Carrier capture and escape in multisubband quantum well lasers

Carrier capture and escape processes between quantum wells and barriers via carrier-polar optical phonon interactions are theoretically studied in multisubband quantum well structures. We find that carriers in each subband have their own minimum capture and escape times when the energy difference between the band edges of the subbands and the barrier is equal to the energy of a longitudinal optical phonon. Our results indicate that carrier escape time is more quantum well structure-dependent while carrier capture time is less structure-dependent. Explicit forms for calculating carrier capture and escape times are given which are crucial for designing the quantum well structures with optimal capture or escape efficiencies