ENERGY RELAXATION IN GAAS ALGAAS 2-DIMENSIONAL STRUCTURES/

In this paper results on energy relaxation in low carrier concentratio n two-dimensional structures over the lattice temperatures, T(l), of 3 K to 150 K are presented. The power loss per carrier as a function of electron temperature, T(e), was experimentally determined using the m obility-field, mobility-temperature thermometric technique. In the aco ustic phonon regime, below about T(l) = 20 K, the power loss per carri er was found to be proportional to T(e) - T(l). Theoretical calculatio ns in this temperature regime predict a similar form but do not agree in magnitude. Above T(l) = 40 K the power loss per carrier was modelle d using an optic phonon scattering model, which includes the effects o f hot phonons, and which predicts a phonon lifetime of 11 ps +/- 1 ps. Between these two regimes, for the multi-quantum well, the experiment al power loss was found to be greater than the theoretical power loss. This discrepancy has been explained by invoking scattering due to opt ic phonon-plasmon coupling. Using the optic phonon-plasmon coupled mod e energy and the scattering time as fitting parameters values of 10 me V for the energy of the coupled mode and 400 ps for the scattering tim e were obtained.