Characterization of thin AISb/AIAs barriers on InAs by mid-infrared intersubband absorption measurements

摘要

We present mid-infrared intersubband absorption measurements on InAs/AlSb coupled-quantum-wells systems with thin AlSb barriers.The AlSb barrier width in our samples is varied between 1 and 4 monolayers, with a strained AlAs boundary layer used for strain compensation.The optical absorption energy difference between the 1-4 and 2-3 transitions is used as a measure of the barrier coupling strength and modeled by a one-band Schroedinger solver.Our results let us conclude that the composite AISb/AIAs barrier behaves like an effective AlSb barrier with an effective thickness that does not include the last As layer.This observation must be taken into account when designing complex heterostructures relying on very thin AlSb, like in InAs/AlSb quantum cascade lasers.