Material characterization of highly strained and partially strain compensated InxGa1-xAs/InyAl1-yAs quantum cascade light emitting diodes grown by MBE for emission in the near infrared (2-4 μm)

Material characterization of quantum cascade (QC) structures aimed at producing emission in the near to mid infrared wavelengths (2-4 μm) is presented. It is proposed that this material system (grown by MBE under stoichiometric growth conditions) can be developed to produce a quantum cascade laser (QCL) operating at communication wavelengths below 2 μm. The In_xGa_1-xAs/In_yAl_1-yAs on a semi-insulating InP substrate material system demonstrates compressive strain in the quantum well (QW) material up to 1.85% (x=0.8) and partially compensating tensile strain in the barrier material of up to 1.86% (y=0.25) both with respect to InP. Presented is a comparison of lattice matched and highly strained devices. Experimental data is provided to demonstrate the excellent optical and electrical characteristics of the material (photoluminescence signals at room temperature and I-V measurements down to 20 K). The results are encouraging for the development of this material system to produce the first QC emission approaching 2 μm using current InGaAs/InAlAs on InP MBE tooling technology.