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Carrier-Induced Defect Saturation in Green InGaN LEDs: A Potential Phenomenon to Enhance Efficiency at Higher Wavelength Regime
ACS Photonics ( IF 7 ) Pub Date : 2021-02-23 , DOI: 10.1021/acsphotonics.0c01969
Dhiman Nag, Tarni Aggarwal, Shreekant Sinha, Ritam Sarkar, Swagata Bhunia, Yi-Fan Chen, Swaroop Ganguly, Dipankar Saha, Ray-Hua Horng, Apurba Laha

Non-radiative defects play a deterministic role in regulating the performance of LEDs. Yet, defect saturation in LEDs is relatively unexplored in the literature. Here, we establish the theoretical background of carrier-induced defect saturation from the band structure of quantum well (QW)-based InGaN LEDs after solving Poisson and Schrödinger’s equations self-consistently. Time dynamics of defect saturation are demonstrated through solving a set of coupled differential rate equations iteratively, considering carrier transitions between different energy levels in the QW region. They indicate an increasing degree of defect saturation with higher carrier injection at steady state. Capacitance versus voltage (CV) measurements on fabricated InGaN MQW LEDs, conducted at low frequencies clearly demonstrate the considerable effect of defect saturation at higher bias. We propose a correction term in the typical RC circuit model for LEDs, considering defect saturation, and solved it analytically to explain the frequency-dependent CV characteristics. Analytical calculation of CV response, based on the modified RC model, shows a fairly satisfactory matching with the experimental data at different frequencies. Also, the frequency dependence of negative capacitance at a higher bias regime is explained through the conductance versus voltage (GV) characteristics.

中文翻译:

绿色InGaN LED中的载流子诱导的缺陷饱和:在较高波长范围内提高效率的潜在现象

非辐射缺陷在调节LED性能方面起决定性作用。然而,LED中的缺陷饱和度在文献中相对未开发。在此,我们通过自洽求解泊松和薛定er方程,从基于量子阱(QW)的InGaN LED的能带结构建立了载流子引起的缺陷饱和的理论背景。考虑到QW区域中不同能级之间的载流子跃迁,通过迭代求解一组耦合的差分速率方程来证明缺陷饱和的时间动态。它们表明,在稳态下,随着较高的载流子注入,缺陷饱和度会增加。在制造的InGaN MQW LED上进行电容与电压(CV)的测量,在低频下进行的测试清楚地表明了在较高偏置下缺陷饱和的显着影响。考虑到缺陷饱和度,我们在针对LED的典型RC电路模型中提出了一个校正项,并进行了解析求解,以解释频率相关的CV特性。基于改进的RC模型的CV响应的分析计算表明,在不同频率下与实验数据的匹配程度令人满意。此外,通过电导率与电压(GV)特性来解释负偏压下负电容的频率依赖性。基于改进的RC模型,显示了在不同频率下与实验数据的相当令人满意的匹配。此外,通过电导率与电压(GV)特性来解释负偏压下负电容的频率依赖性。基于改进的RC模型,显示了在不同频率下与实验数据的相当令人满意的匹配。此外,通过电导率与电压(GV)特性来解释负偏压下负电容的频率依赖性。
更新日期:2021-03-17
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