Multidimensional Conduction-Band Engineering for Maximizing the Continuous-Wave (CW) Wallplug Efficiencies of Mid-Infrared Quantum Cascade Lasers

作者：Botez Dan^*; Shin Jae Cheol; Kirch Jeremy Daniel; Chang Chun Chieh; Mawst Luke James; Earles Thomas

来源：IEEE Journal of Selected Topics in Quantum Electronics, 2013, 19(4): 1200312.

DOI：10.1109/JSTQE.2012.2237387

• Lasers
• quantum-well lasers
• quantum wells (QWs)
• semiconductor lasers
• Stark effect

By tailoring the active-region quantum wells and barriers of 4.5-5.0-mu m-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 T-0 (253 K) and the slope-efficiency characteristic temperature T-1 (285 K), but, due to stronger quantum confinement, the global upper-laser-level lifetime tau(4g) decreases, resulting in basically the same room-temperature (RT) threshold-current density J(th) 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 tau(4g) value while further suppressing carrier leakage. As a result, experimental RT J(th) values from moderate-taper TA 4.8-mu m emitting QCLs are similar to 14% less than for conventional QCLs and T-1 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 tau(4g) value, due to Stark-effect reduction and strong asymmetry. Then, the RT J(th) 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-mu m-emitting QCLs.

• 出版日期2013-8