CARRIER ENERGY RELAXATION-TIME IN QUANTUM-WELL LASERS

Carrier energy relaxation via carrier-polar optical phonon interaction s with hot phonon effects in multisubband quantum-well structures is t heoretically studied by using both bulk longitudinal optical phonons a nd confined longitudinal optical phonons. We find that the width and t he depth of quantum wells only have moderate effects on carrier energy relaxation rates, Our results also indicate that the difference of en ergy relaxation rates between the quantum well and the bulk material i s not significant, We investigate the effects of longitudinal optical phonon lifetimes on the carrier energy relaxation rate, Neglect of the finite decay time of longitudinal optical phonons mill significantly underestimate the carrier energy relaxation time; this not only contra dicts the experimental results but also severely underestimates the no nlinear gain coefficient due to carrier heating, The implications of o ur theoretical results in designing high-speed quantum-well lasers are discussed.