Strain-compensated GaInAs/AlInAs/InP quantum cascade laser materials

Strain-compensated (SC) GaInAs/AlInAs/InP multiple-quantum-well structures and quantum cascade lasers (QCLs) with strain levels of 1% and as high as 1.5% were grown by organometallic vapor phase epitaxy (OMVPE). The structures were characterized by high-resolution X-ray (HRXRD) diffraction and atomic force microscopy (AFM), and narrow-ridge QCL devices were fabricated. HRXRD and AFM results indicate very high quality materials with narrow satellite peaks, well-defined interference fringes, and a step-flow growth mode for 1% SC materials. A marginal broadening of satellite peaks is measured for 1.5% SC structures, but step-flow growth is maintained. QCLs based on a conventional four-quantum-well double-phonon resonant active region design with nominal 1% SC were grown with doping concentration varied from 1 to 4×1017 cm−3 in the active region. The performance of ridge lasers under pulsed conditions is comparable to state-of-the-art results for 4.8 μm devices. QCLs with a novel injectorless four-quantum well QCL design and 1.5% SC operated in pulsed mode at room temperature at 5.5 μm.