| Summary: | 碩士 === 國立臺灣大學 === 物理研究所 === 96 === ZnSeTe systems have been of great interest both for their applications in light emitting devices and for interesting optical properties related to isoeletronic bound excitons (IBE). The photoluminescence (PL) of these systems is usually attributed to excitons bound to isoelectronic centers (ICs). The centers that dominate the optical properties are so-called Te2 and Ten≧3 ICs, where two and three or more Te atoms are bound to the same Zn atom. More recently, the PL of these ZnSeTe systems always have been attributed to the coexistence of the isoelectronic bound excitons and the quantum-confined excitons.
In this thesis, ZnSe doped with Te and doped with ZnTe were grown by using metal organic chemical vapor deposition. The green band emissions obtained from these two different samples not only have different peak energies but are of different origins. For Te-doped sample, the PL emission band is laser power-independent and the lifetime of the PL emission is short, on the other hand, for the ZnTe-doped sample, the energy of the green emission band is laser power-dependent and the PL lifetime is much longer than the Te-doped sample. For the Te-doped sample, the green band emission is attributed to the emission from Te isoelectronic centers, and for the ZnTe-doped sample, the green band emission is attributed to the emission from ZnTe quantum dots. The results demonstrate that there are two different mechanisms for the green band emission in ZnSeTe system and our growth method provide a way of selecting one of the two mechanisms.
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