Mid-IR quantum cascade lasers: Device technology and non-equilibrium Green's function modeling of electro-optical characteristics (Phys. Status Solidi B 6/2014)
M. Bugajski, P. Gutowski, P. Karbownik, A. Kolek, G. Hałdaś, K. Pierściński, D. Pierścińska, J. Kubacka-Traczyk, I. Sankowska, A. Trajnerowicz, K. Kosiel, A. Szerling, J. Grzonka, K. Kurzydłowski, T. Slight and W. Meredith
Article first published online: 5 JUN 2014 | DOI: 10.1002/pssb.201470135
In the Invited Article on pp. 1144–1157, Bugajski et al. present the development of a technology for mid-infrared (∼9.5 μm) GaAs/AlGaAs and AlInAs/InGaAs/InP quantum cascade lasers (QCLs) and discuss basic characteristics of the lasers fabricated at the Institute of Electron Technology, Warsaw (Poland). The developed GaAs/AlGaAs lasers show record pulse powers of 6 W at 77 K and up to 50 mW at 300 K. Relying on the elaborated and cheap GaAs/AlGaAs technology, these lasers might still have a commercial potential. The authors also report the results of an investigation of strain compensated 4.7 μm AlInAs/InGaAs/InP QCLs. The cover picture shows the XRD ω-2Θ scan of a strain compensated Al0.638In0.362As/Ga0.331In0.669As/InP laser together with the simulated diffraction profile. The close resemblance of both indicates a precise reproduction of design parameters. The regularly spaced peaks are the signature of periodic structure. The TEM picture of the core of the active region (background image) shows that the strain compensated wafers can be grown on InP substrates free of misfit dislocations. Bugajski et al. also emphasize that reliable simulation methods capable of dealing with the complicated physical phenomena are necessary to predict the behavior of QCLs and to optimize their performance. The investigated lasers have been analyzed with the aid of the non-equilibrium Green's function (NEGF) method demonstrating the capability of this approach in predicting basic operational characteristics of the devices.