Subpicosecond photocarrier lifetimes in GaSb∕ErSb nanoparticle superlattices at 1.55μm

We demonstrate subpicosecond photocarrier lifetimes at 1.55μm in GaSb∕ErSb nanoparticle superlattices grown by molecular beam epitaxy. Pump–probe measurements were made with a 1.55μm mode-locked laser in transmission geometry to determine the photocarrier lifetime. The lifetime is found to be dependent on the size of the ErSb particles, amount of ErSb, and the distance between layers of particles. Through manipulation of these three parameters the photocarrier lifetime can be tuned down to less than 300fs, the temporal limit of our experiment.