Impact of Momentum Relaxation Process on Miniband Transport in Semiconductor Superlattices

We have systematically investigated current density–bias voltage ( J – V b ) characteristics of GaAs/Al 0. 4 Ga 0. 6 As superlattices (SLs) with almost the same miniband width but with different quantum well thicknesses, L w . Despite similar miniband width, small changes in L w led to a marked variation in J – V b characteristics. By fitting the data with an extended Esaki–Tsu model that includes energy and momentum relaxation processes, we find that the momentum relaxation time depends strongly on L w as L w 3–5 , probably due to increased interface roughness scattering in narrower quantum wells. Our results highlight crucial roles of L w and interface quality in optimizing electron transport in SLs.