GaN基LED外延片的光学电学和应力研究
发布时间：2018-11-27 07:50
【摘要】：目前市场上的GaN基LED都是c面GaN基LED,也就是极性GaN基LED。但是,作为铅锌矿结构的GaN在(001)方向上由于原子数目不相等,存在着自发极化现象,同时也存在压电极化,受极化电场影响,c面GaN基LED的多量子阱能带发生倾斜,使得电子和空穴的分别被限制在异质结界面出的三角势井中,从而阻止了这一些电子和空穴的复合,降低了LED的发光性能。这将带来两个方面的结果,一方面,能带弯曲导致有效的禁带宽度变小,电子空穴复合发光发生红移,即产生量子限制斯塔克效应；另一方面,由于能够复合产生光子的电子和空穴对变少,导致了LED的发光效率变低。本文对极性LED进行了研究,图形化衬底LED的光学性能比平面衬底LED的好。结果表明图形化衬底可以提高(102)面的结晶质量,但这并不是光效提高的真正原因,原因是薄膜内的应力和光线的传播方向的共同作用,其中光线传播方向的改变是主要原因。由于图形化衬底可以很大程度的提高光效,所以我们页展开了一系列衬底图形化的实验,实验条件表明c面蓝宝石的刻蚀条件是最为苛刻的。同时我们在(100)面和(302)面LiAlO2等不同的衬底分别的制得非极性m面和a面GaN基LED。两中非极性LED都可以在10mA的条件下点亮,但是m面LED的光效要远远强于a面LED,发光波长也出现了红移。光效高的主要原因是m面LED薄膜内的载流子密度要大于a面LED薄膜内的载流子密度,而波长发生红移的主要原因是m面LED薄膜内的In含量压高于a面LED薄膜内的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.
【学位授予单位】：上海应用技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN312.8
，
本文编号：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.
【学位授予单位】：上海应用技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN312.8
，
本文编号：2359938
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