Picosecond free-electron laser studies of Auger recombination in arsenic-rich InAs1-xSbx strained layer superlattices at 300 K

Room temperature pump-probe transmission experiments have been performed on arsenic-rich InAs/InAs/sub 1-x/Sb/sub x/ strained layer superlattices (SLS) using a picosecond far-infrared free electron laser. With excitation frequencies well above the fundamental bandgap, near 10 /spl mu/m, large excited carrier concentrations were obtained, allowing the density dependence of the recombination rate to be determined directly. The results have been interpreted in terms of an 8/spl times/8 (k.p) SLS energy band calculation, including the full dispersion for both k in-plane and k parallel to the growth direction. A comparison with identical measurements on epilayers of InSb, of comparable room temperature bandgap, shows that Auger processes have been substantially suppressed in the superlattices, In the non-degenerate regime, where the Auger lifetime scales as /spl tau//sub aug//sup -1/=C/sub 1/N/sub e//sup 2/ a value of C/sub 1/ between 10 and 100 times smaller is obtained for the SLS structures.