InGaN/GaN多量子阱LED载流子泄漏与温度关系研究

通过测量光电流,直接观察了InGaN/GaN量子阱中载流子的泄漏程度随温度升高的变化关系。当LED温度从300K升高到360K时,在相同的光照强度下,LED的光电流增大,说明在温度上升之后,载流子从量子阱中逃逸的数目更多,即载流子泄漏比例增大。同时,光电流的增大在激发密度较低的时候更为明显,而且光电流随温度的增加幅度与激发光子的能量有关。用量子阱-量子点复合模型能很好地解释所观察到的实验现象。实验结果直接证明,随着温度的升高,InGaN/GaN量子阱中的载流子泄漏将显著增加,而且在低激发密度下这一效应更为明显。温度升高导致的载流子泄漏增多是InGaN多量子阱LED发光效率随温度升高而降低的重要原因。

Temperature-dependent Carrier Leakage in InGaN/GaN Multiple Quantum Wells Light-emitting Diodes

By measuring the photocurrent, we directly observed the relationship between the degree of carrier leakage and the temperature in InGaN multiple quantum wells. When LED’s working tem-perature rises from room temperature to 360 K, the photocurrent increases under the same light in-tensity. The increase of the sample’s photocurrent means larger amount of carrier leakage when the temperature rises. At the same time, it is found that the carriers leak more in a lower density, and the increase of photocurrent is related to the emission photon energy. The model of quantum well-quantum dot can explain the phenomena observed in the experiment, such as the rise of temperature shows little influence on carrier leakage when the excitation light wavelength is relatively short, and causes more carrier leakage when the emission light wavelength is longer. Also, this model can well explain that the carriers leak more in a lower density and leak less in a higher density when the tem-perature rises. The experiment results suggest that the carrier leakage is the dominant mechanism for T-droop effect when the temperature rises from 300 to 360 K.