Design and growth of multi-functional InAsP metamorphic buffers for mid-infrared quantum well lasers on InP
We present InAsP multi-functional metamorphic buffers (MFMBs) designed to enable mid-infrared Type-I InAs quantum well (QW) lasers on InP substrates. InAs x P 1-x /InP MFMBs with x = 0.5-0.7 provide a versatile platform for Type-I InAs QW laser diodes in the mid-infrared regime by bridging the lattice mismatch between InAs and InP while simultaneously functioning as the bottom cladding layer for laser structures. Cross-sectional transmission electron microscopy shows that InAs multi-QWs can be grown as thick as 15 nm without forming misfit dislocations on an InAs 0.7 P 0.3 buffer, enabling room-temperature photoluminescence at wavelengths >3 μm. We then compare the performance of lasers grown on InAsP MFMBs and show that the temperature dependence strongly depends on the energy band offset between the QW and the metamorphic InAsP waveguides. Future work could improve performance at longer wavelengths by investigating the use of electron blocking layers and adjusting the device design to minimize parasitic heating.