Carrier Leakage Dynamics in Terahertz Quantum Cascade Lasers
Carrier Leakage Dynamics in Terahertz Quantum Cascade Lasers
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DOI：
10.1109/jqe.2017.2740261
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发表时间：
2017-08
影响因子：
2.5
通讯作者：
A. Albo;Y. Flores
中科院分区：
文献类型：
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作者：
A. Albo;Y. Flores
分析了两种GaAs/Al 0.15Ga 0.85As太赫兹量子级联激光器的输出功率随温度的变化特性最大工作温度T_{max}=200$和177 $K的THz-QCL以及T_{max}=150$ K的GaAs/Al_（0.30）Ga_（0.70）As THz-QCL，并确定了热-当温度升高时，激活的泄漏路径导致激光器性能下降。我们确定了在每个THz-QCL结构中激活的特定载流子泄漏路径，并且能够在整个激光器操作范围内重建输出功率与温度的关系曲线。我们发现，在有源区设计中使用高势垒几乎消除了载流子从上激光能级泄漏到连续谱中，打开了一个非辐射散射路径，从上到下激光能级平行于标准电子LO声子发射。这一效应，加上低能级激光向高势垒器件中连续谱的泄漏减少，显著地降低了T_{max}从177 K降低到150 K。我们进一步展示了如何从较低的激光水平到连续的电子泄漏增强GaAs/Al0.15Ga0.85As的设计与薄的障碍，显着提高激光器的性能（$T_{max}=200$ K）。最后，我们提出了未来高度温度不敏感的THZ-QCL的设计策略。我们的方法提供了一个简单的方法来分析和故障排除THZ-QCL的热激活载流子泄漏动力学。
We analyze the output power versus temperature characteristics of two GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers (THz-QCLs) with maximum operating temperature $T_{max}=200$ and 177 K as well as of one GaAs/Al0.30Ga0.70As THz-QCL with $T_{max}=150$ K and identify the thermally-activated leakage paths responsible for the laser performance degradation as the temperature increases. We identify the specific carrier leakage path active in each THz-QCL structure and are able to reconstruct the output power versus temperature profile over the entire laser operation range. We find that using high barriers in the active region design virtually eliminates carrier leakage from the upper laser level into the continuum, opening a non-radiative scattering path from the upper into the lower laser level parallel to standard electron-LO-phonon emission. This effect, together with the reduced leakage from the lower laser level into the continuum in the high-barrier device, significantly contributes to the $T_{max}$ decrease from 177 to 150 K. We further show how electron leakage from the lower laser level into the continuum is enhanced in a GaAs/Al0.15Ga0.85As design with thin barriers, significantly improving the laser performance ( $T_{max}=200$ K). Finally, we propose future design strategies for highly temperature-insensitive THz-QCLs. Our approach offers a straightforward method to analyze and troubleshoot thermally-activated carrier leakage dynamics in THz-QCLs.