初始應(yīng)力對垂直結(jié)構(gòu)GaN基LED光電性能影響的研究
發(fā)布時間：2019-01-08 18:47
【摘要】：GaN基LED作為照明光源既節(jié)能又環(huán)保,開啟了人類照明的新時代,已經(jīng)與人們的生活息息相關(guān),因此2014年諾貝爾物理獎授予了GaN基LED的相關(guān)研究成果。目前,商品化的GaN基LED按外延襯底劃分共有三條技術(shù)路線,分別是:碳化硅(SiC)、藍寶石(Al2O3)及硅(Si)襯底技術(shù)路線.藍寶石襯底LED市場份額最大,碳化硅襯底LED的市場占有率居中,硅襯底LED盡管市場占有率最小,但它的市場份額正在逐漸擴大且應(yīng)用越來越廣泛。盡管硅襯底技術(shù)路線具有一定局限性,人們還不清楚它將來是否會成為主流技術(shù),但由于它具有諸多顯著優(yōu)點,目前已經(jīng)成為LED領(lǐng)域的一大研究熱點。硅襯底會吸收可見光以及硅襯底上外延的GaN基LED薄膜存在巨大的張應(yīng)力,因此實用化的硅襯底LED均是采用邦定和濕法腐蝕相結(jié)合的技術(shù)將GaN基LED薄膜從外延襯底剝離轉(zhuǎn)移到新的支撐基板上做成垂直結(jié)構(gòu)的芯片。硅襯底GaN基LED薄膜存在巨大的外延張應(yīng)力,在剝離轉(zhuǎn)移到新基板后應(yīng)力會得到一定程度的釋放已有報道,然而,是否可以將硅襯底GaN基LED薄膜應(yīng)力先完全釋放后再邦定到支撐基板上做成垂直結(jié)構(gòu)的芯片以及其光電性能是否會得到改善目前還沒有報道。盡管三條技術(shù)路線的垂直結(jié)構(gòu)LED均已實現(xiàn)商品化并獲得了廣泛應(yīng)用,而且轉(zhuǎn)移到新基板后應(yīng)力的微小變化就會對GaN基LED的光電性能產(chǎn)生明顯影響,然而同種襯底上相同結(jié)構(gòu)的LED薄膜在轉(zhuǎn)移到新的支撐基板時應(yīng)該處于怎樣的初始應(yīng)力狀態(tài)才能使其光電性能發(fā)揮到最佳目前還是研究空白。本文將外延結(jié)構(gòu)相同的GaN基LED薄膜分別直接邦定和應(yīng)力釋放后再邦定到新的支撐基板上,獲得了多種初始應(yīng)力不同的垂直結(jié)構(gòu)LED芯片,并對其光電性能進行了研究。1、當(dāng)LED薄膜用有機柔性粘結(jié)層與基板粘結(jié)在一起,去除硅襯底后,LED薄膜所受來自于硅襯底的張應(yīng)力基本會被完全釋放。2、直接邦定和釋放應(yīng)力后再邦定的芯片其LED薄膜的張應(yīng)力均會得到釋放,其中釋放應(yīng)力后再邦定獲得的芯片其張應(yīng)力釋放較為徹底,而直接邦定得到的芯片其張應(yīng)力釋放較小。3、在制備Si襯底垂直結(jié)構(gòu)GaN基LED芯片的過程中,直接邦定的芯片其LED薄膜所受張應(yīng)力狀態(tài)會逐漸減小,而釋放應(yīng)力后再邦定的芯片剛好相反。4、垂直結(jié)構(gòu)LED芯片的發(fā)光性能不僅僅會受LED薄膜初始應(yīng)力的影響,而且還會受LED薄膜和支撐基板之間金屬邦定層的影響。5、釋放應(yīng)力再邦定的芯片盡管阱層受到的壓應(yīng)力大于直接邦定的芯片,然而通過EQE歸一化處理后,四種芯片的電流Droop效應(yīng)相同。
[Abstract]:GaN based LED, as a lighting source, is not only energy saving and environmental protection, but also opens a new era of human lighting, which is closely related to people's lives. Therefore, the 2014 Nobel Prize in Physics has been awarded to the related research results of GaN based LED. At present, the commercial GaN based LED is divided into three technical routes according to the epitaxial substrate, namely, silicon carbide (SiC), sapphire (Al2O3) and silicon (Si) substrate. The market share of sapphire substrate LED is the largest, and silicon carbide substrate LED has the middle market share. Although silicon substrate LED has the smallest market share, its market share is gradually expanding and being used more and more widely. Although the technology route of silicon substrate has some limitations and it is not clear whether it will become the mainstream technology in the future, it has become a research hotspot in the field of LED because of its many outstanding advantages. The silicon substrate absorbs visible light and there is a great tensile stress on the epitaxial GaN based LED film on the silicon substrate. Therefore, the practical silicon substrates LED are chips with vertical structure from epitaxial substrates to new support substrates, which are transferred from epitaxial substrates to new support substrates by using the technology of bonding and wet etching. There is a huge epitaxial tensile stress in GaN LED films on silicon substrates. It has been reported that the stress will be released to some extent after peeling and transferring to new substrates. Whether the stress of GaN based LED film on silicon substrate can be completely released and then bonded onto the supporting substrate to form a vertical structure chip and whether its photoelectric performance will be improved has not been reported. Although the vertical structure LED of the three technical routes has been commercialized and widely used, and the slight change of the stress after transferring to the new substrate will have a significant effect on the optoelectronic properties of the GaN based LED. However, the initial stress state of the LED thin films with the same structure on the same substrate is still blank. In this paper, GaN based LED thin films with the same epitaxial structure are directly bonded and released respectively to a new supporting substrate. A variety of vertical structure LED chips with different initial stresses are obtained, and their optical and electrical properties are studied. When the LED film is bonded with the substrate by organic flexible bonding layer, the tensile stress of the LED film from the silicon substrate is basically completely released after the silicon substrate is removed. The tensile stress of the LED film will be released both directly and after releasing the stress, and the tensile stress of the chip after releasing the stress will be completely released. However, the tensile stress release of the direct bonding chip is relatively small. 3. In the process of fabricating the GaN based LED chip with vertical structure on the Si substrate, the tensile stress state of the LED film of the direct bonding chip will gradually decrease. The photoluminescence performance of vertical LED chip is not only affected by the initial stress of LED film, but also by the metal bonding between LED film and supporting substrate. Although the pressure stress in the well layer is higher than that in the directly bonded chip, the current Droop effect of the four chips is the same after EQE normalization.
【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】：2015
【分類號】：TN312.8
本文編號：2404986
[Abstract]:GaN based LED, as a lighting source, is not only energy saving and environmental protection, but also opens a new era of human lighting, which is closely related to people's lives. Therefore, the 2014 Nobel Prize in Physics has been awarded to the related research results of GaN based LED. At present, the commercial GaN based LED is divided into three technical routes according to the epitaxial substrate, namely, silicon carbide (SiC), sapphire (Al2O3) and silicon (Si) substrate. The market share of sapphire substrate LED is the largest, and silicon carbide substrate LED has the middle market share. Although silicon substrate LED has the smallest market share, its market share is gradually expanding and being used more and more widely. Although the technology route of silicon substrate has some limitations and it is not clear whether it will become the mainstream technology in the future, it has become a research hotspot in the field of LED because of its many outstanding advantages. The silicon substrate absorbs visible light and there is a great tensile stress on the epitaxial GaN based LED film on the silicon substrate. Therefore, the practical silicon substrates LED are chips with vertical structure from epitaxial substrates to new support substrates, which are transferred from epitaxial substrates to new support substrates by using the technology of bonding and wet etching. There is a huge epitaxial tensile stress in GaN LED films on silicon substrates. It has been reported that the stress will be released to some extent after peeling and transferring to new substrates. Whether the stress of GaN based LED film on silicon substrate can be completely released and then bonded onto the supporting substrate to form a vertical structure chip and whether its photoelectric performance will be improved has not been reported. Although the vertical structure LED of the three technical routes has been commercialized and widely used, and the slight change of the stress after transferring to the new substrate will have a significant effect on the optoelectronic properties of the GaN based LED. However, the initial stress state of the LED thin films with the same structure on the same substrate is still blank. In this paper, GaN based LED thin films with the same epitaxial structure are directly bonded and released respectively to a new supporting substrate. A variety of vertical structure LED chips with different initial stresses are obtained, and their optical and electrical properties are studied. When the LED film is bonded with the substrate by organic flexible bonding layer, the tensile stress of the LED film from the silicon substrate is basically completely released after the silicon substrate is removed. The tensile stress of the LED film will be released both directly and after releasing the stress, and the tensile stress of the chip after releasing the stress will be completely released. However, the tensile stress release of the direct bonding chip is relatively small. 3. In the process of fabricating the GaN based LED chip with vertical structure on the Si substrate, the tensile stress state of the LED film of the direct bonding chip will gradually decrease. The photoluminescence performance of vertical LED chip is not only affected by the initial stress of LED film, but also by the metal bonding between LED film and supporting substrate. Although the pressure stress in the well layer is higher than that in the directly bonded chip, the current Droop effect of the four chips is the same after EQE normalization.
【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】：2015
【分類號】：TN312.8
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2 陳偉超;唐慧麗;羅平;麻尉蔚;徐曉東;錢小波;姜大朋;吳鋒;王靜雅;徐軍;;GaN基發(fā)光二極管襯底材料的研究進展[J];物理學(xué)報;2014年06期
，本文編號：2404986
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