Dephasing of Bloch oscillating electrons in GaAs-based superlattices due to interface roughness scattering

We have investigated dephasing mechanisms of Bloch oscillating electrons in GaAs- based superlattices (SLs) by time-domain terahertz electro-optic sampling method. It was found that dephasing time tau(r) for GaAs/AlAs SLs in the Wannier-Stark regime rapidly becomes shorter with decreasing well width L-w as tau(r) proportional to L-w(3-5). The observed strong Lw dependence of tau(r) indicates that the dominant dephasing mechanism is interface roughness scattering, which was indeed confirmed by quantitative comparison between theory and experiment. It was also found that alloy disorder scattering is negligibly weak even in the case of GaAs/ Al0.3Ga0.7As SLs. (c) 2006 American Institute of Physics.