摻鈷氧化鋅奈米線之光學特性研究

Abstract

稀磁半導體是研究自旋電子學很好的材料。因稀磁半導體在摻入些微磁性材料後能展現出磁性與半導體特性。磁性代表著未配對電子的自旋，摻入半導體可以廣泛被應用在現今半導體科技。摻鈷氧化鋅具有寬能隙與高激子束縛能的優異性質，此獨特光學與電學性質使其成為未來光電元件新穎材料之一。 本文將介紹我如何利用一系列的技術來量測摻鈷氧化鋅奈米線的光學與磁光特性。其中包括利用共焦顯微系統對奈米線量測光激螢光光譜與拉曼光譜，得知其光學性質與晶格震動特性，摻鈷氧化鋅與氧化鋅具有同樣良好的晶格週期排列。並且在低溫下量測到清晰的光激螢光光譜，並對其做變溫量測，得知其光譜如何隨溫度變化。 在磁光量測方面，藉由架設的低溫高磁光學系統得到低溫下的磁光特性。磁光上顯現出光強度的衰弱與反磁位移現象，透過反磁位移可推估材料的激子半徑。

Diluted magnetic semiconductor is a very good material in making spintronics. Because they can be ferromagnetic with very low magnetic impurity concentrations in nonmagnetic semiconductors. Magnetic represents spin of unpair electron. When doping magnetic impurity in semiconductors, they can be applied in semiconductor technology widely. Cobalt doped zinc oxide has excellent properties of wide energy band gap and large exciton binding energy. The excellent optical and electronic properties make it a new material for optoelectronic devices in future. This thesis will introduce how to make use of a series of technology to investigate the optical properties of cobalt doped zinc oxide nanowires. The technology includes using photoluminescence(PL) and magneto-photoluminescence (MPL) spectroscopy of nanowires by using Confocal microscope and dilution function. From those information we can know the optical and lattice vibration properties. The doped zinc oxide shows good lattice period as the bulk zinc oxide. We also measure the temperature dependence of PL. The MPL were measured with a Low Temperature High Magnetic Optics System to get the MPL at low temperature. The PL intensity decreased with increasing magnetic intensity. We also observed diamagnetic shift at different magnetic field. These information were used to deduce the exciton radius of material.