Interface layer control and optimization of InAs/GaSb type-II superlattices grown by molecular beam epitaxy

We reported in the paper the optimization and control of InSb interface properties during molecular beam epitaxy growth of InAs/GaSb superlattice structures. Samples with identical structure but different growth approaches, conventional molecular beam epitaxy (MBE) and migration-enhanced epitaxy (MEE), for interface layers were first prepared and their structural, morphological and optical properties were compared. The MEE samples had significant higher As composition in InSb interface layers and higher luminescence efficiency. Samples with different InSb interface layer thickness were then prepared. By changing the interface layer thickness, one can effectively tune the lattice mismatch and photoluminescence peak wavelength. Though X-ray diffraction satellite peak linewidth and surface roughness of the grown samples changed little, the one with smallest negative lattice mismatch showed the highest luminescence efficiency. Finally a P-I-N superlattice detector structure was grown with controlled interfaces. The full width at half maximum (FWHM) of the 1st-order X-ray diffraction satellite peak of the absorption layers was only 19″. The detector structure showed a cutoff wavelength of 6.3 µm at 77 K. The dark current density at −50 mV bias was 4.3×10−5 A/cm2 and the peak detectivity was 4.2×1011 cm Hz1/2/W.