Ultrafast photoresponse at 1.55 μm in InGaAs with embedded semimetallic ErAs nanoparticles

We have grown epitaxial metal/semiconductor superlattice materials by molecular beam epitaxy that exhibit subpicosecond photocarrier lifetimes at 1.55 μm. The superlattice samples consist of layers of semimetallic ErAs nanoparticles embedded in a semiconducting In0.53Ga0.47As matrix. Time-resolved optical measurements are performed using a fiber-based transmission pump-probe technique with an erbium-doped-fiber mode-locked laser. Photocarrier lifetimes decrease with increasing ErAs deposition and decreasing spacing between the ErAs layers. Further reduction in the lifetime is achieved by selective beryllium doping of the superlattice; measured lifetimes ≤0.3 ps were achieved in optimized structures