InGaN/GaN多量子阱结构发光二极管发光机理转变的低频电流噪声表征

Research on emission transition mechanisms of InGaN/GaN multiple quantum well light-emitting diodes using low-frequency current noise

本文对InGaN/GaN多量子阱结构发光二极管开启后的电流噪声进行了测试,结合低频电流噪声的特点和载流子之间的复合机理,研究了低频电流噪声功率谱密度与发光二极管发光转变机理之间的关系.结论表明,当电流从0.1 mA到10 mA逐渐增大的过程中,InGaN/GaN发光二极管的电流噪声行为从产生-复合噪声逐渐接近于低频1/f噪声,载流子的复合机理从非辐射复合过渡为电子与空穴之间载流子数的辐射复合,并具有标准1/f噪声的趋势,此时多量子阱中的电子和空穴之间的复合趋向于稳定.本文的结论提供了一种表征InGaN/GaN多量子阱发光二极管发光机理转变的有效方法,为进一步研究发光二极管中载流子的复合机理、优化和设计发光二极管、提高其发光量子效率提供理论依据.

In this paper, we measure the emission transition mechanisms in InGaN/GaN multiple quantum well （MQW） light-emitting diodes （LED） using low-frequency current noise from 0.1 to 10 mA. According to the characteristics of the low-frequency current noise and the emission mechanisms of InGaN/GaN LEDs, we study the relationships between low-frequency current noise and current flows through the LEDs. Conclusions indicate that the low-frequency current noise is increased with the increasing current from 0.1 to 10 mA. With a lower current （I 〈1 mA）, it is the generation-recombination noise that dominates in LEDs, and with a higher current （I 〉10 mA） it is the 1/f noise that dominates in LEDs, so there exists an emission transition mechanism in InGaN/GaN MQW LEDs between 0.1 and 10 mA, showing that the mechanism of the carrier recombination changes from non-radiative recombination to a stable fluctuation of carrier numbers. Conclusions of this paper provide an effective method to characterize the emission transition mechanisms, optimize the design of LED so as to improve the quantum e？ciency for InGaN/GaN MQW LEDs.