Long wavelength Infrared Detection, Bands Structure and effective mass in InAs/GaSb Nanostructure Superlattice

Abstract

We have investigated in the bands structure and the effective mass, respectively, along the growth axis and in the plane of InAs (d1=48.5Å)/GaSb(d2=21.5Å) type II superlattice (SL), performed in the envelop function formalism. We studied the semiconductor to semimetal transition and the evolutions of the optical band gap, Eg(Γ), as a function of d1, the valence band offset Λ and the temperature. In the range of 4.2–300 K, the corresponding cutoff wavelength ranging from 7.9 to 12.6 µm, which demonstrates that this sample can be used as a long wavelength infrared detector. The position of the Fermi level, EF = 512 meV, and the computed density of state indicates that this sample is a quasi-two-dimensional system and exhibits n type conductivity. Further, we calculated the transport scattering time and the velocity of electrons on the Fermi surface. These results were compared and discussed with the available data in the literature.