Enhancement of energy relaxation rates at threshold well widths in quantum well structures
A theory is outlined leading to the prediction that the rate of LO-phonon-mediated inter-subband transitions in quantum well structures can vary significantly with varying well widths and attains a maximum at a threshold well width. Using typical parameters for GaAs/Ga0.7Al0.3As superlattices with a fixed barrier width d1=100 AA, the authors demonstrate that the transition rate between the lowest subbands varies by two orders of magnitude for well widths between 50 AA and 180 AA. Results for the corresponding variation of transition rate with well width for the case of an infinite potential well are also given and compared with those for the superlattice.