Subpicosecond photocarrier lifetimes in GaSb ∕ ErSb nanoparticle superlattices at 1.55 μ m

We demonstrate subpicosecond photocarrier lifetimes at 1.55 μ m in GaSb ∕ ErSb nanoparticle superlattices grown by molecular beam epitaxy. Pump-probe measurements were made with a 1.55 μ m 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 300 fs , the temporal limit of our experiment.