Evaluation of Material Systems for THz Quantum Cascade Laser Active Regions

• Published in: Physica status solidi. A, Applications and materials science Vol. 216; no. 1; pp. 1800504 - n/a
• Main Authors: Detz, Hermann, Andrews, Aaron M., Kainz, Martin A., Schönhuber, Sebastian, Zederbauer, Tobias, MacFarland, Donald, Krall, Michael, Deutsch, Christoph, Brandstetter, Martin, Klang, Pavel, Schrenk, Werner, Unterrainer, Karl, Strasser, Gottfried
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 09-01-2019
• Subjects: Active regions (lasers); III–V heterostructures; Infrared radiation; intersubband devices; Lattice matching; Market shares; molecular beam epitaxy; Operating temperature; Parameter identification; Quantum cascade lasers; Quantum wells; superlattices; Systems analysis; Thickness
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201800504

Quantum cascade lasers (QCLs) have been realized in several different material systems. In the mid‐infrared, active regions are predominantly based on In0.53Ga0.47As and InAs as quantum well material. Market‐ready devices routinely provide continuous‐wave operation at room temperature. For their THz counterparts, the situation is less clear. The most common material system for THz QCLs is the inherently lattice‐matched combination of GaAs with Al0.15Ga0.85As barriers. Yet, these devices still only reach a maximum operating temperature of 200 K with a lack of progress within the past years. Based on the identification of key parameters, this work reviews material systems for quantum cascade lasers with an emphasis on material and growth‐related aspects and the goal to identify promising candidates for future device generations. Similar active regions realized in different material systems allow to estimate the gain per unit thickness, as well as total growth times and relative thickness errors.
This work evaluates different material systems for THz quantum cascade laser active regions. Different combinations of quantum well and barrier materials are discussed with respect to growth and design‐related issues including practical aspects like a thickness error estimation. Experimental data from established materials furthermore allow to gauge the suitability of novel candidate materials.