p-GaN插入层调控InGaN基黄绿双波长LED发光光谱

采用MOCVD技术在硅衬底上生长了含有7个黄光量子阱和1个绿光量子阱的混合有源区结构的InGaN基黄绿双波长LED外延材料,研究了电子阻挡层前p-GaN插入层厚度对黄绿双波长LED载流子分布及外量子效率(EQE)的影响。通过LED变温电致发光测试系统对LED光电性能进行了表征。结果表明,100 K小电流时随着电流密度的增大,三组样品的绿光峰与黄光峰相对强度的比值越来越大,且5.5 A·cm^-2的电流密度下,随着温度从300 K逐步降低至100 K,三组样品的绿光峰与黄光峰相对强度的比值也越来越大,说明其载流子都在更靠近p型层的位置发生辐射复合。三组样品的p-GaN插入层厚度为0,10,30 nm时,EQE峰值依次为29.9%、29.2%和28.2%,呈现依次减小的趋势,归因于p-GaN插入层厚度越大,p型层越远离有源区,空穴注入也越浅。电子阻挡层前p-GaN插入层可以有效减小器件EL光谱中绿光峰随着电流密度增加时峰值波长的蓝移(33 nm),实现了对低温发光光谱的调控。

Effect of p-GaN Spacer Layer on Emission Spectrum of Yellow-green Dual Wavelength LED

InGaN-based yellow-green dual wavelength light-emitting diodes(LEDs)with seven pairs of yellow multiple quantum wells(MQWs)and a pair of green QW were grown on patterned Si substrate by metal-organic chemical vapor deposition(MOCVD).Meanwhile the effect of p-GaN spacer layer before the electron blocking layer(EBL)on the carriers distribution and external quantum efficiency(EQE)was investigated.LED photoelectric properties were characterized by LED test system.The results support the integrated EL intensity ratio of green/yellow peak increases with increasing current density at 100 K.And the integrated EL intensity ratio of green/yellow peak increases with decreasing temperature from 300 K to 100 K at a forward current density of 5.5 A·cm^-2.These experiment phenomena indicate that the radiative recombination of carriers occurs in the QW nearest the p-layer.The peaked EQE are 29.0%,29.2%and 28.2%with the thickness of p-GaN spacer layer 0,10,30 nm of three samples.The peaked EQE of three samples decrease because the active region is further from the p-layer and holes are distributed nearer the p-layer with increasing thickness of p-GaN spacer layer.p-GaN spacer layer can effectively reduce the movement(33 nm)of green peak with increasing current density and the cryogenic emission spectrum can be regulated.