The fabrication of quantum cascade lasers emitting at 9 µm is reported. The devices operated in pulsed mode at up to 260 K. The peak powers recorded at 77 K were over 1 W and the slope efficiency η ≈ 0.5-0.6 W/A per uncoated facet. This has been achieved by the use of GaAs/Al0.45Ga0.55As heterostructure, with the "anticrossed-diagonal" design. Double plasmon planar confinement with Al-free waveguide has been used to minimize absorption losses. The double trench lasers were fabricated using standard processing technology, i.e., wet etching and Si3N4 for electrical insulation. The quantum cascade laser structures have been grown by molecular beam epitaxy, with Riber Compact 21 T reactor. The stringent requirements -placed particularly on the epitaxial technology -and the influence of technological conditions on the device structure properties were presented and discussed in depth.
The fabrication technology of AlGaAs/GaAs based quantum cascade lasers is reported. The devices operated in pulsed mode at up to 260 K. The peak powers recorded at 77 K were over 1 W for the GaAs/Al0.45Ga0.55As laser without anti-reflection/high-reflection coatings.
In this paper we investigate chip bonding technology of GaAs/AlGaAs quantum cascade lasers (QCLs). Its results have strong influence on final performance of devices and are essential for achieving room temperature operation. Various solders were investigated and compared in terms of their thermal resistance and induced stress. The spatially resolved photoluminescence technique has been applied for a device thermal analysis. The soldering quality was also investigated by means of a scanning acoustic microscopy. The particular attention has been paid to Au-Au die bonding, which seems to be a promising alternative to the choice between hard and soft solder bonding of GaAs/AlGaAs QCLs operating from cryogenic temperatures up to room temperatures. A good quality direct Au-Au bonding was achieved for bonding parameters comparable with the ones typical for AuSn eutectic bonding process. High performance room temperature operation of GaAs/AlGaAs QCLs has been achieved with the state-of-the-art parameters.
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