Suppression of Auger recombination in arsenic-rich InAs_1-xSb_x strained layer super-lattices

Room-temperature pump-probe transmission experiments have been performed on an arsenic-rich InAs_1-xSb_x strained layer superlattice (SLS) above the fundamental absorption edge near 10 µm using a ps far-infrared free-electron laser. Measurements show complete bleaching at the excitation frequency, with recovery times which are found to be strongly dependent on the pump photon energy. At high excited carrier densities, corresponding to high photon energy and interband adsorption coefficient, the recombination is dominated by Auger processes. A direct comparison with identical measurements on epilayers of InSb, of comparable room-temperature band gap shows that the Auger processes have been substantially suppressed in the superlattice case as a result of both quantum confinement and strain splittings in the SLS structure. In the nondegenerate regime, where the Auger lifetime scales as t^-1_aug=C₁N²_e, a value of C₁ some 100 times smaller is obtained for the SLS structure. The results have been interpreted in terms of an 8×8 k·p SLS energy band calculation, including the full dispersion for both k in plane and k parallel to the growth direction. This is the strongest example of room-temperature Auger suppression observed to date for these long-wavelength SLS alloy compositions and implies that these SLS materials may be attrractive for applications as room-temperature mid-IR diode lasers. © 1996 American Institute of Physics.