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 τr for GaAs/AlAs SLs in the Wannier-Stark regime rapidly becomes shorter with decreasing well width Lw as τr∝Lw3-5. The observed strong Lw dependence of τr 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. [ABSTRACT FROM AUTHOR]