纳米氧化锌的紫外自发辐射与受激辐射

纳米结构的氧化锌兼备了宽直接带隙(E_g=3.34eV)、强激子束缚能(60meV)的优良特性,同时又具备了纳米材料独特的微结构与光电功能,可望成为高效率紫外发光二极管以及低阈值紫外半导体激光器的良好材料。以我们的工作为基础,利用不同结构的ZnO作增益介质,概述了低维ZnO纳米材料中的自发辐射与受激辐射过程,观察到了放大的自发辐射(ASE)与受激振荡现象,并讨论了自发辐射、ASE及受激辐射的产生机制。

UV Spontaneous and Stimulated Emission of Nanostructure Zinc Oxide

ZnO,as a wide direct bandgap and large exciton binding energy semiconductor material,has stimulated great interests because of its promising application in ultraviolet optoelectronic devices,ultraviolet light-emitting diodes and ultraviolet laser diodes.Nanostructural ZnO is beneficial to increase the exciton recombination probability and to lower the pumping power threshold due to the high state density near the band edge.The research progress on ultraviolet spontaneous emission and stimulated emission of nanostructure ZnO is(reviewed) mainly based on some novel morphologies which were fabricated in our experiments by vapor phase transport(VPT) processes.For a ZnO nanostructure with good crystal quality,the photoluminescence pre-(sents) a strong ultraviolet band emission originated from the band-edge excitonic recombination.The perfect crystalline nanostructure with strong UV spontaneous emission is required for ZnO nanolaser.In our experiments,the ultraviolet amplified spontaneous emission(ASE) has been observed in ZnO nanofiber network(arrays) with 6-symmetry structure fabricated on a catalyst-patterned substrate.The UV light was gained in the network arrays and amplified gradually duo to the nature wave guide properties of the ZnO nanofiber branches.When the pumping power is high enough,ASE happened.The UV laser of ZnO have been obtained in three type of resonant cavities,random cavity,Fabry-Perot cavity and whispering gallery mode(WGM) cavity.In our research,ZnO microtubes have been employed as F-P cavity and a UV stimulated emission signal has been obtained and analyzed,which is similar to the phenomena in nanorods,nanobelts and nanocombs reported by other researchers.It is noted that a novel structure of ZnO,single crystal nanodisk has been fabricated in our experiments.It is expected to be as WGM cavity with low loss,low threshold and high quality factor.