Picosecond free-electron laser studies of Auger recombination in arsenic-rich lnAs_1-xSb_x strained layer superlattices at 300 K

Room temperature pump-probe transmission experiments have been performed on arsenic-rich InAs/InAsi_tSbv strained layer superlattices (SLS) using a picosecond farinfrared free electron laser. With excitation frequencies well above the fundamental bandgap, near 10 [un, 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 8x8 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 the Auger processes have been substantially suppressed in the superlattices. In the non-degenerate regime, where the Auger lifetime scales as t_aug^-1 = C₁Ne², a value of C₁ between 10 and 100 times smaller is obtained for the SLS structures. © IEE, 1997.