Dynamics of directly created excitons in asymmetric double quantum wells

In this work, we have studied the dynamics of an electrically pumped exciton that is directly created by hole-assisted electron resonant tunneling in an asymmetric coupled quantum well system. We have numerically integrated in space and time the effective-mass Schrodinger equation for the electron-hole pair taking into account the two-particle nature of the tunneling process. We have also included the time evolution of the transition from spatially indirect to direct excitons. Considering a different exciton binding energy for each quantum well, we have obtained a different charge oscillation semiperiod for each binding energy case. In this way, the possibility is shown of having a new kind of terahertz electromagnetic radiation emerging from such a semiconductor quantum well system after electric pumping.