Room-temperature mid-infrared quantum well lasers on multi-functional metamorphic buffers

The modern commercial optoelectronic infrastructure rests on a foundation of only a few, select semiconductor materials, capable of serving as viable substrates for devices. Any new active device, to have any hope of moving past the laboratory setting, must demonstrate compatibility with these substrate materials. Across much of the electromagnetic spectrum, this simple fact has guided the development of lasers, photodetectors, and other optoelectronic devices. In this work, we propose and demonstrate the concept of a multi-functional metamorphic buffer (MFMB) layer that not only allows for growth of highly lattice-mismatched active regions on InP substrates but also serves as a bottom cladding layer for optical confinement in a laser waveguide. Using the MFMB concept in conjunction with a strain-balanced multiple quantum well active region, we demonstrate laser diodes operating at room temperature in the technologically vital, and currently underserved, 2.5-3.0 μm wavelength range.