InAs-based InAs/GaAsSb type-II superlattices: Growth and characterization

In this paper, the authors reported on the growth of InAs/GaAsSb type-II superlattice materials on InAs substrates. The lattice mismatch between the T2SL materials and the InAs substrates was tuned by varying As beam equivalent pressure and thus the As composition in GaAsSb. The lattice mismatch was as small as −6.5×10−5 when As BEP was 8.0×10−6 Torr. T2SL materials with different InAs thicknesses were then grown and characterized by high resolution X-ray diffraction. The results showed that the lattice mismatch of the superlattices to the InAs substrates was insensitive to the InAs layer thickness in each period. Finally, a P-I-N InAs/GaAsSb T2SL photodiode was grown on an InAs substrate. The photodiode with 14 ML InAs and 7 ML GaAsSb in each period showed a 100% cutoff wavelength of 6.5 μm at 77 K. The dark current density at −30 mV bias was 6.05×10−5 A/cm2 and the resistance-area product at zero bias (R0A) was 435 Ω cm2.The black body detectivity and peak detectivity were 1.34×1011 cm Hz1/2/W and 3.72×1011 cm Hz1/2/W, respectively. The quantum efficiency at 5.0 μm was measured to be 28%.