Growth of bulk 0.1 eV InAsSb on GaAs substrate with InAs-based intermediate buffer layer

We demonstrate the metamorphic growth of InAs_1-xSb_x (x = 0.08 – 0.68) layers on GaAs substrate with an optimized InAs-based intermediate buffer layer by molecular beam epitaxy. The broad range of group-V flux ratio is applied to investigate the effect between Sb incorporation and material quality. We find that high Sb compositions significantly roughen surface morphology, and that optimized growth temperature is crucial to prevent phase separation and surface segregation of Sb atoms. In addition, we achieve a high degree of strain relaxation (~94%) in the metamorphic InAsSb layers even with a 58% Sb composition. This result indicates that our InAs/GaAs virtual substrate is suitable for the growth of an almost fully relaxed InAsSb layer. Also, we investigate a threading dislocation density (TDD) trend with the broad range of Sb compositions, and a drastically increasing TDD trend (> 200 times) was observed. Finally, we report a narrow bandgap of 0.13 eV at 10 K of the InAs_0.42Sb_0.58 layer, which is promising for the detection of longwavelength infrared radiation. This InAsSb layer on GaAs substrate opens up possibility for mid-wavelength and long-wavelength infrared optoelectronics applications.