Saturation of intersubband transitions in p -doped Ga As ∕ Al Ga As quantum wells

Optical saturation experiments have been performed on hh1-hh2 intersubband transitions in two samples of p -doped Ga As ∕ Al Ga As quantum wells. The transitions had energies of 183 and 160 meV and the measured population relaxation times were 2 ± 1.5 and 0.3 ± 0.1 ps , respectively. Modeling of the quantum wells with a 6 × 6 k ⋅ p method shows that intersubband scattering by LO phonons can account for these relaxation times. The valence bandstructure is typically more complicated than the conduction bandstructure in a quantum well but these measurements show that LO phonons are the dominant intersubband scattering mechanism in both cases.