Abstract:In this paper， high quality InAs/InAsSb（Ga-free） type-II superlattice were grown on GaSb substrates by molecular beam epitaxy. The superlattice layers structure consists of 100 periods with 3.8 nm thick InAs layers and 1.4 nm InAs0.66Sb0.34 layers. A specific spike-like defect was found during experiment. The epitaxial layer was characterized and analyzed by high-resolution x-ray diffraction （HRXRD）， atomic force microscope （AFM） and Fourier transform infrared spectroscopy （FTIR）. The results show that the optimized sample is almost zero lattice mismatched， the FWHM of the zeroth order SL peak is 39.3 arcsec， the RMS surface roughness achieves around 1.72? over an area of 10 μm×10 μm. The FTIR absorption spectrum shows a 50% cutoff wavelength of 4.28 μm. And PL spectrum shows that the peak of InAs/InAs0.66Sb0.34 SL is at 4.58 μm. These initial results indicate that the grown InAs/InAsSb SL is stable and reproducible， and thus it is worthy of further investigation.