量子垒生长速率对InGaN基绿光LED性能的影响

利用MOCVD技术在图形化Si(111)衬底上生长了InGaN/GaN绿光LED外延材料。在GaN量子垒的生长过程中,保持NH3流量不变,通过调节三乙基镓(TEGa)源的流量来改变垒生长速率,研究了量子垒生长速率对LED性能的影响。使用二次离子质谱仪(SIMS)和荧光显微镜(FLM)分别对量子阱的阱垒界面及晶体质量进行了表征,使用电致发光测试系统对LED光电性能进行了表征。实验结果表明,垒慢速生长,在整个测试电流密度范围内,外量子效率(EQE)明显提升。我们认为,小电流密度下,EQE的提升归结为量子阱晶体质量的改善;而大电流密度下,EQE的提升则归结为阱垒界面陡峭程度的提升。

Growth Rate of Quantum Barrier on Performance of InGaN-based Green LEDs

InGaN/GaN green light-emitting diodes(LEDs)were grown on patterned silicon(111)substrate by metal-organic vapor deposition(MOCVD)method.During the growth process of GaN quantum barrier(QB),the ammonia flow rate was kept constant and the barrier growth rate was reduced by adjusting the three ethyl gallium(TEGa)flow rate.The effect of quantum barrier growth rate on the LED performance has been investigated.It is found that the external quantum efficiency(EQE)increases obviously in the whole range of test current density when the barrier growth rate is reduced.It suggests that the improvement of EQE at low current density can be attributed to the better crystal quality of quantum well and the increase of EQE at high current density is due to the steeper interface between quantum barrier and quantum well.