Growth of high material quality InAs/GaSb type-Ⅱ superlattice for long-wavelength infrared range by molecular beam epitaxy

By optimizing the Ⅴ/Ⅲ beam-equivalent pressure ratio,a high-quality InAs/GaSb type-Ⅱ superlattice material for the long-wavelength infrared(LWIR) range is achieved by molecular beam epitaxy(MBE).High-resolution x-ray diffraction(HRXRD),atomic force microscopy(AFM),and Fourier transform infrared(FTIR) spectrometer are used to characterize the material growth quality.The results show that the full width at half maximum(FWHM) of the superlattice zero-order diffraction peak,the mismatching of the superlattice zero-order diffraction peak between the substrate diffraction peaks,and the surface roughness get the best results when the beam-equivalent pressure(BEP) ratio reaches the optimal value,which are 28 arc sec,13 arc sec,and 1.63 ?,respectively.The intensity of the zero-order diffraction peak is strongest at the optimal value.The relative spectral response of the LWIR detector shows that it exhibits a 100% cut-off wavelength of 12.6μm at 77 K.High-quality epitaxial materials have laid a good foundation for preparing high-performance LWIR detector.