Electron Tunnelling In Cdte/Cdmnte Double Barrier Structures

Pump and probe nonlinear transmission experiments with femtosecond resolution are used to investigate electron tunnelling between the central CdMnTe well and the outer CdTe wells of a CdTe/CdMnTe double barrier structure. The time dependence of the reduction in oscillator strength resulting from bandfilling at the exciton resonance is used to measure population changes in the outer wells. A tunnelling time of 8 ps is measured when a carrier density of 1 x 10(13) cm(-2) is used. Monte Carlo simulations show that the timescale of tunnelling via LO phonon scattering is 10 ps. A pump induced increase in absorption at energies smaller than that of the exciton resonance is observed at early times and assigned to band-gap renormalisation.