Estimate of the escape time of resonant tunneling electrons from a quantum well in double-barrier heterostructures

An estimate of the escape time of a resonant tunneling wave packet from a quantum well (QW) of double-barrier heterostructures (DBH) is presented by using the properties of the propagator of the system. For large times, regardless of the detailed structure and composition of the system, the probability density of finding electrons inside a QW decays exponentially with time. The escape time is proportional to the reciprocal of energy width Γn of the quasibound states at resonance. The full width at half maximum of the transmission peak is just equal to the energy width of the quasibound states. However, the dwell time of electrons depends on the electron incident direction on the DBH for an asymmetric system. In the symmetric potential the dwell time is equal to twice the escape time.