GaN基LED外延片的光學電學和應力研究
發(fā)布時間：2018-11-27 07:50
【摘要】：目前市場上的GaN基LED都是c面GaN基LED,也就是極性GaN基LED。但是,作為鉛鋅礦結構的GaN在(001)方向上由于原子數(shù)目不相等,存在著自發(fā)極化現(xiàn)象,同時也存在壓電極化,受極化電場影響,c面GaN基LED的多量子阱能帶發(fā)生傾斜,使得電子和空穴的分別被限制在異質結界面出的三角勢井中,從而阻止了這一些電子和空穴的復合,降低了LED的發(fā)光性能。這將帶來兩個方面的結果,一方面,能帶彎曲導致有效的禁帶寬度變小,電子空穴復合發(fā)光發(fā)生紅移,即產生量子限制斯塔克效應；另一方面,由于能夠復合產生光子的電子和空穴對變少,導致了LED的發(fā)光效率變低。本文對極性LED進行了研究,圖形化襯底LED的光學性能比平面襯底LED的好。結果表明圖形化襯底可以提高(102)面的結晶質量,但這并不是光效提高的真正原因,原因是薄膜內的應力和光線的傳播方向的共同作用,其中光線傳播方向的改變是主要原因。由于圖形化襯底可以很大程度的提高光效,所以我們頁展開了一系列襯底圖形化的實驗,實驗條件表明c面藍寶石的刻蝕條件是最為苛刻的。同時我們在(100)面和(302)面LiAlO2等不同的襯底分別的制得非極性m面和a面GaN基LED。兩中非極性LED都可以在10mA的條件下點亮,但是m面LED的光效要遠遠強于a面LED,發(fā)光波長也出現(xiàn)了紅移。光效高的主要原因是m面LED薄膜內的載流子密度要大于a面LED薄膜內的載流子密度,而波長發(fā)生紅移的主要原因是m面LED薄膜內的In含量壓高于a面LED薄膜內的In含量。
[Abstract]:At present, the GaN base LED in the market is c-plane GaN base LED, which is the polar GaN base LED.. However, due to the unequal number of atoms in the (001) direction, GaN, as a lead-zinc structure, has spontaneous polarization and piezoelectric polarization, which is affected by the polarization electric field, and the multi-quantum well energy band of GaN based LED on the c plane is inclined. The electron and hole are confined to the triangular potential well of the heterogeneous boundary, which prevents the recombination of these electrons and holes and reduces the luminescence performance of LED. This will lead to two results. On the one hand, the band bending results in the decrease of the effective band gap and the red shift of the electron hole recombination luminescence, that is, the quantum confinement Stark effect. On the other hand, the luminescence efficiency of LED is reduced due to the reduction of electron and hole pairs which can recombine to produce photons. In this paper, polarity LED is studied. The optical performance of LED on graphic substrate is better than that of LED on planar substrate. The results show that the crystalline quality of the (102) surface can be improved by the graphical substrate, but this is not the real reason for the improvement of the light efficiency, because the stress in the film and the direction of the propagation of the light in the film work together. The change in the direction of light propagation is the main reason. Because the graphic substrate can greatly improve the light efficiency, we have carried out a series of experiments of substrate graphics. The experimental conditions show that the etching conditions of c-plane sapphire are the most stringent. At the same time, we fabricate nonpolar m plane and a plane GaN base LED. on different substrates such as (100) plane and (302) plane respectively. Both non-polar LED can be illuminated under the condition of 10mA, but the light efficiency of m plane LED is much better than that of a plane LED,. The main reason for the high light efficiency is that the carrier density in m plane LED film is higher than that in a plane LED film, and the main reason for the red shift of wavelength is that the In content pressure in m plane LED film is higher than that in a plane LED film.
【學位授予單位】：上海應用技術大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TN312.8
，
本文編號：2359938
[Abstract]:At present, the GaN base LED in the market is c-plane GaN base LED, which is the polar GaN base LED.. However, due to the unequal number of atoms in the (001) direction, GaN, as a lead-zinc structure, has spontaneous polarization and piezoelectric polarization, which is affected by the polarization electric field, and the multi-quantum well energy band of GaN based LED on the c plane is inclined. The electron and hole are confined to the triangular potential well of the heterogeneous boundary, which prevents the recombination of these electrons and holes and reduces the luminescence performance of LED. This will lead to two results. On the one hand, the band bending results in the decrease of the effective band gap and the red shift of the electron hole recombination luminescence, that is, the quantum confinement Stark effect. On the other hand, the luminescence efficiency of LED is reduced due to the reduction of electron and hole pairs which can recombine to produce photons. In this paper, polarity LED is studied. The optical performance of LED on graphic substrate is better than that of LED on planar substrate. The results show that the crystalline quality of the (102) surface can be improved by the graphical substrate, but this is not the real reason for the improvement of the light efficiency, because the stress in the film and the direction of the propagation of the light in the film work together. The change in the direction of light propagation is the main reason. Because the graphic substrate can greatly improve the light efficiency, we have carried out a series of experiments of substrate graphics. The experimental conditions show that the etching conditions of c-plane sapphire are the most stringent. At the same time, we fabricate nonpolar m plane and a plane GaN base LED. on different substrates such as (100) plane and (302) plane respectively. Both non-polar LED can be illuminated under the condition of 10mA, but the light efficiency of m plane LED is much better than that of a plane LED,. The main reason for the high light efficiency is that the carrier density in m plane LED film is higher than that in a plane LED film, and the main reason for the red shift of wavelength is that the In content pressure in m plane LED film is higher than that in a plane LED film.
【學位授予單位】：上海應用技術大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TN312.8
，
本文編號：2359938
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