Electron–plasmon resonance in quantum wells with inverted subband population

The inverted order of subband occupation, n(2) > n(1), in quantum-well heterostructures designed for the intersubband lasers results in a novel effective relaxation mechanism for nonequilibrium electrons in the lower subband due to emission of the intersubband plasmons. In contrast to the cascade relaxation by phonons and intrasubband plasmons, this one-step scattering process efficiently fills the final stares for light-emitting transitions. Resonant screening, which is influenced by the process of intersubband plasmon excitation. leads to downshift and narrowing of the intersubband optical emission spectra. (C) 2000 Elsevier Science B.V. All rights reserved.