MWIR lasers employing GaInSb/InAs broken-gap superlattice active regions and superlattice cladding layers

Substantial progress has been made recently in the development of room temperature MWIR semiconductor lasers. InAs/GaInSb broken-gap superlattices (BGSLs) are attractive candidates for MWIR laser active regions because they possess sufficient degrees of freedom to tailor the valence band structure while keeping the strain low enough to prevent the formation of misfit dislocations. The valence band structure can be optimized to suppress Auger recombination as well as other non-radiative recombination, thereby reducing laser threshold and increasing the maximum operating temperature. Here we report improved MWIR MQW laser diodes with Ga_0.75In_0.25Sb/InAs BGSL quantum wells. The laser structures employ Ga_0.75In_0.25As _0.22Sb_0.78 barrier layers, and InAs/AlSb superlattice cladding layers. The Ga_0.75In_0.25As _0.22Sb_0.78 barriers yield a type-I MQW with the BGSL active region, confining both electrons and holes, as well as enhancing the optical confinement factor of the structure due to their relatively large refractive index. The thicknesses of the Ga_0.75 In_0.25Sb/InAs superlattice constituent layers have been varied to tune the emission wavelength of the devices, and a range of laser wavelengths has been demonstrated