Optical Characterization Of The ZnTe- And ZnSe- Base Coupled Structures

II-VI semiconductors, possessing broad band gap, large exciton binding energy at room temperature, is rationally expected to be promising candidates for nonlinear devices and short wavelength laser. The fabracation of various low dimentional structures and the investigation of the dynamics of carriers is very important for both theoretics researches and applications. This thesis is focused on the dynamics of tunneling and recombination of ZnTe-ZnSe-base coupled low dimentional structures. The following is the major results: 1. The dynamics of carriers in ZnTe/SeZnTe quantum wells is investigated by pump-probe technique. ZnSeTe layer show strong confinemental effects on carriers. Based on these results, the dynamics process of (CdZnTe, ZnSeTe)/ZnTe coupled quantum wells structure was investigated. The introduction of ZnSeTe layer greatly reduced decay time of the carriers in CdZnTe layers, which proves the efficient carriers tunneling is facilitated in this coupled structures. A tunneling time as short as 5.5 ps is obtained. 2. We studied the exciton tunnelling process in athe ZnCdSe/CdSe coupled quantum well/quantum dots (QW/QDs) structure using photoluminescence (PL) spectra and near resonant pump-probe technique. Fast exciton tunnelling (~2ps) from QW to QDs is observed. The influence of barrier thickness on the exciton decay time has also been investigated. These results provide an alternative idea for investigating novel ultrafast exciton tunnelling device based on QW/QDs coupling structure. 3. We investigated PL of CdSe QDs in this type of QW/QDs structure. A strong PL of CdSe QDs was observed in this structure at Rtroom temperature. The temperature dependent PL spectra suggest that the PL properties of CdSe QDs were affected by the auxiliary ZnCdSe QW via excitons tunnelling from QW to QDs. We believe that the QW/QDs coupling structure is also promising for a new type photoelectric device.