Intersubband transitions in InGaAsN/AlGaAs quantum wells with a high confinement energy

摘要

When N is introduced in bulk InGaAs, the N level pushes the conduction band towards lower energies. In InGaAsN quantum wells however this repulsion leads to more complicated situations, in particular when confined levels are close to the N level. We calculate the energy of quantified levels in InGaAsN/AlGaAs quantum wells by using an analytical model based on the band anticrossing model and the repulsion by the nitrogen level. When the confinement becomes large enough to support subbands above the localized nitrogen level, subbands are split and have a dispersion strongly affected by the repulsion by the N level. In this case, intersubband transitions are deeply modified, with a splitting of the transitions and important spectral shifts of the lines, allowing to reach the 3-4 μm spectral range. Due to the admixing of nitrogen wavefunction in the electron wavefunction, the amplitude of the intersubband transitions decreases.