Crucial Aspects of the Device Processing of Quantum Cascade Lasers

The paper presents the studies on technology of ~100 μm-emitting (~3 THz) Al0.15Ga0.85As/GaAs QCLs, the optimized scheme of fabrication of such lasers was elaborated. It was a result of the extensive work on decreasing waveguide losses while ensuring the proper performance of the electrical contacts and effective heat removal. The fabrication comprises Au-based claddings and Au-Au-mounting process. The yielded lasers operate up to the maximum temperature Tmax = 140 K, with threshold current density Jth ~ 1 kA/cm2 at 77 K.