Epitaxial growth and picosecond carrier dynamics at 1.55µm of GaInAs/GaInNAs superlattices

We study GaInAs/GaInNAs superlattice structures grown on InP substrate as potential candidates for photoconductive terahertz devices or saturable absorbers working at 1.55 mum wavelength. The N-rich GaInNAs layers are flat, with no three-dimensional islanding, and act as trapping layers where carriers can recombine rapidly. Carrier lifetime in GaInAs/GaInNAs superlattice was measured for various growth parameters using time-resolved differential transmission experiments at 1.55 mum wavelength. The carrier lifetime is found to depend strongly on N content and can be reduced to 3.8 ps for samples with 14% of N. Moreover, by adding antimony in the GaInNAs layer, a reduction of the carrier lifetime down to 2.8 ps is obtained.