理得出,組分遞增型和倒V型的三角形EBL主要是通過(guò)改善最后一個(gè)勢(shì)壘與EBL之間的晶格匹配來(lái)減少界面處的極化電場(chǎng);最后一種V型的三角形EBL層物理機(jī)理不同于前兩種,一方面主要是因?yàn)镋BL中組分漸變形成的勢(shì)阱對(duì)能帶的拉伸,緩解了最后一個(gè)量子勢(shì)壘與EBL界面處的能帶彎曲,使得電子和空穴的有效勢(shì)壘高度都相應(yīng)的提高和降低了,另一方面,EBL的勢(shì)阱中發(fā)生了較強(qiáng)的空穴聚集效應(yīng)。三角形電子阻擋層的采用增強(qiáng)了對(duì)電子的限制作用、提高了空穴注入效率,因此提升了發(fā)光效率,降低了效率陡降現(xiàn)象。
[Abstract]:In recent years, with the development of high brightness blue light emitting diodes, researchers have gradually shifted their research emphasis to AlGaN based deep ultraviolet light emitting diodes with high Al composition. AlGaN-based deep ultraviolet LED(light emitting diodes have been sterilizing and biochemical detection. Security communication, UV curing, white light solid state lighting, energy and military detection have broad application prospects. At present, it is still very difficult to epitaxially grow high Al component AlGaN based deep ultraviolet LED, which results in very low luminescence efficiency. With the increase of operating current, the output efficiency will decrease rapidly, which limits its large-scale application. Therefore, the luminescence performance of AlGaN based deep ultraviolet LED is improved. It is very important to obtain high efficiency deep ultraviolet LED. In this paper, the background and development of deep ultraviolet LED based on AlGaN, the working principle and related physical characteristics of AlGaN, and the semiconductor device simulation software APSYS of Crosslight Company are briefly described in this paper. The design and optimization of AlGaN based deep ultraviolet LED quantum well structure and P-type electronic barrier layer are introduced in detail by using the model of APSYS software. Two kinds of novel device structures are proposed. The optoelectronic properties of two kinds of AlGaN based deep ultraviolet LED are simulated. The AlGaN based deep ultraviolet LED structures of two-layer and three-layer stepped quantum wells are simulated, respectively. The characteristics of carrier distribution and radiation recombination efficiency are analyzed. It is concluded that the adoption of staggered quantum wells increases the overlap rate of wave functions between electrons and holes on the one hand, and increases the concentration of electrons and holes in active region on the other. The problem of sharp drop in efficiency is greatly improved and the luminescence efficiency is improved. The simulation results show that the luminescence performance of three-layer staggered quantum well structure is better than that of two-layer. The effect of inverted V and V type) on the luminescence properties of AlGaN based deep ultraviolet LED was studied by replacing the traditional AlGaN electronic barrier layer. The different physical mechanisms of improving the luminescence efficiency of the triangular electronic barrier layer (EBLelectron blocking layer) were analyzed. The incremental and inverted V-type triangular EBL decrease the polarized electric field at the interface mainly by improving the lattice match between the last barrier and the EBL, and the last V-type triangular EBL layer is different from the first two kinds of physical mechanism. On the one hand, it is mainly due to the stretching of the band in the potential well formed by the gradual change of the component in EBL, which alleviates the band bending at the interface between the last quantum barrier and the EBL, and makes the effective barrier height of the electron and hole increase and decrease accordingly. On the other hand, there is a strong hole aggregation effect in the potential well of EBL. The use of triangular electron barrier layer enhances the effect of limiting electrons and improves the efficiency of hole injection, so it improves the efficiency of luminescence and reduces the phenomenon of steep drop of efficiency.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TN312.8

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本文編號(hào)：1504831