Electron leakage and its suppression via deep-well structures in 4.5-to 5.0-μm-emitting quantum cascade lasers
Electron leakage and its suppression via deep-well structures in 4.5-to 5.0-μm-emitting quantum cascade lasers
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DOI：
10.1117/1.3509368
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发表时间：
2010-11-01
影响因子：
1.3
通讯作者：
Meyer, Jerry R.
中科院分区：
文献类型：
--
作者：
Botez, Dan;Shin, Jae Cheol;Meyer, Jerry R.
修改了量子级联激光器 (QCL) 的阈值电流密度 J(th) 和外部微分量子效率 eta(d) 的方程，以包括电子泄漏和修正的电子回填项，以考虑注入器中的热电子。我们证明，通过在 4.8μm 发射 QCL 的有源区域中引入深量子阱和高势垒，并通过使注入器和提取器区域的导带边缘逐渐变细，可以显着减少电子泄漏。 J(th) 和 eta(d) 的特征温度分别用 T-0 和 T-1 表示，在 20 至 90 摄氏度的温度范围内达到高达 278 和 285 K 的值，这意味着在相同温度范围内，J(th) 和 eta(d) 的变化比传统的 4.5 至 5.0 μ m 发射高性能 QCL 慢约 2.3。使用热注入电子从上部激光能级到上部活性区能态的热激发模型来估计漏电流，其中一些电子弛豫到下部活性区态，一些散射到上部微带。传统 QCL 和深井 QCL 的估计 T-0 值与实验非常一致。 T-1 值的合理性是通过电子泄漏和波导损耗随温度的增加而增加的。 (C) 2010 年光电仪器工程师协会。 [DOI：10.1117/1.3509368]
The equations for threshold-current density J(th) and external differential quantum efficiency eta(d) of quantum cascade lasers (QCLs) are modified to include electron leakage and the electron-backfilling term corrected to take into account hot electrons in the injector. We show that by introducing both deep quantum wells and tall barriers in the active regions of 4.8-mu m-emitting QCLs, and by tapering the conduction-band edge of both injector and extractor regions, one can significantly reduce electron leakage. The characteristic temperatures for J(th) and eta(d), denoted by T-0 and T-1, respectively, are found to reach values as high as 278 and 285 K over the 20 to 90 degrees C temperature range, which means that J(th) and eta(d) display approximate to 2.3 slower variation than conventional 4.5- to 5.0-mu m-emitting, high-performance QCLs over the same temperature range. A model for the thermal excitation of hot injected electrons from the upper laser level to the upper active-region energy states, wherefrom some relax to the lower active-region states and some are scattered to the upper miniband, is used to estimate the leakage current. Estimated T-0 values are in good agreement with experiment for both conventional QCLs and deep-well QCLs. The T-1 values are justified by increases in both electron leakage and waveguide loss with temperature. (C) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3509368]