Growth of widegap II-VI quantum structures and their optical properties

摘要

The spontaneous formation of II-VI widegap semiconductors have been reviewed with emphasis placed upon the interface morphology and its effects on photoluminescence properties. It is found that a common cation quantum structure such as ZnS/ZnSe ultrathin QW's lead to an island interface which ensures localization at the interface thereby facilitating the growth of QDs at the heterointerface. Such quantum structures show a broad exciton luminescence band with developed low-energy tail, which is characteristic for a QD system with random distribution of lateral confinement. A lineshape analysis of the luminescence band suggests the formation of QDs with an average height of 3 ML and diameter of 2.9 nm. In contrast, the common anion interface such as ZnSe/CdSe ultrathin QWs leads to interface alloying due to large interdiffusivity of metal atoms. The linewidth of exciton luminescence in ZnSe/CdSe ultrathin QWs becomes narrower as the QW thickness decreases. Temperature-dependent, time-resolved, and micro PL properties of the QDs are investigated.