Evidence forΓ−XTransport in Type-I GaAs/AlAs Semiconductor Superlattices

Abstract

We report the first evidence that the I -X transfer mechanism plays a significant role in carrier transport in type-I semiconductor superlattices under an electric field. An anomalously delayed photocurrent was observed in a GaAs/AJAs type-I superlattice under ultrashort optical pulse excitation.This phenomenon can be explained by a switch of the electron transport path from I -I to I -X-I -X, caused by an electric-field induced change of the subband alignment of the second 1 state (I'2) in the well and the Xl state in the adjacent barrier.

Γ to X electron transfer times in type-II GaAs/AlAs superlattices due to emission of confined and interface phonons

“…One possible way of observing these resonances would be by applying an electric field perpendicular to the layers of the superlattice. This could explain the resonant -X transport in type-I GaAs-AlAs observed by Hosoda et al [16].…”

Influence of Γ–X mixing on carrier transport and photoluminescence in GaAs/AlAs type-I superlattices

“…Conversely, in type-I SLs, few electrons are believed to be in the X states due to the direct band configuration. However, very recently, an anomalously delayed photocurrent (Pc) was found in a type-I SL originating from the effects of the X states in the applied electric field by time-of-flight experiments [4]. In this paper, we study the effects of the X states on the dynamics of electron transport and photoluminescence (PL) in three kinds of type-I SLs.…”

Avalanche breakdown mechanism originating from Γ–X–Γ transfer in GaAs/AlAs superlattices

“…7 Since the trapping is faster than the escape, this ⌫ 1 ͑0͒-X 1 (Ϫ1/2͒-⌫ 1 (Ϫ1͒ transport shows a trapping ability, and slows down and degrades the carrier sweep-out. 4,8 When the barrier width is thicker, the ⌫ 1 -X 1 scattering time is faster than the ⌫ 1 -⌫ 2 resonant tunneling time. For example, our estimation of the ⌫ 1 -⌫ 2 resonant tunneling time is ϳ15 ps for sample C, and the time is slower than the ⌫ 1 -X 1 scattering time.…”