Metamorphic growth of 0.1 eV InAsSb on InAs/GaAs virtual substrate for LWIR applications

Epitaxial growth of bulk InAs1-xSbx layer on GaAs substrate could open an opportunity for cost-competitive long-wavelength infrared sensors. Achieving this requires a high-quality metamorphic InAsSb layer with a uniform strain relief buffer design. We report a comprehensive analysis of metamorphic InAsSb layers grown on InAs/GaAs virtual substrate for 0.1 eV low bandgap material with an optimized growth condition and group-V flux control. We find that InAsSb surface roughens significantly with increasing Sb composition up to 58%. Lowering the growth temperature of InAsSb layers from 450 ℃ to 425 ℃ mitigated surface roughening while allowing greater than 90% strain relaxation. Moreover, we also present a dramatically increasing threading dislocation density by more than 200 times as a consequence of high Sb composition. Finally, we demonstrate a narrow energy bandgap of 0.13 eV at 10 K in the InAs0.42Sb0.58 layer, which is close to 0.1 eV at room temperature. This InAsSb film grown on InAs/GaAs template paves the way for long-wavelength infrared optoelectronics applications.