Multidimensional Conduction-Band Engineering for Maximizing the Continuous-Wave (CW) Wallplug Efficiencies of Mid-Infrared Quantum Cascade Lasers
Multidimensional Conduction-Band Engineering for Maximizing the Continuous-Wave (CW) Wallplug Efficiencies of Mid-Infrared Quantum Cascade Lasers
复制标题
用于最大化中红外量子级联激光器的连续波 (CW) 电插效率的多维导带工程
DOI：
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发表时间：
2013
影响因子：
4.9
通讯作者：
T. Earles
中科院分区：
文献类型：
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作者：
D. Botez;J. Shin;J. Kirch;Chun;L. Mawst;T. Earles
通过对发射波长为4.5-5.0 μ m的量子级联激光器（QCL）的有源区量子威尔斯阱和势垒进行剪裁，器件性能得到了显著改善。深阱QCL显著地抑制载流子泄漏，如阈值电流特征温度<sub>T0</sub>（253 K）和斜率效率特征温度<sub>T1</sub>（285 K）的高值所证明的，但是，由于更强的量子限制，全局上激光能级寿命τ<sub>4g</sub>减小，导致与常规QCL基本上相同的室温（RT）阈值电流密度<sub>Jth</sub>。<i></i><i></i><i></i>锥形有源区（TA）QCL，有源区势垒高度从注入到出射势垒的能量增加的器件，导致τ<sub>4g</sub>值的恢复，同时进一步抑制载流子泄漏。结果表明，中锥度TA 4.8 μm QCL的RT<i>J</i><sub>th</sub>值比常规QCL小约14%，<sub>T1</sub>值高达797 K。<i></i>由于斯塔克效应减小和强不对称性，阶梯锥形TA（STA）QCL设计提供了完全的载波泄漏抑制和τ<sub>4g</sub>值的增加。然后，与相同几何形状的常规QCL相比，RT<i>J</i><sub>th</sub>值降低至少25%。反过来，单面，RT脉冲和连续波的最大wallplug效率值为29%和27%的预测为4.6-4.8 μ m发射的QCL。
By tailoring the active-region quantum wells and barriers of 4.5-5.0-μm-emitting quantum cascade lasers (QCLs), the device performances dramatically improve. Deep-well QCLs significantly suppress carrier leakage, as evidenced by high values for the threshold-current characteristic temperature <i>T</i><sub>0</sub> (253 K) and the slope-efficiency characteristic temperature <i>T</i><sub>1</sub> (285 K), but, due to stronger quantum confinement, the global upper-laser-level lifetime τ<sub>4g</sub> decreases, resulting in basically the same room-temperature (RT) threshold-current density <i>J</i><sub>th</sub> as conventional QCLs. Tapered active-region (TA) QCLs, devices for which the active-region barrier heights increase in energy from the injection to the exit barriers, lead to recovery of the τ<sub>4g</sub> value while further suppressing carrier leakage. As a result, experimental RT <i>J</i><sub>th</sub> values from moderate-taper TA 4.8-μm emitting QCLs are ~14% less than for conventional QCLs and <i>T</i><sub>1</sub> reaches values as high as 797 K. A step-taper TA (STA) QCL design provides both complete carrier-leakage suppression and an increase in the τ<sub>4g</sub> value, due to Stark-effect reduction and strong asymmetry. Then, the RT <i>J</i><sub>th</sub> value decreases by at least 25% compared to conventional QCLs of same geometry. In turn, single-facet, RT pulsed and continuous-wave maximum wallplug-efficiency values of 29% and 27% are projected for 4.6-4.8-μm-emitting QCLs.