Intersubband relaxation in modulation-doped multiple-quantum-well structures

Photoexcited carrier behavior in modulation-doped multiple narrow GaAs-${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum-well structures which vary in quantum-well width and doping concentration is investigated with Monte Carlo simulations. The model includes scattering of Γ-valley subband electrons by confined slab and interface-polar-optical phonons and between Γ-valley and L-valley electrons via optical-deformation-potential phonons. The model closely predicts time constants for electron relaxation found experimentally and shows that the effect of including the L-valley transitions in the Monte Carlo simulation is essential.