The transmission intensity of ZnCdSe quantum well/CdSe quantum dot combination structure vs delay time is investigated using femto-second pump-probe measurement.Femto-second pulse with pulse width 130fs and wavelength 537um utilized as pump and probe pulse in the pump-probe measurement is yielded using locking mode Ti:sappire femto-second laser(Spectra-physics laser Co.)and tuned by OPA-800.The transmission intensity of probe pulse vs the delay time between pump pulse and probe pulse is detected using multiplier phototube.The structure of experimental sample is ZnSe buffer/7um ZnCdSe(QW)/15um ZnSe barrier/10um CdSe(QD)/ZnSe.ZnSe

ZnCdSe and CdSe were grown on GaAs substrate by molecular beam epitaxy

and then the GaAs substrate is eroded by corrosive.The absorption peak of exciton in ZnCdSe quantum well of experimental sample is located at 528um.The transmission intensity characteristic with the delay time of probe pulse is shown in Fig.4.On the basis of the condition of experiment

we consider the rise-time of turn-on side is primarily determined by pump pulse lineshape and the down time of turn-off side is donated from exciton decay in ZnCdSe quantum well.Fitting the data of pump-probe experiment

the rising time of 367±60fs and the down-time of 1.3±0.2ps are obtained.Extracting the donation of pulse lineshape in down-time

the exciton decay time is 1ps calculated from turn-off side of the pump-probe transmission curve.